水氮耦合对温室砂培黄瓜基质水盐、氮运移及产量的影响

The Effects of Water-nitrogen Coupling on Transport of Water,Salt and Nitrogen in Matrix-cultured Greenhouse Cucumber

【目的】探究温室砂培黄瓜在不同水氮施用下的基质剖面水盐、氮的分布运移特征及黄瓜产量的差异。【方法】采用二次饱和D-最优设计进行了砂培黄瓜水氮耦合田间试验,试验共设7个处理,每个处理重复3次,每隔20 d测定各处理4个基质层的含水率、EC值、硝态氮量、铵态氮量,并统计了黄瓜产量,研究水氮耦合对温室砂培黄瓜基质剖面水盐、氮运移及黄瓜产量的影响。【结果】灌水水平是影响砂培基质含水率的主要因素,基质剖面上的水分分布表现出湿润峰明显向深层运移的趋势;膜下滴灌有“抑盐压盐”的作用,避免过量灌水施氮是防止基质盐分富集的有效措施;基质中的硝态氮和铵态氮总体上表现出易随水分迁移的特性,黄瓜根系对于铵态氮的吸收存在阈值;黄瓜产量随着灌水水平和施氮量的增加表现出先增加后降低的趋势,符合报酬递减规律。【结论】综合考虑基质剖面水盐、氮的分布运移、黄瓜产量及水氮投入等因素,本研究推荐的水氮耦合方案是灌水上下限设置为80.20%~89.40%、60%,施氮量控制在623~917kg/hm^(2),能够保证黄瓜较好的生长环境、减少水分和氮素淋失风险、避免产生次生盐渍化危害、提高水肥利用效率和黄瓜产量,可为温室砂培黄瓜水肥一体化的推广提供理论依据。

【Background and Objective】Matrix-culture has been increasingly used in vegetable production,but continuous irrigation and fertilization could result in salinization and degradation of the matrix.The purpose of this paper is to experimentally study the impact of different combinations of irrigation and nitrogen(N)fertilization on water,salt and nitrogen dynamics in sandy matrix of cucumber,as well as its consequence for cucumber yield.【Method】The experiment was conducted in a greenhouse and consisted of seven treatments which were designed using the secondary saturated D-optimal design methods.Each treatment had three replicates.All treatments were drip-irrigated.During the experiment,we measured the moisture content,EC,nitrate and ammonium contents at four layers in the matrix after each 20 days,as well as cucumber yield in each treatment.【Result】The irrigation amount controlled water movement in the matrix,and the irrigation water moved downwards in most treatments.Mulching the matrix surface with a membrane can suppress the detrimental effect of salt to some extent,but avoiding excessive irrigation and N application is the best way to reduce salt accumulation in the matrix.Water flow took nitrate and ammonium to move with it in the matrix,and there was a threshold for ammonium below which the cucumber roots were unable to take up.The cucumber yield increased with irrigation and nitrogen fertilization parabolically:increasing first and then declining after the irrigation or fertilization exceeded a threshold.【Conclusion】On average,in terms of moisture content,the optimal water-nitrogen coupling is to set the upper and low soil moisture content in the matrix for irrigation at 80.20%~89.40%and 60%,respectively,N application at 623~917 kg/hm^(2).These not only ensure sufficient water and N to the crop,but also reduce the risk of water and N leaching and secondary salinization of the matrix.