短葶山麦冬块根发育期光合日变化特征对水分胁迫的响应

摘要

以盆栽短葶山麦冬为材料,研究块根发育的3个时期不同土壤水分处理(对照(CK)、轻度胁迫(W1)、中度胁迫(W2)、重度胁迫(w3)4个处理)下短葶山麦冬光合参数和水分利用效率日变化特征.结果表明,不同土壤水分条件下短葶山麦冬光合速率均在10:00达到最大值,光合速率日变化总体表现为单峰型曲线.3个时期光合速率日最大峰值和日平均值都表现为CK＞W1 ＞W2 ＞W3,3个时期的蒸腾速率和气孔导度均表现为CK＞W1 ＞W2 ＞W3,水分利用效率(WUE)日均值以W3最大,并且上午时段大于下午时段.不同土壤水分条件下光合速率、气孔导度和水分利用效率日均值和日峰值均表现为块根膨大前期＞块根发生后期＞块根发生中期,而蒸腾速率日均值则表现为块根发生中期＞块根发生后期＞块根膨大前期.综合分析表明,不同生育时期,水分胁迫导致净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)下降,提高了WUE,Pn下降的原因在不同生育时期表现不同,进入决根膨大期后短葶山麦冬光合速率与水分利用效率表现为上升趋势.%Four different levels of water stress,mild water stress (W1,65％ FC),moderate water stress (W2,50％ FC),severe water stress (W3,35％ FC) and the control (CK,80％ FC) were applied to study the effects of water stress on the diurnal change of photosynthetic characteristics of Liriope muscari (Decne.) Bailey at different growth stages.The net photosynthetic rate reached a maximum at 10∶00am under different soil moisture conditions.The diurnal variation of net photosynthetic rate presented a one-peak curve overall.At theso three stages,the maximum peak and average value of photosynthetic rate were expressed as CK ＞ W1 ＞ W2 ＞ W3,and transpiration rate and stomatal con ductance were CK ＞ W1 ＞ W2 ＞ W3.Under different soil moisture conditions,the daily average and peak value of net photosynthetic rate,stomatal conductance and water use efficiency were early stage of tuber-expanding ＞ later stage of tuber-producing ＞ middle stage of tuber-producing,while the daily average value of transpiration rate was manifestedas as middle stage of tuber-producing ＞ later stage of tuber-producing ＞ early stage of tuber-expanding.Comprehensive analysis showed that at different growth stages,water stress decreased the net photosynthetic rate (Pn),transpiration rate (Tr) and stomatal conductance (Gs),while improve water use efficiency (WUE),reasons for the decline of Pn performance at different growth stages were different.Net photosynthetic rate and water use efficiency showed an upward trend after entering the root enlargement stage.