Preharvest forecasting of castor yield on the basis of weather variables in Banaskantha district of Gujarat 

Abstract

To suggest most suitable pre-harvest forecasting model for Banaskantha district of Gujarat state, the weather data for past 27 years (1982-83 to 2008-09) viz., weekly average of maximum and minimum temperature, morning and evening relative humidity, bright sunshine hours/day and weekly total rainfall (mm) from 32^nd to 52^nd meteorological standard weeks (MSW) were collected from the Agro-Meteorological Observatory, Agronomy Instruction Farm, S. D. Agricultural University, Sardarkrushinagar. The time trend was also included as independent variable. The data on average castor yield (dependent variable) of Banaskantha district were obtained from the Directorate of Agriculture, Gujarat state, Gandhinagar. The step-wise regression procedure was employed by using 23 years data. The prediction equations and forecast of subsequent years were obtained separately for 21 to 23 years data set. The positive and significant effect of the time trend and beneficial effect of weekly total rainfall were observed. The correlation coefficient as weight approach was found superior compared to other approaches. This approach provided suitable pre-harvest forecasting model predicting yield 12 weeks before actual harvest and explained more than 94 % variation in castor yield. The deviations between the predicted and actual yields ranged from 19.85 % to 12.32 %.