干旱胁迫下氮素对不同基因型小麦根系活力和生长的调控

Effect of Nitrogen on Root Vigor and Growth in Different Genotypes of Wheat under Drought Stress

为了探讨不同水氮耦合处理对小麦根系活力和吸收氮素能力的影响,以多穗型小麦品种西农979和大穗型小麦品系2036为材料进行营养液培养试验,设置正常水分供应、轻度和重度水分胁迫及低氮、中氮和高氮处理,研究了不同水氮耦合对小麦根系形态、根系吸收面积、根系活力、植株氮素积累量的影响。结果表明,水分与氮素存在着明显的互作效应,重度水分胁迫和低氮处理都会降低小麦的生物量、根系总吸收面积、活跃吸收面积和活力、氮含量和植株的氮素积累量,低氮处理增加了根长和根冠比。高氮处理的西农979根系总吸收面积、活跃吸收面积和活力较低,中氮处理显著提高,且分别比2036高11%、14%、27%。西农979在中氮和高氮处理之间的氮素积累量无显著性差异。中氮处理下西农979的植株氮素积累量比2036高13%~62%。相关分析表明,小麦的活跃吸收面积、根系活力与植株氮素积累量呈极显著正相关(P<0.01),和根冠比呈极显著负相关(P<0.01)。在轻度水分胁迫下,增加氮素供给能有效提高西农979的根系吸收面积和根系活力;过高的氮素不利于2036根系的生长,表明不同基因型小麦的根系活力和生长对不同水氮耦合的响应不同。通过适宜的水氮耦合调控,有利于创造良好的小麦根系形态,提高根系活力及对水分和养分的吸收能力。

The purposes of this study was to investigate the effects of water and N coupling on root vigor and uptake of nitrogen in wheat.Two different cultivars of wheat Xinong 979 and 2036were planted in Hoagland nutrient solutions.Three treatments of different N levels,low N,normal N and high N and three water regimes,well-watered,moderate drying and severe drying were conducted.The results showed that there was a significant interaction between water regimes and N supply.Severe water stress could decrease the biomass,total absorbing surface,activity absorbing surface,root vigor,nitrogen content and nitrogen accumulation in wheat.Nitrogen deficiency increased the root length and root/shoot,but decreased the biomass,total absorbing surface,activity absorbing surface,activity/total absorbing surface,root vigor,nitrogen content and nitrogen accumulation significantly.The root total absorbing surface,activity absorbing surface and root vigor of Xinong 979 with high N were increased significantly than that of low N and normal N,which are 11%,14%,27% higher than those of 2036,respectively at high N level.Root N accumulation and shoot N accumulation in Xinong 979 had no significant difference between normal N and high N levels.And the plant N accumulation of Xinong 979 was 13%to 62% higher than that of 2036 at normal N level.Correlation analysis showed that activity absorbing surface and root vigor were positively correlated with plant N accumulation（P0.01）,while there was significant negative correlation between activity absorbing surface,root vigor and root/shoot（P0.01）.A negative correlation was observed between root/shoot and plant N accumulation（P0.01）.The increase of nitrogen supply can improve the absorbing surface and root vigor of Xinong 979 effectively,but excessive nitrogen supply was not conductive to the root growth of 2036.These results suggested that the root vigor and growth of wheat with different genotypes respond differently to water and nitrogen coupling.Optimal regulations of water and N supply are beneficial to the formation of good root morphology and increase root vigor,therefore leading to the enhanced ability of absorbing moisture and nutrients.