The Physiological Response Of Different Wheat Cultivars To High Temperature Stress And The Regulation Of Cerous Chloride

With the global warming,extreme high temperature weather often occurs in the late growing period of wheat in north China.In order to explore the response of wheat production to post-anthesis high temperature stress and know the regulating effect of exogenous Cecl3 on heat stress,we screened 26 varieties,Zhengmai366,Xinong979,Luohan,etc.to analyse the changes of 11 physiological indices under post-anthesis high temperature stress（plastic-covered tunnel）,including,the content of leaf relative water content,soluble protein,malondiadehyde（MDA）,photosynthetic rate,activity of superoxide dismutase（SOD）,etc.And,we took each high temperature resistance coefficient as the index of high temperature resistance,and classify different varieties wheat through principal components analysis,grain filling process and grain yield;On the other hand,we selected two varieties with different responses to high temperature stress as experimental meterials,temperature sensitive variety Luohan2 and high temperature resistant variety Zhengmai366,according to the experimental results of two years,and we designed three experimental treatment,natural conditions（CK）,high temperature stress（HT）and pre-spry Cecl3 under high temperature（HT+CE）on the grain-filling stage,to study the regulating effect and thephysiological mechanism of exogenous Cecl3 at the late stage of booting and the early stage of anthesis.The main finding are as follows:1.11 indices were transformed to 5 independent comprehensive indices,which total cumulative rate reached to 80.56% through analysis of principal component.26 wheat cultivars were divided into 3 groups,according to the principal component comprehensive score evaluation value（D）.High resistance to high temperature variety（H）: Zhengmai366,Lankaoaizao8,Yunong416,Jimai47;Medium resistance to temperature resistant variety（M）: Luomai23,Dexuan1,Zhengmai 7698,Zhoumai16,Aikang58,Zhoumai19,Zhoumai27,Fengdecunmai1,Xinmai11,Jimai22;low resistance to temperature resistant variety: Xinong979,Aifeng3,Beijing8,Luohan2,Luohan6,Zhoumai26,Zhengmai18,Hanxuan10,Zhoumai22,Yumai66,Xinong2208,Xinmai18.Among them,Luohan2 was high temperature sensitive variety（S）,it’s heat sensitivity index of 1000-grain weight and yield were higher than 2,the index and coefficient of resistance of 1000-grain weight were less than 80%.2.Compared with high temperature stress treatment,we found that exogenous Ce³⁺ treatment could reduce madlondialdeyde（MDA）content under high temperature stress.On 15 d or 20 d after anthesis,the MDA content decreased by 20.12% and 34.71%,respectively.These show that Ce³⁺could inhibit the process of membrane lipid peroxidation and alleviate the extent of the damage of cell plasma membrane.In addition,the activity of Luohan2 SOD was significantly increased under high temperature stress for 5d than under nomal conditions,but exogenous Ce³⁺ treatment could enhance the activity of SOD under high temperature stress.It is speculated that the mitigation effect of on cell membrance damage may be related to the reduction of ROS accumulation under high temperature stress.Under high temperature stress,the wheat leaf tissue were stained with DAB to a darker color,while the DAB staining was obviously lighter in exogenous Ce³⁺ treatment,indicating that Ce³⁺ alleviated the accumulation of H2O2 in wheat leaf under high temperature stress.3.Under exogenous Ce³⁺treatment,the content of proline,soluble sugar and soluble protein in Luoxan2 were higher than that high temperature conditions,theses showed that Ce³⁺ can promote the accumulation of osmotic substances and stabilize the balance of osmotic regulation.Long-term high temperature stress can cause cell death.According to trypan blue staining,exogenous Ce³⁺ alleviated the wheat leaf cell death under high temperature stress.And exogenous Ce³⁺ could alleviate increase the chlorophyll content of wheat under high temperature stress by 4%-37%,and increased photosynthetic rate and delay the leaf senescence.Under the condition of exogenous Ce³⁺ treatment,the sensitive variety Luohan2 grain-filling rate of high temperature was consistent under high temperature stress,but exogenous Ce³⁺ treatment increased the grain-filling stage of Luohan2 under high temperature stress.The above results showed that Ce³⁺ could alleviate the problems such as shortened grain filling time and accelerated wheat leaves aging under high temperature stress,and help ensure the stability of wheat grain yield under high temperature.