Response Of Tomato Electrophysiology、Growth And Water Use Under Different Water Supply Strategies

The lack of water resources is the key factor restricting the physiological process,growth and yield of crops.Unreasonable irrigation not only affects the growth and yield of crops,but also further aggravates the shortage of water resources.Therefore,it is urgent to implement water-saving irrigation in agricultural planting,and the key lies in water supply.A quick understanding of the water transport and utilization mechanism of plants is helpful to grasp the water demand information of plants in time and provide the basis for water-saving irrigation.Therefore,in order to explore the relationship between plant electrophysiological changes and plant water demand nodes and explore the variable rate irrigation method for greenhouse tomato based on electrophysiological parameters,tomato（Solanum lycopersicum）leaf water potential（Ψ_L）,electrophysiological parameters,photosynthesis,nutrient content,growth,dry matter,yield and water use efficiency were measured under different water supply strategies and irrigation treatments.The results show that:（1）The correlation analysis showed that ITR index was significantly higher than that of other indexesΨ_L,Photosynthesis,chlorophyll content,yield and WUE showed good correlation.Therefore,ITR could better characterize the water status of plants.（2）Under different water supply,when the soil relative water content（RWC_S）was lower than 80%,ITR increased significantly,photosynthesis was seriously inhibited.The plant growth,dry matter accumulation and nutrient absorption were seriously affected,resulting in a significant decrease in yield.Therefore,when RWC_Swas lower than 80%,water supply must be increased to maintain RWCS no less than80%.（3）Under W₂（90%RWC_S+100%RWC_S）treatment,the growth of tomato leaves increasedΨ_Land water transport and use capacity were significantly restored,photosynthetic capacity was improved,growth and dry matter accumulation were increased,but water supply was larger,water use efficiency was lower.Under W₄（70%RWC_S+90%RWC_S）and W₅（60%RWC_S+80%RWC_S）treatments,the photosynthetic capacity of plants was seriously inhibited when suffered from water deficit,the water transport capacity could not be restored after rewatering,and the photosynthesis,growth and dry matter accumulation were significantly lower than those of the control.Under the treatment of W₃（80%RWC_S+100%RWC_S）treatment,the growth rate of tomato leaves increasedΨ_LThe highest rewatering strategy was to increase the water use efficiency and the photosynthetic capacity,which was conducive to the growth and dry matter accumulation of plants.（4）Under different water supply,theΨ_Land water transport capacity increased gradually under two-step rewatering,which showed a certain compensation effect.The water content in leaves increased gradually,the photosynthesis of plants was restored,the growth and dry matter accumulation were also restored to a certain extent,and the nutrient content in plants increased.Under T₃（80%RWC_S+90%RWC_S+100%RWC_S）treatment,the water quality of the treated plants was significantly higher than that of the untreated plants.TheΨ_L,electrophysiology,photosynthesis,growth,nutrient elements and other indicators were basically restored to the control level,the water supply decreased,while the water use efficiency increased significantly,dry weight biomass and yield increased significantly.There was a good effect of water saving and yield increasing,which was the best variable irrigation strategy.（5）Under different water supply strategies,according to the corresponding values of tomato electrophysiological parameters at 80%RWC_S,based on the monitoring of electrophysiological parameters,when the ITR increased to 0.056MΩ·N^-1·S^-1,water supply must be carried out.Among the treatments of different water supply and rewatering,W₃treatment had the best rehydration effect.When ITR increased to 0.046 MΩ·N^-1·S^-1,rewatering began,and stopped when the value of this parameter decreased to 0.016 MΩ·N^-1·S^-1.Among the variable irrigation treatments,T₃treatment had the best effect.When ITR increased to 0.029 MΩ·N^-1·S^-1,rehydration began,and stopped when the value of this parameter decreased to 0.018MΩ·N^-1·S^-1,the first rewatering could be carried out.The irrigation should be stopped when the value of this parameter decreased to 0.014 MΩ·N^-1·S^-1.In this way,the water supply time node prediction method could be established based on the on-line monitoring of blade ITR.