Effect Of Sowing Date On Growth Characteristics Yield And Quality Of Winter Sowing Spring Wheat

To investigate the influence of sowing period on fertility characteristics and yield quality of winter-sown spring wheat varieties in North Xinjiang,three pre-winter sowing periods（mid-October,late October and early November）and spring sowing period（late March,CK）were set in the field from 2017 to 2019,and the effects of pre-winter sowing period on fertility process,stem number dynamics,dry the effects of pre-winter sowing on the fertility process,stem number dynamics,dry matter accumulation and transport,photosynthetic characteristics,filling characteristics,yield composition and seed quality of Xinchun 6,Xinchun 20,Xinchun 27 and Xinchun 43 were systematically investigated.The main results of the study are as follows.1.The seedling emergence rate of winter sown spring wheat（59.13%）was 21.57percentage points lower than that of seasonal sown spring wheat（80.70%）,with large differences between years and small differences between treatments in winter sowing;winter sowing was 9-15 d earlier,8-11 d earlier maturity and 6-18 d longer fertility than spring sowing treatments.Winter sowing reduced the peak total number of stems,with B₃ treatment having higher peak total number of stems and the peak number of total stems and the number of mature spikes were higher in the B₃ treatment,and the number of mature spikes was higher in Xinchun 6 and Xinchun 27,reaching 475×10⁴·hm^-2 and 491×10⁴·hm^-2.2.All photosynthetic parameters of winter sown spring wheat appeared earlier than those of seasonal sown spring wheat.The leaf area index of all varieties was lower at 30 d after flowering,with the decrease ranging from 65%to 88%,and the decrease was lower in B₁and B₃ of Xinchun 6,at 1.86 and 1.78.The SPAD value of flag leaf was higher in B₃treatment at flowering,and the SPAD values of Xinchun 6 and Xinchun 27 were higher among varieties,with the average value of 59.07 and 56.63,and the SPAD values of B₄treatment were lower at 30 d after flowering The net photosynthetic rate of flag leaf varied among varieties in different winter sowing periods.3.The mean value of dry matter accumulation at maturity in winter sown spring wheat was significantly higher than that in spring sown,and the performance of dry matter accumulation at different winter sown periods varied among varieties.The assimilate transfer before and after flowering was higher in Xinchun 6 and Xinchun 27,and the contribution of Xinchun 6 to the seeds after flowering was higher in all sowing periods（≥69.36%）.In the winter sowing period,the post-flowering assimilate transfer was higher in Xinchun 6 and Xinchun 27 B₃ with 8742.00 kg·hm^-2 and 8283.27 kg·hm^-2.4.Among the filling parameters of winter-sown spring wheat,Xinchun 6 and Xinchun 27were better in average filling rate,maximum filling rate,filling fast increase duration and theoretical maximum grain weight,and different pre-winter sowing periods were better than spring sowing in filling rate and filling duration,while other filling parameters performed differently among varieties.5.Winter sowing of spring wheat increased yield compared to spring sowing because winter sowing increased spike number and thousand grain weight.The two-year average yield of winter-sown treatments(7065.99 kg·hm^-2)increased by 17.10%compared with spring sowing,and the number of spike grains and thousand grain weight increased by 30.68%and5.59%,the mean difference in yield between treatments during winter sowing was not significant.With Xinchun 43 and Xinchun 6 showed higher yield in B₂ treatment,respectively.6.Winter sowing reduced wheat grain protein content,sedimentation value and wet gluten content,and the differences in grain quality indexes between treatments in winter sowing were not significant;the differences in sedimentation value and wet gluten content were significant between varieties in the same winter sowing period,with Xinchun 43 and Xinchun 6 being higher.Winter sowing reduced grain protein content,sedimentation value and wet gluten content compared with spring sowing,and there was no effect on grain quality indexes between different winter sowing stages.Considering the factors such as seedling emergence rate,fertility process,material movement,photosynthetic filling characteristics,yield composition and grain quality of winter-sown spring wheat,late October to early November was the suitable sowing period for winter-sown spring wheat in North China.