Agronomic And Yield Characters Response Law Of Sowing Date On Maize Hybrid

Maize is an important food crop in China.Determining suitable sowing date is one of the key technical links to achieve high yield and stable yield of maize,and it is also an important problem to be solved first in the promotion of new varieties.It is helpful to optimize the main promotion area and sowing date scheme of new varieties and give full play to the characteristics and advantages of varieties to analyze the changes and reaction rules of yield and other traits in different sowing periods.In this study,5 sowing dates(April 20—SD1,May 5—SD2,May 20—SD3,June 5—SD4,June 20—SD5)were set for the newly approved maize varieties in 4 prefectural cities of Shandong Province.The agronomic characters,the differentiation process of female spike,the filling characteristics of grain,the variation trend of yield and components and the response to light and temperature factors of each variety under different sowing dates were analyzed.The results were as follows:(1)Response of plant agronomic traits to sowing dateThe plant height,ear height and ear leaf area of each variety increased first and then decreased with the delay of sowing date.The plant height and ear height of each variety were the highest under SD2-SD4 sowing,and the lowest under SD1 or SD5 sowing,respectively.The leaf area per ear of each variety was the maximum under SD2-SD4 sowing period,and the minimum under SD5 sowing period.The position of leaves at the ear position of each variety is basically stable at different sowing dates.(2)Changes in meteorological factors during and during the growth period of varieties under different sowing datesWith the delay of the sowing date,the number of growth days of all varieties was first shortened and then increased.From the sowing date of SD1 to the sowing date of SD4,the main reason was that the number of days from seedling emergence to spinning stage gradually decreased.The number of days from spinning to physiological maturity of all varieties increased under the sowing date of SD5.With the delay of sowing date,the effective accumulated temperature in the growth period of each variety increased first and then decreased,and the highest temperature was reached in the sowing period of SD2 or SD3.(3)The effect of sowing date on the differentiation characteristics of female spikeWith the delay of sowing date,the stage days from seedling emergence to growth cone elongation were shortened,but the time from growth cone elongation to female spike was basically the same under different sowing dates.The number of florets,number of filaments,and seed setting rate of each variety are the highest during the SD2 or SD3 sowing period,which is an important reason for increasing the number of kernel number per ear.(4)Influence of sowing date on yield and component factorsThe yield of each variety was higher in the early May or early June sowing period,respectively.The risk of encountering abnormal high temperature weather was high in the growth period of the mid-May sowing period.Long growth period and high effective accumulated temperature before flowering were beneficial to increase the number of grains per spike,while high temperature and rainy days before and after flowering significantly reduced the number of grains per spike.Long days of growth period and more sunshine hours after flowering were conducive to the increase of 1000-grain weight,high temperature in the filling period was not conducive to the increase of 1000-grain weight,and higher temperature difference was conducive to the increase of 1000-grain weight.(5)Suggestions on the suitable sowing date of various varieties in ShandongIncreasing the population grain number of ZT308 is the key to increase yield.The population grain number of ZT308 can be increased by increasing density to achieve high yield.It is recommended to sow in early and middle June.TT766 has a higher yield during the sowing period of early May and early June,so the summer maize area can be planted in early June.Due to its longer growth period,it should be sown as early as possible to give full play to its advantage of grain number per ear and control its physiological maturity before wheat planting.Overall,TT66 has the highest yield during its sowing period on April 20 th.It is recommended to sow in late April or early May,and early June if it is sown in summer.LD510 has the highest yield when sown in late April and early May,followed by early June.The growth period of this variety is shorter than that of other varieties.In case of late harvest of previous crops,this variety can be selected to postpone the sowing date appropriately.