Yield potential

a DIIAR c/o Polo of Como, Politecnico of Milan, Piazza Leonardo Da Vinci 32, 20133 Milano, Italy ludovico.biagi@polimi.it b DIMeC, University of Modena and Reggio Emilia, via Vignolese 905/B, 41100 Modena, Italy (marco.dubbini, capra.alessandro, cristina.castagnetti)@unimore.it c Department of Mathematics, University of Modena and Reggio Emilia, Via Campi 213/B, 41100 Modena, Italy francesco.unguendoli@unimore.it

Cassava or manioc (Manihot esculenta Crantz), a perennial shrub of the New World, currently is the sixth world food crop for more than 500 million people in tropical and sub-tropical Africa, Asia and Latin America. It is cultivated mainly by resource-limited small farmers for its starchy roots, which are used as human food either fresh when low in cyanogens or in many processed forms and products, mostly starch, flour, and for animal feed. Because of its inherent tolerance to stressful environments, where other food crops would fail, it is often considered a food-security source against famine, requiring minimal care. Under optimal environmental conditions, it compares favorably in production of energy with most other major staple food crops due to its high yield potential. Recent research at the Centro Internacional de Agricultura Tropical (CIAT) in Colombia has demonstrated the ability of cassava to assimilate carbon at very high rates under high levels of humidity, temperature and solar radiation, which correlates with productivity across all environments whether dry or humid. When grown on very poor soils under prolonged drought for more than 6 months, the crop reduce both its leaf canopy and transpiration water loss, but its attached leaves remain photosynthetically active, though at greatly reduced rates. The main physiological mechanism underlying such a remarkable tolerance to drought was rapid stomatal closure under both atmospheric and edaphic water stress, protecting the leaf against dehydration while the plant depletes available soil water slowly during long dry periods. This drought tolerance mechanism leads to high crop water use efficiency values. Although the cassava fine root system is sparse, compared to other crops, it can penetrate below 2 m soil, thus enabling the crop to exploit deep water if available. Leaves of cassava and wild Manihot possess elevated activities of the C4 enzyme PEP carboxylase but lack the leaf Kranz anatomy typical of C4 species, pointing to the need for further research on cultivated and wild Manihot to further improve its photosynthetic potential and yield, particularly under stressful environments. Moreover, a wide range in values of K m (CO2) for the C3 photosynthetic enzyme Rubisco was found among cassava cultivars indicating the possibility of selection for higher affinity to CO2, and consequently higher leaf photosynthesis. Several plant traits that may be of value in crop breeding and improvement have been identified, such as an extensive fine root system, long leaf life, strong root sink and high leaf photosynthesis. Selection of parental materials for tolerance to drought and infertile soils under representative field conditions have resulted in developing improved cultivars that have high yields in favorable environments while producing reasonable and stable yields under stress.

The food legume crops play a crucial role in terms of food and nutritional security and are an important pillar of sustainable food production globally. Food legume crops are important components of cropping systems and provide an opportunity to produce diversified food products for human consumption. Inclusion of these crops into agricultural production systems increases the profitability of cropping systems globally. Their role will be more predominant in the years to come under climate change due to changes in planting environments, increased levels of abiotic stresses, increased demand on these crops in consumption, etc. The present level of productivity of these crops is low firstly because of greater susceptibility to biotic and abiotic stresses. Secondly, they are cultivated on marginal lands under poor environments. Thirdly, low inputs are often applied to them by farming communities during the cropping season. Fourthly, they have indeterminate growth habit and poor genetic yield potential in comparison to cereals. Fifthly, there is often non- adoption of integrated crop production and management technologies by the legume growers. Thus a big challenge is visible to increase the production/productivity of these crops in future particularly when changing climates are overlain on their production areas. The demand for these crops will not decrease in years to come due to the vegetarian eating habits in the Indian sub-continent and in other developing countries, as animal meat is beyond the reach of poor people. So there is a big question in front of policy makers, administrators, scientists, traders and farmers with respect to how to increase the productivity of these crops to meet the future demand for legumes. Therefore, it will be more appropriate to adopt the simplest improved approaches which can be implemented in many countries by the farming communities without much deviation in the existing cropping system to mitigate the climatic changes. After proper scientific analysis of different options and approaches discussed in this chapter it was concluded that integrated crop production and management technologies can be adopted in the future by farming communities globally. Thus it is being recommended that integrated management in legume crops production system should be introduced at a global level to sustain the international legumes production and demand in years to come.

Chickpea is a cool season grain legume of exceptionally high nutritive value and most versatile food use. It is mostly grown under rain fed conditions in arid and semi-arid areas around the world. Despite growing demand and high yield potential, chickpea yield is unstable and productivity is stagnant at unacceptably low levels. Major yield increases could be achieved by development and use of cultivars that resist/tolerate abiotic and biotic stresses. In recent years the wide use of early maturing cultivars that escape drought stress led to significant increases in chickpea productivity. In the Mediterranean region, yield could be increased by shifting the sowing date from spring to winter. However, this is hampered by the sensitivity of the crop to low temperatures and the fungal pathogen Ascochyta rabiei. Drought, pod borer (Helicoverpa spp.) and the fungus Fusarium oxysporum additionally reduce harvests there and in other parts of the world. Tolerance to rising salinity will be a future advantage in many regions. Therefore, chickpea breeding focuses on increasing yield by pyramiding genes for resistance/tolerance to the fungi, to pod borer, salinity, cold and drought into elite germplasm. Progress in breeding necessitates a better understanding of the genetics underlying these traits. Marker-assisted selection (MAS) would allow a better targeting of the desired genes. Genetic mapping in chickpea, for a long time hampered by the little variability in chickpea’s genome, is today facilitated by highly polymorphic, co-dominant microsatellite-based markers. Their application for the genetic mapping of traits led to inter-laboratory comparable maps. This paper reviews the current situation of chickpea genome mapping, tagging of genes for ascochyta blight, fusarium wilt resistance and other traits, and requirements for MAS. Conventional breeding strategies to tolerate/avoid drought and chilling effects at flowering time, essential for changing from spring to winter sowing, are described. Recent approaches and future prospects for functional genomics of chickpea are discussed.

Sub-Saharan Africa has been portrayed as the most vulnerable region to the impacts of global climate change because of its reliance on agriculture which is highly sensitive to weather and climate variables such as temperature, precipitation, and light and extreme events and low capacity for adaptation. This article reviews evidence on the scope and nature of the climate change challenge; and assesses the impact of climate change on agriculture and food security in Sub-Saharan Africa. From the review, it is apparent that the climate in Africa is already exhibiting significant changes, evident by changes in average temperature, change in amount of rainfall and patterns and the prevalence of frequency and intensity of weather extremes. The review also revealed that although uncertainties exist with regards to the magnitude of impacts, climate will negatively affect agricultural production in Sub-Saharan Africa. Specifically, as result of current and expected climate change, the area suitable for agriculture, the length of growing seasons and yield potential, particularly along the margins of semi-arid and arid areas, are expected to decrease. These impacts will affect all components of food security: food availability, food accessibility, food utilisation and food stability and hence increase the risk of hunger in the region. The review thus confirms the general consensus that Sub-Saharan Africa is the most vulnerable region to climate change. It suggests that, policymakers and development agencies should focus on formulating and implementing policies and programmes that promote farm level adaptation strategies currently being practiced by farmers across the region.

Yukon Gem is a yellow-fleshed, medium to early-maturing cultivar suitable for fresh-pack or processing with a high level of resistance to potato virus YO, and moderate foliar and tuber resistance to late blight. Multiple trials demonstrated a higher yield potential than Yukon Gold (yellow-fleshed industry standard). Yukon Gem produces uniform attractive tubers with light yellow skin and splashes of pink around the eyes; with flesh color similar to Yukon Gold. Yukon Gem was obtained from the intercrossing of Brodick and Yukon Gold at North Dakota State University (NDSU). An NDSU seedling tuber was sent and selected at Aberdeen, ID in 1995 and designated NDA5507-3YF. It advanced through the Aberdeen potato breeding program and regional trials in the western and northwestern U.S. Yukon Gem was released in 2006 by the USDA-ARS and the Agricultural Experiment Stations of Idaho, Oregon, and Washington, and is a product of the Northwest Potato Variety (Tri-State) Development Program. Yukon Gem es una variedad de pulpa amarilla, de ciclo medio a temprano, ideal para empaque fresco o para proceso con un alto nivel de resistencia al virus YO, con moderada resistencia del follaje y del tubérculo al tizón tardío. Se ha demostrado en múltiples ensayos un potencial de rendimiento más alto que Yukon Gold (pulpa amarilla, estándar para la industria). Yukon Gem produce tubérculos uniformes atractivos con piel ligeramente amarilla y algo de rosado alrededor de los ojos; con color de pulpa similar al de Yukon Gold. Yukon Gem se obtuvo del entrecruzamiento de Brodick y Yukon Gold en la Universidad Estatal de Dakota del Norte (NDSU). Se envió un minitubérculo de NDSU y se seleccionó en Aberdeen, ID en 1995, designándosele NDA5507-3YF. Avanzó a lo largo del programa de mejoramiento de papa de Aberdeen y en las pruebas regionales en el oeste y noroeste de EUA. Yukon Gem se liberó en el 2006 por el USDA-ARS y por las Estaciones Agrícolas Experimentales de Idaho, Oregon, y Washington, y es un producto del Programa de Desarrollo de Variedades de Papa del Noroeste (Tri-State).

Mark A. Frahm1, Juan Carlos Rosas2, Netzahualcoyotl Mayek-Pérez3, Ernesto López-Salinas4, Jorge A. Acosta-Gallegos5 & James D. Kelly1,∗ 1Dept. of Crop and Soil Sci., Michigan State Univ., E. Lansing, MI 48824; 2EAP / Zamorano, PO Box 93, ...