Effects Of Spacing Pattern And Planting Density On Population Quality And Grain Yield Of Winter Wheat

In order to clarify the effects of spacing pattern and planting density on grain yield and population quality, a field experiment with split plot design was carried out in Gaocheng County, Hebei Province during 2006-2007 growing season, with a winter wheat cultivar Henong 822 as materials. The experiment included three spacing patterns, 15 cm equal row spacing, 20 cm equal row spacing and 16.7 -16.7 -26.7 cm unequal row spacing, and four planting densities, i.e., 180, 300, 420 and 540 seedlings per m~2. The main results were summarized as follows:1. The grain yield, population culms, leaf area index and dry matter accumulation with the same planting density were almost the highest under the row space 15 cm, and followed by those of 20 cm and 16.7 -16.7 -26.7 cm spacing patterns. The leaf area index, dry matter accumulation and grain yield of wheat for the planting density 300 seedlings per m~2 was almost the highest, followed by those of the planting density 420, 180 and 540 seedlings per m~2. The population culms increased with the increasing of planting density under all the three spacing patterns. And the population culms of 540 seedlings per m~2 were the highest, followed by those of 420, 300 and 180 seedlings per m~2. The highest grain yield was achieved for the combination of 15 cm row spacing and the planting density 300 seedlings per m~2.2. Under the same planting density, light transmission percentage in wheat population was the highest under the row space 20 cm, then followed by those of 16.7 -16.7 -26.7 cm and 15 cm spacing patterns. The leaf chlorophyll SPAD of wheat leaves was almost the highest under the row space 20 cm, and followed by those of 15 cm and 16.7 -16.7 -26.7 cm. Photosynthetic rate (P_n) of canopy leaves was the highest under the row space 15 cm, then that 20 cm, and the lowest for that of 16.7 -16.7 -26.7 cm. Light transmission percentage for the wheat population of 180 and 540 seedlings per m~2were high, and the leaf chlorophyll SPAD of the two planting densities were decreased slowly after anthesis. The difference of photosynthetic rate (P_n) of canopy leaves among the four planting densities was not significant. In a word, the use efficiency of solar energy was almost the highest under 15 cm, and followed by 20 cm and 16.7 -16.7 -26.7 cm spacing patterns. On the other hand, the use efficiency of solar energy for wheat population with planting density 300 or 420 seedlings per m~2 was relatively higher than that of 180 or 540 seedlings per m~2.3. The grain filling rate and period decreased significantly with the increase of planting density. The grain filling rate was higher and the grain filling period was longer for the row spaces 15 cm and 20 cm than those of 16.7 -16.7 -26.7 cm. Furthermore, the grain filling rate was the highest under the row space 20 cm, but the grain filling period was longer under the row space 15 cm than those of the other two spacing patterns.4. The experiment showed that the grain/leaf ratio was almost the highest under the row space 16.7 -16.7 -26.7 cm, followed by those of 20 cm and 15 cm spacing patterns. The grain/leaf ratio decreased when the densities increased from 180 to 420 seedlings per m~2, but increased little when the densities increased from 420 to 540 seedlings per m~2.5. The dry weight of leaf sheath per wheat plant, dry weight of stem per centimeter, diameter and mechanical strength of the basal second internode are indexes to evaluate the stem strength and lodging resistance. All of the indexes except mechanical strength were the highest for wheat plants under the row space 15 cm, followed by 16.7 -16.7 -26.7 cm and 20 cm. And the mechanical strength of the basal second internode was the highest under the row space 20 cm, followed by 16.7 -16.7 -26.7 cm and 15 cm spacing patterns. All the indexes above decreased gradually with the increase of planting densities6. Culm per wheat plant was the highest under the row space 15 cm, followed by those of 20 cm and 16.7 -16.7 -26.7 cm. The secondary roots per wheat plant was higher under the row space 15 cm than those of under 16.7 -16.7 -26.7 cm and 20 cm. Culms and secondary roots per wheat plant were all decreased with the densities increasing.In brief, the quality of population and wheat plants of the combination between 15 cm spacing pattern and 300 seedlings per m was better, and the grain yield of this combination was also the highest. So the optimum combination of spacing pattern and planting density for the cultivar Henong 822 was 15 cm and 300 seedlings per m~2.