Effect of Climate on Yam Tuberization in the Guinea Savanna Ecological Zone of Nigeria: The Case Study of Kwara State

Abstract

The response of yam tuber development to its micro-climate was monitored at the National Centre for Agricultural Mechanization (NCAM) for two yam growing seasons. The micro climate data measured include air temperature, rainfall, number of rain days, relative humidity, soil temperature at intervals of 5cm, 20cm, 30cm and 40cm and soil moisture with depths at 0-15cm, 15-30cm and 30-45cm. Measurement of yam tuber circumference and length were taken on monthly basis from the period of tuber initiation (34 WAP) to period of tuber maturity (50 WAP) using thread and measuring tape. Monthly means of weather elements from research plot was calculated, grouped and summarized using descriptive statistics of mean and percentages. Dependency of yam tuber development on meteorological factors was examined through statistical analysis of correlation and regression. Based on this, the period of tuber development in Kwara State was identified and categorized. The growth in yam tuber responds positively more to rainfall frequency than rainfall amount. Again soil temperature at 5cm depth was identified to be more critical for efficient yam tuberization. Farmers in the study area are advised to improve on the materials used for mulching to increase yam yield.