Variations in nut yield of coconut and dry spell in different agro-climatic zones of India

Coconut is the major perennial crop in coastal areas of India. It is mainly grown under rainfed conditions in areas of high rainfall. However, these plantations face summer drought situations as the rainfall distribution is restricted to only 4 to 5 months a year, leaving remaining period as dry. The objective of the study is to quantify the dry spell and to deduce the influence of rainfall and dry spell on the nut yield in major coconut growing areas situated in different agro-climatic zones of India. viz., western coastal area — hot sub-humid per-humid (represented by Kasaragod in Kerala and Ratnagiri in Maharashtra), Western Ghats — hot sub-humid per-humid (represented by Kidu in Karnataka); hot semi-arid (represented by Arsikere in Karnataka); and eastern coastal plains — hot sub-humid (represented by Veppankulam in Tamil Nadu and Ambajipeta in Andhra Pradesh). Variation in annual rainfall was from a maximum of 3337.7 mm (Kasaragod) to a minimum of 718.23 mm (Arsikere). Dry spell was longer in Ratnagiri (216 days) and Arsikere (202 days), and shorter at Kidu (146 days). The annual nut yield under rainfed conditions varied from 68 (Ambajipeta) and 66 (Kasaragod) to 41 (Arisekere) and 30 (Kidu). Impact of variations in dry spell on nut yield was discernible from the study. In view of the long duration (44 months) between the inflorescence initiation to nut maturation, the occurrence of dry spell in any one year would affect the yield for the subsequent three to four years. It can be inferred that the longer dry spell affects the nut yield for next four years to follow with stronger impact on fourth year, irrespective of the total rainfall.