Drought stress is one of the major environmental factors limiting peanut (Arachis hypogea L.) productivity. Peanut response to drought varies depending on genotypic characteristics, crop growth stages, and environmental conditions. The objective of this study was to evaluate the effects of drought stress and rehydration on symbiotic nitrogen fixation and carbon isotope discrimination in peanut genotypes with varying drought tolerance. Experiments were conducted for 2 years in rainout shelters under three irrigation regimes: irrigated control, middle-season drought with rehydration, and late-season drought with rehydration. Reduction in percentages of shoot N derived from the atmosphere (%Ndfa) occurred under both drought treatments in both years; a greater reduction occurred under middle-season drought than under late-season drought. Middle-season drought negatively affected carbon isotope discrimination in both years, although there were no significant differences under late-season drought. Variabilities in %Ndfa and carbon isotope discrimination were found among different genotypes. Under middle-season drought, both %Ndfa and carbon isotope discrimination were higher in drought-tolerant lines than drought-susceptible lines. The most drought-tolerant lines had the highest N-fixing capacity under both drought treatments. Additionally, there was a positive correlation between %Ndfa and carbon isotope discrimination under both drought treatments. In most genotypes, %Ndfa remained unchanged after rehydration; only a few genotypes showed a slight increase in %Ndfa after rehydration following both drought treatments. Our data suggested that symbiotic nitrogen fixation in many peanut genotypes was negatively affected by drought and may not recover from the damage caused by drought upon rehydration.

中文翻译：

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干旱胁迫下花生 (Arachis hypogaea L.) 基因型共生固氮和碳同位素鉴别的变异性

干旱胁迫是限制花生生长的主要环境因子之一（Arachis hypogeaL.) 生产力。花生对干旱的反应因基因型特征、作物生长阶段和环境条件而异。本研究的目的是评估干旱胁迫和补水对具有不同耐旱性的花生基因型共生固氮和碳同位素鉴别的影响。在三种灌溉制度下的避雨棚进行了为期 2 年的实验：灌溉控制、中季干旱补水和晚季干旱补水。在这两年的两种干旱处理下，来自大气的地上部 N 百分比 (%Ndfa) 均出现减少；与晚季干旱相比，季中干旱的降幅更大。中季干旱在这两年都对碳同位素歧视产生了负面影响，尽管在季末干旱情况下没有显着差异。在不同的基因型中发现了 %Ndfa 和碳同位素鉴别的差异。在中期干旱条件下，耐旱品系的％Ndfa 和碳同位素辨别力均高于易旱品系。在两种干旱处理下，最耐旱的品系具有最高的固氮能力。此外，在两种干旱处理下，%Ndfa 与碳同位素鉴别之间存在正相关。在大多数基因型中，%Ndfa 在再水化后保持不变；在两种干旱处理后的再水化后，只有少数基因型的 %Ndfa 略有增加。