Pollen Viability and Stigma Receptivity Studies in Three Varieties of Sorghum Grown in Sokoto State

Understanding pollen viability and stigma receptivity is fundamental to crop improvement through controlled pollination, and their characterisation in locally cultivated sorghum varieties in Sokoto State, North West Nigeria, provides essential information for breeding programmes in the region. This study assessed pollen viability and stigma receptivity dynamics in three sorghum (Sorghum bicolor) varieties: SK5912, IESV-92012DL, and Kaura, grown at the Sokoto State College of Agriculture Demonstration Farm during the 2023 rainy season. Pollen viability was evaluated at 6-hour intervals after anthesis using three methods: tetrazolium chloride staining, fluorescence diacetate staining, and in vitro germination on agar medium. Stigma receptivity was assessed by hydrogen peroxide test, aniline blue staining for callose detection, and compatibility of hand pollination at 6-hour intervals across the receptive period. Pollen viability was highest at anthesis (94 to 97% across varieties) and declined to below 50% by 12 hours post-anthesis in all varieties. IESV-92012DL showed the most rapid viability loss. Stigma receptivity in all varieties peaked at 24 to 48 hours after feathering and persisted for up to 72 hours. SK5912 had the longest stigmatic receptivity window (78 hours). The study concludes that the optimal timing for controlled crosses in Sokoto State field conditions is morning (6 to 9 am) when both viability and receptivity overlap most reliably, with practical implications for the sorghum improvement programme of the Lake Chad Research Institute.

Keywords: sorghum, pollen viability, stigma receptivity, controlled pollination, Sokoto State