Effect of Sowing Date and Planting Density on the Yield Formation of a Winter Wheat Cultivar Henong 822

In order to clarify the suitable combination of sowing date and planting density under the condition of increaing accumulative temperature before over-winter of winter wheat,a field experiment with split plot design was conducted at Gaocheng County,the middle area of Hebei Province,during 2006～2007.The main plots were three sowing dates of October 7,13 and 19,and the split plots were four planting densities of 180,300,420 and 540 seedlings per m2.The main results were that,the effect of sowing date on total culms(main stems + tillers) was statistically significant only during early growing stages,but the effect of planting density on total culms was significant during all the growing stages.The effect of sowing date on all the three yield components of wheat was not significant,but the effect on grain yield was significant because of the accumulative effect of planting density on yield components.The effect of planting density on yield and yield components were all significant statistically.Also,the interactions of sowing date and planting density on spike number per m2,grains per spike and grain yield were significant.The comparison among the average yield of four densities for the same sowing date showed that,the average yield of wheat sown at October 7 was significantly higher than that sown at October 19,but not significant to that sown at October 13.The difference among the grain yields of the three planting densities,300,420 and 540 seedlings per m2,was not significant,but the grain yields of the three planting densities were all very significantly higher than that of the density of 180 shoots per m2.According to the grain yield of all the combinations of sowing date and planting density,October 7 is the best sowing date of winter wheat,with the corresponding density of 300 seedlings per m2;October 7 to 13 is the suitable sowing period,with the corresponding density of 300～420 seedlings per m2.This conclusion about the suitable sowing period is also consistent to the result based on the accumulative temperature before over-winter of winter wheat.