Impact of Populus deltoides and Dalbergia sissoo shelterbelts on wheat- a comparative study

The impact of Populus deltoides and Dalbergia sissoo shelterbelts on wheat yields was studies in farmers' fields in Chandigarh, NW India. The fields were bordered by 2-row belts of each species in a W.-E. direction, with 4 m spacing within rows and 5 m between rows. The P. deltoides trees were nearly 6 yr old at the time of the study (average height 15.9 m, diameter at breast height (dbh) 22.8 cm) and the D. sissoo trees were nearly 10 yr old with height 14.8 m and dbh 25.45 cm. A reduction in the growth and yield of wheat was noticed in the sheltered fields compared with unsheltered open fields. More losses were observed on the northern sides of the shelterbelts than on the southern sides. The performance of wheat, particularly in the initial 0-3 m block, however, was more deleteriously affected in the fields sheltered by P. deltoides than those sheltered by D. sissoo. In P. deltoides sheltered fields reductions in crop density, biomass and yield continued up to the 9-12 m block, except plant height which was reduced only up to the 6-9 m block. In contrast, in the fields sheltered by D. sissoo the decrease in growth and yield of wheat was mainly in the first 2 blocks (0-3 and 3-6 m) from the tree belt. No apparent change thereafter was noticed in either of the sheltered fields. The conclusion was that wheat performed better in the fields sheltered by D. sissoo, an indigenous tree, than those by P. deltoides, an exotic, and that performance was better on the south of shelterbelts than on the north side