Trend analysis in climatic variables and impacts on rice yield in Nigeria

The effects of changes in meteorological parameters on rice yield variations were considered. Weather parameters, temperature (T), rainfall (R), relative humidity (RH) and solar radiation (SR), and rice yield variation for Ibadan were analyzed. Meteorological parameters were obtained from the International Institute for Tropical Agriculture while rice yield data were obtained from the Africa Rice Centre both in Nigeria for three decades (1980–2010). Trends analysis of past and recent variations using the weather parameters obtained showed trends of variability of each parameter with respect to rice yield. Mann–Kendall trend and Sen's slope tests were performed on the respective meteorological variables while correlation, multiple regression and variability index (VI) were also computed for these parameters. Results showed that T, RH and rice yield were negative and decreased significantly (P < 0.001) while R and SR showed statistically non-significant increasing trends in the last three decades. R and T decreased at the rate of 3% per year and 0.03% per decade, respectively. Results of annual VI showed that decreases observed in RH, SR and rice yield were rather recent. T, SR and R were found to have the most significant effect on rice yield of all the meteorological parameters considered.