摘要
土壤养分供应变异很大,植物根系生长对这种养分变异的响应非常敏感。为了探索水稻根系生长对N素供应响应的动态变化规律以及这种适应性变化与水稻N效率之间的关系,采用水培方法,以两个苗期不同N效率水稻品种桂单4号和南光为研究材料,比较了不同铵硝比、不同浓度NH_4^+、不同浓度NO_3^-和不同浓度NH_4NO_3对水稻根系构型参数的影响。结果表明:NH_4^+和NH_4NO_3供应显著降低了总根长、总根表面积和总根体积,且有增加平均根直径的趋势;而NO3-供应在0~1mmol/L浓度范围内,增加了总根长、总根表面积和总根体积,降低了平均根直径,但当NO_3^-供应超过1mmol/L后,NO_3^-却有降低总根长、总根表面积和总根体积的趋势,对平均根直径没有明显影响。苗期N高效基因型桂单4号总根长和总根表面积在各种N素营养条件下均显著高于N低效基因型南光。上述结果表明,NH_4^+和NH_4NO_3都抑制了水稻根系生长,而NO_3^-为低浓度诱导、高浓度抑制根系生长,根长和根表面积,对提高水稻N效率贡献较大。
Plant root systems are extremely sensitive to availability and distribution of nutrients within soil. In order to explore how rice roots respond to NH4+ and NO3- supply and whether the responsibility is related to rice N efficiency, effects of NH4+:NO3- ratio in N supply on parameters of root architecture through solution culture experiment using rice plants of two different genotypes, GD4 and NG, was tested. The results showed that both NH4+ and NH4NO3 significantly decreased total root length, total root surfarea, and total root volume but slightly increased average root diameter. NO3- less than 1 mmol/L increased total root length, total root surfarea, and total root volume but decreased average root diameter, whereas when rice roots were exposed to NO3- concentration more than 1 mmol/L, the situation was contrary to that of NO3- concentration less than 1 mmol/L. Total root length and total root surfarea of N-efficient rice genotype GD4 were higher than that of N-inefficient rice genotype NG. In conclusion, NH4+ and NO3- had different effects on rice root growth, inhibitory effects for NH4+, stimulative effect for low NO3- concentrations whereas inhibitory effects for high NO3- concentrations, and root length and root surfarea may contribute to the improvement of rice N efficiency.
出处
《土壤》
CAS
CSCD
北大核心
2007年第5期766-771,共6页
Soils
基金
国家自然科学基金重大项目(30390083)资助
