Impact of tree management on growth and production behaviour of intercrops under rainfed agroforestry

This investigation was aimed to evaluate the impact of changes in incident radiation through crown modification on crop performance. Different shade intensities created through tree crown management significantly affected growth, physiological attributes and yield related parameters in Vigna mungo (syn. Phaseolus mungo) and Pisum sativum grown as understorey field crops with Morus alba under rain fed conditions. The crown management treatments namely, no crown removal, 25, 50 and 75 crown removal resulted in 91, 85, 63 and 47 shade, respectively. Plant height, number of flowers, leaf area of crops was reduced significantly with the increase in shade. intensities and decrease in distance from t~e tree trunk. Higher pods per plant, grains per pod, grain yield and harvest index were observed at lower shade intensities. Growth and yield was maximum in open control (without tree); while unmanaged canopy of Morus trees caused overall yield reduction of 42 beneath canopy up to 3 m distance from the tree trunk. The crown management regulated physiological attributes in the field crops. The maximum photosynthetic rate was recorded for open plot plants, which declined in plants beneath dense canopy. The amount of water transpired from the crop plants decreased with increase in shade intensity. The conversion efficiency was maximum for plants growing as sole crop which decreased with increasing shade intensities. Based on the results of present investigation, it can be recommended that out of the four tree canopy management options tried i.e. 0, 25, 50 and 76 crown removal; 75 crown removal causing least negative effects on crop growth and yield may be adopted as a compromised crown management practice.