INDUCED ALLOTETRAPLOIDY IN SESAME

Abstract

Allotetraploidy was induced by means of colchicine treatment in Sesamum indicum L. x S. mulayanum Nair, hybrids. The allotetraploid resembled diploid hybrid having pansy violet colouration of corolla (intermediate between two parents), blackish seed coat with reticulation and resistance to insect, Antigastra catalaunalis (like wild parents), but it differed from the parents as well as the diploid hybrid showing luxurious growth in respect of height, branching, flower, fruit and seed characters. Gametic complement revealed n = 26 chromosomes appearing in different combinations of bivalents (15.6), quadrivalents (5.1), trivalents (0.04) and univalents (0.16) per cell. Allosyndesis leading to multivalent association of chromosomes might be responsible for reduction in pollen fertility and seed formation in the allotetraploid. But total yield in the 4n hybrid was higher than that in the diploid. Genetic relationship between the two species has also been indicated.