Mechanisms of potassium uptake efficiency and dynamics in the rhizosphere of safflower and sunflower in different soils

Potassium uptake efficiency of safflower and sunflower was studied under semi-controlled conditions in loamy and sandy soils. Both species performed better in loamy soil. Safflower had higher agronomic efficiency and higher relative root length under suboptimal K supply. Safflower had higher specific root density and less root radius at all K levels. Safflower had higher relative root-shoot ratio under suboptimal K in loamy soil. Both species had similar K-influx at low and optimal K in loamy soil, while sunflower had higher influx under suboptimal and optimal supplies in sandy soil. Safflower had higher shoot demand in both soils under suboptimal and optimal K. Both species depleted similar amounts of soil solution-K under suboptimal K in sandy soil, while sunflower was more efficient under suboptimal levels in loamy soils. Sunflower depleted more extractable-K under both suboptimal and optimal K. Safflower could be considered K-uptake efficient crop.Acknowledgments Technical support by Mrs. Susane Koch in Department of Plant Nutrition and Yield Physiology, University of G€ottingen, Germany is gratefully acknowledged for her help in plant and soil samples analysis. Funding Financial support for this study was obtained from the German Academic Exchange Service (DAAD), Palestinian funding program for research and training “ZAMALAH,” and the Dutch EP-NUFFIC through NICHE-233 project

Mechanisms of Phosphorous Uptake Efficiency of Safflower and Sunflower Grown in Different Soils

Plant species vary in their phosphorous (P) use efficiency under suboptimal P supplies using different strategies, but the mechanisms are not clearly documented for some alternative plant species. Safflower was considered as low input oil crop, but its P uptake efficiency mechanism was not fully investigated. Therefore P uptake efficiency of safflower was studied as compared to sunflower under semi-controlled conditions in sandy and loamy soils. Both species responded strongly to increasing P supplies in both soils and performed better in loamy soil. Both species had similar agronomic P efficiency in both soils, indicated by similar external P requirement under P-deficient conditions. Under P deficiency, safflower had less relative shoot and root production when they were grown in sandy soils and the opposite was found in terms of loamy soil. Safflower had the disadvantage of less root length and root shoot ratio in both soils under low and high P supplies but had the advantage of higher specific root density, less root radius, and slower shoot growth rate. Under P deficiency in both soil types, both species responded similarly in terms of P influx, depleting P from soil solution and P concentration in shoots. Under high P supply, P influx and P concentration in shoots was less in safflower in both soil types. Safflower was characterized by higher shoot demand on roots for P under low and high P supplies in both soil types. Therefore the cause of high root demand on P in safflower roots at low and high P supplies stems from the low root shoot ratio of safflower at both P supplies, low P concentration and low P influx of safflower at high P supplies not because of higher shoot growth rate of safflower at low and high P supplies. Therefore using different measures of utilization efficiency parameters to differentiate plant species and genotypes to superior and inferior could be in some cases misleading.Financial support for this study was obtained from the German Academic Exchange Service (DAAD), through a Re-invitation Programme for Former Scholarship Holders (A/12/08202 and 50068612), the Palestinian funding program for research and training “ZAMALAH”, and the Dutch EP-NUFFIC through NICHE-233 project. Technical support by Mrs. S. Koch in department of plant nutrition and yield physiology, George-August University, Goettingen, Germany for her generous help in plant and soil samples analyses is gratefully acknowledged

Citramalic acid and salicylic acid in sugar beet root exudates solubilize soil phosphorus

<p>Abstract</p> <p>Background</p> <p>In soils with a low phosphorus (P) supply, sugar beet is known to intake more P than other species such as maize, wheat, or groundnut. We hypothesized that organic compounds exuded by sugar beet roots solubilize soil P and that this exudation is stimulated by P starvation.</p> <p>Results</p> <p>Root exudates were collected from plants grown in hydroponics under low- and high-P availability. Exudate components were separated by HPLC, ionized by electrospray, and detected by mass spectrometry in the range of mass-to-charge ratio (m/z) from 100 to 1000. Eight mass spectrometric signals were enhanced at least 5-fold by low P availability at all harvest times. Among these signals, negative ions with an m/z of 137 and 147 were shown to originate from salicylic acid and citramalic acid. The ability of both compounds to mobilize soil P was demonstrated by incubation of pure substances with Oxisol soil fertilized with calcium phosphate.</p> <p>Conclusions</p> <p>Root exudates of sugar beet contain salicylic acid and citramalic acid, the latter of which has rarely been detected in plants so far. Both metabolites solubilize soil P and their exudation by roots is stimulated by P deficiency. These results provide the first assignment of a biological function to citramalic acid of plant origin.</p

Формирование здорового образа жизни студентов

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