Climate based coconut yield model for Arsikere taluk of Hassan district in Karnataka
Coconut has a prolonged reproductive phase of 44 months from the initiation of the inflorescence primordium to full maturity of the nuts. Weather affects all stages of the long development cycle, and thus there is likely to be extended predictability based on climate variability. Arasikere taluk of Hassan district, which has a major share of coconut area of Karnataka state, is frequently experiencing deficit rainfall coupled with a decline in groundwater level. Hence, an attempt was made to relate the coconut sample survey data of Coconut Development Board with climate data of Arsikere taluk of Hassan district. Mean nut yield per palm, per year in the Arasikere taluk was 49.2. Among the villages, Gijihalli recorded significantly lower nut yield (42.2) followed by Jajur (48.8) and Aggunda (55.3). Mean maximum, and minimum temperature during 2010-2017 was 32.40C and 19.50C respectively, with an average annual rainfall of 840 mm. Annual rainfall during 2011, 2012 and 2016 was below normal compared to other years. Correlation of monthly nut yield per palm with rainfall showed a significant positive correlation with the previous three to four years rainfall. Long dry spell during primordial initiations to nut maturity during consecutive two years 2011 and 2012 has resulted in significantly low nut yield during 2014. Rainfall during 2013 and 2014 was comparatively better, resulting in significantly higher nut yield during 2016 compared to 2014. Among the different stages, the primordium initiation stage and the ovary development stages were more strongly and significantly influenced by the weather parameters during all the years. Rainfall during button development stage followed by Tmax and rainfall during the spadix emergence stage showed a significant contribution to the weather-based regression model. Future climate of Arasikere showed an increase in annual rainfall mainly during September and October but declined during November/December period. Maximum and minimum temperature showed an increase by 1-1.50C which may increase the evaporative demand and dry spell duration resulting in moisture stress thus highlighting the importance of rainwater harvesting to take advantage of increased rainfall under future climatic condition. The future climate scenario may also favour the attack of pests like eriophyid mite.
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