No abstract

Stemphylium leaf blight, caused by Stemphylium vesicarium, is a very important fungal disease in onions since its epidemics are able to affect both the bulb yield and the seed quality. The aim of this study was to screen onion genotypes at stage I (seed to bulb) and further screen the identified resistant and susceptible genotypes at stage II (bulb to seed). One hundred and fifty-seven genotypes were screened against SLB under artificially inoculated field conditions. Results revealed a significant variation among the morphological and biochemical traits studied. Correlation studies revealed a significant and negative correlation between percent disease incidence (PDI), pseudostem width, neck thickness, and dry matter. Fifteen genotypes were identified as moderately resistant, and the rest were categorized as susceptible. Bulbs of the genotypes, identified as moderately resistant, were again screened for resistance in stage II. All the genotypes were categorized as moderately susceptible. Biochemical analysis revealed that total foliar phenol content, pyruvic acid, catalase, and peroxidase increased up to 20 days after inoculation (DAI) and thereafter declined. Protein content was highest in the initial stage and declined at 10, 20, and 30 DAI. The higher biochemical activity was observed in moderately resistant category genotypes compared with the susceptible ones. Correlation analysis showed a highly significant and negative correlation of PDI with total foliar phenol content (TFPC), pyruvic acid, catalase, peroxidase, and protein content. To conclude, it was observed that screening against SLB should be done at both the stages (stage I and Stage II) to identify resistant onion genotypes. Direction selection for genotypes with high dry matter, higher phenols, and enzymes may be an alternative pathway to select genotypes for a robust resistance breeding program.

In the present investigation, phenotypic and genotypic correlation coefficients were estimated among 19 characters of 51 maize genotypes, to find out the association between grain yield and its contributing characters. Grain yield per plant significantly and positively correlated with plant height, ear height, number of kernels per row, number of kernels per ear, shelling percentage and test weight at genotypic and phenotypic basis. Observable correlations among different traits was confirmed through phenotypic correlation, actual correlation could be known through genotypic correlation only, which eliminates environmental influence. Genotypic correlation permits prediction of correlated response and evaluation of relative influence of one character on other. Genotypic correlation in particular is helpful in construction of selection indices.

Background: Turmeric is an age old herbaceous plant belonging to the family Zingiberaceae growing in Tropical Africa and India with huge national and international demands. Conventionally, turmeric accessions are characterized using morphological and agronomical traits but less work is done in molecular characterization which is needed for thorough trait identification. Methods: The investigation was carried out during Kharif 2016-17 and comprised of thirty diverse genotypes of turmeric analyzed for genetic variability and molecular diversity which were evaluated in randomized block design with two replications. Fresh tender leaves were used to isolate DNA and PCR was performed with 9 SSR markers. Result: The values of phenotypic coefficient of variation were slightly higher than genotypic coefficient of variation. Highest heritability was observed for days to maturity, genetic advance was observed highest for green rhizome yield. Out of 9 SSR markers, primer pair 5, 6, 7, 8 and 9 were reported to exhibit 100% polymorphism, whereas; in terms of PIC, primer pairs 6 and 9 were found to be highly efficient ones. The similarity coefficient ranged from 0.44 to 1.00 and dendogram categorized the 30 genotypes into two main clusters.