Root distribution pattern studies to assess the foraging zone in Melia dubia Cav.

Abstract

Melia dubia is one of the important tree species in agroforestry models across India owing to its multifarious utilities, compatibility with various agricultural, horticultural and forage crops. Inspite of its pan India prevalence, research data pertaining to the spatial distribution of its root system is scarce which is primarily responsible for determination of the capacity to absorb water and nutrients preferentially over other allied crops. Belowground competitions are the major constraints to successful intercropping in woody/agroforestry ecosystems and thus spatial distribution of tree roots assumes paramount importance. The root distribution pattern of selected trees in a twelve-year-old Malabar neem (Melia dubia Cav.) plantation grown at 4 m x 4 m spacing was studied using the logarithmic spiral trench technique to assess the level of competitive/complementary impacts of the root system. Root intensity decreased steadily as the root diameter classes increased with function to soil depth as well as lateral distance. It was observed that 65.07 % of the total roots observed on the profile wall of the trench were fine roots (size class 2.5 to5.0 mm). Major share of the fine roots occupied near to the base of tree and 60.14% of fine roots were found to be accumulated in upper 20 cm layer of soil. In terms of lateral distance, maximum number of fine roots were recorded near the tree at 0.26 m with root intensity 431.1 m-2, and 65.85% of fine roots were found to be concentrated within 80 cm lateral distance from the tree.