A study of genetic diversity in 20 okra genotypes for 22 morphological and agronomic traits (13 quantita- tive and 9 qualitative) was laid out in randomized block design with three replications during 2015-16. The phenotyp- ic and genotypic variances, phenotypic (PCV) and genotypic coefficients of variation (GCV), heritability, genetic ad- vance of the characters were studied. The genotypes demonstrated wide range of variability for all characters. In this study PCV was higher than its corresponding GCV thus revealing the role of environmental factors. High heritability (h2b) was recorded for all characters except for days to first flowering (27.76%) and days to 50% flowering (34.67%) which have moderate values. Genetic advance in per cent of mean was high for all the characters ex- cept moderate for first flowering node (12.88%), fruit length (17.59%), fruit diameter (13.99%) as well as low for days to first flowering (1.69%) and days to 50% flowering (2.28%). The higher value of genetic advance indicates that selection of genotypes on the basis of these characters is desirable. Fruit yield showed positive and highly significant (at 1% level of significance) genotypic association with fruit diameter, number of fruits per plant, average fruit weight and number of seeds per pod. The genotypes, viz. Kashi Kranti, Kashi Satdhari, VROB-159, Punjab-8 and Kashi Mohini were found promising for most of the yield contributing traits. These genotypes could be used further in hybrid breeding programme.
Molecular markers are vastly used as tool for screening of disease resistant/tolerant plant genotypes in early stage of growth in an environment-independent manner. In tomato (Solanum lycopersicum L.), the major biotic stresses like tomato yellow leaf curl virus, Fusarium wilt, tomato spotted wilt virus and root knot nematode cause severe crop loss. Recently, DNA based molecular markers for the screening of resistance alleles for the abovementioned diseases have been reported in tomato. In the present study, a total of eighteen tomato genotypes have been screened for the presence of possible resistance alleles, using sequence characterized amplified region(SCAR) molecular markers. Resistance allele-specific bands for Fusarium wilt disease, tomato spotted wilt disease and partial resistance allele-specifc band for root knot disease have been identified in some of the genotypes used in the present study. However, none of the genotypes was found to contain Ty3 resistance allele-specific band for resistance to tomato yellow leaf curl disease. Thus, possible resistance sources have been identified for three out of the four biotic stresses, mentioned earlier. Thus, the present study has screened the 18 tomato genotypes at molecular level for presence of resistance alleles for biotic stress, which might be further evaluated and explored in future tomato breeding programmes, targeting biotic stress resistance in tomato. At the same time, the study documents the applicability of molecular markers for rapid disease screening in tomato in an environment independent manner.
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