COMBINING ABILITY FOR YIELD AND YIELD ATTRIBUTES IN INDIAN MUSTARD (Brassica juncea (L.) CZERN. & COSS.)
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Date
2021
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AAU, Jorhat
Abstract
Indian mustard [Brassica juncea (L.) Czern. & Coss.] holds a notable position among the oilseed crops grown in the world and has emerged to be the second most important oilseed crop in India. However, the crop is not popular among the farmers of Assam as it does not fit well into the cropping system due to the longer duration required for its maturity. Thus, developing a mustard variety with short height, shorter duration without compromising the yield can change it into a valuable crop in Assam. The disease Alternaria blight seems to be a major issue in the area affecting the yield up to a great extent, thereby attracting attention for its consideration during the study of the yield parameters. The research was guided with a target to the analysis of variability among the parents and F1s, character interrelationship, and combining ability in the diallel cross. Ten genotypes were grown in the Rabi 2019-20 containing three Alternaria blight tolerant lines, two high yielding lines (under Assam conditions), four single zero varieties, and one genotype that was a double zero variety belonging to the Brassica napus species. Diallel crosses were made between five selected parents to produce F1 progeny including reciprocals to study the nature of gene action involved in the expression of quantitative traits which were subsequently grown in Rabi 2020-21 along with other genotypes. Some of the other crosses that were presumed to be consequential were also developed and evaluated to develop breeding materials having quality oil content with lower amounts of erucic acid with the least impairment in yield.
The analysis of variance (pooled) revealed significant variation among the parents for all the characters under study indicating the presence of exploitable variation among the genotypes included in the experiment. Moderate genotypic coefficient of variation and phenotypic coefficient of variance for most of the characters and high broad-sense heritability was observed for all the traits under study. High genetic advance coupled with high heritability was observed for the characters, foot length, thousand seed weight, seed yield per plant, plant height, number of primary branches, number of secondary branches and biological yield per plant which denotes the probable preponderance of additive gene effects and selection may be effective.
Since yield is polygenecally controlled and highly influenced by the environment, selection based on yield alone is not effective. From correlation analysis studies in both the years, it can be concluded that days to maturity and plant height were the major yield attributing traits which showed strong negative genotypic correlation with the character, yield per plant. The path analysis of both the years revealed that the characters, days to 50% flowering, number of secondary branches per plant, number of pods per main shoot and number of seeds per siliqua had direct positive effects on seed yield per plant.
From the analysis of variance for combining ability, significant variation among the parents, among the total crosses, among F1s and among the reciprocals was inferred, which indicates the presence of genetic differences among the parental genotypes and their prepotency. Moreover, the significance of the difference between Parent vs F1s was observed for all the characters under study, which suggests the presence of heterosis, while in the case of F1 vs Reciprocal, significant variation was observed for most of the characters. This denotes the preponderance of reciprocal effect. From the evaluation of GCA in parents, the genotypes EC339000 and Pusa Mahek were found to be good combiners with high GCA for early maturity, early days to 50% flowering and low foot length, while, TM-2 for seed yield per plant. The crosses TM-2 x PM21, followed by PHR2 x PM21 depicted positive significant SCA effects for seed yield per plant and also exhibited high positive significant heterosis over better parent for the character.
The banding patterns of 10 SSR gene-linked markers were studied, out of which 9 primers showed polymorphism. The PIC value was calculated which ranged from 0.190 to 0.927. Clustering was done based on Jaccard coefficient of similarity and the genotypes DLSC-1 and Pusa Mahek were found to be most similar, whereas, TM-2 and PM-22 exhibited the least similarity. The marker data generated can be utilized in further breeding programmes.