Karyomorphological studies of six commercially cultivated edible cucurbits: bitter gourd, sponge gourd, ridge gourd, snake gourd, ash gourd and cucumber

Information about chromosomal characteristics is helpful to geneticists and plant breeders in crop improvement programmes. The karyomorphological analysis of six commercially cultivated edible species of Cucurbitaceae, namely Luffa cylindrica, L. acutangula, Trichosanthes anguina, Benincasa hispida, Cucumis sativus and Momordica charantia were investigated. The chromosome numbers of these six cucurbits are 2n = 26, 26, 22, 24, 14, and 22 respectively. All of the cucurbits possessed very small chromosomes of the ranges 1.71–1.25 μm in L. cylindrica, 1.84–1.15 μm in L. acutangula, 2.87–1.76 μm in T. anguina, 2.78–1.52 μm in B. hispida, 2.17–1.26 μm in C. sativus and 1.93–1.15 μm in M. charantia. The karyotypes of L. cylindrica, L. acutangula and T. anguina are fully symmetric, consisting of all metacentric chromosomes. The other three, B. hispida, C. sativus and M. charantia, showed symmetric karyotypes, having both metacentric and sub-metacentric chromosomes. Benincasa hispida possesses two pairs of sub-metacentric chromosomes; C. sativus and M. charantia have one pair each. These data add to information about karyo-systematics which helps to study inter-species and inter-generic relationships. This study may also be helpful to cucurbit breeders in their future crop improvement programmes.