Abstract

We investigated the effect of row spacing on the structure and radiation utilization efficiency of summer soybean crops in Northern China during the 2006 and 2007 growing seasons. The experiment consisted of 5 planting patterns resulting in the same plant population density (3.09 × 10⁵ plant/ha), where row spacing was 18, 27, 36, 45 and 54 cm. We observed a significant negative correlation between DM weight and row spacing in both years. Dry matter was mainly allocated to the middle-lower strata of the canopy. The LAI of all treatments decreased with row spacing increments. At podding stage, PAR interceptionratio showed a minimum at 12:00 and decreased with row spacing between 11:00 to 13:00. The RUE of row spacing 18 and 27 cm was significantly higher than those of other treatments. There was a significant positive correlation between seed number and plant growth rate. The yield of row spacing 18 and 27 cm were significantly higher than those of row spacing 45 and 54 cm. The results indicate that summer soybean population of relatively uniform distribution could improve population structure, increases the PAR interception and RUE under rainfed agriculture in Northern China.

Key words: Glycine max, dry matter, radiation utilization efficiency, growth, development.

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