GENETIC STUDIES IN MAIZE (Zea mays L.)
| dc.contributor.advisor | Chakraborty, M. | |
| dc.contributor.author | PANDIT, MADHAV | |
| dc.date.accessioned | 2017-06-16T07:05:14Z | |
| dc.date.available | 2017-06-16T07:05:14Z | |
| dc.date.issued | 2015 | |
| dc.description | GENETIC STUDIES IN MAIZE (Zea mays L.) | en_US |
| dc.description.abstract | Maize (Zea mays L.) has been extensively used in the crop improvement researches using a wide range of genotypes in a wide range of environmental condition. Genetic diversity analysis of available germplasm lines, type of gene action involved in the inheritance of yield and yield related traits, screening and characterization of available genotypes in variable environmental condition are the basic plant breeding approaches that have been carried out throughout the decades for the improvement of the crop. Present investigation was done under three major objectives. First, to unfurl the genetic diversity among maize genotypes based on qualitative and quantitative traits and SSR markers. Second, study of nature of gene action and interaction in flowering, maturity and yield traits. And the third, screening of maize lines for drought tolerance using morpho-physiological traits and estimated stress indices. Knowledge of germplasm diversity among elite breeding materials has a significant role in the crop improvement program. Heterosis can be exploited with high desirability from the cross between two diverse inbreds than narrow ones. Diversity assessment is carried to elucidate the genetic distance between/among two or more genotypes so that they can be clustered based on their extent of similarity. A suitable marker system is of prime importance in diversity assessment based on the purpose of diversity analysis. In present experiment, twenty maize genotypes grown under the RCBD were assessed for genetic diversity based on 14 quantitative traits, 9 qualitative traits and 18 SSR based markers to prepare three different UPGMA dendrograms from the Jacquard’s similarity/dissimilarity coefficients. Different levels of polymorphism were observed in all the qualitative traits except for kernel colour. Wider range of variation was observed across the genotypes most influentially on plant height, ear height, days to tasseling, days to silking and kernel yield per plant. The primer pairs produced 92 different markers with PIC value ranging from 0 to 0.87. Three dendrograms prepared from three sets of marker system were in no or poor correlation based on the dis/similarity coefficients. The clustering patterns in different dendrograms were distinctly different with significant diversity between and within clusters. So, the inbreds from distinct clusters can be used as parents to exploit high heterosis. Estimation of the types of gene action involved in the expression of traits, the level of additive and dominance effects and the heritability in broad and narrow sense are very important in designing a breeding method for improving the trait of interest. Knowledge of the way genes act and interact will determine which breeding system can optimize gene action more efficiently. In the present experiment, a six generation based “Generation mean analysis” was performed for the five plant traits in three different cross combinations. Three cross combinations for the study of gene effects in five plant parameters gave the significant role of different gene action and interactions in different materials. In days to silking and days to maturity, dominance effect was found to play predominant role in inheritance. Along with, different types of interactions played important roles in different crosses. Ear height was found to be inherited through additive gene action with complex gene interactions. The yield components (cob weight and per day productivity) were found inherited mainly through dominance action along with important role of di-genic non-allelic interactions. So, the earliness and higher yield improvement for the materials under study could be made through hybridization technique. The screening of newly developed lines for their performance in variable environmental conditions has became the major concern over decades to cope with the several biotic and abiotic stresses prevailing due to global climate change. Superiority in yield and yield stability throughout the variable moisture status are the major criteria for screening genotypes as drought tolerant. In this experiment, 100 test genotypes, along with replicated 3 controls in augmented design grown in two soil moisture levels (viz. stress and non-stress condition), were compared for their mean yield and yield attributing traits. A suitable stress index for the drought screening, estimated from the plot mean and grand mean, were identified. For the stress indices, KiSTI, YI, STI, GMP, MP and DRI were found to be most suitable for drought screening in maize lines. The results from field observations and estimation of stress indices showed that morpho-physiological traits and stress indices could make the suitable criteria for identification of drought tolerant genotypes. Drought tolerant genotypes identified through average ranking assigned to them were: 95, 62, 39, 30, 18, 89, 20, 103, and 66. Such identified drought tolerant genotypes/accessions would make a greatly important breeding material for the future breeding programs. | en_US |
| dc.identifier.uri | http://krishikosh.egranth.ac.in/handle/1/5810020844 | |
| dc.keywords | GENETIC STUDIES IN MAIZE (Zea mays L.) | en_US |
| dc.language.iso | en_US | en_US |
| dc.pages | 81 | en_US |
| dc.publisher | Birsa Agricultural University, Kanke, Ranchi, Jharkhand | en_US |
| dc.sub | Genetics and Plant Breeding | en_US |
| dc.subject | null | en_US |
| dc.theme | GENETIC STUDIES IN MAIZE (Zea mays L.) | en_US |
| dc.these.type | M.Sc | en_US |
| dc.title | GENETIC STUDIES IN MAIZE (Zea mays L.) | en_US |
| dc.type | Thesis | en_US |