Effects Of Temperature Stress On Physiological Characteristics And Yield Of Greenhouse Sweet Peppe

Sweet pepper is a temperature-sensitive greenhouse crop.In order to study the effects of high and low temperature stress on the photosynthetic characteristics and biochemical indicators of sweet pepper during the seedling and fruiting stages,"Yellow Tai Chi" sweet pepper was used as the experimental material.Four groups of high temperature treatments(32℃/22℃,35℃/25℃,38℃/28℃,41℃/31℃)and four groups of low temperature treatments(16℃/6℃,19℃/9℃,22℃/12℃,25℃/15℃)were set,with 28℃/18℃ as the control group.The treatments lasted for 3,5,7,and 9 days.Photosynthetic parameters,chlorophyll fluorescence dynamic curves,enzyme activity indices of leaves,physiological indices,and yield were measured to explore the effects of temperature stress on the physiological ecology of sweet pepper during the seedling and fruiting stages and to construct high and low temperature stress disaster grade indicators.The results showed that:(1)Under low temperature stress,as the treatment temperature decreased and the time of stress increased,the LSP,AQE,and Pmax of sweet pepper leaves at the seedling stage all showed a decreasing trend,while LCP showed an increasing trend.Low temperature stress inhibited the light energy utilization ability of sweet pepper and had a greater impact on the fruiting period than the seedling stage.The SOD,POD,and CAT enzyme activities of sweet pepper leaves at the seedling stage showed an initial increase followed by a decrease with the increase in time,while the MDA content showed the opposite trend.The SOD,POD,and CAT enzyme activities of sweet pepper leaves at the fruiting stage showed a decrease followed by an increase with the increase in time.The lower the stress temperature and the longer the duration of stress,the higher the reduction rate of sweet pepper yield.Low temperature stress had a more severe impact on yield during the fruiting stage than during the seedling stage.(2)Under high temperature stress,as the treatment temperature increased and the duration of stress increased,the LSP,AQE,and Pmax of sweet pepper leaves at both the seedling and fruiting stages showed a decreasing trend overall.At temperatures of 32-35℃,the impact of high temperature stress on the photosynthesis of sweet pepper during the seedling stage was more severe than during the fruiting stage;at temperatures of 38-41℃,the impact of high temperature stress on the photosynthesis of sweet pepper during the seedling stage was slightly lower than during the fruiting stage.The SOD,POD,and CAT activities of sweet pepper leaves at the seedling stage showed an initial increase followed by a decrease,while the MDA content increased continuously as the treatment time increased.The SOD activity of fruiting stage leaves was higher than that of the control group,while the POD activity increased first and then decreased with the increase in treatment time,and the CAT activity increased first and then decreased with the increase in treatment time at temperatures of 32-35℃,but showed a decreasing trend at temperatures of 35-38℃.The MDA content increased with the increase in treatment time.High temperature stress inhibited the growth and development of sweet pepper at different levels.The higher the stress temperature and the longer the duration of stress,the greater the reduction in yield during the fruiting stage.High temperature stress had a more severe impact on yield during the fruiting stage than during the seedling stage.Low temperature stress inhibited the photosynthesis of sweet pepper,and the effect on the fruit stage was far beyond the seedling stage;the lower the stress temperature and the longer the stress time,the lower the yield of sweet pepper,and the effect on the fruit stage was more than that on the seedling stage.High temperature stress inhibits the photosynthesis of sweet pepper.At 32-35°C,the impact on the seedling stage is more severe than that at the fruit stage,and the opposite is true at 38-41°C.The higher the stress temperature,the longer the treatment time,and the higher the yield of sweet pepper at the fruit stage.Low,and the impact on the fruit stage is more serious than the seedling stage.