Pre-harvest sprouting (PHS) is a common threat to cereal crops in which the grain maturation phase takes place under rainy, moist conditions. Susceptibility to PHS is higher in sorghum genotypes displaying low levels of seed dormancy before harvest maturity. Other attributes such as glume or panicle morphology may also affect susceptibility to PHS. Breeding for resistance to PHS in grain sorghum requires the identification of grain physiological and morphological attributes affecting this trait, and a protocol for phenotyping and rating genotypes according to their susceptibility to PHS. In this work, we tested germination under laboratory conditions using detached grains and intact panicles for a panel of 20 sorghum genotypes including 11 parental lines, 6 hybrids and 3 reference inbred lines with contrasting PHS response. Records for natural sprouting in the field for these genotypes were also included in the analysis. Multivariate analyses of germination data allowed separation of genotypes into two major categories (resistant and susceptible to PHS). Laboratory germination data correlated significantly with PHS in the field. In most genotypes, the glumes had a significant, inhibitory effect on germination. The low levels of grain dormancy were observed among high tannin backgrounds, and vice versa, indicating that a pigmented testa alone does not provide resistance to PHS. Altogether, the phenotyping protocol allowed the classification of sorghum genotypes according to their susceptibility to PHS and the identification of different attributes useful for breeding for PHS resistance in this crop.

中文翻译：

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高粱抗采前发芽的表型分析

收获前发芽 (PHS) 是谷类作物的常见威胁，其中谷物成熟阶段发生在多雨、潮湿的条件下。收获成熟前种子休眠水平低的高粱基因型对 PHS 的易感性较高。颖片或圆锥花序形态等其他属性也可能影响对 PHS 的易感性。高粱抗 PHS 的育种需要确定影响该性状的谷物生理和形态属性，以及根据其对 PHS 的易感性对基因型进行表型分析和评级的方案。在这项工作中，我们使用分离的谷物和完整的圆锥花序在实验室条件下测试了一组 20 个高粱基因型的发芽率，其中包括 11 个亲本系、6 个杂种和 3 个具有对比 PHS 响应的参考自交系。这些基因型在田间自然发芽的记录也包括在分析中。发芽数据的多变量分析允许将基因型分为两大类（抗 PHS 和易受 PHS 影响）。实验室发芽数据与田间 PHS 显着相关。在大多数基因型中，颖片对萌发具有显着的抑制作用。在高单宁背景中观察到低水平的谷物休眠，反之亦然，这表明单独的有色种皮不能提供对 PHS 的抗性。总而言之，表型分析方案允许根据高粱基因型对 PHS 的敏感性进行分类，并确定可用于培育该作物的 PHS 抗性的不同属性。