Studies On Canopy Eco-Phsiology Characters In Different Yielding Soybean

Using digital plant canopy imager and photosynthesis analyzer system to measure canopy structure characters, photosynthetic physiology and mini-ecological environment in different yielding soybean cultivars or lines with different maturities, the canopy physiological and ecological traits of high yielding cultivars or lines were discussed for theory reference to application of rational cultivation techniques and effective selection criterion of ecological breeding targets.The result of two years experiment indicated that the relationship between LAI, foliage inclination angle, the variation of horizontal foliage distribution and radiation characters in canopy was significant; light was the important factor to affect the photosynthetic activities of leaf; the temperature difference between leaf and air was a reflection of whether the leaf state good or not; the influence of CO2 concentration and relative humidity on leaf physiological activities was not obvious. The relationship between seed weight and leaf area in each layer of soybean population was tremendously significant, which showed obvious relationship between leaf and pod as well.The study stated the canopy structure characters of high yielding soybean as follows: suitable plant height, comparatively large node number which enlarge space of yield formation, high LAI and LAD during reproductive stage, leaf withering slowly after R5 stage, uniform foliar orientation in the horizontal plane, more dry matter accumulation, high solar energy using efficiency, small variance of photosynthetic rate between upper layer and bottom layer of canopy and relatively high photosynthetic rate of the whole canopy, maintaining good photosynthesis activity during reproductive stage, which enhance photosynthesis productivity and increase pod number, seed number and seed weight per plant, especially pod and seed number on upper and medium layer where yield mainly formed.Since the variances of height, node and leaf number in soybean cultivars with varied maturities formed different colony space, the characters of high yielding colony in varied maturity cultivars would be different. Compared with late cultivars, the value of light interception of early cultivars was more important for the yield formation, the leaves in high yielding canopy developed faster before RS stage, foliage inclination angle was smaller, leaves more flatted, which benefited to intercept more solar energy; however, the colony of late soybean cultivars was more closure and LAI was larger, so small foliage inclination angle in each layer of high yielding colony would be benefit for the solar radiation to penetrate into the internal canopy, which improved the light environment in colony and was good for yield formation.