Trends in climate and productivity and the relationship between climatic variables and productivity in black pepper.

Abstract

Trend analysis of the climatic parameters (past two decades) in major black pepper growing areas of the country showed in general that rainfall is decreasing while temperature is increasing. Black pepper productivity also showed a decreasing trend. Studies on the relationship between climatic parameters and productivity in black pepper showed that December and January rainfall had negative correlation while April and May rainfall had positive correlation. Minimum temperature had positive correlation in higher elevations while both Tmax and Tmin had negative correlation with productivity in plains. Results on the extent of relationship between climatic parameters and productivity revealed that Tmax and Tmin influenced yield more than rainfall or rainy days. Normalized yield deviations (NYD) were worked out (deviations from the mean for two decades) for different stations based on the climatic data for the past two decades. This was regressed with rainfall, Tmax and Tmin to get regression line which can predict the yield deviations if values for rainfall, Tmax and Tmin are substituted in the equation. However, apart from the weather parameters used for the study, other weather variables such as light and humidity and other factors such as cost of cultivation and price for theproduce, diseases and management practices definitely have a role in production and productivity of black pepper.