Effect of Rainfall on Yield Related Traits and Total Carotenoids Contents of 42 Accessions of Provitamin A Cassava at Two Cropping Seasons in Ibadan

Abstract

Cassava crop improvement is a function of selecting superior genotypes that meets the end-users needs and preference. This is done via genotype testing at different environments thereby subjecting the materials to the elements of climate and other environmental factors. In pro-vitamin a cassava genotypes, dry matter (DM), total carotenoids (TC), and fresh root yield (FYLD) are important traits for improving economic status, nutritional health and livelihoods of farmers and processors. This study evaluated the effect of rainfall patterns on 42 provitamin A Cassava accessions for FYLD, DM, TC at different months (6,9&12 months after planting) and for two seasons (2019/2020 and 2020/2021) in Ibadan. The study shows that the relationship between TC and FYLD were more variable at second season than in the first season. The relationships between TC & DM and FYLD & DM at both seasons showed similar variability. The rainfall pattern shows that higher rainfall trend was noticed at the first cropping season (2019/2020) than 2020/2021 cropping seasons. At different months categories and across cropping season, rainfall recorded the least value of 4.58mm at 6 Months After Planting (MAP) which was in the month of December, increased at 9 MAP (Mar) and all through the 12 MAP (107.05mm). Traits relationship with rainfall shows that yield increased with rainfall, DM (25.70%) was highest during the months of least rainfall (4.58mm) and decreased (16.40%) as rainfall (52.09mm) starts during the 9 MAP and at 12 MAP, when the rainfall was 107mm, the DM was 18.76%. Total carotenoids were highest at 6 MAP with 13.76 µg/g when the rainfall was least and decreased (13.04 µg/g) with increased rainfall. During the first cropping season, DM and TC were higher with higher rainfall but with reduced fresh root yield while at second season, when the rainfall was lower, fresh root yield was higher.