膜下滴灌水氮对棉花根系形态和生物量分配变化的影响

Effects of water and nitrogen on root morphological characteristics and biomass distribution under film drip Irrigation

通过挖掘法,研究了膜下滴灌不同生育期棉花根系形态特征和生物量分配对不同水氮的响应。结果表明:花铃期,正常灌水促进了根系和地上部的生长,根、地上部干重、根表面积指数、平均根长密度显著增加,根冠比下降。无论灌水量如何,施氮促进了根系和地上部的生长,但对地上部的促进作用远大于根系,表现为根冠比下降。吐絮期,在低氮条件下,灌水量增加,根干重、地上部干重显著增加。在中氮和高氮条件下,不同的灌水量对根干重没有影响。无论施氮量如何,灌水量增加,平均根长密度、根表面积指数显著下降,地上部干重明显增加,根冠比下降。水分胁迫时,中氮的根干重明显高于低氮和高氮处理,而施氮对地上部干重,平均根长密度的影响不明显,根表面积有降低的趋势。正常灌水时,施氮量增加,根干重、根长密度、根表面积指数显著降低,地上部干重以中氮水平最高。花铃期至吐絮期,根干重随生育期的延长明显增加。水分胁迫条件下,平均根长密度、根表面积指数随生育期的延长有增加的趋势。正常灌水条件下,平均根长密度、根表面积指数随生育期的延长下降。

The distribution of biomass and root morphological characteristics in different irrigation amounts and nitrogen application were investigated by digging and image analysis methods for root sampling and measurement.The results indicated： during flowering and boll-setting stage,normal irrigation amount promoted root and shoot growth.Root and shoot dry weight,root area index and average root length density significantly increased with the increase of irrigation amount.At two irrigation amount levels,nitrogen supply had an obvious promotion effect on plant growth.The promotion effect of nitrogen supply on above ground was more than root.These caused root shoot ratio decrease.During boll opening stage,root and shoot dry weight obviously increased with the increase of irrigation amount under low nitrogen supply.Under high and mediate nitrogen supply,irrigation amount had no difference,but root area index,average root length density,root shoot ratio decreased,shoot dry weight increased.Under the conditions of water stress,root dry weight of mediate was higher than low and high nitrogen supply.Increasing nitrogen supply had no effects on root dry weight,average root length density,average root length density had a decreasing trend.Under normal irrigation amount,root dry weight,average root length density,average root length density significantly reduced.Shoot dry weight in mediate nitrogen supply was more than in low and high nitrogen.During flowering and boll-setting stage to boll opening stage,root and shoot increased with the stage developing.Under water stress,average root length density,root shoot ratio had an increasing trend.Under normal irrigation amount,root length density,root area index declined.