Comparative Study On Growth And Yield Of Corn In Different Sowing Dates In Hebei Plain

The extreme scarcity of water resources in the North China Plain has become a key factor restricting the sustainable development of agriculture in the region.The one-crop spring corn planting model can replace the winter wheat-summer corn annual multiple cropping model at the cost of water ecology in the region.However,the current spring corn yield is lower than the output target,which hinders the promotion of this planting model.Therefore,in this study,Zhengdan 958 and Xianyu 335 were used as experimental materials.In 2018,SD1(April 28)and SD2(June 19)were set for two sowing dates,and in 2019,five sowing conditions were set as follows:SD1(April 15),SD2(April 30),SD3(May 15),SD4(May 30),SD5(June 14).To study the response of corn growth and yield composition at different sowing dates to meteorological conditions,to analyze the meteorological conditions at different growth stages of corn in different sowing dates in the past 30 years,to determine the most suitable sowing date in the region,It provides a theoretical basis for the study of high-yield corn and adjustment of planting structure in the region.The research results are as follows:(1)The total growth days of Zhengdan 958 and Xianyu 335 are shortened with the sowing period.The main meteorological factors that affect the growth period are the average temperature,average low temperature,and average maximum temperature during the entire growth period.The corn sown in mid and late April was subjected to drought stress during the jointing-large mouth period,which was significantly different from other agronomic traits during the sowing period.Maize plant height and ear height increased with the sowing date,and there was no obvious difference in stem thickness.SD5 Xianyu 335 fell before the tasseling period,so late sowing of varieties with weak lodging resistance will increase the probability of lodging.The maximum LAI of the two varieties and the total photosynthesis of the group showed an increasing trend with the delay of the sowing date.With the sowing period,the maximum dry matter growth rate of the two varieties is advanced,the maximum accumulation rate is increased,and the linear growth period is shortened,but the dry matter accumulation amount during the linear growth period increases.The dry matter accumulation of various organs during the mature period,the dry matter transport before flowering and the contribution rate to the grain all increase with the delay of the sowing date.(2)Under the condition of late sowing,the SPAD value of ear leaves decreased slowly,and the senescence rate of early sowing corn leaves was faster.The drought stress at the jointing-large-mouth stage and the high-temperature stress at the large-mouth-maturity stage caused the nitrogen concentration and nitrogen accumulation in the stem and sheath of the early sowing maize to be significantly higher than that in late sowing,and the nitrogen accumulation in grain was lower than that in late sowing.There was no significant difference in leaf nitrogen redistribution and its contribution rate to grains during different sowing periods.The nitrogen redistribution in stem and sheath and its contribution rate to grains were significantly lower than those in late sowing.(3)The maximum 100-grain weight of two varieties with the sowing period was delayed.The early sowing corn was affected by the high temperature in the jointing-large mouth period and the large mouth-milk maturity period.The growth of female ears was restricted and the number of grains of the ears was significantly reduced.The grain weight of spikes increased with the delay of sowing date.The maximum filling rate(Vmax),average filling rate(Vmean),and the growth amount(Wmax)at the maximum filling rate of a single ear grain increase with the sowing date.(4)Compared with the SD2 sowing period in 2019,the SD1 sowing period in 2018 is less affected by adversity stress,and the output is higher than in 2019.Both 2018 and 2019 yields will increase with the delay of the sowing date.Early sowing,especially the corn sown in April,will greatly reduce the yield.The number of ears is a limiting factor affecting yield.The drought stress at the jointing-large-mouth stage reduced the accumulation of LAI and dry matter in early-sowing maize.The growth of female spikes was inhibited and affected the development of grains.The high temperature during the critical period of grain formation led to a decrease in pollen vigor and the number of grains in ears.The spinning duration of each sowing period and output are extremely negatively correlated.Adversity stress prolongs the spinning time,reduces the number of grains per ear,and provides more material supply for a single grain.(5)According to the analysis of meteorological factors in the past 30 years,the limiting factors of maize yield in the sowing period of mid and late April were the double stress of drought in the vegetative growth period and high temperature and drought in the flowering period.The limiting factor of maize yield in the sowing period of mid and late May was the high temperature stress in the flowering period.The lower temperature in the late growth stage of corn in the mid-June sowing period affects grain filling.