Germination Inducing Activity of Cotton (Gossypium hirsutum L.) Genotypes on Striga hermonthica (Del.) Benth

Abstract

Striga hermonthica, an Orbanchaceae, is a devastating root parasitic weed on Poaceous crop. The infection by Striga starts with germination of its seed, which is induced by germination stimulant secreted by the host and non host root. Most of germination stimulant are stricolagtons SLs, whichhave been discovered as plant hormones that regulate the development of different plant parts. Amount and composition of SLs may vary among different plant species as well as among different cultivars of the same species. The first natural SLs were, isolated from the root exudates of cotton (Gossypium hirsutum L.) and given the name strigol. Cotton is major crop in the Sudan and recently cotton production in the rain-fed area, where Striga is most prevalent, is receiving much attention. The present investigation was set to study genotypic variability in efficacy of cotton (Gossypium hirsutum L.) as a trap crop for Striga, was match with objective to developing cost effective control in prevalent Striga endemic area. Laboratory experiments of three cotton genotypes were grown in a greenhouse, harvested, severed into roots, stems, leaves, flowers, bolls and seeds, air dried and powdered and tested for germination inducing activity (GIA). The GIA for the powder varied with plant part and crop cultivar. Irrespective of cultivar GIA was highest for roots (31.9-49.9%) and lowest for bolls (16.59-26.52%). Among cultivars Hamid showed the highest overall GIA (48.9% germination) while Barac (c) 67 showed the lowest (16.5% germination). GIA declined with plant age. Further, GIA of Hamid was superior to that of Barakat and Barac (c) 67. GIA of cotton cv Hamid root powder increased with powder amount, reached a maximum (67.5% germination) and subsequently declined. GIA of cotton cv Hamid root exudates increased with volume and time, reached a peak (38.45% germination) at 15µL 30 DAS and subsequently declined. GIA of roots exudates of cotton cv Hamid collected in situ from potted plants, were tended to increase by plants density. Cotton shoots and roots powder and roots exudates effectively induced germination of Striga seeds. Conclusion: The present study result cotton cv. Hamid shoots and roots powder and roots exudates the most effective to induced germination of Striga seeds.