Vol. 79 No: 5

Title:
Distribution and genetic diversity of Cucumis sativus var. hardwickii (Royle) Alef in India

Authors:
I. S. BISHT, K.V. BHAT, S. P. S. TANWAR, D. C. BHANDARI, KAMAL JOSHI and A. K. SHARMA

pp: 783-791

Abstract:
Cucumis sativus var. hardwickii (Royle) Alef, a wild sympatric botanical variety of C. sativus L. var. sativus has long grown in the foothills of the western Himalayas and is believed to be either a progenitor or feral relative of the cultivated cucumber. It is a source of several valuable genes for the improvement of cultivated cucumber but is poorly represented in major genebanks world over. A detailed inventory of C. s. var. hardwickii from various parts of the country was therefore made for collecting the germplasm accessions, and assessing the genetic diversity in the assembled germplasm. The species is widely and abundantly distributed in the north-western Himalayas, followed by fair distribution in the Western Ghats, and sporadic distribution in the Eastern Ghats, Chhota Nagpur plateau and the central Plateau region at elevations from 800 to 1700 m.a.s.l. Of the 41 accessions collected from these regions, a set of 29 representative accessions (including one cultivated landrace) were used for assessing the diversity for morphological and RAPD markers. Some of the populations were relatively more vigorous in growth, late maturing and had more laterals. High diversity for morphological as well as RAPD markers was observed, although the clustering of accessions with respect to the composition of specific groups was not identical. In each region, the presence of segregating populations of natural crosses between C. s. var. hardwickii X C. s. var. sativus were observed, indicating the existence of free gene flow between these two taxa. This underlines the importance of collecting more populations of the weedy races (natural hybrids).The results indicate the presence of high genetic diversity for useful traits, hence C. s. var. hardwickii has high potential for the improvement of cultivated cucumber.

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