In this paper twelve barley (Hordeum vulgare L.) genotypes were screened for salt tolerance durin... more In this paper twelve barley (Hordeum vulgare L.) genotypes were screened for salt tolerance during seed germination in the Crop Production Department, Faculty of Agriculture, Jordan University of Science and Technology, Irbid, Jordan. To evaluate salt tolerance during germination, 30 seeds of each genotype were placed on towel paper in 9 cm Petri dishes containing 20 mL distilled water or 1:1 M ratio NaCl and CaCl 2 solutions at various concentrations [(control), 100, 200, 300 mM] to give electrical conductivities (EC) of 0.05 (control), 10.6, 19.0 and 27.0 dS mG , respectively. Our data indicated that salinity level × genotype interaction 1 effects (p<0.05) were observed for seed germination percentage, seed viability and ion uptake. Seed germination decreased significantly by increasing salinity level. Germination was significantly diminished at the highest level of salt (300 mM) with significant variation among genotypes and the genotype ACSAD1430 had higher germination percentage than other tested genotypes. Results presented in this article also indicated that the increasing seed pretreatment duration by hyper-saline medium significantly reduced seed recovery when transferred to distilled water. Also our data indicated that the increasing seed pretreatment duration by hyper-saline medium significantly reduced seed recovery when transferred to distilled water. The N a concentration of seeds after imbibitions significantly increased with increasing salinity with a considerable variation among genotypes. K concentration also affected by salinity. Generally, increasing salt stress significantly decreased K concentration in barley seeds after one day of imbibitions. The present study indicated that salt stress must be removed from soil surface for successful seedling establishment.
We explored the relationship between hyper-spectral surface reflectance data derived from a handh... more We explored the relationship between hyper-spectral surface reflectance data derived from a handheld spectroradiometer and foliar chlorophyll content of pecans. Canopy scale hyperspectral remotely sensed data and foliar chlorophyll content determined with SPAD meter were collected simultaneously from two mature pecan orchards for two years. One pecan orchard was located in a clay loam soil and the other in a sandy loam soil. Hyperspectral surface reflectance data were correlated to chlorophyll content. The relationship between remotely-sensed data and SPAD was high (R 2 ≥ 0.8) to moderate (0.8 ≥ R 2 ≥ 0.6) in the first year, and generally weak (R 2 < 0.6) in the second year in both orchards. In the first year, canopy reflectance within the wavelength range 500 to 720 nm of the pecan orchard in the clay loam soil had a moderate to strong relationship (R 2 > 0.6) with SPAD compared to other wavelengths across the canopy reflectance spectrum (i.e. 350-500 and 730-2450 nm). Contour map revealed that the band ratios with a numerator consisting of any wavelength within the 600 to 680 nm range and a denominator of any wavelength along the visible and near infrared spectrum (350-1600 nm) had high correlations with SPAD in both orchards in the first year. The vegetation indices NDVI, mNDVI, SIPI, SIPI2 and PSRI also had high regression values (0.91 ≥ R 2 ≥ 0.87) with SPAD in clay loam site and moderate regression (0.73 ≥ R 2 ≥ 0.67) in sandy loam site in the first year. Overall, canopy surface reflec-tance data holds promise for studying foliar chlorophyll content in pecan orchards.
Rising awareness over the environmental impacts of some commonly used materials such as peat-base... more Rising awareness over the environmental impacts of some commonly used materials such as peat-based growing media has urged researchers to assess more environmentally friendly products. The aim of this study was to evaluate the effect of two soilless substrates [tuff (granulated volcanic material, 0-4 mm) and 2:1 peatmoss+perlite (2:1 P+P)] on growth and flower quality of two cultivars of Asiatic lily (Lilium ×elegans Thunb.) cvs 'Fangio' and 'Ercolano'. Two bulbs of both cultivars were grown in 12 L pots filled with tuff or 2:1 P+P substrate. Substrate properties, plant growth, plant physiology, number of days to flowering and flower quality were assessed. Data revealed that tuff substrate had lower water holding capacity (WHC) and electrical conductivity (EC) than 2:1 P+P media. Conversely, tuff had higher bulk density and pH than 2:1 P+P substrate. The 2:1 P+P substrate had higher shoot length and leaf area than tuff in both cultivars. However, tuff substrate increased flowers number per plant in 'Fangio' by 8% and 'Ercolano' by 18% compared to 2:1 P+P. Volcanic tuff can last for many years (compared to peatmoss) and therefore, frequent replacement of the substrate is not a prerequisite. Additionally, 2:1 P+P had no superior impact on lily (compared to tuff) except for shoot length and leaf area. For these reasons, we recommended that tuff be used as an alternative to peatmoss in soilless production of lily in order to enhance flower quality and mitigating agricultural negative impact on the environment.
The present article reviews the scientific literature on soilless culture and provided a critical... more The present article reviews the scientific literature on soilless culture and provided a critical examination of the micro-environmental factors that can affect horticultural crop growth and productivity, including , soilless substrate, fertigation solution, salin-ity, nutrient content and pH and plant-microorganism interaction. In addition, the role of precision agriculture such as, remote sensing in soilless system performance is reviewed. Soilless substrate source (organic and inorganic) and particle size can affect mineral content, oxygen level, salinity and pH of the nutrient solution, as well as the microorganism diversity and abundance. Organic substrates had more microorganism communities compared to inorganic substrates. Microorganism inoculation (e.g. fungi) of inorganic substrate to increase microorganism abundance is completely ineffective. However, environ-mentalists do not recommend the use of peat-based organic substrates because it leads to loss of soil organic carbon and destruction of wetlands. Agricultural demands for sustainable, environmental friendly soilless system highlights the benefits of using inorganic substrate (rock-wool and volcanic tuff) and the re-use of nutrient solution (closed systems) to avoid water and nutrient losses. Interestingly, biological control of root rot pathogens in closed soil-less systems is more effective than open or conventional due to the lower variety of microorganism community in closed structures. However, substrate salinity is the main challenge in closed soilless systems. The use of salt-tolerance cultivars, large volume tanks to minimize electrical conductivity and pH changes and sub irrigation with low concentration nutrient solution are the main approaches to reduce salinity in growing substrates. Several precision agricultural techniques based on advanced sensing technologies such as smart irrigation systems and surface reflectance data from crop canopy may increase soilless system efficiency. These techniques are based on crop water demands, not fixed watering schedules and have the potential to optimize water and nutrient use efficiency.
Monitoring and assessment of agricultural land degradation is of vital importance for better land... more Monitoring and assessment of agricultural land degradation is of vital importance for better land and water management planning and reclamation. It requires setting baseline information and basic analysis at specific time and space. About 33 geo-referenced soil sampling spots were selected in two agricultural production locations in the Kingdom of Bahrain to assess the status and preliminary causes of land degradation. Soil samples were taken from 13 sites in Diraz location while 19 samples were taken from Budayyi location. The samples were taken to 90 cm depth at 30 cm intervals. Standard procedures were followed to determine soil physiochemical properties. In addition, field observations on farm condition, distance from the sea, method of irrigation and irrigation water source were taken. Some of the soil samples were deliberately taken from outside the irrigated basins among trees compared with samples taken from inside the actively growing area for comparison. The results indicated that the salinity level was significantly (P < 0.001) higher at the 0-30 cm soil depth compared with 30-60 cm or 60-90 cm depths in both locations. The distance from the sea did not show clear correlation with surface soil salinity in Budayyi area compared with Diraz. Both locations showed significantly higher salinity levels on samples taken outside the actively growing areas compared with those taken from within. The effect is more prominent at the 0-30 cm depth. The observed variability on salinity levels may be attributed to farm management practices and deteriorating quality of ground water. Thus, agricultural land degradation in Bahrain cannot be attributed to ground water deterioration alone. The use of tertiary treated sewage water (TSE) may ease the pressure on ground water, but the pH of the TSE should be carefully monitored and managed with proper studies on leaching requirements to avoid further salinity complications.
Abstarct Agricultural productivity and sustainability are the most challenges facing many arid an... more Abstarct Agricultural productivity and sustainability are the most challenges facing many arid and semiarid regions as these regions are characterized by severe shortage of good quality water for irrigation and saline water is very common. The trend in recent years has been towards conversion of conventional agriculture to soilless agriculture (mainly closed system) which is considered to be a more efficient use of water system. The aim of this research was to examine the response of three sweet pepper cultivars (Capsicum annum L., cvs. Flaviano, Sonar, Alzado) to different levels of salinity under soilless recirculating conditions. Plants were grown in concrete troughs filled with zeolite in a closed soilless system using nutrient solutions with NaCl corresponding to electrical conductivity levels [1.8 (control), 4 and 8 dS m-1 ]. The sweet pepper proved to be sensitive to the increasing salinity of nutrient solution as the total and marketable fruit yield, fruit number and single fruit weight decreased in all tested cultivars with increasing salinity level. However, genotypic variation for fruit yield and yield components have been noticed. The cultivar Flaviano produced higher fruit yield than the other two cultivars regardless of salinity level. In all cultivars, leaves had higher Na + and Cl-concentrations than fruits, which increased with increasing salinity; while K + in leaves was higher than fruits and decreased by salinity. Leaves and fruits of the cultivar Flaviano accumulated higher K + and lower Na + and Cl-than the other two cultivars. This suggests that Flaviano was the most tolerant cultivar to salinity among tested cultivars as it showed less reduction in fruit yield and its components due to salinity.
Remote-sensing techniques can detect and up-scale leaf-level physiological responses
to large are... more Remote-sensing techniques can detect and up-scale leaf-level physiological responses to large areas, and provide significant and reliable information on water use and irrigation management. The objectives of this study were to screen leaf-level physiological changes that occur during the cyclic irrigation of pecan orchards to determine which responses best represent changes in moisture status of plants and link plant physiological changes to remotely sensed surface reflectance data derived from the Landsat Thematic Mapper and Enhanced Thematic Mapper Plus (ETM+). The study was conducted simultaneously on two southern New Mexico mature pecan orchards. For both orchards, plant physiological responses and remotely sensed surface reflectance data were collected from trees that were either well watered or in water deficit. Remotely sensed variables included reflectance in band 1, the ratio between shortwave infrared (SWIR) bands (B5:B7), the normalized difference vegetation index, and SWIR moisture indices. Midday stem water potential (Ψsmd) was the best performing leaf-level physiological response variable for detecting moisture status in pecans. The B5:B7 ratio positively and significantly correlated with Ψsmd in five of six irrigation cycles while multiple linear regression weighted with six remotely sensed surface reflectance variables revealed a significant relationship with moisture status in all cycles in both orchards (R2 > 0.73). Because changes in the B5:B7 band ratio and multiple regression of spectral variables correlate with the moisture status of pecan orchards, we conclude that remotely sensed data hold promise for detecting the moisture status of pecans.
The objective of this study was to assess the effect of foliar application of gibberellic acid (G... more The objective of this study was to assess the effect of foliar application of gibberellic acid (GA3) on strawberry (Fragaria × ananassa Duch cvs. 'BG4.370' and ' Splendor') morphology, physiology [photosynthesis rate (Pn), stomatal conductance (gs) and transpiration (E)], yield, and fruit total soluble solids. Five different GA3 levels were used; control (0.0), 50, 100, 200 and 1000 mg/l. Gibberellic acid treatments were sprayed twice, the first at the 5 th leaf stage and the second 10 d after the first application. Plants under control were sprayed with tap water only. Foliar application of GA3 decreased the time needed to flowering and increased Pn, gs, E, pedicel length, soluble solids (°Brix) in both cultivars and across GA3 levels, compared to untreated control. Conversely, GA3-treated plants had lower chlorophyll content index (SPAD), marketable yield and individual fruit weight. Overall, foliar application of GA3 increased shoot morphology and physiology (Pn, gs and E) but did not improve strawberry fruit quality and yield. In fact, this study revealed that for these cultivars and those GA3 concentrations, the incidence of malformed fruits and unmarketable yield can be significant.
ADDITIONAL INDEX WORDS. bulb, cut flower, Lilium ·elegans SUMMARY. Soilless substrates enhance gr... more ADDITIONAL INDEX WORDS. bulb, cut flower, Lilium ·elegans SUMMARY. Soilless substrates enhance growing environment, nutrient content, and water quality in the growing medium. The objective of this study was to assess the influence of substrate particle size on growth and flower quality (flower number and length per plant) of two asiatic hybrid lily (Lilium ·elegans) cultivars Fangio and Ercolano. Plants were grown in 12-L pot under greenhouse conditions. Five grades of particle-size substrate, consisting of granulated volcanic material (tuff) were used as treatments. These sizes were 0 to 2, 0 to 4, 0 to 8, 2 to 4, and 4 to 8 mm. Fertigation was applied daily. Plant morphology, physiology, and flower quality were determined during flowering stage. Treatments of 2 to 4-and 4 to 8-mm tuff had lower water holding capacity (WHC), bulk density, electrical conductivity (EC), and pH compared with 0 to 2-and 0 to 4-mm tuff. In addition, plant height, leaf area, and flower quality of 'Fangio' were higher compared with 'Ercolano'. Chlorophyll content and fluorescence were similar among all treatments. Leaf fresh weight, leaf area, shoot dry weight, root dry weight, and flower quality were higher in sizes of 0 to 4-, 2 to 4-, and 4 to 8-mm than 0 to 2-mm tuff, especially those from 'Fangio'. The 0 to 4-mm substrate had an optimal and consistent flower quality results in both cultivars when compared with other tuff sizes. Overall, the results presented here suggest that using 0 to 4-mm tuff substrate holds promise for improving growth and flower quality of asiatic hybrid lily grown under soilless culture.
Soil amendment using organic fertilizer has been used widely to dispose animal waste, reduce envi... more Soil amendment using organic fertilizer has been used widely to dispose animal waste, reduce environmental pollution and improve soil and fruit quality. The objective of this two-year study was to assess the influence of organic and conventional systems on growth, marketable yield, head quality (chlorogenic acid and cynarin concentration) and soil chemical properties of globe artichoke (Cynara cardunculus). Cultivars used were De-serto, Lulu, Romolo, 11-018, 12-179, Green Globe Improved and Imperial Star. Fertilizers were applied to both conventional and organic soil through drip irrigation system. In both years, significant differences were found across cultivars and soil type. Although cultivar response to soil system treatments were inconsistent across the two growing seasons, the cv. Imperial Star had the lowest marketable yield and head quality. Artichoke grown in the conventional field had higher plant height and width, chlorophyll content index (SPAD), leaf area index (LAI), stomatal conductance (gs), photosynthesis (Pn) and marketable yield. Conversely, artichoke head quality from the organic field was higher than conventional. Organic system increased chlorogenic acid by 31% and cy-narin by 12% compared to the conventional system. In fact, after two years of soil amendment, organic fertilizer improved soil respiration-CO 2 (soil health indicator) by 20-fold compared to chemical fertilizer (conventional field). Overall, based on this two-year study we suggest organic farming as the best system to improve soil and head quality of globe artichoke, but it may not be the best option for farmers when yield is the primary target short-term.
The impact of nitrogen application on the growth of olive trees has been well studied. However, l... more The impact of nitrogen application on the growth of olive trees has been well studied. However, little is known about the role of levels and forms of N on the development of roots and physiological traits during establishment of young trees. The objective of this 2-year study was to evaluate the influence of N source and level on shoot morphology (tree height, stem diameter, and branch number) and physiology [leaf area and fresh weight, photosynthesis (P n), transpiration (E), and stomatal conductance (g s)], root components (length, diameter, surface area, and fork number) and N content of young olive (Olea europaea cv. Arbequina) cuttings. Three-month-old olive cuttings were planted in 15-L pots filled with a growing substrate composed of peatmoss + bark + sand (2:1:1/by volume) and placed in a screen house. Two N levels, 2.8 and 5.6 g/tree, and control (0 N) and four N sources, calcium nitrate (CN, 12%N, 17%Ca +2), ammonium nitrate (AN, 35%N), urea (46%N), and the slow-release Osmocote (OSC, 18%N, 6%P, 12%K) were evaluated. Effects of low-(2.8 g/tree) and high N (5.6 g/tree) levels on shoot components (plant height, diameter, branch number, leaf area, and fresh weight) and gas exchange (P n , g s and E) were similar implying that the low rate of N was adequate for the establishment of young olive cuttings. Nitrogen sources, particularly AN and CN had significant effects on shoot and root morphology, physiology, and leaf and root N concentration. In fact, AN and CN were the best fertilizer sources for olive transplants in term of root and shoot growth. Overall, 2.8 g/tree N level and AN or CN sources were the best treatments for newly established olive 'Arbequina' trees. Root components treated with high N rate (5.6 g/tree N) using the slow-release fertilizer (OSC) was similar to those treated with the low AN rate (2.8 g/tree N). Therefore, for nursery containerized olive trees of 'Arbequina' or other cultivars with comparable growth rates, we recommend to apply the CN or AN source at 2.8 g/tree N or the controlled-released fertilizer OSC at 5.6 g/tree N.
In Texas there is a need to screen and identify high quality and more productive globe artichoke ... more In Texas there is a need to screen and identify high quality and more productive globe artichoke cultivars. The objective of this study was to determine morphological, physiological, head quality and yield responses of early and mid-season globe artichoke cultivars. The standard 'Imperial Star' (IS, early season, Condor Seed Co.) and the new '12-179' (mid-season, Big Heart Seed Co.) cultivars were transplanted November 2014 at Uvalde in the Wintergarden region and Brownsville in the Lower Rio Grande Valley of Texas. Plant measurements were conducted during the vegetative stage (90-130 days after planting, DAP) and reproductive stage (150-190 DAP). At the early stage, plant height of '12-179' was significantly higher (P=0.04 to 0.08) than IS in both sites. The cultivar '12-179' also had higher photosynthetic rates than IS at the Uvalde location. No significant differences were found between cultivars in other gas exchange measurements, plant width, chlorophyll content index (SPAD), and leaf area index (LAI). However, LAI of '12-179' was significantly higher than IS in Brownsville at the reproductive stage. Head and heart weights were similar for both cultivars, but head length was significantly longer (P=0.006) for '12-179' as compared to IS. Four harvests were performed during a 42-day period, with the major peak of production (48% of the total) on April 21, 2015. The main difference between cultivars was in total marketable yield, with '12-179' producing 9.8 t ha-1 higher marketable yields (23.9 t ha-1) than IS (14.1 t ha-1). Conversely, unmarketable yield (deformed, opened) of 12-179 was 3.5 t ha-1 compared with 5.7 t ha-1 for IS. Overall, the new cultivar '12-179' demonstrated superior performance to 'Imperial Star', and therefore is recommended for adoption into commercial production practices in southwest Texas.
ADDITIONAL INDEX WORDS. Carya illinoinensis, drought, irrigated agriculture, water relations ABST... more ADDITIONAL INDEX WORDS. Carya illinoinensis, drought, irrigated agriculture, water relations ABSTRACT. Demand for New Mexico's limited water resources coupled with periodic drought has increased the necessity for tree water status monitoring to guide irrigation scheduling of pecan (Carya illinoinensis) orchards. The objectives of this study were to assess the impact of water status developed during the flood irrigation dry-down cycles on photosynthesis (P n), and gas exchange [stomatal conductance (g S) to H 2 O (g H2O), transpiration (E), and intercellular CO 2 (c i)] and to establish values of midday stem water potential (C smd) that are needed to maintain P n and gas exchange of pecan. We conducted the study simultaneously on two southern New Mexico mature pecan orchards from 2011 through 2013. Flood irrigation as determined by grower practice was used on both orchards and P n , g H2O , E, and c i were assessed at C smd of-0.4 to-2.0 MPa. Photosynthesis and gas exchange were higher in pecan trees shortly after irrigation than trees exhibiting water deficit near the end of a flood irrigation dry-down cycle. The decline in P n was markedly noticeable when C smd dropped below-0.9 MPa. We attributed the reduction in P n mostly to stomatal limitation. The decline in P n and g H2O exceeded 50% when C smd ranged from-1.5 to-2.0 MPa. For those reasons, we recommended that pecan orchards be maintained at C smd higher than-0.90 MPa to prevent significant reductions in carbon assimilation and gas exchange.
Production of medicinal/aromatic (MA) herb plants to meet the ever increasing demand for these pl... more Production of medicinal/aromatic (MA) herb plants to meet the ever increasing demand for these plants is a major challenge facing countries in arid and semiarid regions which are characterized by limited water and land resources. Recently, soilless cultivation of medicinal plants has gained a great attention in both protected environment and outdoor conditions, due to many advantages like potential for higher yields and quality, cleaner products, year round production, with minimized use of water in comparison to conventional soil-based cultivation. The objectives of this study were to introduce five highly valued MA crops (sage, German chamomile, Jordanian chamomile, thyme and mint) into Arabian Gulf region. As the region is characterized by harsh environment, fragile ecosystems and limited water resources and arable lands, and these crops are native to Mediterranean climates and are not being grown in Gulf region, therefore, these crops were cultivated using re-circulating soilless system, and their growth was evaluated and yield was compared to soil-based yields. Results of this research showed that all studied crops were well adapted to the soilless system and outyielded the soil cultivated by 264, 313, 220, 247, and 243%, of herbal biomass for sage, German and Jordanian chamomiles, thyme and mint, respectively with much less water use (up to 70% save). Flower yields of soilless grown German and Jordanian chamomile outyielded the soil cultivated by 199 and 334%m respectively. Results suggest that introduction of these crops into Gulf region was successful especially with using soilless technology with high water saving as well as a variety of other important herbaceous medicinal plants. 1 1 اﻟ ﻟﻠﺰراﻋﺔ ﻗﺎﺑﻮس اﻟﺴﻠﻄﺎن ﻣﺮآﺰ اﻟﺒﺤﺮﻳﻦ ،اﻟﻌﺮﺑﻲ اﻟﺨﻠﻴﺞ ﺟﺎﻣﻌﺔ ،ﺗﺮﺑﺔ وﺑﺪون ﻤﺘﻄﻮرة ؛ 2 اﻟﺤﺎﻟﻲ اﻟﻌﻨﻮان : اﻟﻌﻠﻮم ﺟﺎﻣﻌﺔ ،اﻟﺰراﻋﺔ آﻠﻴﺔ اﻷردن ،ارﺑﺪ ،اﻷردﻧﻴﺔ واﻟﺘﻜﻨﻮﻟﻮﺟﻴﺎ اﻟﻤﻠﺨﺺ : ﺗﻮاﺟﻪ اﻟﻌﺮﺑﻲ اﻟﺨﻠﻴﺞ ﻣﻨﻄﻘﺔ دول ﻣﺜﻞ اﻟﺠﺎف وﺷﺒﻪ اﻟﺠﺎف اﻟﻤﻨﺎخ ذات اﻟﺪول ﻓﻲ واﻟﻌﻄﺮﻳﺔ اﻟﻄﺒﻴﺔ اﻟﻨﺒﺎﺗﺎت واﺳﺘﺪاﻣﺔ إﻧﺘﺎج إن ﺗﺤﺪ اﻟﺰراﻋﻴﺔ واﻷراﺿﻲ اﻟﻤﺎﺋﻴﺔ اﻟﻤﺼﺎدر ﻣﺤﺪودﻳﺔ ﺑﺴﺒﺐ وذﻟﻚ اﻟﻨﺒﺎﺗﺎت هﺬﻩ ﻋﻠﻰ اﻟﻤﺘﺰاﻳﺪ اﻟﻄﻠﺐ ﺗﻠﺒﻴﺔ اﺟﻞ ﻣﻦ آﺒﻴﺮا ﻳﺎ. اﺳﺘﺰراع ﻟﻘﻲ ﻟﻘﺪ ﻟﻠﻤﻴﺰات وذﻟﻚ ﺧﺎرﺟﻬﺎ او اﻟﻤﺤﻤﻴﺔ اﻟﻈﺮوف ﺗﺤﺖ ﺳﻮاءا اﻟﺪول ﻣﻦ آﺜﻴﺮ ﻓﻲ آﺒﻴﺮا اهﺘﻤﺎﻣﺎ اﻷﺧﻴﺮة اﻟﺴﻨﻮات ﻓﻲ ﺗﺮﺑﺔ ﺑﺪون اﻟﻄﺒﻴﺔ اﻟﻨﺒﺎﺗﺎت ﺗﻘﺪ اﻟﺘﻲ اﻟﻨﺎﺗ وﻧﻈﺎﻓﺔ اﻟﻌﺎﻟﻴﺔ واﻟﻨﻮﻋﻴﺔ اﻟﻌﺎم وﻃﻮال اﻟﻌﺎﻟﻲ اﻹﻧﺘﺎج ﻣﺜﻞ اﻟﺘﻘﻨﻴﺔ هﺬﻩ ﻣﻬﺎ ﺞ وآﻔﺎءة اﻟﻤﻴﺎﻩ ﻓﻲ اﻟﻜﺒﻴﺮ اﻟﺘﻮﻓﻴﺮ إﻟﻰ ﺑﺎﻻﺿﺎﻓﺔ اﻟﺘﺮﺑﺔ ﻓﻲ اﻟﺘﻘﻠﻴﺪﻳﺔ اﻟﺰراﻋﺔ ﻣﻊ ﻣﻘﺎرﻧﺔ اﺳﺘﺨﺪاﻣﻬﺎ. واﻟﻌﻄﺮﻳﺔ اﻟﻄﺒﻴﺔ اﻟﻨﺒﺎﺗﺎت ﻣﻦ ﻋﺪد زراﻋﺔ وﺗﻘﻴﻴﻢ ادﺧﺎل إﻟﻰ اﻟﺪراﺳﺔ هﺬﻩ ﺗﻬﺪف) ،اﻟﻤﻴﺮﻣﻴﺔ واﻟﻨﻌﻨﺎع ،اﻟﺰﻋﺘﺮ ،اﻟﺒﺎﺑﻮﻧﺞ (وﻣﻘﺎرﻧ اﻟﺘﺪوﻳﺮ ﻧﻈﺎم ﺑﺎﺳﺘﺨﺪام ﺗﺮﺑﺔ ﺑﺪون اﻟﺰراﻋﺔ ﻇﺮوف ﺗﺤﺖ اﻟﻤﻨﻄﻘﺔ ﻓﻲ اﻟﻤﺴﺘﺰرﻋﺔ ﻏﻴﺮ ﺔ اﻟﺤﻘﻞ ﻓﻲ اﻟﺘﻘﻠﻴﺪﻳﺔ اﻟﺰراﻋﺔ ﻇﺮوف ﺗﺤﺖ اﻹﻧﺘﺎج ﻣﻊ ذﻟﻚ. ﻧﻈﺎم ﻣﻊ ﺗﻤﺎﻣﺎ ﻣﺘﻜﻴﻔﺔ آﺎﻧﺖ اﻟﻤﺪروﺳﺔ اﻟﻨﺒﺎﺗﺎت ﺟﻤﻴﻊ ﺑﺎن اﻟﻨﺘﺎﺋﺞ أﻇﻬﺮت وﺗﻔﻮﻗﺖ ﺗﺮﺑﺔ ﺑﺪون اﻟﺰراﻋﺔ اﻟﺘﺮﺑﺔ ﻓﻲ اﻟﺘﻘﻠﻴﺪﻳﺔ اﻟﺰراﻋﺔ ﻧﻈﺎم ﺗﺤﺖ اﻟﻤﺰروﻋﺔ ﺗﻠﻚ ﻋﻠﻰ اﻟﻌﺸﺒﻴﺔ اﻟﻤﺎدة إﻧﺘﺎج ﻓﻲ ﺑﺤﻮاﻟﻲ 264 ، 313 ، 220 ، 247 و ، 243 % اﻟﺘﻮﻓﻴﺮ اﻟﻰ ﺑﺎﻻﺿﺎﻓﺔ ،اﻟﺘﻮاﻟﻲ ،ﻋﻠﻰ واﻟﻨﻌﻨﺎع ،اﻟﺰﻋﺘﺮ ،اﻻردﻧﻲ اﻟﺒﺎﺑﻮﻧﺞ ،اﻻﻟﻤﺎﻧﻲ اﻟﺒﺎﺑﻮﻧﺞ ،اﻟﻤﻴﺮﻣﻴﺔ ﻣﻦ ﻟﻜﻞ ﻟﻠﻤﻴﺎﻩ اﻟﻌﺎﻟﻲ. اﻻزه اﻧﺘﺎج ﺗﻔﻮق وﻗﺪ ﺑﺤﻮاﻟﻲ ﺗﺮﺑﺔ ﺑﺪون ﺑﺎﻟﺰراﻋﺔ اﻟﻤﺰروع اﻻردﻧﻲ واﻟﺒﺎﺑﻮﻧﺞ اﻻﻟﻤﺎﻧﻲ اﻟﺒﺎﺑﻮﻧﺞ ﻓﻲ ﺎر 199 و 334 % ، ﺑﺎﻟﺘﺮﺑﺔ اﻟﻤﺰروع ذﻟﻚ ﻋﻦ ،اﻟﺘﻮاﻟﻲ ﻋﻠﻰ. ﻧﺎﺟﺤﺎ آﺎن اﻟﻤﺪروﺳﺔ اﻟﻨﺒﺎﺗﺎت إﻧﺘﺎج ﻓﻲ ﺗﺮﺑﺔ ﺑﺪون اﻟﺰراﻋﺔ ﺗﻘﻨﻴﺔ اﺳﺘﺨﺪام إن ﻋﻠﻰ ﻳﺪل وهﺬا اﻟﺘﻘﻨﻴ هﺬﻩ اﺳﺘﺨﺪام ﺑﺎﻻﻣﻜﺎن واﻧﻪ ،آﺒﻴﺮ ﺑﺸﻜﻞ اﻟﻌﺮﺑﻲ اﻟﺨﻠﻴﺞ ﻣﻨﻄﻘﺔ ﻓﻲ اﻟﻬﺎﻣﺔ اﻷﺧﺮى اﻟﻄﺒﻴﺔ اﻟﻨﺒﺎﺗﺎت زراﻋﺔ ﻓﻲ ﺔ. اﻟﻤﻔﺘﺎﺣﻴﺔ اﻟﻜﻠﻤﺎت : اﻟﺒﺤﺮﻳﻦ ،ﻟﻠﺰراﻋﺔ ﻗﺎﺑﻮس اﻟﺴﻠﻄﺎن ﻣﺮآﺰ ،اﻟﻤﺎﺋﻴﺔ اﻟﺰراﻋﺔ ،اﻟﻨﻌﻨﺎع ،اﻟﺒﺎﺑﻮﻧﺞ ،اﻟﻤﻴﺮﻣﻴﺔ ،اﻟﺰﻋﺘﺮ .
Effective nutrition and irrigation are important nursery strategies to produce high-quality seedl... more Effective nutrition and irrigation are important nursery strategies to produce high-quality seedlings able to withstand heat and drought stress in the field. The objectives of this study were 2-fold, first to identify the influence of two nitrogen (N) levels (75 and 150 mg · L L1) and two fertigation (FR) methods, overhead (OH) and flotation (FL) of artichoke (Cynara cardunculus cv. Green Globe Improved) transplants on root/shoot growth and leaf physiology during the nursery period. A repeated greenhouse experiment was conducted and morphophysiological measurements were determined at 4 and 7 weeks after seeding (WAS). The second objective was to determine the impact of the nursery treatments (FR method and N level) on the subsequent crop growth and yield under three field irrigation methods [surface drip, subsurface drip, and overhead-linear system (OH-L)]. Field measurements were conducted at 50 and 150 days after field transplanting (DAT) during Fall-Winter 2015. Transplants fertilized with 75 mg · L L1 N (low N) had improved root components as compared to those with 150 mg · L L1 N (high N), especially at 4 WAS. The low N transplants had higher root surface area, root length, root branching, thinner root diameter, and less shoot area than the high N transplants. Wilting for low N transplants was 13.5% less than that for high N at 5 DAT, with a total yield similar or slightly higher than those of high N. Although growth of OH and FL transplants was statistically similar at transplanting, those irrigated with OH (greenhouse) had a 10% higher yield than FL irrigated transplants, regardless of the field irrigation method evaluated. Overall, low N level (75 mg · L L1 N) applied with OH irrigation in the nursery positively improved the transplant root system and transplant quality of artichoke seedlings.
Lily growers adapt intensive fertigation programs to produce superior flowers, which raises subst... more Lily growers adapt intensive fertigation programs to produce superior flowers, which raises substrate salinity and input cost. Soil salinity negatively impact growth and productivity and lead to several environmental problems. The objective of this study was to evaluate the effectiveness of K + (applied as K2SO4 drench application) in ameliorating the negative effects of irrigation-saline water in Asiatic lily growth, physiology, and flower quality. Both lily cultivars bulbs were grown in 10 L pots filled with 3:1 peat moss: perlite. Treatments were three levels of irrigation saline water (electrical conductivity (EC), 0.5 (control), 3.0 and 6 dS m-1) and two K (applied as K2SO4) concentrations 10 and 15 mmol l-1. Irrigation with saline water significantly increased soil salinity and pH, especially in 6 dS m-1 salt level. As a result, the 6.0 dS m-1 treatment reduced stem diameter, plant height and total leaf area. In addition, gas exchange (specifically, Pn and E) in control (0.5 dS m-1) plants during the vegetative stage was significantly higher than the 6.0 dS m-1 treatment. During flowering, irrigation with 6.0 dS m-1 saline water significantly reduced flower number per stem, H* color coordinate and flower diameter. Interestingly, the response of lily flower to moderate salt stress (3 dS m-1) was similar to control (0.5 dS m-1) treatment. The 3 dS m-1 sa-linity treatment had similar color density coordinates (L*, C*, H*), days to flowering, and flower longevity when compared to control (0.5 dS m-1). Additionally, K2SO4 treatment (15 mmol l-1) potentially improved lily growth (gas exchange and stem diameter) during vegetative stage. Overall, irrigation with moderate levels of salts (3 dS m-1) has no negative impact on lily growth and productivity. Furthermore, supplementary K + applied as K2SO4 (15 mmol l-1) can alleviate the negative impact of salinity during the vegetative growth.
A field study was conducted to determine the effect of arbuscular mycorrhizal (AM) fungi
inoculat... more A field study was conducted to determine the effect of arbuscular mycorrhizal (AM) fungi inoculation on bulb yield and mineral acquisition of two onion (Alium cepa L.) cultivars (Giza 20 and Texas Grano) grown under well-watered and water-stressed conditions. Onion seedlings were transplanted into planting furrows after treatment with or without the AM fungi Glomus mosseae or G. fasciculatum. Root colonization with AM fungi occurred in both cultivars under waterstressed and well-watered conditions, but the extent of AM fungi root colonization was higher under well-watered than under water-stressed conditions. Water stress had significantly reduced bulb yields and mineral acquisition in both cultivars either inoculated or un-inoculated plants. However, inoculation with AM fungi has improved onion bulb yield and mineral acquisition (P, Cu, Fe and Zn concentrations) irrespective soil moisture. The results indicated that Texas Grano cultivar benefited more than Giza 20 cultivar from AM fungi inoculation especially under water-stressed conditions. The improved yield and mineral acquisition due to AM fungi inoculation demonstrated the importance of mycorrhizal inoculation to reduce the effects of drought stress on onion grown under field conditions in dry and semi-dry areas.
Plastic house shading could have unpredictable effects on plant growth, fruit quality, production... more Plastic house shading could have unpredictable effects on plant growth, fruit quality, production and insect pest infestation. A plastic house experiment was conducted in Jordan Valley in Jordan to assess the impact of two shading treatments on cucumber yield production, quality and pest populations. Shading treatments were green shadow (GS), plaster (P) (calcium carbonate) and control (no shading). Results showed that shading had a significant impact on light intensity inside the plastic house, whitefly and mite infestations, leaf-level physiology and fruit yield and quality. Both GS and P significantly reduced light intensity (permeabil-ity) inside the greenhouse. Whitefly and mite infestations were statistically higher in control compared to GS and P treatments. Additionally, GS treatment had higher fruit yield compared to P and control. Althoughcontrol treatment had higher photosynthe-sis ratethan shade treatments (green and white). The same plants (control) had lower yield and fruit quality than green and white shade treatments. In fact, shading increased fruit weight, length, color darkness, total soluble solids and firmness compared to un-shaded control fruit. Therefore, it is concluded that plastic house shading using GS might potentially reduce insect infestation and improve fruit yield and quality in cucumber during summer time.
In this paper twelve barley (Hordeum vulgare L.) genotypes were screened for salt tolerance durin... more In this paper twelve barley (Hordeum vulgare L.) genotypes were screened for salt tolerance during seed germination in the Crop Production Department, Faculty of Agriculture, Jordan University of Science and Technology, Irbid, Jordan. To evaluate salt tolerance during germination, 30 seeds of each genotype were placed on towel paper in 9 cm Petri dishes containing 20 mL distilled water or 1:1 M ratio NaCl and CaCl 2 solutions at various concentrations [(control), 100, 200, 300 mM] to give electrical conductivities (EC) of 0.05 (control), 10.6, 19.0 and 27.0 dS mG , respectively. Our data indicated that salinity level × genotype interaction 1 effects (p<0.05) were observed for seed germination percentage, seed viability and ion uptake. Seed germination decreased significantly by increasing salinity level. Germination was significantly diminished at the highest level of salt (300 mM) with significant variation among genotypes and the genotype ACSAD1430 had higher germination percentage than other tested genotypes. Results presented in this article also indicated that the increasing seed pretreatment duration by hyper-saline medium significantly reduced seed recovery when transferred to distilled water. Also our data indicated that the increasing seed pretreatment duration by hyper-saline medium significantly reduced seed recovery when transferred to distilled water. The N a concentration of seeds after imbibitions significantly increased with increasing salinity with a considerable variation among genotypes. K concentration also affected by salinity. Generally, increasing salt stress significantly decreased K concentration in barley seeds after one day of imbibitions. The present study indicated that salt stress must be removed from soil surface for successful seedling establishment.
We explored the relationship between hyper-spectral surface reflectance data derived from a handh... more We explored the relationship between hyper-spectral surface reflectance data derived from a handheld spectroradiometer and foliar chlorophyll content of pecans. Canopy scale hyperspectral remotely sensed data and foliar chlorophyll content determined with SPAD meter were collected simultaneously from two mature pecan orchards for two years. One pecan orchard was located in a clay loam soil and the other in a sandy loam soil. Hyperspectral surface reflectance data were correlated to chlorophyll content. The relationship between remotely-sensed data and SPAD was high (R 2 ≥ 0.8) to moderate (0.8 ≥ R 2 ≥ 0.6) in the first year, and generally weak (R 2 < 0.6) in the second year in both orchards. In the first year, canopy reflectance within the wavelength range 500 to 720 nm of the pecan orchard in the clay loam soil had a moderate to strong relationship (R 2 > 0.6) with SPAD compared to other wavelengths across the canopy reflectance spectrum (i.e. 350-500 and 730-2450 nm). Contour map revealed that the band ratios with a numerator consisting of any wavelength within the 600 to 680 nm range and a denominator of any wavelength along the visible and near infrared spectrum (350-1600 nm) had high correlations with SPAD in both orchards in the first year. The vegetation indices NDVI, mNDVI, SIPI, SIPI2 and PSRI also had high regression values (0.91 ≥ R 2 ≥ 0.87) with SPAD in clay loam site and moderate regression (0.73 ≥ R 2 ≥ 0.67) in sandy loam site in the first year. Overall, canopy surface reflec-tance data holds promise for studying foliar chlorophyll content in pecan orchards.
Rising awareness over the environmental impacts of some commonly used materials such as peat-base... more Rising awareness over the environmental impacts of some commonly used materials such as peat-based growing media has urged researchers to assess more environmentally friendly products. The aim of this study was to evaluate the effect of two soilless substrates [tuff (granulated volcanic material, 0-4 mm) and 2:1 peatmoss+perlite (2:1 P+P)] on growth and flower quality of two cultivars of Asiatic lily (Lilium ×elegans Thunb.) cvs 'Fangio' and 'Ercolano'. Two bulbs of both cultivars were grown in 12 L pots filled with tuff or 2:1 P+P substrate. Substrate properties, plant growth, plant physiology, number of days to flowering and flower quality were assessed. Data revealed that tuff substrate had lower water holding capacity (WHC) and electrical conductivity (EC) than 2:1 P+P media. Conversely, tuff had higher bulk density and pH than 2:1 P+P substrate. The 2:1 P+P substrate had higher shoot length and leaf area than tuff in both cultivars. However, tuff substrate increased flowers number per plant in 'Fangio' by 8% and 'Ercolano' by 18% compared to 2:1 P+P. Volcanic tuff can last for many years (compared to peatmoss) and therefore, frequent replacement of the substrate is not a prerequisite. Additionally, 2:1 P+P had no superior impact on lily (compared to tuff) except for shoot length and leaf area. For these reasons, we recommended that tuff be used as an alternative to peatmoss in soilless production of lily in order to enhance flower quality and mitigating agricultural negative impact on the environment.
The present article reviews the scientific literature on soilless culture and provided a critical... more The present article reviews the scientific literature on soilless culture and provided a critical examination of the micro-environmental factors that can affect horticultural crop growth and productivity, including , soilless substrate, fertigation solution, salin-ity, nutrient content and pH and plant-microorganism interaction. In addition, the role of precision agriculture such as, remote sensing in soilless system performance is reviewed. Soilless substrate source (organic and inorganic) and particle size can affect mineral content, oxygen level, salinity and pH of the nutrient solution, as well as the microorganism diversity and abundance. Organic substrates had more microorganism communities compared to inorganic substrates. Microorganism inoculation (e.g. fungi) of inorganic substrate to increase microorganism abundance is completely ineffective. However, environ-mentalists do not recommend the use of peat-based organic substrates because it leads to loss of soil organic carbon and destruction of wetlands. Agricultural demands for sustainable, environmental friendly soilless system highlights the benefits of using inorganic substrate (rock-wool and volcanic tuff) and the re-use of nutrient solution (closed systems) to avoid water and nutrient losses. Interestingly, biological control of root rot pathogens in closed soil-less systems is more effective than open or conventional due to the lower variety of microorganism community in closed structures. However, substrate salinity is the main challenge in closed soilless systems. The use of salt-tolerance cultivars, large volume tanks to minimize electrical conductivity and pH changes and sub irrigation with low concentration nutrient solution are the main approaches to reduce salinity in growing substrates. Several precision agricultural techniques based on advanced sensing technologies such as smart irrigation systems and surface reflectance data from crop canopy may increase soilless system efficiency. These techniques are based on crop water demands, not fixed watering schedules and have the potential to optimize water and nutrient use efficiency.
Monitoring and assessment of agricultural land degradation is of vital importance for better land... more Monitoring and assessment of agricultural land degradation is of vital importance for better land and water management planning and reclamation. It requires setting baseline information and basic analysis at specific time and space. About 33 geo-referenced soil sampling spots were selected in two agricultural production locations in the Kingdom of Bahrain to assess the status and preliminary causes of land degradation. Soil samples were taken from 13 sites in Diraz location while 19 samples were taken from Budayyi location. The samples were taken to 90 cm depth at 30 cm intervals. Standard procedures were followed to determine soil physiochemical properties. In addition, field observations on farm condition, distance from the sea, method of irrigation and irrigation water source were taken. Some of the soil samples were deliberately taken from outside the irrigated basins among trees compared with samples taken from inside the actively growing area for comparison. The results indicated that the salinity level was significantly (P < 0.001) higher at the 0-30 cm soil depth compared with 30-60 cm or 60-90 cm depths in both locations. The distance from the sea did not show clear correlation with surface soil salinity in Budayyi area compared with Diraz. Both locations showed significantly higher salinity levels on samples taken outside the actively growing areas compared with those taken from within. The effect is more prominent at the 0-30 cm depth. The observed variability on salinity levels may be attributed to farm management practices and deteriorating quality of ground water. Thus, agricultural land degradation in Bahrain cannot be attributed to ground water deterioration alone. The use of tertiary treated sewage water (TSE) may ease the pressure on ground water, but the pH of the TSE should be carefully monitored and managed with proper studies on leaching requirements to avoid further salinity complications.
Abstarct Agricultural productivity and sustainability are the most challenges facing many arid an... more Abstarct Agricultural productivity and sustainability are the most challenges facing many arid and semiarid regions as these regions are characterized by severe shortage of good quality water for irrigation and saline water is very common. The trend in recent years has been towards conversion of conventional agriculture to soilless agriculture (mainly closed system) which is considered to be a more efficient use of water system. The aim of this research was to examine the response of three sweet pepper cultivars (Capsicum annum L., cvs. Flaviano, Sonar, Alzado) to different levels of salinity under soilless recirculating conditions. Plants were grown in concrete troughs filled with zeolite in a closed soilless system using nutrient solutions with NaCl corresponding to electrical conductivity levels [1.8 (control), 4 and 8 dS m-1 ]. The sweet pepper proved to be sensitive to the increasing salinity of nutrient solution as the total and marketable fruit yield, fruit number and single fruit weight decreased in all tested cultivars with increasing salinity level. However, genotypic variation for fruit yield and yield components have been noticed. The cultivar Flaviano produced higher fruit yield than the other two cultivars regardless of salinity level. In all cultivars, leaves had higher Na + and Cl-concentrations than fruits, which increased with increasing salinity; while K + in leaves was higher than fruits and decreased by salinity. Leaves and fruits of the cultivar Flaviano accumulated higher K + and lower Na + and Cl-than the other two cultivars. This suggests that Flaviano was the most tolerant cultivar to salinity among tested cultivars as it showed less reduction in fruit yield and its components due to salinity.
Remote-sensing techniques can detect and up-scale leaf-level physiological responses
to large are... more Remote-sensing techniques can detect and up-scale leaf-level physiological responses to large areas, and provide significant and reliable information on water use and irrigation management. The objectives of this study were to screen leaf-level physiological changes that occur during the cyclic irrigation of pecan orchards to determine which responses best represent changes in moisture status of plants and link plant physiological changes to remotely sensed surface reflectance data derived from the Landsat Thematic Mapper and Enhanced Thematic Mapper Plus (ETM+). The study was conducted simultaneously on two southern New Mexico mature pecan orchards. For both orchards, plant physiological responses and remotely sensed surface reflectance data were collected from trees that were either well watered or in water deficit. Remotely sensed variables included reflectance in band 1, the ratio between shortwave infrared (SWIR) bands (B5:B7), the normalized difference vegetation index, and SWIR moisture indices. Midday stem water potential (Ψsmd) was the best performing leaf-level physiological response variable for detecting moisture status in pecans. The B5:B7 ratio positively and significantly correlated with Ψsmd in five of six irrigation cycles while multiple linear regression weighted with six remotely sensed surface reflectance variables revealed a significant relationship with moisture status in all cycles in both orchards (R2 > 0.73). Because changes in the B5:B7 band ratio and multiple regression of spectral variables correlate with the moisture status of pecan orchards, we conclude that remotely sensed data hold promise for detecting the moisture status of pecans.
The objective of this study was to assess the effect of foliar application of gibberellic acid (G... more The objective of this study was to assess the effect of foliar application of gibberellic acid (GA3) on strawberry (Fragaria × ananassa Duch cvs. 'BG4.370' and ' Splendor') morphology, physiology [photosynthesis rate (Pn), stomatal conductance (gs) and transpiration (E)], yield, and fruit total soluble solids. Five different GA3 levels were used; control (0.0), 50, 100, 200 and 1000 mg/l. Gibberellic acid treatments were sprayed twice, the first at the 5 th leaf stage and the second 10 d after the first application. Plants under control were sprayed with tap water only. Foliar application of GA3 decreased the time needed to flowering and increased Pn, gs, E, pedicel length, soluble solids (°Brix) in both cultivars and across GA3 levels, compared to untreated control. Conversely, GA3-treated plants had lower chlorophyll content index (SPAD), marketable yield and individual fruit weight. Overall, foliar application of GA3 increased shoot morphology and physiology (Pn, gs and E) but did not improve strawberry fruit quality and yield. In fact, this study revealed that for these cultivars and those GA3 concentrations, the incidence of malformed fruits and unmarketable yield can be significant.
ADDITIONAL INDEX WORDS. bulb, cut flower, Lilium ·elegans SUMMARY. Soilless substrates enhance gr... more ADDITIONAL INDEX WORDS. bulb, cut flower, Lilium ·elegans SUMMARY. Soilless substrates enhance growing environment, nutrient content, and water quality in the growing medium. The objective of this study was to assess the influence of substrate particle size on growth and flower quality (flower number and length per plant) of two asiatic hybrid lily (Lilium ·elegans) cultivars Fangio and Ercolano. Plants were grown in 12-L pot under greenhouse conditions. Five grades of particle-size substrate, consisting of granulated volcanic material (tuff) were used as treatments. These sizes were 0 to 2, 0 to 4, 0 to 8, 2 to 4, and 4 to 8 mm. Fertigation was applied daily. Plant morphology, physiology, and flower quality were determined during flowering stage. Treatments of 2 to 4-and 4 to 8-mm tuff had lower water holding capacity (WHC), bulk density, electrical conductivity (EC), and pH compared with 0 to 2-and 0 to 4-mm tuff. In addition, plant height, leaf area, and flower quality of 'Fangio' were higher compared with 'Ercolano'. Chlorophyll content and fluorescence were similar among all treatments. Leaf fresh weight, leaf area, shoot dry weight, root dry weight, and flower quality were higher in sizes of 0 to 4-, 2 to 4-, and 4 to 8-mm than 0 to 2-mm tuff, especially those from 'Fangio'. The 0 to 4-mm substrate had an optimal and consistent flower quality results in both cultivars when compared with other tuff sizes. Overall, the results presented here suggest that using 0 to 4-mm tuff substrate holds promise for improving growth and flower quality of asiatic hybrid lily grown under soilless culture.
Soil amendment using organic fertilizer has been used widely to dispose animal waste, reduce envi... more Soil amendment using organic fertilizer has been used widely to dispose animal waste, reduce environmental pollution and improve soil and fruit quality. The objective of this two-year study was to assess the influence of organic and conventional systems on growth, marketable yield, head quality (chlorogenic acid and cynarin concentration) and soil chemical properties of globe artichoke (Cynara cardunculus). Cultivars used were De-serto, Lulu, Romolo, 11-018, 12-179, Green Globe Improved and Imperial Star. Fertilizers were applied to both conventional and organic soil through drip irrigation system. In both years, significant differences were found across cultivars and soil type. Although cultivar response to soil system treatments were inconsistent across the two growing seasons, the cv. Imperial Star had the lowest marketable yield and head quality. Artichoke grown in the conventional field had higher plant height and width, chlorophyll content index (SPAD), leaf area index (LAI), stomatal conductance (gs), photosynthesis (Pn) and marketable yield. Conversely, artichoke head quality from the organic field was higher than conventional. Organic system increased chlorogenic acid by 31% and cy-narin by 12% compared to the conventional system. In fact, after two years of soil amendment, organic fertilizer improved soil respiration-CO 2 (soil health indicator) by 20-fold compared to chemical fertilizer (conventional field). Overall, based on this two-year study we suggest organic farming as the best system to improve soil and head quality of globe artichoke, but it may not be the best option for farmers when yield is the primary target short-term.
The impact of nitrogen application on the growth of olive trees has been well studied. However, l... more The impact of nitrogen application on the growth of olive trees has been well studied. However, little is known about the role of levels and forms of N on the development of roots and physiological traits during establishment of young trees. The objective of this 2-year study was to evaluate the influence of N source and level on shoot morphology (tree height, stem diameter, and branch number) and physiology [leaf area and fresh weight, photosynthesis (P n), transpiration (E), and stomatal conductance (g s)], root components (length, diameter, surface area, and fork number) and N content of young olive (Olea europaea cv. Arbequina) cuttings. Three-month-old olive cuttings were planted in 15-L pots filled with a growing substrate composed of peatmoss + bark + sand (2:1:1/by volume) and placed in a screen house. Two N levels, 2.8 and 5.6 g/tree, and control (0 N) and four N sources, calcium nitrate (CN, 12%N, 17%Ca +2), ammonium nitrate (AN, 35%N), urea (46%N), and the slow-release Osmocote (OSC, 18%N, 6%P, 12%K) were evaluated. Effects of low-(2.8 g/tree) and high N (5.6 g/tree) levels on shoot components (plant height, diameter, branch number, leaf area, and fresh weight) and gas exchange (P n , g s and E) were similar implying that the low rate of N was adequate for the establishment of young olive cuttings. Nitrogen sources, particularly AN and CN had significant effects on shoot and root morphology, physiology, and leaf and root N concentration. In fact, AN and CN were the best fertilizer sources for olive transplants in term of root and shoot growth. Overall, 2.8 g/tree N level and AN or CN sources were the best treatments for newly established olive 'Arbequina' trees. Root components treated with high N rate (5.6 g/tree N) using the slow-release fertilizer (OSC) was similar to those treated with the low AN rate (2.8 g/tree N). Therefore, for nursery containerized olive trees of 'Arbequina' or other cultivars with comparable growth rates, we recommend to apply the CN or AN source at 2.8 g/tree N or the controlled-released fertilizer OSC at 5.6 g/tree N.
In Texas there is a need to screen and identify high quality and more productive globe artichoke ... more In Texas there is a need to screen and identify high quality and more productive globe artichoke cultivars. The objective of this study was to determine morphological, physiological, head quality and yield responses of early and mid-season globe artichoke cultivars. The standard 'Imperial Star' (IS, early season, Condor Seed Co.) and the new '12-179' (mid-season, Big Heart Seed Co.) cultivars were transplanted November 2014 at Uvalde in the Wintergarden region and Brownsville in the Lower Rio Grande Valley of Texas. Plant measurements were conducted during the vegetative stage (90-130 days after planting, DAP) and reproductive stage (150-190 DAP). At the early stage, plant height of '12-179' was significantly higher (P=0.04 to 0.08) than IS in both sites. The cultivar '12-179' also had higher photosynthetic rates than IS at the Uvalde location. No significant differences were found between cultivars in other gas exchange measurements, plant width, chlorophyll content index (SPAD), and leaf area index (LAI). However, LAI of '12-179' was significantly higher than IS in Brownsville at the reproductive stage. Head and heart weights were similar for both cultivars, but head length was significantly longer (P=0.006) for '12-179' as compared to IS. Four harvests were performed during a 42-day period, with the major peak of production (48% of the total) on April 21, 2015. The main difference between cultivars was in total marketable yield, with '12-179' producing 9.8 t ha-1 higher marketable yields (23.9 t ha-1) than IS (14.1 t ha-1). Conversely, unmarketable yield (deformed, opened) of 12-179 was 3.5 t ha-1 compared with 5.7 t ha-1 for IS. Overall, the new cultivar '12-179' demonstrated superior performance to 'Imperial Star', and therefore is recommended for adoption into commercial production practices in southwest Texas.
ADDITIONAL INDEX WORDS. Carya illinoinensis, drought, irrigated agriculture, water relations ABST... more ADDITIONAL INDEX WORDS. Carya illinoinensis, drought, irrigated agriculture, water relations ABSTRACT. Demand for New Mexico's limited water resources coupled with periodic drought has increased the necessity for tree water status monitoring to guide irrigation scheduling of pecan (Carya illinoinensis) orchards. The objectives of this study were to assess the impact of water status developed during the flood irrigation dry-down cycles on photosynthesis (P n), and gas exchange [stomatal conductance (g S) to H 2 O (g H2O), transpiration (E), and intercellular CO 2 (c i)] and to establish values of midday stem water potential (C smd) that are needed to maintain P n and gas exchange of pecan. We conducted the study simultaneously on two southern New Mexico mature pecan orchards from 2011 through 2013. Flood irrigation as determined by grower practice was used on both orchards and P n , g H2O , E, and c i were assessed at C smd of-0.4 to-2.0 MPa. Photosynthesis and gas exchange were higher in pecan trees shortly after irrigation than trees exhibiting water deficit near the end of a flood irrigation dry-down cycle. The decline in P n was markedly noticeable when C smd dropped below-0.9 MPa. We attributed the reduction in P n mostly to stomatal limitation. The decline in P n and g H2O exceeded 50% when C smd ranged from-1.5 to-2.0 MPa. For those reasons, we recommended that pecan orchards be maintained at C smd higher than-0.90 MPa to prevent significant reductions in carbon assimilation and gas exchange.
Production of medicinal/aromatic (MA) herb plants to meet the ever increasing demand for these pl... more Production of medicinal/aromatic (MA) herb plants to meet the ever increasing demand for these plants is a major challenge facing countries in arid and semiarid regions which are characterized by limited water and land resources. Recently, soilless cultivation of medicinal plants has gained a great attention in both protected environment and outdoor conditions, due to many advantages like potential for higher yields and quality, cleaner products, year round production, with minimized use of water in comparison to conventional soil-based cultivation. The objectives of this study were to introduce five highly valued MA crops (sage, German chamomile, Jordanian chamomile, thyme and mint) into Arabian Gulf region. As the region is characterized by harsh environment, fragile ecosystems and limited water resources and arable lands, and these crops are native to Mediterranean climates and are not being grown in Gulf region, therefore, these crops were cultivated using re-circulating soilless system, and their growth was evaluated and yield was compared to soil-based yields. Results of this research showed that all studied crops were well adapted to the soilless system and outyielded the soil cultivated by 264, 313, 220, 247, and 243%, of herbal biomass for sage, German and Jordanian chamomiles, thyme and mint, respectively with much less water use (up to 70% save). Flower yields of soilless grown German and Jordanian chamomile outyielded the soil cultivated by 199 and 334%m respectively. Results suggest that introduction of these crops into Gulf region was successful especially with using soilless technology with high water saving as well as a variety of other important herbaceous medicinal plants. 1 1 اﻟ ﻟﻠﺰراﻋﺔ ﻗﺎﺑﻮس اﻟﺴﻠﻄﺎن ﻣﺮآﺰ اﻟﺒﺤﺮﻳﻦ ،اﻟﻌﺮﺑﻲ اﻟﺨﻠﻴﺞ ﺟﺎﻣﻌﺔ ،ﺗﺮﺑﺔ وﺑﺪون ﻤﺘﻄﻮرة ؛ 2 اﻟﺤﺎﻟﻲ اﻟﻌﻨﻮان : اﻟﻌﻠﻮم ﺟﺎﻣﻌﺔ ،اﻟﺰراﻋﺔ آﻠﻴﺔ اﻷردن ،ارﺑﺪ ،اﻷردﻧﻴﺔ واﻟﺘﻜﻨﻮﻟﻮﺟﻴﺎ اﻟﻤﻠﺨﺺ : ﺗﻮاﺟﻪ اﻟﻌﺮﺑﻲ اﻟﺨﻠﻴﺞ ﻣﻨﻄﻘﺔ دول ﻣﺜﻞ اﻟﺠﺎف وﺷﺒﻪ اﻟﺠﺎف اﻟﻤﻨﺎخ ذات اﻟﺪول ﻓﻲ واﻟﻌﻄﺮﻳﺔ اﻟﻄﺒﻴﺔ اﻟﻨﺒﺎﺗﺎت واﺳﺘﺪاﻣﺔ إﻧﺘﺎج إن ﺗﺤﺪ اﻟﺰراﻋﻴﺔ واﻷراﺿﻲ اﻟﻤﺎﺋﻴﺔ اﻟﻤﺼﺎدر ﻣﺤﺪودﻳﺔ ﺑﺴﺒﺐ وذﻟﻚ اﻟﻨﺒﺎﺗﺎت هﺬﻩ ﻋﻠﻰ اﻟﻤﺘﺰاﻳﺪ اﻟﻄﻠﺐ ﺗﻠﺒﻴﺔ اﺟﻞ ﻣﻦ آﺒﻴﺮا ﻳﺎ. اﺳﺘﺰراع ﻟﻘﻲ ﻟﻘﺪ ﻟﻠﻤﻴﺰات وذﻟﻚ ﺧﺎرﺟﻬﺎ او اﻟﻤﺤﻤﻴﺔ اﻟﻈﺮوف ﺗﺤﺖ ﺳﻮاءا اﻟﺪول ﻣﻦ آﺜﻴﺮ ﻓﻲ آﺒﻴﺮا اهﺘﻤﺎﻣﺎ اﻷﺧﻴﺮة اﻟﺴﻨﻮات ﻓﻲ ﺗﺮﺑﺔ ﺑﺪون اﻟﻄﺒﻴﺔ اﻟﻨﺒﺎﺗﺎت ﺗﻘﺪ اﻟﺘﻲ اﻟﻨﺎﺗ وﻧﻈﺎﻓﺔ اﻟﻌﺎﻟﻴﺔ واﻟﻨﻮﻋﻴﺔ اﻟﻌﺎم وﻃﻮال اﻟﻌﺎﻟﻲ اﻹﻧﺘﺎج ﻣﺜﻞ اﻟﺘﻘﻨﻴﺔ هﺬﻩ ﻣﻬﺎ ﺞ وآﻔﺎءة اﻟﻤﻴﺎﻩ ﻓﻲ اﻟﻜﺒﻴﺮ اﻟﺘﻮﻓﻴﺮ إﻟﻰ ﺑﺎﻻﺿﺎﻓﺔ اﻟﺘﺮﺑﺔ ﻓﻲ اﻟﺘﻘﻠﻴﺪﻳﺔ اﻟﺰراﻋﺔ ﻣﻊ ﻣﻘﺎرﻧﺔ اﺳﺘﺨﺪاﻣﻬﺎ. واﻟﻌﻄﺮﻳﺔ اﻟﻄﺒﻴﺔ اﻟﻨﺒﺎﺗﺎت ﻣﻦ ﻋﺪد زراﻋﺔ وﺗﻘﻴﻴﻢ ادﺧﺎل إﻟﻰ اﻟﺪراﺳﺔ هﺬﻩ ﺗﻬﺪف) ،اﻟﻤﻴﺮﻣﻴﺔ واﻟﻨﻌﻨﺎع ،اﻟﺰﻋﺘﺮ ،اﻟﺒﺎﺑﻮﻧﺞ (وﻣﻘﺎرﻧ اﻟﺘﺪوﻳﺮ ﻧﻈﺎم ﺑﺎﺳﺘﺨﺪام ﺗﺮﺑﺔ ﺑﺪون اﻟﺰراﻋﺔ ﻇﺮوف ﺗﺤﺖ اﻟﻤﻨﻄﻘﺔ ﻓﻲ اﻟﻤﺴﺘﺰرﻋﺔ ﻏﻴﺮ ﺔ اﻟﺤﻘﻞ ﻓﻲ اﻟﺘﻘﻠﻴﺪﻳﺔ اﻟﺰراﻋﺔ ﻇﺮوف ﺗﺤﺖ اﻹﻧﺘﺎج ﻣﻊ ذﻟﻚ. ﻧﻈﺎم ﻣﻊ ﺗﻤﺎﻣﺎ ﻣﺘﻜﻴﻔﺔ آﺎﻧﺖ اﻟﻤﺪروﺳﺔ اﻟﻨﺒﺎﺗﺎت ﺟﻤﻴﻊ ﺑﺎن اﻟﻨﺘﺎﺋﺞ أﻇﻬﺮت وﺗﻔﻮﻗﺖ ﺗﺮﺑﺔ ﺑﺪون اﻟﺰراﻋﺔ اﻟﺘﺮﺑﺔ ﻓﻲ اﻟﺘﻘﻠﻴﺪﻳﺔ اﻟﺰراﻋﺔ ﻧﻈﺎم ﺗﺤﺖ اﻟﻤﺰروﻋﺔ ﺗﻠﻚ ﻋﻠﻰ اﻟﻌﺸﺒﻴﺔ اﻟﻤﺎدة إﻧﺘﺎج ﻓﻲ ﺑﺤﻮاﻟﻲ 264 ، 313 ، 220 ، 247 و ، 243 % اﻟﺘﻮﻓﻴﺮ اﻟﻰ ﺑﺎﻻﺿﺎﻓﺔ ،اﻟﺘﻮاﻟﻲ ،ﻋﻠﻰ واﻟﻨﻌﻨﺎع ،اﻟﺰﻋﺘﺮ ،اﻻردﻧﻲ اﻟﺒﺎﺑﻮﻧﺞ ،اﻻﻟﻤﺎﻧﻲ اﻟﺒﺎﺑﻮﻧﺞ ،اﻟﻤﻴﺮﻣﻴﺔ ﻣﻦ ﻟﻜﻞ ﻟﻠﻤﻴﺎﻩ اﻟﻌﺎﻟﻲ. اﻻزه اﻧﺘﺎج ﺗﻔﻮق وﻗﺪ ﺑﺤﻮاﻟﻲ ﺗﺮﺑﺔ ﺑﺪون ﺑﺎﻟﺰراﻋﺔ اﻟﻤﺰروع اﻻردﻧﻲ واﻟﺒﺎﺑﻮﻧﺞ اﻻﻟﻤﺎﻧﻲ اﻟﺒﺎﺑﻮﻧﺞ ﻓﻲ ﺎر 199 و 334 % ، ﺑﺎﻟﺘﺮﺑﺔ اﻟﻤﺰروع ذﻟﻚ ﻋﻦ ،اﻟﺘﻮاﻟﻲ ﻋﻠﻰ. ﻧﺎﺟﺤﺎ آﺎن اﻟﻤﺪروﺳﺔ اﻟﻨﺒﺎﺗﺎت إﻧﺘﺎج ﻓﻲ ﺗﺮﺑﺔ ﺑﺪون اﻟﺰراﻋﺔ ﺗﻘﻨﻴﺔ اﺳﺘﺨﺪام إن ﻋﻠﻰ ﻳﺪل وهﺬا اﻟﺘﻘﻨﻴ هﺬﻩ اﺳﺘﺨﺪام ﺑﺎﻻﻣﻜﺎن واﻧﻪ ،آﺒﻴﺮ ﺑﺸﻜﻞ اﻟﻌﺮﺑﻲ اﻟﺨﻠﻴﺞ ﻣﻨﻄﻘﺔ ﻓﻲ اﻟﻬﺎﻣﺔ اﻷﺧﺮى اﻟﻄﺒﻴﺔ اﻟﻨﺒﺎﺗﺎت زراﻋﺔ ﻓﻲ ﺔ. اﻟﻤﻔﺘﺎﺣﻴﺔ اﻟﻜﻠﻤﺎت : اﻟﺒﺤﺮﻳﻦ ،ﻟﻠﺰراﻋﺔ ﻗﺎﺑﻮس اﻟﺴﻠﻄﺎن ﻣﺮآﺰ ،اﻟﻤﺎﺋﻴﺔ اﻟﺰراﻋﺔ ،اﻟﻨﻌﻨﺎع ،اﻟﺒﺎﺑﻮﻧﺞ ،اﻟﻤﻴﺮﻣﻴﺔ ،اﻟﺰﻋﺘﺮ .
Effective nutrition and irrigation are important nursery strategies to produce high-quality seedl... more Effective nutrition and irrigation are important nursery strategies to produce high-quality seedlings able to withstand heat and drought stress in the field. The objectives of this study were 2-fold, first to identify the influence of two nitrogen (N) levels (75 and 150 mg · L L1) and two fertigation (FR) methods, overhead (OH) and flotation (FL) of artichoke (Cynara cardunculus cv. Green Globe Improved) transplants on root/shoot growth and leaf physiology during the nursery period. A repeated greenhouse experiment was conducted and morphophysiological measurements were determined at 4 and 7 weeks after seeding (WAS). The second objective was to determine the impact of the nursery treatments (FR method and N level) on the subsequent crop growth and yield under three field irrigation methods [surface drip, subsurface drip, and overhead-linear system (OH-L)]. Field measurements were conducted at 50 and 150 days after field transplanting (DAT) during Fall-Winter 2015. Transplants fertilized with 75 mg · L L1 N (low N) had improved root components as compared to those with 150 mg · L L1 N (high N), especially at 4 WAS. The low N transplants had higher root surface area, root length, root branching, thinner root diameter, and less shoot area than the high N transplants. Wilting for low N transplants was 13.5% less than that for high N at 5 DAT, with a total yield similar or slightly higher than those of high N. Although growth of OH and FL transplants was statistically similar at transplanting, those irrigated with OH (greenhouse) had a 10% higher yield than FL irrigated transplants, regardless of the field irrigation method evaluated. Overall, low N level (75 mg · L L1 N) applied with OH irrigation in the nursery positively improved the transplant root system and transplant quality of artichoke seedlings.
Lily growers adapt intensive fertigation programs to produce superior flowers, which raises subst... more Lily growers adapt intensive fertigation programs to produce superior flowers, which raises substrate salinity and input cost. Soil salinity negatively impact growth and productivity and lead to several environmental problems. The objective of this study was to evaluate the effectiveness of K + (applied as K2SO4 drench application) in ameliorating the negative effects of irrigation-saline water in Asiatic lily growth, physiology, and flower quality. Both lily cultivars bulbs were grown in 10 L pots filled with 3:1 peat moss: perlite. Treatments were three levels of irrigation saline water (electrical conductivity (EC), 0.5 (control), 3.0 and 6 dS m-1) and two K (applied as K2SO4) concentrations 10 and 15 mmol l-1. Irrigation with saline water significantly increased soil salinity and pH, especially in 6 dS m-1 salt level. As a result, the 6.0 dS m-1 treatment reduced stem diameter, plant height and total leaf area. In addition, gas exchange (specifically, Pn and E) in control (0.5 dS m-1) plants during the vegetative stage was significantly higher than the 6.0 dS m-1 treatment. During flowering, irrigation with 6.0 dS m-1 saline water significantly reduced flower number per stem, H* color coordinate and flower diameter. Interestingly, the response of lily flower to moderate salt stress (3 dS m-1) was similar to control (0.5 dS m-1) treatment. The 3 dS m-1 sa-linity treatment had similar color density coordinates (L*, C*, H*), days to flowering, and flower longevity when compared to control (0.5 dS m-1). Additionally, K2SO4 treatment (15 mmol l-1) potentially improved lily growth (gas exchange and stem diameter) during vegetative stage. Overall, irrigation with moderate levels of salts (3 dS m-1) has no negative impact on lily growth and productivity. Furthermore, supplementary K + applied as K2SO4 (15 mmol l-1) can alleviate the negative impact of salinity during the vegetative growth.
A field study was conducted to determine the effect of arbuscular mycorrhizal (AM) fungi
inoculat... more A field study was conducted to determine the effect of arbuscular mycorrhizal (AM) fungi inoculation on bulb yield and mineral acquisition of two onion (Alium cepa L.) cultivars (Giza 20 and Texas Grano) grown under well-watered and water-stressed conditions. Onion seedlings were transplanted into planting furrows after treatment with or without the AM fungi Glomus mosseae or G. fasciculatum. Root colonization with AM fungi occurred in both cultivars under waterstressed and well-watered conditions, but the extent of AM fungi root colonization was higher under well-watered than under water-stressed conditions. Water stress had significantly reduced bulb yields and mineral acquisition in both cultivars either inoculated or un-inoculated plants. However, inoculation with AM fungi has improved onion bulb yield and mineral acquisition (P, Cu, Fe and Zn concentrations) irrespective soil moisture. The results indicated that Texas Grano cultivar benefited more than Giza 20 cultivar from AM fungi inoculation especially under water-stressed conditions. The improved yield and mineral acquisition due to AM fungi inoculation demonstrated the importance of mycorrhizal inoculation to reduce the effects of drought stress on onion grown under field conditions in dry and semi-dry areas.
Plastic house shading could have unpredictable effects on plant growth, fruit quality, production... more Plastic house shading could have unpredictable effects on plant growth, fruit quality, production and insect pest infestation. A plastic house experiment was conducted in Jordan Valley in Jordan to assess the impact of two shading treatments on cucumber yield production, quality and pest populations. Shading treatments were green shadow (GS), plaster (P) (calcium carbonate) and control (no shading). Results showed that shading had a significant impact on light intensity inside the plastic house, whitefly and mite infestations, leaf-level physiology and fruit yield and quality. Both GS and P significantly reduced light intensity (permeabil-ity) inside the greenhouse. Whitefly and mite infestations were statistically higher in control compared to GS and P treatments. Additionally, GS treatment had higher fruit yield compared to P and control. Althoughcontrol treatment had higher photosynthe-sis ratethan shade treatments (green and white). The same plants (control) had lower yield and fruit quality than green and white shade treatments. In fact, shading increased fruit weight, length, color darkness, total soluble solids and firmness compared to un-shaded control fruit. Therefore, it is concluded that plastic house shading using GS might potentially reduce insect infestation and improve fruit yield and quality in cucumber during summer time.
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Papers by Yahia Othman
to large areas, and provide significant and reliable information on water use and
irrigation management. The objectives of this study were to screen leaf-level physiological
changes that occur during the cyclic irrigation of pecan orchards to determine
which responses best represent changes in moisture status of plants and link plant
physiological changes to remotely sensed surface reflectance data derived from the
Landsat Thematic Mapper and Enhanced Thematic Mapper Plus (ETM+). The study
was conducted simultaneously on two southern New Mexico mature pecan orchards.
For both orchards, plant physiological responses and remotely sensed surface reflectance
data were collected from trees that were either well watered or in water deficit.
Remotely sensed variables included reflectance in band 1, the ratio between shortwave
infrared (SWIR) bands (B5:B7), the normalized difference vegetation index, and
SWIR moisture indices. Midday stem water potential (Ψsmd) was the best performing
leaf-level physiological response variable for detecting moisture status in pecans. The
B5:B7 ratio positively and significantly correlated with Ψsmd in five of six irrigation
cycles while multiple linear regression weighted with six remotely sensed surface
reflectance variables revealed a significant relationship with moisture status in all
cycles in both orchards (R2 > 0.73). Because changes in the B5:B7 band ratio and
multiple regression of spectral variables correlate with the moisture status of pecan
orchards, we conclude that remotely sensed data hold promise for detecting the
moisture status of pecans.
inoculation on bulb yield and mineral acquisition of two onion (Alium cepa L.) cultivars (Giza 20
and Texas Grano) grown under well-watered and water-stressed conditions. Onion seedlings were
transplanted into planting furrows after treatment with or without the AM fungi Glomus mosseae
or G. fasciculatum. Root colonization with AM fungi occurred in both cultivars under waterstressed
and well-watered conditions, but the extent of AM fungi root colonization was higher
under well-watered than under water-stressed conditions. Water stress had significantly reduced
bulb yields and mineral acquisition in both cultivars either inoculated or un-inoculated plants.
However, inoculation with AM fungi has improved onion bulb yield and mineral acquisition (P, Cu,
Fe and Zn concentrations) irrespective soil moisture. The results indicated that Texas Grano cultivar
benefited more than Giza 20 cultivar from AM fungi inoculation especially under water-stressed
conditions. The improved yield and mineral acquisition due to AM fungi inoculation demonstrated
the importance of mycorrhizal inoculation to reduce the effects of drought stress on onion grown
under field conditions in dry and semi-dry areas.
to large areas, and provide significant and reliable information on water use and
irrigation management. The objectives of this study were to screen leaf-level physiological
changes that occur during the cyclic irrigation of pecan orchards to determine
which responses best represent changes in moisture status of plants and link plant
physiological changes to remotely sensed surface reflectance data derived from the
Landsat Thematic Mapper and Enhanced Thematic Mapper Plus (ETM+). The study
was conducted simultaneously on two southern New Mexico mature pecan orchards.
For both orchards, plant physiological responses and remotely sensed surface reflectance
data were collected from trees that were either well watered or in water deficit.
Remotely sensed variables included reflectance in band 1, the ratio between shortwave
infrared (SWIR) bands (B5:B7), the normalized difference vegetation index, and
SWIR moisture indices. Midday stem water potential (Ψsmd) was the best performing
leaf-level physiological response variable for detecting moisture status in pecans. The
B5:B7 ratio positively and significantly correlated with Ψsmd in five of six irrigation
cycles while multiple linear regression weighted with six remotely sensed surface
reflectance variables revealed a significant relationship with moisture status in all
cycles in both orchards (R2 > 0.73). Because changes in the B5:B7 band ratio and
multiple regression of spectral variables correlate with the moisture status of pecan
orchards, we conclude that remotely sensed data hold promise for detecting the
moisture status of pecans.
inoculation on bulb yield and mineral acquisition of two onion (Alium cepa L.) cultivars (Giza 20
and Texas Grano) grown under well-watered and water-stressed conditions. Onion seedlings were
transplanted into planting furrows after treatment with or without the AM fungi Glomus mosseae
or G. fasciculatum. Root colonization with AM fungi occurred in both cultivars under waterstressed
and well-watered conditions, but the extent of AM fungi root colonization was higher
under well-watered than under water-stressed conditions. Water stress had significantly reduced
bulb yields and mineral acquisition in both cultivars either inoculated or un-inoculated plants.
However, inoculation with AM fungi has improved onion bulb yield and mineral acquisition (P, Cu,
Fe and Zn concentrations) irrespective soil moisture. The results indicated that Texas Grano cultivar
benefited more than Giza 20 cultivar from AM fungi inoculation especially under water-stressed
conditions. The improved yield and mineral acquisition due to AM fungi inoculation demonstrated
the importance of mycorrhizal inoculation to reduce the effects of drought stress on onion grown
under field conditions in dry and semi-dry areas.