Responses Of Three Garden Plants' Physiological And Biochemical Processes To Different Drought Patterns And Rewatering

Water is a component of all living things,and photosynthesis of plants require the participation of water.Drought is an unavoidable disaster in nature.The lack of water directly affects the growth status and survival time of plants.At present,the rapid development of urban gardens has led to a continuous decrease in water resources and an increasing demand for water for urban environmental maintenance.Under the background of increasing environmental requirements for garden plants,garden workers urgently need to study and solve the problem of drought resistance of garden plants.Studying the strategies of different types of plants to deal with drought can have important implications for our scientific and reasonable selection of plant types,and provide a theoretical basis for predicting the future dynamic changes of ecosystems and the allocation of garden plants.In this study,common garden tree species in Hefei,Anhui Province:Koelreuteria bipinnata var.integrifoliola,Photinia×frasery and Viburnum odoratissimum var.awabuki were used as objects.The pot-weighing and water-control method was used to simulate similar droughts in different degrees in nature.Photosynthetic,physiological and hydraulic parameters.The findings are as follows:(1)Both rapid drought and slow drought have caused Koelreuteria bipinnata var.integrifoliola,Photinia ×frasery and Viburnum odoratissimum var.awabuki early morning water potential,noon water potential,photosynthetic rate,stomatal conductance,transpiration rate,and water use efficiency to decrease in different degrees.Compared with the slow drought treatment,the indexes decreased rapidly and the amplitude was large.Whether rapid drought or slow drought,Photinia×frasery always maintained a relatively high photosynthetic rate,and the water potential remained at a high level.(2)Under drought stress,the total biomass of the three tree species,Koelreuteria bipinnata var.integrifoliola,Photinia×frasery and Viburnum odoratissimum var.awabuki all significantly decreased.The species and drought intensity of the seedlings affected the biomass allocation mechanism of plants.The stem biomass of Koelreuteria bipinnata var.integrifoliola is reduced,and Viburnum odoratissimum var.awabuki mainly reduces the root biomass.The roots and stems of Photinia×frasery are significantly reduced;under slow drought stress,the biomass of all organs decreased,Koelreuteria bipinnata var.integrifoliola is still significantly reduced in stems.(3)In this experiment,the soluble sugar concentration and starch concentration of various organs in Photinia×frasery and Viburnum odoratissimum var.awabuki changed significantly.Under rapid drought,the cell membranes of Koelreuteria bipinnata var.integrifoliola,Photinia×frasery and Viburnum odoratissimum var.awabuki have been damaged to varying degrees,and in the late stage of drought,the cell membranes were severely damaged,producing more malondialdehyde.It is also verified that the rapid drought model has exceeded the drought tolerance of the three plants.During the initial period of slow drought,the cell membrane of Koelreuteria bipinnata var.integrifoliola was obviously destroyed.Later,it gradually adapted to the external drought environment,and the cell membrane did not suffer damaging damage.As the stress time increases or the stress level deepens,the three light and pigments,chlorophyll a,chlorophyll b,and carotenoids,display a trend of increasing continuously or increasing first and then decreasing.(4)After rehydration in the early and middle stages,the soluble sugar concentration in the leaves of Koelreuteria bipinnata var.integrifoliola and Viburnum odoratissimum var.awabuki decreased,indicating that Koelreuteria bipinnata var.integrifoliola and Viburnum odoratissimum var.awabuki improved drought resistance through the accumulation of soluble sugar.Before and after rehydration,the soluble sugar concentration of Photinia×frasery leaves increased,and at the same time,the starch concentration decreased,showing the strong recovery ability and drought tolerance of Photinia xfrasery.(5)After mid-term rehydration,Koelreuteria bipinnata var.integrifoliola and Viburnum odoratissimum var.awabuki increased with the available water,and the content of malondialdehyde decreased rapidly,indicating that the amount of active oxygen produced was reduced and the damage to the cell membrane system was also reduced.The content of malondialdehyde in Photinia×frasery has been increasing,which shows that Photinia×frasery can adapt to the stress through other ways to maintain the continuity of the species when it is exposed to stress.