Despite the ability of sorghum [Sorghum bicolor (L.) Moench] to withstand harsh environmental conditions, it is susceptible to water-deficit stress during grain filling. To identify postflowering, drought-tolerant sorghum genotypes, parents of nested association mapping populations were evaluated under controlled and water-deficit conditions in greenhouse and field conditions. In both experiments, water-deficit stress was imposed by withholding water during the grain-filling period. In field experiments, rootzone soil moisture was measured weekly using a neutron probe to quantify the plant available water under well-watered and water-deficit conditions. Investigations were focused on determining the variability in the grain-filling pattern across different positions within the panicles (intra-panicle) of 11 different sorghum genotypes. Water-deficit conditions characterized by low plant available water had a consistently negative association with grain number along different positions in the panicle. Our findings indicate that maintaining grain numbers per panicle under postflowering water deficit is more important than increasing individual grain weight. Among the tested genotypes, SC35 and SC1103 were most tolerant to water-deficit conditions under greenhouse and field conditions, respectively. Currently available biparental populations developed using these genotypes provide an opportunity to enhance tolerance to postflowering water-deficit stress in sorghum.

中文翻译：

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缺水胁迫改变高粱穗内粒数

尽管高粱的能力 [ Sorghum bicolor(L.) Moench] 能够承受恶劣的环境条件，在灌浆过程中容易受到缺水压力的影响。为了鉴定开花后的耐旱高粱基因型，在温室和田间条件下，在受控和缺水条件下对嵌套关联作图种群的亲本进行了评估。在这两个实验中，缺水胁迫是通过在灌浆期停水来施加的。在田间试验中，每周使用中子探针测量根区土壤水分，以量化在充足浇水和缺水条件下植物可用水量。研究的重点是确定 11 种不同高粱基因型的穗内（穗内）不同位置的籽粒灌浆模式的变异性。以低植物可用水为特征的缺水条件与穗中不同位置的籽粒数始终呈负相关。我们的研究结果表明，在开花后水分亏缺情况下保持每穗粒数比增加个体粒重更重要。在测试的基因型中，SC35 和 SC1103 分别在温室和田间条件下对缺水条件的耐受性最强。目前使用这些基因型开发的双亲种群为提高高粱对花后缺水胁迫的耐受性提供了机会。我们的研究结果表明，在开花后水分亏缺情况下保持每穗粒数比增加个体粒重更重要。在测试的基因型中，SC35 和 SC1103 分别在温室和田间条件下对缺水条件的耐受性最强。目前使用这些基因型开发的双亲种群为提高高粱对花后缺水胁迫的耐受性提供了机会。我们的研究结果表明，在开花后水分亏缺情况下保持每穗粒数比增加个体粒重更重要。在测试的基因型中，SC35 和 SC1103 分别在温室和田间条件下对缺水条件的耐受性最强。目前使用这些基因型开发的双亲种群为提高高粱对花后缺水胁迫的耐受性提供了机会。