Root growth in Jatropha and its implications for drought adaptation

The relative drought tolerance of Jatropha curcas is, so far, not very well understood. To understand its physiological adaptation to drought-stress, the root growth viz; root length density (RLD), root dry weight (RDW), biomass accumulation and resources allocation for roots of adult trees grown in the field were assessed. The tap root in Jatropha branches perpendicular to the ground with many lateral roots. The rooting depth was 1.4 m with a greater root length distribution at the surface soil. It depicted a low root to plant ratio when the tap root was not included. The root branching in Jatropha suggested that it may help containing soil erosion although its contribution to drought tolerance is seemingly conservative. The drought response of Jatropha can be categorized as drought avoidance, considering its regular dormant state, drought-stress induced leaf drop and a limited root growth.