Browsing by Author "BRIJESH KUMAR MEHTA"
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ThesisItem Open Access Studies on effects of sugary-1 and shrunken-2 genes on grain sweetness in sweet corn genotypes(DIVISION OF GENETICS ICAR-INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI, 2015) BRIJESH KUMAR MEHTA; Firoz Hossain)Sweet corn has emerged as one of the popular choices worldwide, and is used as vegetable and component of soups and various snacks items. It is also an important source of fibre, minerals, and vitamins. In India, only three sweet corn composites viz., Madhuri, Priya and Win-Orange have been developed by public sector organization. HSC-1 is the only single cross sweet corn hybrid released for hilly regions of India. It is therefore important to develop diverse high yielding sweet corn hybrids with elevated sweetness. Twenty one sh2sh2- and eleven sh2sh2/su1su1-based hybrid combinations generated among sweet corn inbreds developed at IARI, New Delhi, were evaluated in replicated trials with three sowing dates with each having harvest date at 20-, 24- and 28- days after pollination (DAP). Significance of genotype and genotype × sowing date interactions were observed for date of anthesis, cob- and fodder-yield. Brix value, a measure of kernel sweetness exhibited significant genotype × sowing date, genotype × harvest date, genotype × sowing date × harvest date interactions. Brix value in general attained peak at 24-DAP, though some genotypes recorded highest brix at 20- and 28- DAP. Brix value could not differentiate sh2sh2- and sh2sh2/su1su1-based hybrids, although organoleptic test reported higher kernel sweetness among sh2sh2/su1su1-based hybrids. Cob- and fodder-yield did not show any correlation with brix, while brix recorded at 20-, 24- and 28-DAP were positively correlated. Most of the experimental sweet corn hybrids displayed cob yield heterosis over national check, Madhuri. Among the hybrids, MGUSCH-3, MGUSCH-12, MGUSCH-26 and MGUSCH-27 were identified as promising and were at par with the hybrid checks viz., Sugar-75, ASKH-1 and ASKH-2. These hybrids possess more brix (MGUSCH-3: 21.4%, MGUSCH-12: 21.0%, MGUSCH-26: 20.1% and MGUSCH-27: 22.1%), than Sugar-75 (18.4%), ASKH-1 (19.0%) and ASKH-2 (19.6%). Further, these hybrids were also early maturing as compared to Sugar-75. These four hybrids thus possess great potential for cob- and fodder-yield, and kernel sweetness. In order to develop new heterotic combinations, 48 diverse inbreds with sh2sh2-, su1su1- and sh2sh2/su1su1- genetic constitutions were analyzed for genetic diversity using 56 SSR markers. Polymorphism information content of the markers ranged from 0.14-0.74, while major allele frequency varied from 0.29- 0.92. Wide range of genetic dissimilarity (0.33-0.87) was also observed among the inbreds. Cluster analyses grouped the inbreds into three major clusters, and genetic relationships depicted were in broad congruence with the pedigree. The study identified genetically diverse inbreds that can be used to develop potential hybrid combinations in sh2sh2- and sh2sh2/su1su1- genetic background.