不同供氮形态下水稻苗期磷吸收累积与根系形态的关系

【目的】植物根系形态对于适应低磷胁迫具有一定的可塑性,对提高磷的吸收利用具有重要意义。因此,本研究以长江中下游地区主推的102个水稻品种为供试材料,研究根系形态与水稻幼苗磷吸收利用的相关性。【方法】采用国际水稻所营养液培养方法,研究在NH_4^+-N和NO_3^--N供应条件下苗期植株生物量、磷含量和磷素累积量及其与根系形态指标的相关性。【结果】研究结果表明,在相同供氮水平(40 mg/L)下,供应NH_4^+-N时,水稻苗期平均生物量为67.87 mg/株,比供应NO_3^--N时高4.27 mg/株;水稻苗期平均磷含量为0.49%,比供应NO_3^--N时高0.10%;水稻苗期平均磷累积量为0.37 mg/株,比供应NO_3^--N时高0.10 mg/株。在NH_4^+-N条件下,水稻根系形态指标变异系数呈现根尖数>总根长>分支数>总根面积>交叉数>总根体积>平均根系直径的规律;在NO_3^--N条件下,水稻根系形态指标变异系数呈现根尖数>分枝数>总根长>总根面积>交叉数>总根体积>平均根系直径的趋势。在NH_4^+-N条件下,总根长、总根面积、分枝数、交叉数四个形态指标与植株生物量、磷含量、磷累积相关最为显著(P<0.01),而在NO_3^--N培养下,总根长、总根面积、根尖数、交叉数与植株生物量及磷素吸收累积指标相关性最为显著(P<0.01)。【结论】供应氨态氮,水稻营养指标与根系形态指标的相关性更高。水稻苗期根系总根长、总根面积、交叉数可作为水稻磷高效评价的重要指标。

Correlation Between Root Morphology and Accumulation of Phosphorus in Rice Seedlings under Different N Forms

【Objective】Plant root morphology has certain plasticity for adapting to low phosphorus stress, and is of great significance for improving phosphorus absorption and utilization. Therefore, we used 102 major rice varieties in the middle and lower reaches of the Yangtze River as the tested materials to study the correlation between root morphology and phosphorus uptake of rice seedlings.【Method】Hydroponic experiments were conducted to investigate the influences of NH4 +-N and NO3 ?-N at the same concentration (40 mg·L^-1) on dry weight, P concentrations and contents as well as the root morphology.【Result】At the six-leaf stage of rice incubated under the same concentration of nitrogen, the average biomass of the rice seedlings amounted to 67.87 mg per plant in the NH4 +-N solution, 4.27 mg higher than that in the NO3 --N solution. The average P content was 0.49% when grown in the NH4 +-N solution, 0.10% higher than that of rice seedlings grown in the NO3 --N solution. In addition, the average accumulation of P in the seedlings was 0.37 mg per plant when supplied with NH4 +-N, 0.10 mg higher than that supplied with NO3 --N. The coefficient of variation of root morphological indexes were in the order of the number of tips > total root length > the number of branches > total root area > the number of crossing > the total root volume > average diameter in the NH4 +-N solution;the coefficient of variation of root morphological indexes were in the order of the number of tips > the number of branches > total root length > total root area > the number of crossing > the total root volume > average diameter in the NO3 --N solution. The total root length, total root area, branching number and crossing number were significantly correlated with biomass, P content, and P accumulation in rice plants in the NH4 +-N solution;whereas the total root length, total root area, tip number and crossing number were significantly correlated with biomass, P content, and P accumulation in rice plants in the NO3 --N solution.【Conclusion】The correlations between P uptake and the indices of root morphology when plants were supplied with NH4 +-N were higher than those supplied only with NO3 --N. The total root length, total root area and crossing number might be important indicators for evaluating the P use efficiency of rice at seedling stage.