Effects of drip irrigation on canopy and soil temperature, leaf gas exchange, flowering and nut setting of mature coconut (Cocos nucifera L.)

Abstract

Coconut (Cocos nucifera L.) yield is greatly influenced by environmental factors with rainfall playing a major role in replenishing the soil moisture reservoir within the root zone. Soil water deficits reduce transpiration from the palm, leading to an increase in canopy temperature which in turn could reduce photosynthesis and yield. The primary objective of this study was to investigate the effects of drip irrigation on temperature changes in the canopy microclimate, leaf gas exchange, flowering and nut setting of mature coconut palms. Three water regimes were imposed on 20 year old coconut palms and the above-mentioned parameters were observed over a period of two years. Results showed that irrigation lowered the temperature of the canopy microclimate and the nut surface temperature, and thereby reduced the possibility of empty nut formation during dry spells. Further, irrigation reduced stomatal resistance and thereby probably nullified the effects of drought on photosynthesis. Irrigation increased the female flower production and reduced immature nut fall during droughts, thus improving the yield. Application of 80 litres of water per palm per day lowered the canopy temperature more than 40 litres of water and significantly improved female flower production and nut setting.