Cytogenetical treatise of Indian representative species of Cucumis. A karyotypic approach

Abstract

Karyomorphological studies have been carried out in nine species and five varieties of the genus Cucumis representing Indian gene pool. The present investigations reveal the occurrence of two somatic chromosome numbers 2n = 14, 24 in the genus. C. ritchiei and C. indicus the two new species, were found to be having somatic chromosome numbers of 2n = 24 and 2n = 20 respectively. The wild species viz. C. hystrix, C. setosus, C. prophetarum, C. dipsaceus, C. indicus have very less number of median-centromeric chromosomes, high asymmetry indices, while melon groups have intermediate number of median -centromeric chromosomes. C. sativus, C. callosus, C. ritchiei show lesser number median-cen-tromeric chromosomes and very less asymmetry indices. The importance of karyotypic variation with respect to speciation within the genus Cucumis have been discussed.