Some eco-physilolgical characteristics at R_(4)-R_(5) stage in relation to soybean yield differing in maturities

Digital plant canopy imager and photosynthesis analyzer system were used to analyze the characteristics of canopy structure, photosynthetic physiology and micro-environmental factors at R_(4)-R_(5) stage in different yielding soybean cultivars or lines with different maturities. The results showed that the common characteristics of high yielding soybean cultivars were high lai, uniform foliage distribution in all horizontal directions, less variance of photosynthetic rate between top and bottom leaves in canopy and relatively higher photosynthetic rate of the whole canopy. All these characters combined in all resulted in higher canopy photosynthetic productivity, and pod number, seed number and seed weight per plant, especially pod and seed number in top and middle canopy were increased. The characters of high yielding canopy varied among maturities. Light interception was more important to early cultivars. Less foliage inclination angle was benefit to intercept more solar energy during yield formation. As late soybean cultivars had a more closure canopy and higher lai, greater foliage inclination angle in all layers of high yielding canopy made more solar radiation penetrate into canopy, which was beneficial to yield formation.