Genotypic and Phenotypic Correlation and Path Analysis for Growth and Yield Contributing Traits in Bread Wheat (Triticum aestivum L.)
Abstract
Thirty-eight advanced bread wheat lines were evaluated in Randomised Block Design with four replications at Agriculture Research Station, S. D. Agricultural University, Ladol (Gujarat) during rabi 2020-21 season to evaluate the association of yield and yield-related traits and determine the direct and indirect effects of yield-related traits on grain yield. The results of the study'scorrelation analysis showed grain yield per plot had highly significant and positive correlation with number of effective tiller per meter and biological yield per plot at both genotypic and phenotypic level, that indicated that these are major contributors for increasing the grain yield per plot and selection could be more effective for these traits. The estimates of genotypic correlation coefficient were higher for most of the characters than phenotypic correlation coefficient, indicating a strong inherent association among various characters. Path analysis revealed that the biological yield per plot followed by spike length had the highest positive direct effect on grain yield per plot whereas number of effective tillers per meter followed by 1000 grain weight and number of grain per spike revealed negative high direct effect on grain yield per plot. Hence, the present investigation can be helpful as selection criteria to increase grain yield in bread wheat based on these above-mentioned traits viz., biological yield per plot and spike length. These character have to be rank the first in any breeding program to improve wheat grain yield.
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Introduction
Bread wheat (Triticum aestivum L.)is one of the most crucial staple crops in the world, with a rich history dating back thousands of years. Its journey from ancient times to the present day has witnessed significant transformations in cultivation, breeding, and utilization. The mid-20th century witnessed a transformative phase in wheat cultivation with the advent of the Green Revolution. Scientists like Norman Borlaug developed high-yielding wheat varieties, leading to increased global wheat production. This revolution significantly impacted food security and helped alleviate hunger in many parts of the world. In recent decades, advancements in molecular genetics and biotechnology have revolutionized wheat breeding. Researchers have focused on developing varieties with improved yield, disease resistance, and nutritional content. Genetic modification and genome editing techniques are being explored to enhance wheat'sadaptability to changing environmental conditions. Globally wheat occupies an area of 222.11 million hectares with production of 778.6 million metric tonnes and productivity is 3.51 t/ha (OECD/FAO 2021/22). Wheat is cultivated in almost all the states of India but its extensive cultivation is confined to Uttar Pradesh, Madhya Pradesh, Punjab, Haryana, Rajasthan, Bihar and Gujarat. In India wheat occupies an area of 31.13 million hectares under irrigation with production of 109.59 million tonnes and productivity is 3.52 t/ha (Directorate of Economics and Statistics, DAC and FW 2021/22). While, In Gujarat wheat occupies an area of 1.3 million hectares with production of 4.3 million tonnes and productivity is 3156.29 Kg/ha (Directorate of Agriculture, Gujarat State 2020-21). Wheat is cultivated under irrigated as well as rainfed conditions. The eight-fold increase in wheat production (10.40 million tonnes in 1965-66 to 109.59 million tonnes in 2021/22) (Directorate of Economics and Statistics, DAC and FW 2019-20) during the last five decades has been a remarkable and unparalleled achievement.
Transcriptomic studies have shown that over 30000 genes are expressed in the developing wheat grain (Wan et al., 2008) while, proteomic analysis of mature grain has revealed the presence of about 1125 individual components (Skylas et al., 2000). The study of different characters and their relationship with other is an important criterion design to break genetic barriers of yield. Whereas, correlation studies are helpful in determining the component of a complex traiti.e. grain yield. However, they do not provide an exact magnitude of direct and indirect effect towards the yield. Therefore, path coefficient analysis is an important tool to partition the correlation coefficient into direct and indirect effect of the independent variables on the dependent variables.
Conclusion
The estimates of genotypic correlation coefficient were higher for most of the characters than phenotypic correlation coefficient, indicating a strong inherent association among various characters. The results of the study'scorrelation analysis showed that at both the genotypic and phenotypic levels, the grain yield had a high and positive association with the number of efficient tillers per meter and the biological yield per plot at both genotypic and phenotypic level. The grain yield showed significant positive correlation with number of grain per spike and 1000 grain weight at both genotypic and phenotypic level. This has been indicating that more attention should give to this character to improve the grain yield of bread wheat. According to path analysis studies revealed that positive and direct effect towards grain yield per plot was observed by biological yield per plot, days to heading, spike length, plant height, harvest index, days to maturity and protein content, whereas number of effective tiller per meter, sedimentation value, 1000 grain weight and number of grain per spike had showed negative direct effect on grain yield per plot. Thus, characters biological yield per plot, days to heading, spike length, plant height, harvest index, days to maturity and protein content turned out to be the major components traits for grain yield per plot and direct selection for these traits will be rewarded for improvement of grain yield in wheat. Therefore, choosing individuals with these qualities will immediately aid in boosting bread wheat'sgrain yield. The Residual effect in path coefficient analysis was low indicating a high contribution of independent traits to the dependent trait.
