Selection of Suitable Planting Density for High Yield of Hengdan 6272 in Summer Maize Planting Area of Central South of Hebei Province

In order to ascertain the suitable planting density and the density tolerance of summer maize varieties Hengdan 6272 in summer maize growing area of middle and south of Hebei Province,5 planting densities(60 000,67 500,75 000,82 500 and 90 000 plants/hm2)was desighed in the row spacing of 0.6 m to study the changes of economic traits and yield of maize under different planting densities.The results showed that with the increase of planting density,the yield of Hengdan 6272 increased at first and then decreased,and the yield difference between different density treatments reached a significant level,the planting density of 67 500 plants/hm2 had the highest yield(9 419.81 kg/hm2),and the yield under planting density of 75 000 kg/hm2 was followed(9 347.97 kg/hm2),the difference between them was not significant.The maize barreness was 0 when the planting density was less than or equal to 67 500 plants/hm2,and above it which was gradually increased with the increase of planting density.The bald tip length was gradually increased,panicle length shortened,grain weight gradually decreased,the changes of ear row number and grain number per row was not obvious with the increase of planting density,when the planting density was 67 500 plants/hm2 ear row number and grain number per row were maximum.The suitable planting density of Hengdan 6272 was 67 500 plants/hm2,under the condition the yield was the highest,the percentage of empty stalk of the plant was low,the spike bald tip was short,and the economic characters was higher.