玉米根系特征的基因型差异及与氮吸收效率的关系

在4个硝酸盐浓度下进行2个玉米品种盆栽砂培试验,研究玉米根系特征的基因型差异对硝酸盐浓度的响应及与氮素吸收效率的关系。结果表明,氮高效品种郑单958在硝酸盐浓度为0.08、0.8、4.0 mmol/L时,根重、根幅、根长、根表面积、根体积、分枝数、分形维数、根系活力均显著高于氮低效玉米品种内单314。各根系形态指标随硝酸盐浓度的增加逐渐增加,当硝酸盐浓度从4.0 mmol/L增加至8.0 mmol/L时,不同基因型品种间差异不显著。在低氮胁迫条件下,玉米主要通过增加细根比例、增加根表面积吸收更多的氮素;在氮素供应充足条件下,通过增加根系平均直径,形成高密的分枝系统吸收氮素。进一步通径分析表明,根长与根体积对氮吸收效率直接影响最大,是氮吸收效率差异的主要原因。

Genotype Differences in Root Characteristics by Maize and Its Relations to Nitrogen Uptake Efficiency

Two maize hybrids cultivated in pots experiment to reveal genotype differences in root characteristics by maize for the response of nitrate concentration and its relations to nitrogen uptake efficiency at four nitrate levels. The result showed that ZD958, a N efficient variety significantly higher than ND314, a N inefficient variety in root dry weight, root extent, root length, root surface, root volume, NO. of branches, fractal dimension and root vigour at three nitrate concentrations(0.08, 0.8, 4.0 mmol/L). Each index of root morphology gradually increased with the increase of nitrate concentration, when nitrate concentrate from 4.0 mmol/L increased to 8.0 mmol/L, the difference was not significant. Under the condition of nitrogen supply, maize in order to uptake more nitrogen by increasing root mean diameter and forming density branches system. Path analysis showed that root length and root volume had the largest influence on nitrogen uptake efficiency. Thus, Nitrogen efficient varieties of total root length, root volume was significantly higher than that of nitrogen inefficient varieties, that was a major cause of nitrogen uptake efficiency differences.