The effect of N form and solution pH on the carboxylic and phenolic acid content of cranberry (Va... more The effect of N form and solution pH on the carboxylic and phenolic acid content of cranberry (Vaccinium macrocarpon Ait. cv. Searles) shoots and roots was determined in a greenhouse experiment. The predominant carboxylic acids measured were malate and citrate. Protocatechuic acid was the dominant phenolic acid detected. Total organic acid concentrations were unaffected by N form supplied. In shoots, higher total concentrations of organic acids were found at pH 4.5 than at 6.5 in the shoot, but there was little pH effect in the roots.
Winter annual cover crops, winter rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth), c... more Winter annual cover crops, winter rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth), can reduce weed density and build soil quality in organic production systems. There is interest in integrating cover crops and reduced tillage with organic vegetable production, but few studies have been conducted in regions with short growing seasons and cool soils such as the upper Midwest. We evaluated no-tillage production of tomato (Solanum lycopersicum L.), zucchini (Cucurbita pepo L.), and bell pepper (Capsicum annuum L.) planted into winter rye, hairy vetch, and a winter rye/hairy vetch (WR/HV) mixture that were mechanically suppressed with a roller–crimper at two locations in Minnesota. Average marketable yields of tomato, zucchini, and bell pepper in the rolled cover crops were reduced 89%, 77%, and 92% in 2008 and 65%, 41%, and 79% in 2009, respectively, compared with a no-cover control. Winter rye and the WR/HV mixture reduced average annual weed density at St. Paul by 96% for...
... 1993, 27, 1943-1946 Rapid Hydrolysis of Atrazine to Hydroxyatrazine by Soil Bacteria Raphl T.... more ... 1993, 27, 1943-1946 Rapid Hydrolysis of Atrazine to Hydroxyatrazine by Soil Bacteria Raphl T. Mandelbaum,tl* Lawrence P. Wackett,'gt and Deborah L. Allan ... Literature Cited (1) Gianessi, LP Resources 1987, 89, 1-4. (2) Kaufman, DD; Kearney, P. C. Residue Rev. ...
Proteoid roots are a unique adaptation that allow white lupin (Lupinus albus L. var Ultra) to sur... more Proteoid roots are a unique adaptation that allow white lupin (Lupinus albus L. var Ultra) to survive under extreme phosphorus (P) deficient conditions. The cascade of events that signals P-deficiency induced gene expression in proteoid roots remains unknown. Through promoter::GUS analysis we showed that expression of acid phosphatase (LaSAP1) in P-deficient proteoid roots depends on DNA located from −465 bp to
Plant Nutrition — Physiology and Applications, 1990
AGRIS record. Record number, NL9003405. Titles, Role of root cell walls in iron deficiency of soy... more AGRIS record. Record number, NL9003405. Titles, Role of root cell walls in iron deficiency of soybean (Glycine max) and aluminium toxicity of wheat (Triticum aestivum). Personal Authors, Allan, DL (Minnesota Univ., St. Paul, MN (USA). Dept. ...
Enrichment cultures containing atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) a... more Enrichment cultures containing atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) at a concentration of 100 ppm (0.46 mM) as a sole nitrogen source were obtained from soils exposed to repeated spills of atrazine, alachlor, and metolachlor. Bacterial growth occurred concomitantly with formation of metabolites from atrazine and subsequent biosynthesis of protein. When ring-labeled [14C]atrazine was used, 80% or more of the s-triazine ring carbon atoms were liberated as 14CO2. Hydroxyatrazine may be an intermediate in the atrazine mineralization pathway. More than 200 pure cultures isolated from the enrichment cultures failed to utilize atrazine as a nitrogen source. Mixing pure cultures restored atrazine-mineralizing activity. Repeated transfer of the mixed cultures led to increased rates of atrazine metabolism. The rate of atrazine degradation, even at the elevated concentrations used, far exceeded the rates previously reported in soils, waters, and mixed and pure cultu...
*White lupin (Lupinus albus) forms specialized cluster roots characterized by exudation of organi... more *White lupin (Lupinus albus) forms specialized cluster roots characterized by exudation of organic anions under phosphorus (P) deficiency. Here, the role of nitric oxide (NO) in P deficiency-induced cluster-root formation and citrate exudation was evaluated. *White lupin plants were treated with the NO donor sodium nitroprusside (SNP) and scavenger or inhibitor of NO synthase under conditions of P deficiency (0 muM) or P sufficiency (50 muM). *Phosphorus deficiency enhanced NO production in primary and lateral root tips, with a greater increase in cluster roots than in noncluster roots. NO concentrations decreased with cluster root development from the pre-emergent stage, through the juvenile stage, to the mature stage. The P deficiency-induced increase in NO production was inhibited by antagonists of NO synthase and xanthine oxidoreductase, suggesting the involvement of these enzymes in NO production. SNP markedly increased the number of cluster roots. Citrate exudation from different root segments in P-deficient roots was positively correlated with endogenous root NO concentrations. *These findings demonstrate differential patterns of NO production in white lupin, depending on root zone, developmental stage and P nutritional status. NO appears to play a regulatory role in the formation of cluster roots and citrate exudation in white lupin under conditions of P deficiency.
Abstract Chelator-buffering methods with N-(2-hydroxyethyl) ethylenedinitrilotriacetic acid (HEDT... more Abstract Chelator-buffering methods with N-(2-hydroxyethyl) ethylenedinitrilotriacetic acid (HEDTA) are used to elucidate Poaceae growth response to micronutrient metal activities including (Zn 2+), but reliable hydroponic methods that maintain stable (Zn 2+) for ...
Rhizodeposition has been proposed as one mechanism for the accumulation of significant amounts of... more Rhizodeposition has been proposed as one mechanism for the accumulation of significant amounts of N in soil during legume growth. The objective of this experiment was to directly quantify losses of symbiotically fixed N from living alfalfa (Medicago sativa L.) roots to the rhizosphere. We used 15N-labeled N2 gas to tag recently fixed N in three alfalfa lines [cv. Saranac, Ineffective Saranac (an ineffectively nodulated line), and an unnamed line in early stages of selection for apparent N excretion] growing in 1-m long polyvinylchloride drainage lysimeters in loamy sand soil in a greenhouse. Plants were in the late vegetative to flowering growth stage during the 2-day labelling period. We determined the fate of this fixed N in various plant organs and soil after a short equilibration period (2 to 4 days) and after one regrowth period (35 to 37 days). Extrapolated N2 fixation rates (46 to 77μg plant−1 h−1) were similar to rates others have measured in the field. Although there was significant accretion of total N in rhizosphere compared to bulk soil, less than 1% was derived from newly fixed N and there were no differences between the ‘excreting’ line and Saranac. Loss of N in percolate water was small. These results provide the first direct evidence that little net loss of symbiotically-fixed N occurs from living alfalfa roots into surrounding soil. In addition, these results confirm our earlier findings, which depended on indirect 15N labelling techniques. Net N accumulation in soil during alfalfa growth is likely due to other processes, such as decomposition of roots, nodules, and above ground litter, rather than to N excretion from living roots and nodules.
The effect of N form and solution pH on the carboxylic and phenolic acid content of cranberry (Va... more The effect of N form and solution pH on the carboxylic and phenolic acid content of cranberry (Vaccinium macrocarpon Ait. cv. Searles) shoots and roots was determined in a greenhouse experiment. The predominant carboxylic acids measured were malate and citrate. Protocatechuic acid was the dominant phenolic acid detected. Total organic acid concentrations were unaffected by N form supplied. In shoots, higher total concentrations of organic acids were found at pH 4.5 than at 6.5 in the shoot, but there was little pH effect in the roots.
Winter annual cover crops, winter rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth), c... more Winter annual cover crops, winter rye (Secale cereale L.) and hairy vetch (Vicia villosa Roth), can reduce weed density and build soil quality in organic production systems. There is interest in integrating cover crops and reduced tillage with organic vegetable production, but few studies have been conducted in regions with short growing seasons and cool soils such as the upper Midwest. We evaluated no-tillage production of tomato (Solanum lycopersicum L.), zucchini (Cucurbita pepo L.), and bell pepper (Capsicum annuum L.) planted into winter rye, hairy vetch, and a winter rye/hairy vetch (WR/HV) mixture that were mechanically suppressed with a roller–crimper at two locations in Minnesota. Average marketable yields of tomato, zucchini, and bell pepper in the rolled cover crops were reduced 89%, 77%, and 92% in 2008 and 65%, 41%, and 79% in 2009, respectively, compared with a no-cover control. Winter rye and the WR/HV mixture reduced average annual weed density at St. Paul by 96% for...
... 1993, 27, 1943-1946 Rapid Hydrolysis of Atrazine to Hydroxyatrazine by Soil Bacteria Raphl T.... more ... 1993, 27, 1943-1946 Rapid Hydrolysis of Atrazine to Hydroxyatrazine by Soil Bacteria Raphl T. Mandelbaum,tl* Lawrence P. Wackett,'gt and Deborah L. Allan ... Literature Cited (1) Gianessi, LP Resources 1987, 89, 1-4. (2) Kaufman, DD; Kearney, P. C. Residue Rev. ...
Proteoid roots are a unique adaptation that allow white lupin (Lupinus albus L. var Ultra) to sur... more Proteoid roots are a unique adaptation that allow white lupin (Lupinus albus L. var Ultra) to survive under extreme phosphorus (P) deficient conditions. The cascade of events that signals P-deficiency induced gene expression in proteoid roots remains unknown. Through promoter::GUS analysis we showed that expression of acid phosphatase (LaSAP1) in P-deficient proteoid roots depends on DNA located from −465 bp to
Plant Nutrition — Physiology and Applications, 1990
AGRIS record. Record number, NL9003405. Titles, Role of root cell walls in iron deficiency of soy... more AGRIS record. Record number, NL9003405. Titles, Role of root cell walls in iron deficiency of soybean (Glycine max) and aluminium toxicity of wheat (Triticum aestivum). Personal Authors, Allan, DL (Minnesota Univ., St. Paul, MN (USA). Dept. ...
Enrichment cultures containing atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) a... more Enrichment cultures containing atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) at a concentration of 100 ppm (0.46 mM) as a sole nitrogen source were obtained from soils exposed to repeated spills of atrazine, alachlor, and metolachlor. Bacterial growth occurred concomitantly with formation of metabolites from atrazine and subsequent biosynthesis of protein. When ring-labeled [14C]atrazine was used, 80% or more of the s-triazine ring carbon atoms were liberated as 14CO2. Hydroxyatrazine may be an intermediate in the atrazine mineralization pathway. More than 200 pure cultures isolated from the enrichment cultures failed to utilize atrazine as a nitrogen source. Mixing pure cultures restored atrazine-mineralizing activity. Repeated transfer of the mixed cultures led to increased rates of atrazine metabolism. The rate of atrazine degradation, even at the elevated concentrations used, far exceeded the rates previously reported in soils, waters, and mixed and pure cultu...
*White lupin (Lupinus albus) forms specialized cluster roots characterized by exudation of organi... more *White lupin (Lupinus albus) forms specialized cluster roots characterized by exudation of organic anions under phosphorus (P) deficiency. Here, the role of nitric oxide (NO) in P deficiency-induced cluster-root formation and citrate exudation was evaluated. *White lupin plants were treated with the NO donor sodium nitroprusside (SNP) and scavenger or inhibitor of NO synthase under conditions of P deficiency (0 muM) or P sufficiency (50 muM). *Phosphorus deficiency enhanced NO production in primary and lateral root tips, with a greater increase in cluster roots than in noncluster roots. NO concentrations decreased with cluster root development from the pre-emergent stage, through the juvenile stage, to the mature stage. The P deficiency-induced increase in NO production was inhibited by antagonists of NO synthase and xanthine oxidoreductase, suggesting the involvement of these enzymes in NO production. SNP markedly increased the number of cluster roots. Citrate exudation from different root segments in P-deficient roots was positively correlated with endogenous root NO concentrations. *These findings demonstrate differential patterns of NO production in white lupin, depending on root zone, developmental stage and P nutritional status. NO appears to play a regulatory role in the formation of cluster roots and citrate exudation in white lupin under conditions of P deficiency.
Abstract Chelator-buffering methods with N-(2-hydroxyethyl) ethylenedinitrilotriacetic acid (HEDT... more Abstract Chelator-buffering methods with N-(2-hydroxyethyl) ethylenedinitrilotriacetic acid (HEDTA) are used to elucidate Poaceae growth response to micronutrient metal activities including (Zn 2+), but reliable hydroponic methods that maintain stable (Zn 2+) for ...
Rhizodeposition has been proposed as one mechanism for the accumulation of significant amounts of... more Rhizodeposition has been proposed as one mechanism for the accumulation of significant amounts of N in soil during legume growth. The objective of this experiment was to directly quantify losses of symbiotically fixed N from living alfalfa (Medicago sativa L.) roots to the rhizosphere. We used 15N-labeled N2 gas to tag recently fixed N in three alfalfa lines [cv. Saranac, Ineffective Saranac (an ineffectively nodulated line), and an unnamed line in early stages of selection for apparent N excretion] growing in 1-m long polyvinylchloride drainage lysimeters in loamy sand soil in a greenhouse. Plants were in the late vegetative to flowering growth stage during the 2-day labelling period. We determined the fate of this fixed N in various plant organs and soil after a short equilibration period (2 to 4 days) and after one regrowth period (35 to 37 days). Extrapolated N2 fixation rates (46 to 77μg plant−1 h−1) were similar to rates others have measured in the field. Although there was significant accretion of total N in rhizosphere compared to bulk soil, less than 1% was derived from newly fixed N and there were no differences between the ‘excreting’ line and Saranac. Loss of N in percolate water was small. These results provide the first direct evidence that little net loss of symbiotically-fixed N occurs from living alfalfa roots into surrounding soil. In addition, these results confirm our earlier findings, which depended on indirect 15N labelling techniques. Net N accumulation in soil during alfalfa growth is likely due to other processes, such as decomposition of roots, nodules, and above ground litter, rather than to N excretion from living roots and nodules.
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