Effect Of Delaying Sowing Date On Agronomic Traits And Yield Of Different Winter Wheat Varieties

In this experiment,31 winter wheat varieties widely used in wheat production in the eastern Huang-Huai region or newly approved to be popularized were selected as test materials under field conditions.The traditional sowing date of October 8(T1)and the delaying sowing date of October 22(T2)were set as two sowing date treatments.The application of high-yield and high-efficiency cultivation techniques suitable for late sowing in the eastern Huang-Huai region was determined through comprehensive analysis of tillering occurrence and panicle formation,spike-to-stem ratio and grain number per panicle,flag leaf SPAD value,leaf area and grain weight,yield changes and variety differences of different varieties under delaying sowing date.The main results were shown as follows: 1.Effect of delaying sowing date on yield of different winter wheat varietiesCluster analysis was conducted according to the yield changes of delaying sowing date wheat compared with conventional sowing date,31 winter wheat varieties were divided into 4 types: delaying sowing date varieties with large yield increase,delaying sowing date varieties with small yield increase,delaying sowing date varieties with flat yield and delaying sowing date varieties with reduced yield.Among them,there are 7 varieties with large yield increase(19.06%)by delaying sowing date,namely Liangxing 99,Taishan 28,Qingnong 2,Jimai 20,Yannong 999,Tanmai 98 and Shan Nong 30.Ten varieties with small yield increase(10.21%)were sown late,namely Taimai 198,Zhouyuan 9369,Rumai 1,Jimai 23,Taishan 27,Shiluan 02-1,Tainong 19,Shan Nong 29,Taikemai 33 and Linmai 4.There are 6 varieties of late sowing flat products,namely Shan Nong 24,Qimai 2,Xinmai 296,Jinan 17,Jimai 22 and Shan Nong 32.There are 8 varieties with delaying sowing date and yield reduction(11.89%),namely Yannong 173,Tainong 33,Luyuan 502,Hemai 19,Jimai 229,Shan Nong 28,Denghai 202 and Yannong 19.2.Effect of delaying sowing date on yield formation of different winter wheat varietiesThe spike number per unit area of delaying sowing date wheat showed a constant or decreasing trend as a whole.Cluster analysis was carried out according to the variation of spike number under the condition of delaying sowing date.The 31 varieties were divided into 3 types: varieties with the same(varying from-1.47% to 1.47%)spike number of delaying sowing dates,varieties with slightly decrease(5.41%)in spike number of delaying sowing dateand varieties with significantly decrease(15.29%)in spike number of delaying sowing date.Delaying sowing date reduced the maximum tiller number of different varieties in spring,and the change of tiller percentage under delaying sowing date determined the change of spike number.The grain number per panicle of delaying sowing date wheat showed a constant or rising trend.Cluster analysis was carried out according to the variation of the number of grain per panicle under the condition of late sowing.The 31 varieties were divided into 3 types: varieties with significantly increase(22.45%)in number of grain per panicle,varieties with slightly increase(10.18%)in number of grain per panicle and varieties with unchange(varying from-2.18% to 2.18%)in number of grain per panicle.The increase or stability of the number of grain per panicle in delaying sowing date wheat ears is mainly related to the change of spike-stem ratio during flowering.The variation of grain weight of delaying sowing date wheat varieties is relatively complicated.Cluster analysis was carried out according to the change of grain weight under the condition of delaying sowing date.The 31 winter wheat varieties were divided into 4 types: varieties with increased grain weight in delaying sowing date,varieties with unchanged grain weight in delaying sowing date,varieties with slightly decreased grain weigh t in delaying sowing date,and varieties with significantly decreased grain weight in delaying sowing date.The increase of single leaf area of flag leaf is beneficial to increase grain weight of delaying sowing date wheat.The stability or increase of grain number per panicle under the condition of delaying sowing date is an important yield component factor that affects the yield change of delaying sowing date wheat.The yield of varieties with the same number of grain per panicle decreased,and the increase rate of grain per panicle was higher or equal to the decrease rate of one or both factors of the number of grain per panicle and grain weight.Delaying sowing date could stabilize or increase the yield.3.Effect of delaying sowing date on yield of winter wheat dry matter and harvest indexCluster analysis was carried out according to the change of dry matter accumulation in shoot at mature stage under the condition of delaying sowing date.31 winter wheat varieties were divided into 4 types: varieties with significantly increased(18.39%)dry matter in delaying sowing date,varieties with slightly increased(9.85%)dry matter in delaying sowing date,varieties with unchanged(varying from-2.51% to 2.51%)dry matter in delaying sowing date,and varieties with decreased(9.31%)dry matter in delaying sowing date.Cluster analysis was carried out according to the changes of harvest index under the condition of ldelaying sowing date.31 winter wheat varieties were divided into 3 types: varieties with increased(9.04%)harvest index in delaying sowing date,varieties with unchanged(varying from-2.63% to 2.63%)harvest index in delayinging sowing date and varieties with dreased(7.74%)harvest index in delaying sowing date.The increase,maintenance and decrease in yield of most varieties planted late are closely related to the change of dry matter accumulation in mature period.For the 17 varieties with increase yield in delaying sowing date,except Tacoma 33,the increase of dry matter accumulation was the reason for the increase of the other 16 varieties.For the 6 varieties with late sowing and flat yield,the stability of yield was mainly due to the stability of dry matter accumulation and yield index.The yield reduction of 8 varieties with delaying sowing date is related to the decrease of dry matter,harvest index or both.When delaying sowing date,high yield and high efficiency cultivation techniques in wheat areas in the east of Huanghuai River,7 wheat varieties such as Shan Nong 30,Qingnong 2,Shiluan 02-1,Taishan 28,Linmai 4,Shan Nong 29 and Tanmai 98 can be selected according to local climatic conditions and planting habits to achieve high and stable yield.The relevant conclusions also need to be verified through repeated tests at multiple points and for many years.