Root distribution pattern of the wild jack tree (Artocarpus hirsutus Lamk.) as studied by 32P soil injection method

Abstract

Root distribution of the wild jack tree (Artocarpus hirsutus) was determined by selective placement of 32P at various depths and lateral distances from the tree, in Kerala, India. In eight-and-a-half-year-old trees growing on a lateritic site, absorption of 32P from a lateral distance of 75 cm and 30 cm depth was much greater than from 150 and 225 cm lateral distance and 60 and 90 cm depth. Root activity declined with increasing depth and lateral distance. Most of the physiologically active roots were concentrated within a radius of 75 cm and 30 cm depth, although the tap root might reach even deeper. Possibly, surface accumulation of feeder roots may cause considerable overlap of the tree and crop root zones in intercropping situations. However, as the tree roots seldom extend beyond 2.25 m laterally from the trunk, the effect of overlapping root zones and the associated competitive effects may not be a serious problem for intercropping during the first few years (<10 years after planting) of tree growth.