Abstract:

Root morphology in plants may be related to phosphorus (P) efficiency by affecting the absorption characteristics of the root system. However, genotypic variation in root morphological characteristics of common bean (Phaseolus vulgaris L.) as affected by P availability has not been well clarified. In the present study, systematic studies were conducted in a P-buffered sand culture system using three pairs of common bean parental materials with contrasting root traits in response to P deficiency. The results indicate that P availability significantly affects bean root morphology. Common bean tends to have smaller root system, shorter and coarser roots at low P availability. Genotypic variation in root morphology was observed among different genotypes in response to P availability. The P efficient genotypes appear to have larger, finer and longer root systems than the P inefficient genotypes, and such a variation was particularly obvious in the basal roots. From allomeric analysis, we found that morphological characteristics of the basal roots contribute more to P efficiency than those of the tap roots. Further studies with the F9 recombinant inbred lines derived from one of the most contrasting parental pairs, DOR364 and G19833, confirmed the above findings, indicating that those morphological characteristics are inheritable hence provide potential for genetic improvement. Root morphology in plants may be related to phosphorus (P) efficiency by affecting the absorption characteristics of the root system. However, genotypic variation in root morphological characteristics of common bean (Phaseolus vulgaris L.) as affected by P availability has not been well clarified. In the present study, systematic studies were conducted in a P-buffered sand culture system using three pairs of common bean parental materials with contrasting root traits in response to P deficiency. The results indicate that P availability significantly affects bean root morphology. Common bean tends to have smaller root system, shorter and coarser roots at low P availability. Genotypic variation in root morphology was observed among different genotypes in response to P availability. The P efficient genotypes appear to have larger, finer and longer root systems than the P inefficient genotypes, and such a variation was particularly obvious in the basal roots. From allomeric analysis, we found that morphological characteristics of the basal roots contribute more to P efficiency than those of the tap roots. Further studies with the F9 recombinant inbred lines derived from one of the most contrasting parental pairs, DOR364 and G19833, confirmed the above findings, indicating that those morphological characteristics are inheritable hence provide potential for genetic improvement.

菜豆根形态特性的基因型差异与磷效率
廖红 严小龙*

（华南农业大学植物营养遗传研究室、根系生物学研究中心，广州510642）

摘要：应用磷控释砂培以及计算机图象分析技术,研究了磷效率差异显著的菜豆(Phaseolus vulgaris L.)亲本及其重组自交系后代的根形态特性及其与磷效率的关系.试验结果表明,供磷状况显著影响菜豆根系形态学特性.在低磷胁迫下,菜豆根系总根长变短、根部生物量减少,根直径增大.菜豆根形态特性对低磷有效性的适应性反应具有显著的基因型差异.在低磷条件下磷高效率基因型的根系比磷低效率基因型相对根部生物量较大、总根长较长,根表面积较大.异计分析表明,菜豆基根根形态特性在低磷条件下的适应性变化对磷效率的贡献远远大于主根,并且这些适应性变化是可以遗传的,表明通过对菜豆根形态特性进行遗传改良来提高磷效率有一定的可行性.

关键词： 菜豆；根形态；磷效率；基因型差异

Key words: common bean, root morphology, phosphorus efficiency, genotypic variation