中国苜蓿产量及水分利用效率对种植年限响应的Meta分析

Meta-analysis of alfalfa yield and WUE response to growing ages in China

为探究种植年限对苜蓿产量和水分利用效率(WUE)的影响,确定不同生境下苜蓿最适宜的种植年限,本研究以中国为研究区域,以3~5年生苜蓿为对照,通过检索文献整合已发表的相关田间试验数据,截至2019年5月共获得80篇文献、1496组苜蓿产量和220组WUE试验数据,将数据按照年降水量(<200 mm,200~400 mm,400~800 mm和≥800 mm)、施肥措施(施肥和不施肥)、水分管理(灌溉和雨养)进行分组,采用整合分析方法(Meta-analysis,包括异质性检验、综合效应量计算、发表偏倚检验和亚组分析),系统探究了种植年限对苜蓿产量和水分利用效率的时空效应与影响因素,并定量分析了环境因子与不同种植年限苜蓿产量以及WUE的关系。本研究结果表明,随种植年限的延长草产量和WUE呈现先升后降的趋势,3~5龄为苜蓿盛产期,而6~8龄苜蓿WUE最高。苜蓿种植年限受环境因素及水肥措施影响,干旱、半干旱区,苜蓿最适宜的种植年限为3~5年;半湿润区,苜蓿最适宜的种植年限可延长至6~8年,但湿润区由于温湿度过高,使得苜蓿最适宜的种植年限缩短至3~5年。施肥可适当延长苜蓿种植年限,但灌溉并不能有效延长苜蓿种植年限。

In order to explore optimal alfalfa stand age in different environments,a meta-analysis was conducted to determine how yield and water use efficiency(WUE)of alfalfa(Medicago sativa)change with stand age in China.A total of 80 articles published before May 2019 were chosen from domestic and foreign journals(including 1496 available comparisons of yield and 220 available comparisons of WUE).Each article abstracted included data on annual precipitation,fertilization practices and water regime.Site annual rainfall was classified as<200 mm,200-400 mm,400-800 mm or≥800 mm.Fertilization practice was recorded as fertilization or no fertilization,and water regime was classified as irrigation or rainfall.The analytical steps in each case consisted of a heterogeneity test,a comprehensive effect size calculation,a publication bias test,and influence factor analysis.It was found that forage yield and WUE of alfalfa were highest in three-five and six-eight year old stands,and then decreased gradually.Also,the yield and WUE decline in older stands of alfalfa may be related to reduction in soil water storage and soil fertility and their interaction.Based on the forage yield and WUE data examined in this study,peak performance occurs in three-five year old stands in arid regions,semi-arid regions and humid regions,but can extended to six-eight year old stands in semi-humid regions.The data indicate that alfalfa stand peak performance and longevity are more effectively extended by fertilization than by irrigation.