Effect Of Temperature And Radiation On The Stalk Lodging Resistance Of Maize Under Different Sowing Dates

Object:Lodging is an important production problem that causes the decrease of yield and quality of maize and increases the costs of harvesting.In this study,was designed to make clear the effect of sowing dates on the stalk lodging resistance of maize,screen out the key indicators that affect the stalk lodging resistance at different growth stages,compare the difference of lodging resistance under different temperature and light environment conditions in the development of maize stalks,and explore the relationship between the temperature and radiation factors and lodging indexes,thus providing theoretical and practical basis for cultivation of lodging resistant maize.Methods:Five different sowing dates were set from April to May in 2017-2019 in Qitai farm,Xinjiang,which were ranged from SD1 to SD5.In 2017,the medium variety,KWS9384??10?of effective accumulation temperature of 2300??was planted at two densities:9.0×10⁴ plants ha^-1and 12.0×10⁴plants ha^-1.In 2018,three varieties with different maturity were selected:early variety of KWS2030??10?of effective accumulation temperature of 2000??,medium variety of KWS9384,and late variety of KWS3564??10?of effective accumulation temperature of 2900??,the planting density was 12.0×10⁴plants ha^-1.In 2019,the experiment in 2018 was repeated with a plant density of 9.0×10⁴ plants ha^-1.We measured such relevant indicators as stalks lodging in the silking,milk and physiological maturity stages,compared the differences of maize stalks lodging resistance in different sowing dates,screened out the key indicators that affect the stalk breaking force?SBF?of maize in different growth stage,as well as analyze the relationship between the temperature and radiation factors in development process of stalk and the anti-lodging indexes.Results:With the delay of the sowing date of maize,the days from sowing to emergence,the days from emergence to jointing,the days from jointing to silking were all decreased,but the filling stage was prolonged.The whole growth period of early variety showed a shortening trend with the delay of sowing date,the whole growth period of medium variety?SD5?was prolonged significantly,but the late variety?late-sowed?was hardly to mature.Maize's jointing to silking stage is the key period for stalk morphogenesis,dry material accumulation and mechanical strength formation.And the morphogenesis is earlier than the formation of internodes strength.With the delay of the sowing date,the internodes elongation rate is accelerated,the rapid growth period and rind penetration strength?RPS?formation period are advanced,dry weight and RPS were increased.The stalk strength and plant morphology were influenced by the conditions of the temperature and light in different years.The moisture content of basal internodes decreased with the passing of growth period and dry weight per unit length?DWUL?,which showed an increasing trend.The mechanical strength and morphology of basal internodes at R1 are the main factors affecting the lodging resistance of the stalk,the ear height and the accumulation of material in the stalk determine the stalk's lodging resistance at R3,and the lodging resistance of the stalk at R6 is influenced by the material accumulation of the stalk and ear.The resources of temperature and radiation accumulated from jointing to silking stage have a positive effect on stalk lodging resistance of the medium-late cultivars at R1.And the more light and temperature resources accumulated during the whole growth period,the more beneficial to the stalk lodging resistance of maize.Conclusion:Maize growing process before silking stage will shorten with the delay of sowing date due to the increase of light and temperature resources,while the lack of light and temperature resources in the later stage will prolong the filling process,and the whole growth period is shortened.But the late sowing of medium-late cultivars'growth period was prolonged or unripe.The key indicators affecting maize stalk lodging resistance are different during different growth periods,the accumulation of material is an important prerequisite for lodging resistance and the lower ear height is the effective guarantee.In general,the more light and temperature resources accumulated during the whole growth period are beneficial to the lodging resistance of maize stalk.