Effects Of Different Sowing Dates And Densities On Yield And Quality Of Silage Maize In Northwest He Bei Province

In order to cope with global warming,it is of great significance for the sustainable development of silage maize industry to study the effects of climate change on the growth,yield and quality of silage maize.In Xuanhua County of Zhangjiakou in 2018,experiments on different sowing dates and densities were carried out with Zhongyuan Dan32(ZYD32),Dajing Jiu26(DJJ26)and Henan Silage 23(YQZ23)as experimental materials.By adjusting sowing dates,the climate factors such as temperature and precipitation during the growth period of silage maize were coordinately adjusted,which affected the growth and development of Silage Maize and ultimately affected the yield and quality of silage maize.The response of growth,yield and quality of Silage Maize to climate factors such as temperature and precipitation under different sowing dates and densities was systematically studied.The relationship between climate factors and growth,yield and quality of silage maize was discussed.The suitable sowing date,density and key climate factors for high yield and high quality of Silage Maize in Northwest Hebei were defined.The results are as follows:1.Sowing date affects the growth process of silage maize.Early sowing slowed down the growth process and prolonged the growth period of silage maize;delayed sowing date and accelerated the growth process;higher temperature in the early growth period of late sowing,shortened the days from sowing date to seedling emergence and seedling emergence to jointing stage,which shortened the whole growth period,ZYD32 from 139 days to 101 days in turn,DJ26 and YQZ23 from 153 days to 128 days in turn.There was no significant difference between densities.2.Among the sowing date treatments,the three varieties showed the same performance,and their yields gradually decreased with the delay of sowing date.The yield of ZYD32 decreased with the increase of density.The highest yield of 90 000 plants per hm-2 was 28.01 t per hm-2.The yield of DJ26 and YQZ23 tended to increase with the increase of density.The highest yield performance of 12 500 plants per hm-2 was 28.28 t per hm-2 and 28.24 t per hm-2,respectively.With the delay of sowing date and the increase of density,leaf weight,stem weight and female ear weight of the three varieties decreased.Compared with DJJ26,the yield of three varieties was the highest,followed by YQZ23 and ZYD32.3.The sowing date regulates the main climatic factors of temperature and precipitation during the growth period of Silage Maize in the field.The accumulated temperature of S1-S4 growth period can meet the accumulated temperature demand of physiological maturity of ZYD32.The accumulated temperature of S4-S5 restricts the accumulated temperature demand of physiological maturity of DJ26 and YQZ23.The main climatic factors affecting silage maize yield are daily average temperature at seedling stage,effective accumulated temperature at grain stage,effective accumulated temperature and precipitation during whole growth period.4.The main climatic factors affecting the quality of silage maize are effective accumulated temperature and precipitation.Effective accumulated temperature and precipitation negatively affected the contents of acid and neutral detergent fibers,and positively affected the contents of crude protein and fat.5.Sowing date and density significantly affected the quality of silage maize.With the delay of sowing date and the increase of density,the content of acid detergent fiber and neutral detergent fiber increased gradually,showing S5 > S4 > S3 > S2 > S1.ZYD32,DJ26 and YQZ23 were sown on April 15,and the content of acid detergent fiber and neutral detergent fiber in silage could be reduced by using medium and low density.With the postponement of sowing date,the crude protein content of silage maize increased first and then decreased;the crude protein content of Silage Maize at D2 density was higher than that of D1 and D3;the crude protein content of three varieties was the highest under S2D2 treatment,with the crude protein content of ZYD32 being 10.49%,YQZ23 being 9.88%,and DJ26 being 9.06%.With the postponement of sowing date,the fat content of Silage Maize decreased gradually;with the increase of density,the fat content of Silage Maize decreased gradually;it showed that low density had an increasing effect on fat content,and the higher density,the more disadvantageous to the accumulation of fat content.Under the treatment of S1D1,ZYD32 had the highest fat content(3.14%),followed by DJ26(2.99%)and YQZ23(2.87%).6.Under the condition of light and heat resources in the agro-pastoral ecotone of Northwest Hebei,the reasonable sowing date of Silage Maize should be between April 15 and April 30,ZYD32 could be postponed to June 10 at the latest,DJ26 and YQZ23 could be postponed to May 20 at the latest,and the density should be between 90000 and 112500 plants per hm-2.