[Objectives] It is important to understand the root response to local N and P supply among genotypic differences to help breeding nitrogen (N) and phosphorus (P) efficient maize cultivars as nutrient distribution in soils is heterogeneous naturally.[Methods] A split-root solution culture system was set up to evaluate root response to local N-and P-supplementation in three maize hybrids.[Results] The root responses of the three genotypes showed different to local N or P supplement.Compared to NE15,JD20 and ZN99 were more sensitive to local N supply.Root length of JD20 and ZN99 in rich N side increased by 79％ and 50％ respectively,comparing with no N side,especially in the part with lateral root diameter ≥ 0.12 mm.Similar response was not shown as significant in NE15 root as the other two genotypes.After P supplement treatment,however,the root dry weight and axial root length of NE 15 were increased by 38％ and 24％ respectively in +P side compared to the no P supply,while the lateral root length of ZN99 was increased by 35％ in +P side.The majority of root length increase of JD20 and ZN99 were found in root diameter greater than 0.12 mm part in rich N side,while NE15 genotype increased its root length mostly with root diameter between 0.12 to 0.24 mm in +P side.In ZN99 samples,the fine roots with diameter ≤ 0.12 mm were increased most significantly in +P side.Not only different responses to single nitrogen and phosphorus supplement by maize genotypes,but also interaction between genotypes and nutrient supplement were found.In JD20,the lateral roots (especially those with diameter ＞ 0.12 mm) were more responsive to local N than local P supply.While NE 15 showed more root dry weight gain affected by local P than local N supply.[Conclusions] The different response of heterogeneous N or P supply from different maize genotypes provides information how to use local N and P supply efficiently to increase maize production.%[目的]土壤养分具有异质性,揭示不同基因型玉米根系对于养分异质性的响应规律,对提高不同玉米品种氮、磷利用效率具有重要意义. [方法]本试验在水培条件下,利用分根系统研究3个玉米杂交种苗期根系对氮、磷两种养分局部供应响应的基因型差异. [结果]根系对局部供氮的响应存在基因型差异,浚单20和中农玉99侧根生长对局部供氮的响应较敏感,显著提高了局部供氮(+N)一侧的侧根长,增幅达到79％、50％,而NE15无显著响应;浚单20和中农玉99主要提高了+N一侧直径大于0.12 mm的侧根长度.根系生长对于局部供磷(+P)的反应同样存在基因型差异,NE15显著提高+p一侧根系生物量和轴根长,增幅达到38％和24％,中农玉99显著提高+p一侧的侧根长达到35％;在+P侧,浚单20主要增加了直径大于0.12 mm的侧根长度,NE15主要增加直径介于0.12～0.24 mm的侧根长度,而中农玉99主要增加直径小于0.12 mm的极细侧根长度.局部供氮对3个品种侧根生长的促进作用强于局部供磷,而对缺氮一侧根系生长的抑制作用均大于缺磷一侧.不同玉米基因型苗期根系生物量、侧根长(尤其是直径＞ 0.12 mm的侧根)对于局部供应氮、磷存在显著的互作效应,局部供氮对浚单20的侧根生长(尤其是直径＞ 0.12 mm的侧根)的促进作用显著高于局部供磷,而NE15的根系生长(尤其是根系生物量)对局部供磷的响应强度大于局部供氮. [结论]对于不同养分特性的玉米杂交种,苗期根系对局部供应不同种类养分的响应存在显著的基因型差异,在生产中可以针对品种特性采取不同的施肥措施,以便发挥其生物学潜力.
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