水稻根系形态与氮素吸收累积的相关性分析

【目的】氮肥过量施用，不仅造成氮肥大量流失，还增加了农业生产成本，对生态环境带来了巨大的威胁。水稻根系形态作为影响养分吸收和利用的主要因素之一，明确其与氮素吸收累积的相关性是提高氮素利用效率、降低环境污染的有效途径。【方法】利用营养液培养方法，研究了 55 个水稻品种在 NH₄+-N 和 NO₃–-N 供应条件下苗期植株生物量、氮含量和氮素累积量及其与根系形态指标的相关性。【结果】在 NH₄+-N 培养下，水稻营养指标与根系形态指标的相关性高于其在 NO₃–-N 培养下的相关性。在相同供氮水平下，供应 NH₄+-N 的水稻苗期平均生物量为 55.77 mg/plant，比供应 NO₃–-N 的量高 4.94 mg/plant；水稻苗期平均氮含量为 4.22%，比供应 NO₃–-N 的高 0.72%；水稻苗期平均氮累积量为 1.91 mg/plant，比供应 NO₃–-N 的苗期平均氮累积量高 0.67 mg/plant。在 NH₄+-N 和 NO₃–-N 两种氮素形态培养条件下，水稻根系形态指标品种间根尖数变异系数最大，平均根系直径变异系数最小。总根体积、总根面积、总根长、分枝数四个形态指标与植株生物量、植株氮含量、植株氮累积量相关性最为显著，且相关系数 (r) 呈总根体积 > 总根面积 > 总根长 > 分枝数的规律。在 NH₄+-N 培养下的水稻营养指标与根系形态指标的相关性要高于其在 NO₃–-N 培养下的相关性。【结论】水稻苗期总根体积、总根面积、总根长、分枝数可作为水稻氮高效评价的重要指标。

Correlation between root morphology and nitrogen uptake of rice

[Objectives] Excessive application of nitrogen fertilizers lead to nitrogen loss and the cost increase of agricultural production.Root morphology is one of main factors that affect absorption and utilization of nutrients by rice.In this study,we investigated the relationship between root morphology and nitrogen uptake and accumulation of rice.[Methods] Hydroponic experiments were conducted with 55 rice cultivars to examine relationships between the plant nitrogen uptake and several indices of root morphology using both NH4+-N and NO3--N solution.[Results] The correlation coefficients between the nitrogen uptake and root morphology indices when N was supplied as NH4+-N were higher than those when supplied as NO3--N.After the six leaf stage of rice,under the same solution concentration of nitrogen,the average biomass of rice seedlings was 55.77 mg per plant in the NH4+-N solution,which was increased by 4.94 mg per plant compared with the NO3--N solution.The average nitrogen content of rice seedlings was 4.22％ when grown in the NH4+-N solution,which was increased by 0.72％,and the average accumulation of nitrogen in the seedlings was 1.91 mg per plant when supplied with the NH4+-N,which was increased by 0.67 mg per plant compared with the NO3-N solution.There were significant differences in the root morphology indices between plants supplied with the NH4+-N and NO3-N under the same concentration.The higher the coefficient of variation of root morphology was,the higher the greater difference between rice cultivars was.The root branch number was most highly correlated with the root morphology indices,whereas the mean root diameter was the least correlated.These differences reflected that there was a larger variation in root branching values,and less variation in mean root diameters among the 55 rice cultivars.The total root volume,total root area,total root length and branching number were significantly correlated with biomass,nitrogen content,and nitrogen accumulation in rice plants at the seedling stage,and the correlation coefficients were in order:the total root volume ＞ the total root area ＞ total root length ＞ the number of branches.The correlations between the nitrogen uptake and the indices of root morphology when plants were supplied with NH4+-N were higher than those when supplied with NO3--N.[Conclusions] The total root volume,total root area,total root length,and the number of branches may be important indicators for evaluating the nitrogen use efficiency ofrice at the seedling stage.