Photosynthesis, growth and yield of soybean and maize in a tree-based agroforestry intercropping system on the Loess Plateau

Abstract

Agroforestry is the most effective way to restore the disturbed lands on the Loess Plateau and to develop the poor local economy. In order to maximize the potential benefits of tree-based intercropping systems, photosynthesis, growth and yield of soybean and corn were studied by measuring photosynthetic active radiation (PAR), plant water deficit and soil moisture in a 4-year-old plantation of walnut (Juglans regia L.) and plum (Prunus salicina) grown at a spacing of 5 m × 3 m on the Loess Plateau. The effects of tree competition significantly reduced PAR, net assimilation (NA), growth and yield of individual soybean or corn plants growing nearer (1 m near tree row) to tree rows. NA was highly correlated with growth and yield of the both crops. These correlations were higher for corn than soybeans, with corn, rather than soybeans being more adversely impacted by tree shading. Plum, rather than walnut had the greatest competitive effect on PAR and NA. Daily plant water deficits were non-significantly and poorly correlated with NA and growth and yield of the both crops. However, soil moisture (20 cm depth) was significantly correlated with biomass and yield of both crops. Possible remediation strategies are discussed to reduce tree competitive interactions on agricultural crops.