EFFECT OF MULCHES AND COVER CROPS ON WATER STATUS AND GAS EXCHANGE OF COCONUT (Cocos nucifera L.) PALMS IN GRAVELLY SOILS

Abstract

Two field experiments were conducted in gravelly soils (Andigama series) inSri Lanka to investigate the effect of different mulches and cover crops,utilized to conserve soil moisture, on water status, gas exchange andrelated soil parameters of coconut palms {Cocos nucifera L. var typica).The results revealed that mulching only the manure circle was not effectivein improving the palm water status, gas exchange and soil water statusduring dry periods in Andigama soil series (gravelly soils). The mulchestested were coconut husks, coir dust, straw, black polythene and driedcoconut fronds. The palms were equally sensitive to soil water depletionand responded to the water deficit by increasing the stomatal resistanceirrespective of the mulch treatment. When the manure circle was mulchedwith dried coconut fronds, and the rest of the land was also mulched with afive cm thick layer of coir dust, the palms showed an improved gasexchange ability than palms growing in bare land or with cover crops duringthe dry period.