水氮调控对轻度盐化土滴灌棉花根系生长的影响

Effects of water and nitrogen fertilization on root growth of cotton under drip irrigation in mildly salinized soil

为探讨轻度盐渍化地区不同水氮配比对滴灌棉花根系生长的影响,本文基于轻度盐胁迫下水氮耦合试验,确定轻度盐渍化农田棉花种植的合理水氮组合。采用当地主栽棉花品种“农丰133”,开展轻度盐胁迫(4~5 g·kg^-1)及滴灌条件下水氮二因素三水平桶栽试验,研究3个施氮水平:300、600 kg·hm^-2和900 kg·hm^-2尿素(分别标记为N1、N2和N3),3个灌水水平:2750、3750 m^3·hm^-2和4750 m^3·hm^-2(分别标记为W1、W2和W3)对滴灌棉花根系生长的影响。结果表明:轻度盐胁迫下,灌水和施氮产生的交互作用对棉花根表面积和根平均直径有显著影响,根表面积和根平均直径均随灌溉定额或施氮量的增加而减小。灌水量和施氮量对棉花0~20 cm土层根体积调控作用不明显。轻度盐化土滴灌棉花根表面积、根平均直径及根体积垂直方向主要分布在0~30 cm土层,且随土层深度的增加逐渐降低;水平方向主要分布在滴头下方。灌溉定额3750 m^3·hm^-2,尿素施用量600 kg·hm^-2有利于轻度盐化土滴灌棉花根系生长,在各处理间棉花产量最高,为5854.5 kg·hm^-2。

In order to explore the effects of different water and nitrogen combinations on root growth of cotton under drip irrigation in mildly salinized areas,this experiment coupled water and nitrogen under mild salt stress to determine the reasonable combination of water and nitrogen for cotton cultivation in mildly salinized cropland.We used‘Nongfeng 133’,a local main cotton variety,to carry out a two-factor and three-level barrel cultivation experiment under mild salt stress(4~5 g·kg^-1)and drip irrigation conditions.The effects of three nitrogen levels and three water levels on root growth of cotton under drip irrigation were studied.Three urea rates with nitrogen levels of 300,600 kg·hm^-2 and 900 kg·hm^-2 were labeled as N1,N2,and N3,respectively,and three irrigation levels of 2750,3750 kg·hm^-2 and 4750 m^3·hm^-2 were labeled as W1,W2,and W3,respectively.The results showed that under mild salt stress,the interaction between irrigation and nitrogen had significant effects on root surface area and average root diameter.Both root surface area and average root diameter decreased with increasing irrigation quota or nitrogen application.The effects of irrigation and nitrogen application rate on root volume of cotton in 0~20 cm soil layer were not significant.Under the condition of drip irrigation in mild salinized soil,the root surface area,average root diameter,and root volume of cotton were mainly distributed in the soil layer of 0~30 cm,and decreased gradually with the increase in soil depth in the vertical direction.In the horizontal distribution,roots were mainly distributed under the emitters.It was beneficial to the growth of cotton root system under drip irrigation of mild salinized soil when the irrigation quota was 3750 m^3·hm^-2 and the urea application amount was at 600 kg·hm^-2,and the cotton yield achieved the highest,5854.5 kg·hm^-2,under this condition.