EVALUATION OF ONSET AND CESSATION OF RAINFALL AND TEMPERATURE ON MAIZE YIELD IN AKURE, ONDO STATE NIGERIA

Temperature and Rainfall are important variables that affect maize yield and as such this study aimed at evaluating the impact of onset and cessation of rainfall and temperature on maize yield in Akure. To achieve this objective, climatic parameters comprising daily rainfall and temperature (maximum and minimum temperature) 1981-2016 for Akure, were obtained from the archive of the Nigerian Meteorological Agency, NiMet. The daily rainfall data were summed to obtain monthly and subsequently, yearly rainfall. Similarly, average annual temperature values were calculated from daily temperature values. Annual maize yield data for the same period 2000-2016 were obtained from Ondo state Agricultural Development Programme. Walter’s method, as modified by Olaniran (1983), was then used to determine onset, cessation and length of growing season. The significance of the annual trend of these climatic parameters were also tested using an approach involving z-test and p-value analysis. Likewise the significance of all the climatic parameters in contributing to maize yield was also determined based on the p-value approach under a null hypothesis. The coefficients of determination (R2) and Pearson correlation coefficient (r) in relation to the SLR and MLR models, were calculated. All data analysis was done by python programming language and excel. Result showed a slight decreasing trend for rainfall, increasing trend for maximum, minimum and maize production. Their associated p-values are, p(0.6925, 0.5794, 0.5136 and 0.0630) which showed that the trend over the years were not statistically significant at the 1, 5 and 10% levels; However maize production was significant at 10% significant level. The mean onset, cessation and length of growing season for maize production in Akure were 8th March ±9, 21st October ±21 and 239days ±27days. The relationship between maize yield and all climatic variable in association with SLR model showed that rainfall is the major contributing variable to maize production in Akure, Ondo State at all significant levels. p-value (0.009539) r = 61%, R2 = 37%. The p-value in association with MLR model, also showed that rainfall is significant at 5 and 10%. p(0.019412) , r=72%, R2 = 51.The study therefore recommends that Organisations like Nigeria Federal Department of Agriculture should equip farmers with adequate knowledge of rainfall onset, cessation and length