不同根构型大豆对低磷的适应性变化及其与磷效率的关系

Adaptive Changes of Soybean Genotypes with Different Root Architectures to Low Phosphorus Availability as Related to Phosphorus Efficiency

【目的】探讨土壤低磷胁迫下大豆的根形态、构型适应性变化的基因型差异及其与大豆生长和磷效率的关系。【方法】采用具有不同根构型和磷效率的51个大豆品种,分别在广东省博罗县和英德县两个试验点的酸性缺磷红壤上,分春播和夏播两个季节进行田间试验,测定低磷、高磷处理下根形态、构型的差异及其与大豆生长和磷效率的关系。【结果】低磷处理下供试大豆基因型间生物量和产量具有极显著的基因型差异;供试大豆基因型的根形态、构型与磷效率密切相关,浅根型大豆根系具有合理的三维空间分布和较长的总根长,其磷效率和产量最高;低磷条件下,浅根构型和深根构型的大豆基因型根构型可塑性最小,中间根构型的大豆供试材料根构型最不稳定,可塑性最大。【结论】缺磷是供试酸性红壤上大豆生长的主要限制因子之一,大豆具有适应低磷土壤的遗传潜力;土壤中磷的有效性等环境因素对根构型具有调节作用;具有较好根形态构型的大豆基因型有利于从耕层土壤中吸收有效磷和其它养分,其产量和磷效率均较高。

[Objective] The aim of this study was to investigate the genotypic variations for adaptive changes in root morphology and architecture in response to low soil P availability and their relationships to plant growth and phosphorus （P） efficiency. [Method] Field experiments were conducted in two filed sites located in Boluo and Yingde counties of Guangdong Province in both spring and summer seasons. Totally 51 soybean genotypes contrasting in root architecture and P efficiency were compared for their root morphological and architectural traits and their relationships to plant growth and P efficiency under both low-P and high-P conditions. [Result] Great genotypic variations were observed for the tested genotypes under low-P conditions. Root architecture and morphology were closely related to plant P efficiency. Genotypes with shallow root architecture had an optimal three-dimensional root configuration and longest total root length, thus having the highest P efficiency and seed yield under low P conditions. Root plasticity of genotypes with either deep or shallow root architecture was lower than those with intermediate root architecture, indicating that root architecture was most stable in the former two groups under low P conditions. [Conclusion] Low P availability is one of the primary constraints to soybean growth in the experimental soils, and soybean demonstrates a great genetic potential in adaptation to low P soils. Environmental factors, such as P availability of soil, may regulate soybean root architecture. Optimal root morphology and architecture may facilitate absorption of available P and other nutrients in the cultivated soil layer, thus significantly increase P efficiency and seed yield of soybean under low P conditions.