滴灌条件下芹菜叶片膨压变化特征及其影响因素研究

Change in Turgor Pressure in Celery Leaf under Drip Irrigation and Its Determinants

【目的】探明滴灌芹菜的叶片膨压变化特征及其影响因素。【方法】采用叶片膨压探针在线监测充分灌溉(FI)和非充分灌溉(NI)下的滴灌芹菜叶片膨压变化参数(Pp、Pp^(*)),同步记录相关温室环境因子与植物典型水分生理指标,分析膨压变化参数(Pp、Pp^(*))在不同灌水条件下的变化特征,并利用多元回归、通径分析和时间错位法探讨叶片膨压变化对各影响因素的响应。【结果】①不同处理及不同生育期的典型晴日下,芹菜叶片Pp^(*)均呈昼高夜低的单峰型日变化趋势,但NI处理的Pp^(*)启动时间较FI处理提前,且其峰值较FI处理高39.3%~66.7%。②不同灌水处理下,Pp^(*)与气孔导度(Gs)、蒸腾速率(Tr)的日变化趋势相同,且呈正相关;Pp^(*)与叶水势(Ψ)负相关。③灌溉能显著影响芹菜叶片膨压变化,不同处理灌水前Pp峰值和谷值逐渐上升,灌水后二者迅速下降,但NI处理下的Pp变化幅度更剧烈。④典型晴日不同处理下,芹菜叶片Pp^(*)与大气温度(TA)、饱和水汽压差(VPD)显著正相关,与相对湿度(RH)、风速(WS)显著负相关。通径分析显示,TA对Pp^(*)的直接影响最显著,VPD对Pp^(*)的间接影响最显著。而逐步回归结果表明,WS对Pp^(*)的影响只在NI处理下显著。各生育期Pp^(*)与TA间均存在时滞效应,但NI处理下二者的时滞时间较FI处理增长了10~30 min,形成的时滞圈面积增大4%~9.5%。【结论】综上,芹菜叶片膨压变化特征与灌溉条件、气象因子密切相关,水分供应不足时膨压变化参数的峰值增大,与温度的时滞效应增强。

【Objective】Turgor pressure in crops varies with root water uptake as a response to occurrence of water stress.This paper investigates how turgor pressure in the leaf of celery responds to drip irrigation and the factors which affect the pressure variation.【Method】The experiment was conducted in a greenhouse.It consists of sufficient irrigation(FI)and deficit irrigation(NI)treatment.Change in leave turgor pressure,characterized by expansion parameters Pp and Pp^(*),in each treatment was measured using a probe.We also measured the environmental factors and physiological traits of the plant,and analyzed their relationship with Pp/Pp^(*)using multiple regression,path analysis and time warping methods.【Result】①The parameter Pp^(*)maximized at daytime and minimized at night on typical sunny days,regardless of the irrigation treatments and growing stage.However,Pp^(*)started to increase earlier in NI than in FI treatment,with the peak of Pp^(*)in the former being 39.3%~66.7%higher than that in the latter.②The diurnal change in Pp^(*)was similar to that in the stomatal conductance(Gs)and transpiration rate(Tr).Pp^(*)was positively correlated to Gs and Tr,but negatively to leaf water potential(Ψ).③The change in leaf turgor pressure varied with irrigation.The maximum and minimum Pp increased gradually priori to irrigation and decreased rapidly after irrigation,especially in the NI treatment where the change was more profound.④Pp^(*)was positively correlated to atmospheric temperature(TA)and vapour pressure deficit(VPD),but negatively to relative humidity(RH)and wind speed(WS).Path analysis showed that the highest correlation between Pp^(*)and TA,and VPD was an indirect factor affecting Pp^(*).Stepwise regression indicated that WS impacted Pp^(*)significantly only in NI.We also found that the impact of TA on Pp^(*)was not instant but existed a delay,especially in NI where the delay was more than 10~30 min than that in FI.【Conclusion】Variation in leaf turgor pressure in greenhouse celery was closely related to irrigation amount and meteorological factors.Insufficient irrigation increased the maximum turgor-pressure variation parameter but delayed the effect of atmospheric temperature on the turgor pressure.