玉米根系对土壤氮、磷空间异质性分布的响应

氮、磷资源富集区（patches）通常独立存在,揭示植物根系对异质性氮、磷分布的响应,对于通过根系调控充分挖掘根系高效获取氮、磷资源的生物学潜力,提高氮、磷资源利用效率具有重要的理论与实践意义。通过盆栽试验研究了3种氮、磷供应方式（氮磷均匀供应,氮磷混合局部供应,氮磷分开局部供应）对玉米根系生长和分布以及氮、磷吸收的影响。结果表明,氮磷混合和分开局部供应均显著增加了玉米根系干重。与均匀供应处理相比,氮磷混合局部供应使玉米总根长、根干重、根质量比分别增加了28%,66%和31%,磷吸收量减少了35%,但对地上部干重和氮吸收量没有显著的影响。相比之下,氮磷分开局部供应使根和地上部干重均增加55%,氮、磷吸收量分别提高58% 和81%,但对总根长和根冠干物质分配比例无显著影响;与局部供氮相比,局部供磷显著刺激了根系的生长,表明更多的干物质优先分配到局部供磷的区域。由此可见,与氮磷混合局部供应相比,在氮、磷资源分开供应条件下,玉米通过改变根系形态和分布来协调和整合对氮、磷资源的响应,从而强化根系对不同土壤氮、磷资源的摄取能力,这为优化氮、磷资源的管理和空间配置提供了重要依据。

Root responses of maize to spatial heterogenous nitrogen and phosphorus

The resource rich regions (patches) of nitrogen or phosphorus usually exist independently in soil, and understanding how roots respond to spatial heterogenous nitrogen and phosphorus has important implications for exploring biological potential through rhizosphere management to improve the uptake efficiency of nitrogen and phosphorus by roots, and realizing efficient acquisition and utilization of nitrogen and phosphorus resource. A pot experiment was carried out to reveal the effect of three modes of localized nitrogen and phosphorus supply (nitrogen and phosphorus uniform supply, local supply in separation, and local supply in combination) on the root growth and distribution, as well as nitrogen and phosphorus uptake by maize. The results show that localized application of nitrogen and phosphorus significantly increased the root dry weight regardless of supply pattern in separation or in combination. Compared with the uniform supply treatment,local supply in combination significantly increased total root length, root dry weight and root mass ratio by 28%, 66% and 31%, respectively, but decreased phosphorus uptake by 35%. No significant difference was observed in shoot dry weight and nitrogen uptake. By contrast, local supply in separation significantly increased root and shoot dry weight by 55% and 55% respectively, enhanced nitrogen and phosphorus uptake by 58% and 81% respectively, but there was no significant difference in total root length and root mass ratio. In addition, compared with the nitrogen supply patches, the phosphorus supply patches stimulated the root growth significantly, indicating that maize tends to allocate more dry matter to phosphorus supply area than nitrogen supply area. It is concluded that maize can integrate the root responses to both nitrogen and phosphorus supply through altering root morphology and distribution under local nitrogen and phosphorus supply in separation relative to combination condition, to enhance the root acquiring ability for soil nitrogen and phosphorus resources, which provides an important foundation to optimize the spatial arrangement of nitrogen and phosphorus and nutrient resource management.