Abstract:
An effective regression method for the examination of the stability of the treatments in repeated experiments was introduced by Finlay and Wilkinson (1963). A new justification for the employment of this method was evolved and this does not require the logarithmic transformation of the data to induce linearity of regression. A treatment has greater than average, average or less than average stability according as the regression coefficient b</> 1. The data from permanent manorial trials conducted at Rice Research Station, Pattambi from 1973 to 1979 were used to show that the method of regression coefficients to study stability and the method of analysis of groups of experiments are equivalent. This was the first attempt in that direction. Method of analysis of principal components was used to suggest a new weather index based on rainfall and temperature which are considered to be important weather para meters. The number of wet days did not have any significant correlation with the mean yields of treatments. In the kharif season mean daily humidity was significantly correlated with the yield. Whereas all other parameters such as mean daily rainfall, mean daily temperature, mean daily maximum temperature, mean daily minimum temperature, maen daily maximum humidity, mean daily wind velocity and mean daily hours of sunshine did not have any significant correlation. In the rabi season mean yield of Jaya had a correlation of -0.5713 with the mean daily temperature, 0.91131 with mean daily maximum temperature, -0.6802 with mean daily minimum temperature -0.5888 with mean daily minimum humidity and 0.88193 with hours of sunshine. A modified procedure was suggested to estimate the weekly rainfall of a place. This was obtained by applying the method of Surendran et.al. (1977) to logarithms instead of the weekly annual rainfalls. Incidentally it gave a method for suggesting the adequacy of the length of the date for estimation. Theoretical distribution of the weekly rainfall at Pattambi were indicated. All of them were found to obey beta distribution.
