Trends and spatial analysis of temperature and rainfall patterns on rice yields in Nigeria

Abstract

Trends and spatial analysis of temperature and rainfall on rice yield in Nigeria was carried out. Forty year of past trends (1970–2010) was conducted with climate data obtained from the International Institute of Tropical Agriculture, Ibadan, Nigeria while upland rice yield data were obtained from the Food and Agriculture Organization. Six cities, one in each of the six agro-ecological zones which were Calabar, Enugu, Ikeja, Ilorin, Kaduna, and Maiduguri were selected. Geographic information systems mapping for spatial analysis of temperature and rainfall over Nigeria was carried out. Mann–Kendall, Sens' tests, Pettitt's, and Buishand's tests and multiple linear regressions were used as statistical tools for analysis. Increasing rainfall trends in Enugu, Calabar, and Ikeja but decreasing trends were observed in Ilorin Kaduna and Maiduguri while temperature showed increasing trends in all the cities in the last four decades. Statistically significant positive trends of rice yield, rainfall, and temperature were observed in Ikeja and Maiduguri in the last four decades. Mann–Kendall tests showed that rice yield and temperature had generally statistically significant positive trends in Calabar Ilorin Kaduna, and Enugu while rainfall and yield were significant in Calabar Enugu but not significant in Ilorin and Maiduguri adaptation strategies to genetically modify rice varieties and effective water use strategies in areas of rainfall deficit are recommended to ensure food security.