Root architectural responses to phosphorus (p) availability may be an important trait for P acquisition efficiency. In the present study, The authors examined the effects of P availability on root architectural responses of different common bean genotypes. Five common bean (Phaseolus vulgaris L.) genotypes representing different origins and ecotypic races were compared both in a specially designed paper pouch system and a stratified P buffer sand culture system with computer image analysis. The results showed that root architecture was regulated by P availability. P deficiency led to form a shallower root system, as indicated by increased relative distribution of basal root length in the upper layers and decreased the growth angle of basal roots. There was significant genetic variation in root architecture in response to P deficiency both in the paper pouch system and the stratified sand culture system. Under low P conditions some genotypes were more gravitropically sensitive to low P availability, resulting in producing a shallower root system and enhanced root exploration into the surface soil, where soil available P is more concentrated. G19833 and DOR364, which were most contrasting in P efficiency, were also very different in root architectural response to P availability. The results from this study suggest that P availability regulates root architecture and P deficiency leads to shallower root architecture in beans. The genetic potential of root architecture provides the possibility of selecting this trait for improving P acquisition efficiency in common bean.
菜豆根构型对低磷胁迫的适应性变化及基因型差异
廖红 严小龙
（华南农业大学植物营养遗传研究室，广州510642）
摘要： 利用特殊设计的营养袋纸培和分层式磷控释砂培等根系生长系统结合计算机图像分析技术，以基根根长在生长介质各层的相对分布和基根平均生长角度为指标，定量测定菜豆（Phaseolus vulgaris l.）根构型在低磷胁迫下的适应性变化及其与磷效率的关系。结果表明，菜豆根构型对低磷胁迫具有适应性反应，在缺磷条件下基根向地性减弱，基根在生长介质表层相对分布增多、基根平均生长角度（与水平线夹角）变小，从而导致整个根系较浅。供试菜豆根构型对低磷胁迫的适应性反应具有显著基因型差异，缺磷时G19833 等基因型向地性明显减弱，基根向高磷剖面趋向生长的能力较强，因而具有较高的磷吸收效率。研究结果表明根构型变化是菜豆适应低磷胁迫的可能机理之一，为通过改变植物根构型来提高磷吸收效率提供了依据。
关键词： 菜豆；根构型；根向地性；磷效率
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