Cytomorphology of Some Wild and Cultivated Members of Trichosanthes L

抄録

Agrnonomic and cytogenetic analyses have been carried out in Trichosanthes anguina L., T. cucumerina L., T. palmata Roxb., and T. dioica Roxb. with its cultivars and wild relative.
Some of the agronomic parameters such as flowering time, leaf and fruit morphology and yield have been found useful for delineating the cultivars. The higher yield is correlated with late flowering as demonstrated in ‘Kali’ and ‘Damodar’. The fruit weight is highest in ‘Damodar’ (46.05gm±3.35) while ‘Lata Bombai’ and ‘Sanjiban’ bear lighter fruits (31.42gm±5.30 and 30.54gm±6.75 respectively). The yield measured as quantity of fruits produced per plot (3m×1.5m) in a season varies between different cultivars. The cultivar ‘Kali’ shows by far the best performance in yield (120.20kg±12.08) which is followed by ‘Damodar’, ‘Kalyani’, ‘Lata Bomai’, ‘Sanjiban’ and the wild form.
Uniformly 22 chromosomes have been recorded in the somatic complements of all the taxa investigated. The gametic number of 11 chromosomes is uniformly represented in all the members analysed.
The genus Trichosanthes L. is characterized by a graded karyotype with metacentric to submetacentric medium sized chromosomes ranging in length from 5.74μm to 1.48μm. The somatic complements of the gynoecious cultivars of T. dioica and androecious T. palmata possess more than three pairs of chromosomes with secondary constrictions while the gynoecious form of wild T. dioica, monoecious T. cucumerina and T. anguina are distinguished by the presence of only three pairs of such chromosomes. A heteromorphic pair of chromosomes is represented in all the cultivars of T. dioica. The total haploid chromatin length has been found to vary between different taxa. The disparity index, in general, is lower in the wild taxa investigated.
The heterozygous constitution of the taxa as indicated in the occurrence of chromosomal heteromorphy has probably arisen during long cultivation and selection. The significant role of structural alterations of chromosomes in inter-and intra-specific diversification has been demonstrated in the genus Trichosanthes L.