Effects Of Temperature Stress On Growth Physiology And Yield Of Fresh Maize

The planting area of fresh maize in Hubei province and even the whole country has developed rapidly.In order to increase the unit price of sales,Farmers often plant earlier or later to bring fresh maize to market earlier or later.In order to increase the sales unit price,growers often advance or delay the sowing time to promote or delay the listing of fresh maize.However,early or late sowing may affect the yield and quality of fresh maize under the stress of low temperature at seedling stage and high temperature from tasseling to silking stage.In this study,fresh food maize(Zea may L.)Yuxiang Jin,E Tianyu 5,Jin Zhongyu,Yutian 16,Taimei Tian 3 and Wantian 2015 were used as materials.The field test of early sowing and low temperature was set as March 10(SD1),March 20(SD2)and April 01(SD3),and the field test of late sowing and high temperature was set as May 08(SD4),May 18(SD5)and May 28(SD6).To study the effects of low temperature stress in vegetative growth stage and high temperature stress in reproductive growth stage on the growth and development of fresh maize,filaments activity,yield and component factors of fresh maize.The effects of low temperature stress on root characters and antioxidant enzyme content of fresh maize and high temperature stress on pollen activity of fresh maize were studied by pot culture and in vitro culture experiments with artificial climate box.Principal component analysis was performed on the growth and development of fresh maize,filament activity,root character and yield,and the main influencing factors on the stress resistance evaluation of fresh maize were determined.The low temperature resistance and high temperature resistance of 6 varieties of fresh maize tested were scored,and the high yield and quality varieties with better stress resistance were compared,in order to provide the cultivation technology and theoretical basis for the production of fresh maize.The main conclusions of the study are as follows:(1)Low temperature stress inhibited seedling preservation rate,plant growth and development,root character and yield of early sowing fresh maize in different degrees.Under low temperature condition,the duration from sowing to jointing stage was prolonged,which resulted in the whole growth period was prolonged obviously.With the decrease of temperature,the average plant height,ear height,per ear gross weight,ear diameter,net grain weight and 100 grain weight of fresh maize decreased.The average yield,effective ear number and protein content of maize showed a parabolic trend,but the difference did not reach a significant level.Under low temperature stress,the cells of fresh maize were damaged and the content of MDA increased.The antioxidant system in the plant reacted quickly,and the activities of SOD,POD and CAT increased significantly to resist cold injury stress.(2)High temperature stress can prolong the interval between tasseling and silking of fresh maize,significantly inhibit the number of filaments,growth rate of filaments and pollen activity of fresh maize,directly affect pollination and fruiting of fresh maize,lead to significantly larger bald tip,and significantly decreased gross weight per ear,kernel number per ear and yield.With the increase of temperature,the average root-shoot ratio,root length,root surface area,effective panicle number,net grain weight and 100 grain weight of fresh maize increased gradually,while the average plant height,ear height and stem diameter decreased correspondingly.(3)Five principal components were selected to explain the changes of the growth,physiology and yield of fresh maize under low temperature stress,accounting for 76.5%of the variability.The results showed that maize root traits,field seedling preservation rate,yield,effective panicle number,root-shoot ratio,grain number per ear and average diameter had a high weight on the stress resistance evaluation of fresh maize.Among the six varieties tested,Taimei Tian No.3(B5)and Wantian 2015(B6)had better resistance to low temperature stress than other varieties,and their comprehensive scores of stress resistance were 2.0 and 0.5,respectively.(4)Through principal component analysis,a total of 6 principal components were extracted under high temperature conditions to explain the effects of high temperature stress on the growth,development and yield of fresh maize,accounting for 78.7% of the variability.High temperature stress had significant effects on root traits,yield,effective panicle number,filament activity,stem diameter,kernel number per ear,100 kernel weight and root-shoot ratio of maize,which played a very important role in the evaluation of high temperature resistance of fresh maize.Under high temperature conditions,Taimeitan No.3(B5)and Wantian 2015(B6)had higher resistance to high temperature stress than other varieties.To sum up,fresh maize sown early or late may suffer from low or high temperature damage,resulting in reduced production.Among the six fresh food maize varieties tested,Taimei Tian No.3,Wantian 2015 and Yuetian No.16 could be selected for early sowing in spring,and Taimei Tian No.3,Wantian 2015 and Etianyu No.5 could be selected for late sowing in summer,among which Taimei Tian No.3 had higher resistance to low temperature stress and high temperature injury in early sowing and was the preferred variety for early or late sowing.