The study on photosynthesis, biomass and fine root growth dynamics of soybean in walnut-soybean agroforestry system
Abstract Soybean in the walnut-soybean agroforestry system in the Loess Plateau of China was focused in this research. The effects of walnut soybean intercropping on soybean growth in the Loess Plateau were determined by measuring the biomass, photosynthetic rate and root growth dynamics of soybean, so as to provide a basis for rational agroforestry models in the Loess Plateau. The results show that soybean reached the highest net photosynthetic rate during flowering period, with the net photosynthetic rate of intercropped soybean, which was 20.4000µmol·m-2·s-1, significantly higher than that of its monocropped counterpart. Soybean biomass reached the maximum during the pod-bearing period, with intercropped soybean biomass being 25.4879g, significantly higher than that of its monocropped counterpart. The mean diameter and increased density of soybean fine roots reduced along with increased soil depth. In particular, both the diameter (0.43mm) and increased density (930cm/dm3) of intercropped soybean fine roots were evidently higher than those of monocropped soybean(0.35mm, 780cm/dm3) , but the result was opposite in 40-60cm soil depth; with increasing cropping years, fine roots of intercropped soybean tended to be mainly distributed in soil at a depth between 0 and 20cm from the fifth year. Compared with soybean monoculture, walnut soybean agroforestry system is more conducive to soybean growth in the Loess Plateau.