水分胁迫和氮素营养对小麦根苗生长及水分利用效率的效应

EFFECTS OF WATER STRESS AND NITROGEN NUTRITION ON ROOT AND SEEDLING GROWTH AND WATER USE EFFICIENCY OF WHEAT

采用目前生产上广泛种植的小麦品种小偃６号，在一种特制木盒（２０ｃｍ×６ｃｍ×５０ｃｍ）中土培，研究了水分胁迫和氮素营养对小麦根系和幼苗生长及水分利用效率（ＷＵＥ）的效应，小麦根系生长在双层尼龙网之间，土壤中的水分和养分可以被正常吸收，但主根和侧根不能穿过。结果表明：在土壤含水量为田间持水量的４０％一７０％范围内，随着土壤干旱程度的增加，小麦根长（ＲＬ）、根干重（ＲＤＷ）、叶面积（ＬＡ）和ＷＵＥ显著降低。氮肥的效应更为复杂。随着土壤水分胁迫的增加，降低氮肥使用量对ＲＤＷ、ＬＡ和ＷＵＥ的提高较为有利。就促进根系生长而言，不同土壤湿度下相应的氮肥适宜配比为Ｗ４０％Ｎ７５、Ｗ５５％Ｎ９６．、Ｗ７０％Ｎ１２０ｋｇ／ｈｍ￣２；对提高小麦ＷＵＥ来讲，土壤湿度与氮肥的适宜配比为Ｗ４０％Ｎ６０、Ｗ５５％Ｎ８５、Ｗ７０％Ｎ１５０ｋｇ／ｈｍ￣２。值得注意的是，氮肥对ＲＤＷ的作用比对ＲＬ的作用更为重要。本文提出，根据土壤含水量调节氮肥用量是旱农地区促进小麦根系生长，提高ＷＵＥ的有效方法。

This paper reported the effects of water stress and nitrogen nutrition on root and seedlinggrowth and WUE;the most efficient way to promote root growing,to improve WUE of wheat. The study was conducted in a kind of wooden boxes (20 cm×6 cm×50 cm)with 7 replications. The contemporary wheat variety, Xiaoyan No. 6 was used. Wheat seedling grown between nylonnets were harvested at 47 days after sowing. As water stress increasing , RL. ,RDW, LA andWUE decreases observably under condition of soil water content as 40一70%of water contentcapacity.The effect of nitrogen is more complex. That is of benefit to RDW,LA and WUE to de-crease application of nitrogen to soil as water stress increasing. The optimum combines of waterand nitrogen to promote root growth are W40%N75,W55%N96 and W70%N120kg/hm￣2, toenhance WUE are W40%N60,W55%N85 and W70%N150kg/hm￣2. Noteworthy is that the ef-fect of nitrogen on RDW is more important than on RL. It is proposed that adjust the usage of ni-trogen to soil according to soil moisture is efficient way to promote rcot growth and enhanceWUE of wheat in dryland farming.