玉米根系对局部氮磷供应响应的基因型差异

Differential response of maize roots to heterogeneous local nitrogen and phosphorus supply and genotypic differences

【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。

【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 NE15 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 NE15 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.