在4个硝酸盐浓度(0.08、0.8、4.0、8.0mmol/l处理下,进行2个玉米品种(郑单958、内单314)的盆栽砂培试验,旨在揭示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在硝酸盐浓度在0.08、0.8、4.0mmol/l时,根重、根幅、根长、根表面积、根体积、分枝数、分形维数、根系活力都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4.0mmol/l增加到8.0mmol/l时,不同基因型品种间差异不显著。在8.0mmol/l的高浓度硝酸盐处理下,根系的平均直径较大,根系的分枝多,分形维数达到最大。在0.08mmol/l的硝酸盐胁迫的条件下,根系生长受到抑制,0-0.2mm径级内细根比例较高浓度硝酸盐细根比例大。说明在低氮胁迫条件下,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,因此,玉米苗期氮高效品种的总根长,根体积显著高于氮低效品种,是氮吸收效率差异的主要原因。
英文摘要:
Two maize hybrids (ZD958,ND314) cultivated in pots experiment in order 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(0.08、0.8、4.0、8.0mmol/l).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 concentration(0.08,0.8,4.0mmol/l).Each index of root morphology gradually increased with the increase of nitrate concentration, when nitrate concentrate from 4.0mol/l increased to 8.0mol/l,the difference was not significant, its show that 4.0mmol/l was the optimal concentration for two maize hybrids. Root mean diameter, NO. of branches and fractal dimension were lager at 8.0mmol/l nitrate concentration; At 0.08mmol/l nitrate stress condition, the root growth was restrained and the proportion of root length distributed in 0-0.2mm diameter were higher than at 8.0mmol/l nitrate concentration, its explain that maize mainly increased the proportion of fine root and root surface area to uptake more nitrogen under the condition of nitrate stress; 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 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, is a major cause of nitrogen uptake efficiency differences.
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