Effect of different trees on the yield of rainfed wheat crop.
A study was conducted to determine the effects of mulberry (Morus alba), poplar (Populus deltoides), safed siris (Albizia procera) and subabool (Leucaena leucocephala) on the yield of rainfed wheat crop at Dhaulakuan, District Sirmour in Himachal Pradesh. Trees were planted in August 1987 in 3 blocks in a randomized block design with 2.5 m between trees and 25 m between rows (in N.-S. orientation), with trees of each species planted in groups of 8. Wheat (var. Sonalika) was planted in October 1992. Yield data were collected from different blocks of wheat at distances of 2, 4, 6, 8 and 10 m from each tree base and analysed statistically. Significant differences were observed between treatments. In the case of safed siris, subabool and the no-tree control, blocks at 10 and 8 m distances from the trees gave a higher wheat yield, and those at 6, 4 and 2 m distances a lower yield (in that order). Blocks adjacent to mulberry and poplar showed a reduced yield up to 4 m distance, but at 6 m and higher distances, there was a negligible effect on wheat yield. Overall yields were highest under subabool, where they were not much reduced from the no-tree yields, and decreased successively under safed siris and poplar, being lowest under mulberry. Tree growth (height and diameter data are given for 1993) was most in poplar, followed by subabool, safed siris and mulberry.