膜下滴灌水氮对棉花根系构型的影响

 通过分层挖掘法，研究了膜下滴灌棉花根系构型对水氮的响应。结果表明：灌水量增加，根干重增加，根长、根表面积降低。表土层根干重、根长下降，深土层增加，各土层根表面积下降。高氮对根系具有明显的抑制作用，各土层根干重、根长、根表面积下降。水氮交互对根干重、平均根长、亚表土层根干重、表土层和深土层根长、根表面积影响明显。灌水300 mm，根干重及根干重在亚土层中的分布以276kg·hm^-2最高。施氮对平均根长密度的影响差异不明显。低氮和高氮促进深土层根长、根表面积增加。灌水600 mm，深土层根长以276kg·hm^-2最高，各土层根表面积随供氮水平的增加下降。水分是影响皮棉产量的主要因子，水分胁迫降低了氮肥的增产效应，氮肥促进了灌水的增产效果，但过多的氮肥供应降低增产效果。

Effects of Water and Nitrogen on Cotton Root Architecture under Film Drip Irrigation

Responses of nitrogen and water on root architecture were investigated by layered digging. The results indicated that: with the increasing of irrigation amount, root dry weight increased, root length and root surface area reduced. Root dry weight and root length decreased in top soil layers and increased in deep soil layers. Root surface area decreased in whole soil layers. High nitrogen supply had obvious inhibitory effects, manifested as the decreasing of root dry weight and root length and root surface. Water and nitrogen interaction had significant influences on root dry weight, average root length density, root dry weight of subsurface layers,root length and root surface area of top soil layers and deep soil layers. When irrigation amount was 300 mm, root dry weight and the distribution of root dry weight in subsurface layers reached the maximum at 276 kg·hm~(-2) nitrogen supply. Nitrogen supply had no effect on average root length density. Low nitrogen and high nitrogen had promoting effect on the increasing of root length and root surface area. When irrigation amount was 600 mm, root length of deep soil layers reached the maximum at 276 kg·hm~(-2) nitrogen supply. With nitrogen supply increased, root surface area of whole soil layers increased. Water is the main factor of effect yield. Water stress weakened the yield increasing effect of nitrogen. Nitrogen promoted the yield increasing effect of water, but too much nitrogen supply decreased this effect.