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The variability of a biological population is a result of the genetic Essay
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Nov 19th, 2019

The variability of a biological population is a result of the genetic Essay

The variability of a biological population is a result of the genetic make – up of the individuals in this population in relation to their respective environments. To begin an effective breeding program it is absolutely necessary to evaluate genetic variability with parameters such as genotypic coefficient of variation, heritability estimates and genetic advance. All efforts to improve yield in chickpea and their economic return are now aimed at the genetic variability manipulation.Sreelakshmi et al. 2010. studied 40 genotypes of chickpea and concluded that days to maturity, number of pods per plant and seed yield exhibited high GCV and PCV.

Kuldeep et al. 2014. experimented on 100 advance breeding lines of chickpea and observed high GCV and PCV for seed yield per plant, 100- seed weight, harvest index, number of effective pods per plant, total number of pods per plant and number of secondary branches. Desai et al. 2015 carried out eperiment on 48 chickpea genotypes and observed that 100 sed weight followed by methionine content, number of pods per plant, seed yield per plant and number of seeds per pod exhibited highest GCV values.

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Jha et al. 2015. investigated 62 chickpea genotypes and reported that highest PCV and GCV was observed in membrane stability. Reddy et al. 2017. studied the population of F2 generation of cross BG-212 x ICCV-07305 of chickpea and found that the estimates of PCV and GCV were high for the characters pods per plant, branches per plant, seed yield per plant, 100 ” seed weight and days to flowering.Hasan and Deb. 2017. carried out experiment using eight genotypes of chickpea and found that number of pods per plant exhibited highest phenotypic variation followed by number of seeds per plant and plant weight at harvest. It was also observed that number of seeds per plant showed highest GCV, while high PCV was observed in number of pods per plant.Dev et al. 2017. studied 60 genotypes of chickpea and reported that the characters harvest index, plant height, 100 seed weight and number of seeds per pods, seed yield per plant, secondary branches per plant and primary branches per plant showed high to moderate GCV and PCV. Singh et al. 2018. tested sixteen chickpea genotypes and reported high genotypic coefficient of variation for seed yield per plant followed by harvest index, number of pods per plant, 100 seed weight and plant height. Kumar et al. 2018. carried out experiment using 65 lines of chickpea and concluded that GCV and PCV were high for the following traits grain yield per plot, biologiacal yield, effective pods per plant,100- seed weight and primary branches per plant.Joshi et al. 2018. studied 252 intra-specific recombinant inbred lines of chickpea and observed high GCV for biological yield, seed yield, harvest index and 100-seed weight. Kishor et al. 2018. used 40 chickpea genotypes for his experiment and concluded that high GCV and PCV were seen in number of pods per plant followed by biological yield per plant, number of seeds per plant, seed yield per plant, number of primary branches par plant, 100-seed weight. Avinalappa and Raghunath. 2018. studied 22 desi chickpea genotypes and reported that number of seeds per pod, 100-seed weight and seed yield per plant showed maximum genotypic coefficient of variation and phenotypic coefficient of variation, where as minimum PCV and GCV was recorded for number of primary branches per plant.Arora et al. 2018. studied 50 genotypes of kabuli chickpea and observed that maximum variability was present in number of pods per plant while, minimum was observed in number of days to maturity.further reported thathigh GCV and PCV were found in number of days to flowering followed by number of days to maturity and 100 seed weight.Barad et al. 2018. conducted experiment on 50 diverse genotypes of kabuli chickpea which reveled that number of primary branches per plant exhibited high PCV and GCV followed by seed yield per plant and 100 seed weight.Mohammed et al. 2019. experimented using 202 landraces of chickpeqa and observed that days to maturity showed low PCV and GCV, while grain yield per plant showed high values of GCV and PCV.Gediya et al. 2019. carried out experiment using 58 genotypes of chickpea and concluded that high PCV and GCV were observed for secondary branches per plant, pods per plant, seeds per pod, seeds per plant, hundred seed weight, seed yield per plant and harvest index. HERITABILITY AND GENETIC ADVANCEThe ratio of genotype variance to complete variance (phenotypical variance) is the heritability in broad sense. It is calculated from total genetic variance which consists of additive, dominance and epistatic variances. The assessments of broad sense heritability help to select elite genotypes from homozygenous populations. The genetic advance is known as improvement in the mean genotypic value of selected plants over the parental population. It is the selection measure of the genetic gain. It contributes to understanding the type of gene action in the expression of different polygenic characteristics and to the determination of genetic action for genetic improvement of various polygenic traits.Sreelakshmi et al. 2010. experimented on 40 chickpea genotypes and reported that seed yield, number of pods per plant and number of fruiting branches per plant showed high heritability with high genetic advance.Kuldeep et al. 2014. experimented on 100 advance breeding lines of chickpea and reported high heritability and high genetic advance as percentage of mean for seed yield per plant following 100 – seed weight, harvest index, number of effective pods per plant and total number of pods per plant. Desai et al. 2015 carried out eperiment on 48 chickpea genotypes and reported that methionine content along with 100 seed weight, number of pods per plant and days to flowering had high heritability coupled with high genetic advance.Jha et al. 2015. observed that membrane stability exhibited highest heritability followed by pods per palnt and days to maturity.Reddy et al. 2017. conducted experiment on the population of F2 generation of cross BG-212 x ICCV-07305 of chickpea and reported that the high broad senseheritability was seen in pods per plant followed by days to flowering, 100 ” seed weight, seed yield per plant,plant height and branches per plant, while the characters plant height, seed yield per plant,pods per plant, branches per plant. 100 seed weight and days to flowering showed high genetic advance as percentage of mean.Singh et al. 2018. tested sixteen chickpea genotypes and observed high heritability for 100 seed weight, plant height, days to maturity, number of pods per plant, biological yield per plant, harvest index, seed yield per plant and days to 50 per cent flowering. High genetic advance as percentage of mean was observed for seed yield per plant, harvest index, 100 seed weight, number of pods per plant and biological yield per plant. Kumar et al. 2018. carried out experiment using 65 lines of chickpea and concluded that plant height, number of primary branches per plant, number of secondary branches per plant, total number of pods per plant, effective pods per plant, biological yield, 100 ” seed weight, grain yield per plant and grain yield per plot showed high heritability coupled with high genetic advance.Joshi et al.2018. reported that biological yield, seed yield, harvest index and 100-seed weight exhibited high heritability coupled with high genetic advance.Kishor et al. 2018. concluded that high heritability coupled with high genetic advance as percentage of mean were observed for number of pods per plant, biological yield per plant, number of seeds per plant, seed yield per plant and number of primary branches per plant.Shengu et al. 2018. observed high heritability for seed yield per hectare, days to maturity, seed yield, yield per plot, 100 – seed weight, number of pod length, plant height, number of primary branch per plant, days to emergence and days to flowering, where as low heritability was observed for number of secondary branch per plant, number seed per pod and of pod per plant. Barad et al. 2018. carried out experiment using 50 kabuli genotypes of chickpea and reported that high heritability along with high genetic advance was found in traits number of primary branches per plant followed by number of secondary branches per plant, plant height, reproductive phase duration, days to 50% flowering, number of pods per plant seed yield per plant and 100 seed weight.Mohammed et al. 2019. concluded that grain yield, number of pods per plant and biomass yield showed high heritability and genetic advance as percent of mean.CORRELATION COEFFICIENT ANALYSISCorrelation coefficient is a statistical measure to determine the degree of relation and the direction of two or more variables. A positive correlation value demonstrates that the two variables change in the same direction, whereas two variables move in the opposite direction in the negative correlations. It measures the mutual relationship between different plant characteristics and determines the selection component characteristics on which the genetic yield improvement can be based. The available literature on chickpea’s correlation analysis are reviewed as follows:Sreelakshmi et al. 2010. conducted experiment on 40 genotypes of chickpea and revealed that positive and significant correlation with seed yield per plant was exhibited by days to 50% flowering, days to maturity, number of fruiting branches per plant and number of pods per plant. Pandey et al. 2013. reported that grain yield per plant was positively and significantly correlated with days to flowering, plant height, number of branches per plant, number of pods per plant and 100 seed weight. Kuldeep et al. 2014. concluded that plant height, number of primary branches, number of secondary branches, number of pods per plant, number of effective pods per plant and 100-seed weight were positively and significantly correlated to seed yield per plant. Bala et al. 2015. experimented on twenty five chickpea genotypes and reported that pods per plant, harvest index, biological yield per plant and primary branches per plant showed significant and positive correlations with seed yield per plant at phenotypic level.Johnson et al. 2015. carried out research using 112 chickpea genotypes and concluded that positive correlations with seed yield per plant were exhibited by biological yield per plant and harvest index.Jha et al. 2015. reported that high positive correlation was present between days to maturity and membrane stability while positive correlations were present between days to 50% flowering and plant height, pods/plant and plant height, pods /plant and membrane stability.Banik et al. 2017. experimented on 60 chickpea genotypes and reported that seed yield per plant was positively and significantly correlated with number of pods per plant, plant height, number of secondary branches per plant, plant spread, 100 seed weight, and number of primary branches per plant while it was negatively correlated with 50 per cent flowering and number of seeds per plant.Astereki et al. 2017. revealed that the correletion between seed yield and number of pods per plant and harvest index were significant and positive.Singh et al. 2017. conducted experiment using 43 genotypes of chickpea which revealed that seed yield per plant exhibited highly significant and negative correlation with days to 50% flowering while significant and positive correlation was present between seed yield per plant and pods per plant.Agrawal et al. 2018. found that number of primary branches, number of secondary branches, biological yield, harvest index, 100 seed weight and days to maturity were positively and significantly associated with grain yield per plant under normal sown conditions, while under late sown conditions chlorophyll index, number of primary branches, total number of pods per plant, effective pods per plant, biological yield, harvest index and 100 seed weight were positively and significantly associated with grain yield per plant.Kumar et al. 2018. observed that the characters biological yield per plant, 100 seed weight, harvest index and pods per plant showed highly positive significant correlations with seed yield per plant in both timely and late sown environments. Thakur et al. 2018. observed that seed yield per plant showed high significant positive correlation with test weight, harvest index, total number of pods per plant, number of secondary branches and total number of seeds per plant.Shengu et al. 2018 observed positive and high significant correlation between grain yield and yield per plot, 100 – seed weights and yield per plot while negative and significant correlation was observed between pod length and yield per plot.Singh et al. 2018. performed experiment using 16 genotypes of chickpea and found that significant and positive correlations were present between the characters like 100 seed weight and plant height, number of secondary branches per plant and plant height, days to heading and days to maturity, days to maturity, number of primary branches and number of secondary branches per plant, seed yield, number of pods per plant and number of seeds per pod and between seed yield, biomass and harvest index.Jida and Alemu 2019. used 19 elite varieties of chickpea for their experiment and revealed that correlations between grain yield, biological yield, number of seeds per plant, number of pods per plant and number of primary branches were positive and significant.Gediya et al. 2019. experimented on 58 genotypes of chickpea and reported that seed yield per plant exhibited significant and positive genotypic correlaations with pods per plant (0.728**), seeds per plant (0.648**), 100 seed weight (0.338**) and harvest index (0.683**). PATH COEFFICIENT ANALYSISThe path coefficient analysis is simply a standardized partial regression coefficient, dividing a coefficient of correlation into direct and indirect effect measurements. The cause of the association of two variables is measured by path analysis. It is based on every possible simple correlation between different characters. It helps to determine the yield characteristics and is useful for indirect selection. The following literature on path analysis is available in Chickpea:Qurban et al. 2010. conducted experiment using 20 elite genotypes and 3 standard checks of chickpea and concluded that maximum direct effect on grain yield was contributed by 100 seed weight followed by pods per plant, secondary branches per plant, seeds per pod, days taken to maturity and number of primary branches per plant. Also negative direct effect on grain yield was contributed by number of days taken to flowering, plant height and biomass per plant.Zali et al. 2011. studied 17 genotypes of chickpea and reported that number of days to 50% maturity (98.43%), number of days to 50% flowering (98.19%), plant height (58.87%), number of secondary branches (45.81%), number of primary branches (42.03%) and number of seeds per plant (35.42%) exhibited high heritability values.Kuldeep et al. 2014. revealed that maximum direct effect on seed yield was displayed by number of effective pods per plant and 100 ” seed weight.Bala et al. 2015. experimented using twenty five chickpea genotypes and observed that positive and high direct effects on seed yield per plant were exhibited by biological yield per plant and harvest index.Johnson et al. 2015. carried out research using 112 chickpea genotypes and observed that harvest index, biological yield and pods per plant had highest positive direct effect on seed yield per plant.Banik et al. 2017. conducted experiment using sixty chickpea genotypes and reported that path coefficient analysis of number of pods per plant had highest direct effect on seed yield per plant which was followed by 100- seed weight, plant height and days to maturity, while number of seeds per pod and days to 50% flowering had negative effect on seed yield.Dev et al.2017. conducted research using 60 chickpea genotypes and concluded that genotypic and phenotypic path coefficient analysis of biological yield and harvest index showed high and positive direct effects on seed yield per plant. Kumar et al. 2018. observed that path analysis of biological yield per plant displayed highly positive direct effects towards seed yield per plant followed by harvest index and 100- seed weight. Biological yield showed significantly positive indirect effect on seed yieldvia 100- seed weight, pods per plant, plant height, primary branches per plant and days to 50% flowering.Agrawal et al. 2018. concluded that high positive direct effect on grain yield per plant was displayed by biological yield, effective pods per plant, harvest index, primary branches per plant and secondary branches per plant.Attri et al. 2018. revealed that direct and positive effect on sed yield per plant was showed by plant height, primary branches, secondary branches, pod per plant, 100 seed wt, while the characters like days to 50% flowering and days to maturity gave indirect effects on seed yield per plant via plant height and 100 ” seed weight. Singh et al. 2018. experimented using 16 genotypes of chickpea and reported that direct effect on seed yield was exhibited by harvest index. Further revealed that harvest index showed high and positive indirect effect on seed yield through plant height, number of pods per plant, number of seeds per pod and biomass while, exhibited low and negative indirect effects through days to heading, days to maturity, 100 seed weight and number of primary branches per plant.Gediya et al. 2019. studied 58 chickpea genotypes and concluded that significant and direct effects on seed yield per plant were exhibited by pods per plant (0.198), seeds per plant (0.672), harvest index (0.170) and 100 seed weight (0.665).

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