调亏灌溉对多年生黑麦草光合特性的影响及阈值的确定

Effects of regulated deficit irrigation on photosynthetic characteristics in Perennial Ryegrass and the determination for irrigation threshold

本研究以干旱半干旱区栽培面积较大的多年生黑麦草(Lolium perenne)品种"首相"和"潘多拉"为研究对象,使用人工控制灌水量的方法在生长季节使黑麦草经历"干旱胁迫-复水"的5个循环处理,研究其在不同调亏灌溉及复水处理下光合特性的变化趋势。结果表明,两个品种黑麦草叶片的净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和PSⅡ原初光能转化效率(Fv/Fm)随着土壤相对含水量(RSWC)的降低而下降,当RSWC下限值不同时,各指标的下降程度不同,且复水后的恢复程度也不同。灌溉下限在RSWC为50%时,各指标变化幅度较小;灌溉下限在RSWC为40%时,两个品种黑麦草受害程度加大;灌溉下限在RSWC为20%时,两个品种黑麦草均受到严重伤害,复水后各指标不能完全恢复。两个品种比较,"首相"比"潘多拉"抗旱性强。说明调亏灌溉对多年生黑麦草具有明显的RSWC限制范围,品种之间表现不同,"首相"最佳灌溉RSWC下限为40%,"潘多拉"为50%。

This study was conducted in the greenhouse with perennial ryegrass(Lolium perenne) varieties Premier and Panterra,which are largerly planted in semiarid areas.The experiment with controlled soil water contents was conducted to study the effects of five treatments repeated drying and re-watering on photosynthetic characteristics.The results indicated that variation tendency of two varieties of perennial ryegrass on photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductance(Gs) and photochemistry activity of PS Ⅱ(Fv/ Fm) decreased with RSWC decreasing.The activities of photosynthetic parameters in different relative soil water content had different variation trends and also had different recovery level after rehydration.When the relative soil water content was the lower irrigation limit which is 50% RSWC caused stress effect to grasses,it will not cause greater harm.While the treatment which lower irrigation limit was 40% RSWC,two varieties of Perennial ryegrass injury were more and more serious.Both of the two grasses at the end of the drought stage showed severe stress(lower irrigation limit of20% RSWC) injury,and can not recovered rapidly in the physiological function after rehydration.The comparative result between the two grasses: Premier has the better drought resistance than Panterra.These are suggested that Regulated irrigation on Perennial ryegrass has obvious for RSWC,and showed different result between the two grasses: Premier is 40% RSWC; Panterra is 50% RSWC.