Tree Growth, Biomass and Productivity of Wheat Under Five Promising Clones of Populus deltoides in Agrisilviculture System

摘要

Variations in growth and above- and below-ground biomass of five promising clones (G3, G48, 65/27, D121 and S7C1) of Populus deltoides and their effect on productivity of wheat under agrisilviculture system were evaluated. Diameter at breast height (dbh) and tree height were consistently higher in clone 65/27 and lowest in clone S7C1. Total biomass varied from 48.5 to 62.2 Mg ha-1 in 6-year old clones; it followed the order 65/27 > D121 > G48 > G3 > S7C1. Stem wood accounted for 60.4-68.9% of total biomass, followed by coarse roots (12.2-18.9%), branches (12.3-15%), leaves (3.02-6.9%) and fine roots (1.5-2.7%). Grain yield of wheat was highest (3.66 Mg ha-1) in sole crop and decreased by 15-30.3% under different clones. The straw yield also showed similar trend. The reduction of grain and straw yield of wheat in clones was in order: S7C1 < G3 < D121< 65/27 < G48. Available N, P and K in the soil improved significantly after 6 years of poplar planting. N was highest under clone S7C1 and lowest under clone G48, while P was lowest under clone 65/27 and higher under clone G3. K was higher in clone S7C1 and lower in clone 65/27. At 0-20 cm depth, N increased from 14.9 to 24.1 %, P from 17.2 to 23.3% and K from 3.1 to 5.1% under different clones after 6 years of planting.