Impact of Precipitation over the Productivity of Sugarcane in Major Agro-climatic Zones of Tamil Nadu

Sugarcane is one of the traditional crops grown abundantly across the state of Tamil Nadu due to the lengthening of the period of monsoon and its diversified uses in different agro-based industries. Precipitation, a significant factor for sugarcane cultivation, has an impact on its productivity differs for different agro-climatic zones. A secondary data of district wise precipitation and sugarcane productivity of Tamil Nadu for the 30 years (1985 - 2014) were also collected. The impact of precipitation over the productivity of various crops can be explained by using the Standard Precipitation Indices (SPI) data and applying Principal Component regression (PCR) technique. Initially, SPI, A drought monitoring index, represents a Z-Score, was calculated seasonally for different agro-climatic zones. As there was a severe collinearity between the SPI values of seasons, Principal component regression analysis was used to study the impact of precipitation on the sugarcane productivity by considering the SPI values of four seasons along with time as regressor variables. The study showed that the productivity of sugarcane in Cauvery Delta zone and Western Zone mainly depended upon the precipitation during South west monsoon and North East monsoon periods. However, the productivity of sugarcane in North East zone was mostly dependent on the precipitation of Cold Weather period when compared to all other seasons. Unlikely, North west and Southern zones are not significantly influenced by the precipitation.