Effect of pre-sowing hardening treatments using various plant growth substances on cowpea germination and seedling establishment

Abstract

Seed germination and seedling establishment of two cowpea varieties IT87D-941-1 (IPI) and Kanannado (LPI) were carried out in the laboratory in Kano, Nigeria under the prevailing laboratory conditions of 25±2°C and 45-60% relative humidity. The cowpea seeds were presoaked in various solutions of 5ppm and 10ppm Indole acetic acid (IAA), Gibberellic acid (GA3) and Ascorbic acid (AA), concentrations respectively. The soaked seeds were air dried for 24hrs and thereafter sown in various flasks containing dried cotton wool. The result of the study showed significant difference in percentage germination among the cowpea varieties and hormone concentrations (P<0.001). Seeds treated with 5ppm IAA and GA3 showed significant increases in percentage germination and seedling growth in the two cowpea varieties. Germination and seedling growth decreased markedly with increasing hormone concentration. Seeds pre-soaked in distilled water responded poorly. Based on these results, 5ppm concentrations of IAA and GA3 were found to be the best for enhancing seedling growth in cowpea and it is therefore recommended for cowpea seedling establishment. The result also emphasized that pre-sowing hardening treatment
of cowpea seeds in IAA and GA3 could significantly enhance their germination and seedling growth. This suggested that hormone treated cowpea seed have the potential of overcoming adverse effect of water stress in tropical Savannah.

Keywords: Plant growth substances, Cowpea, Germination, Seedling Establishment