Effect of water deficit (drought) on growth/productivity of coconut
Decrease in the production of female flowers, reduce nut setting, increase button nut shedding, increase immature nut fall, reduce nut size, reduce nut production ,reduce copra out-turn, dropping /wilting of leaves, and death of coconut seedlings/palms are the result of water deficit during prolong rain free periods. Coconut yields of 4500-8000 nuts/ac/yr or more have been achieved in several well managed coconut states even under rain fed conditions. In most states are at least few (10%) palms yielding more than 80 nuts/palm/yr even during the drought. Studies show that about 2/3 of the potential coconut production is generally lost due to either poor nut setting or immature nut fall as a result of water deficit conditions. A coconut palm yielding 80-120 nuts/palm/yr in good rainy years may reduce its yield to 40 nuts/palm/yr or less after a drought period. But with appropriate supplementary irrigation, the coconut yield could be maintained at a stable high yield of 100-140 nuts/palm/yr or more, continuously, irrespective of the drought. Research conducted at the coconut research institute and elsewhere has shown that the supplementary irrigation of coconut increases nut yield by 30-60% and copra yield by 54% or more. Hence supplementary irrigation could increase the coconut yield. Installation of an irrigation system is expensive and requires some scientific knowledge. It is essential to have a continuous supply of irrigation water even during the drought (adequate under groundwater, aquifer, and river). Further, the irrigation should be implemented as a complete package including relevant fertilizer/agronomic/management practices.