Canopy Physiology and Characteristics of Yield Components during Reproductive Stage in Soybean Hybrids

Abstract

Utilization of soybean hybrid is an effective way to increase soybean yield. We used two soybean hybrids(HybSoy-1and HybSoy-2) and two conventional varieties(CV) with the same maturity(Jiyu 72 and Jilin 30) as materials to explore physiological characters of canopy, traits of yield and yield components, and the physiological mechanism of increasing yield in soybean hybrid at reproductive stage. The result showed that, from 2010 to 2011, compared with CV, the yields of soybean hybrids were increased by 13.9% and 16.7%. Leaf chlorophyll contents at late growth stages, photosynthetic rates at R2(full bloom)–R7(beginning maturity) and leaf area indices(LAI) at R2–R4(full pod) were all significantly higher than those of CV; the maximum LAI of HybSoy-1 and HybSoy-2 in 2010 were 8.09 and 8.30, far more than those of CV, and LAI at late growth stages were not decreased sharply. Biomasses of all varieties reached a peak at R6 stage, while those of soybean hybrids at R2–R7 were higher than those of conventional varieties with significant difference between them at P0.05 and P0.01; the means and maximum accumulation rates of biomasses were 0.06 g d–1and 0.20 g d–1more than those of conventional varieties, respectively; and the days of speeding up or slowing down dry matter accumulation rate were ahead of 3.09 days and 5.85 days than those of CV, respectively, so premature advantage of dry matter accumulation was also obvious. As for yield components, there was no significant difference between hybrids and conventional soybean varieties on 100-seed weight, grain weight and pod weight of main stem, but grain weight and pod weight of branch in soybean hybrids were significantly higher than those in conventional varieties.There was no significant difference in the ratio of grain weight to biomass and the ratio of grain weight to stem weight between soybean hybrids and conventional soybean varieties. All results showed that the yields of soybean hybrids mainly depend on the strong canopy, high speed of dry matter accumulation, and higher biomass.