A pot experiment with 17 diverse genotypes of cucumber with four levels of salt stress viz., 0, 2, 4 and 6 dS m -1 was carried out during 2006. ANOVA revealed significant differences amongst genotypes and genotype 9 salt stress interaction indicating the genetic variability and differential response of the genotypes to different salt stress levels. The salt stress adversely affected the biochemical parameters; effects were severe under 4 dS m -1 . No genotype could survive at 6 dS m -1 . Sodium content, Na ? -K ? ratio, proline, reducing sugars, phenol and yield reduction (%) increased significantly as the salt stress increased. Potassium, chlorophyll, membrane stability index and fruit yield decreased significantly under salt stress in all genotypes. However, the genotypes CRC-8, CHC-2 and G-338 showed lower accumulation of sodium, lesser depletion of potassium, lower Na ? -K ? ratio and higher accumulation of proline, reducing sugars, phenols, better membrane stability and lower yield reduction (%) under salt stress, while CH-20 and DC-1 were sensitive to salt stress. Thus, a combination of traits such as higher membrane stability, lower Na ? -K ? ratio, higher osmotic concentration and selective uptake of useful ions and prevention of over accumulation of toxic ions contribute to salt stress tolerance in cucumber. These traits would be useful selection criteria during salt stress breeding in cucumber.

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We present here the first comprehensive genetic characterization of snapmelon landraces from the humid tropics of eastern India. The genetic diversity among 42 snapmelon landraces collected from four agro-ecological regions of eastern India (eight agro-ecological subregions) was assessed by measuring variation at 16 simple sequence repeat (SSR) marker loci, at various traits including plant habit and fruit type, yield (two associated traits), disease resistance and biochemical composition (total soluble solids, ascorbic acid, carotenoids and titrable acidity). Differences between accessions were observed in a number of plant and fruit traits. Snapmelon germplasm with high acidity, elevated carotenoid content and resistance to cucumber mosaic virus were identified in the collection. The SSR analysis indicated that there is a high level of genetic variability within snapmelon germplasm. Comparison of the genetic variability between snapmelons of eastern India and melons from north, south and central regions of India and reference accessions of melon from Spain, France, Japan, Korea, Maldives, Iraq, Zambia, Israel using SSRs showed that Indian snapmelon germplasm is not closely related to melon accessions from other parts of the world and that there are regional differences between Indian melon accessions. Eastern India snapmelon has unique traits, so it is important that more germplasm from this region is sampled and preserved.

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Investigation of genetic diversity is essential for the selection of parents for crop breeding and conservation of genetic resources. To estimate the genetic variability and population structure in the midst of 45 accessions of sponge gourd brought together from different geographical areas of India, morphological traits and two molecular markers, ISSR and SCoT markers were compared. Principal components analysis of 20 morphological traits showed 72.70% variability and significant positive correlations between fruit traits. All three marker techniques clustered all accessions into two groups with few outgroups. High level of polymorphism was observed among ISSR (74.6%) and SCoT (71.5%) primers. The Bayesian model revealed the hidden grouping and showed admixture type of population. The diversity pattern is influenced by genetic marker used, as different molecular markers have different polymorphism evaluation efficiency. This study can be helpful in amplifying the genetic base and selection of specific traits for breeding. Thus, ISSR and SCoT markers are potential marker for identification in sponge gourd and provide valuable data on its genetic correlation and structure.