Evaluation of pearl millet (Pennisetum glaucum L.) genotypes for growth, yield and yield attributing traits in Vindhyan region of Uttar Pradesh

Introduction

Pearl millet (Pennisetum glaucum L.), a significant coarse grain millet from the Poaceae family, is a diploid plant with a chromosome number of 2n=14 (Sattler FT et al., 2019) [14] . Known for its hardiness and drought resistance, this crop has been cultivated for thousands of years and originates from Africa. It is usually stated to as bajra, bulrush millet, or cat tail millet, Pearl millet is a vital cereal crop due to its nutritious grains and its ability to flourish in low-water, low-energy environments, as well as some of the most challenging and marginal conditions globally. It is a warm-season crop that grows in areas with rainfall ranging from 150-700mm and is cultivated on approximately 27 million hectares, primarily in Asia (>10 million ha) and Africa (about 18 million ha), producing around 36 million tons annually (Yadav OP and Rai KN, 2013) [18] . Considerate variability is crucial for breeders to identify genotypes with high variability and strong performance in yield and its components. Selecting genetically stable parents early in the breeding program is vital for its success. Hence, comprehending the nature of genotypes is important for breeders to test and choose the most efficient ones.

Breeding genotypes with broad adaptability is a longstanding goal for plant breeders. Genotypes significantly effect multi environmental trials, and genotype-environment interactions can restrict selection in both high and low yielding environments. Thus, evaluating the environmental sensitivity of genotypes is necessary to achieve higher yields. Environments where crops cultivate consist of numerous factors each season, including weather conditions, which are crucial in determining the yield potential of a genotype. Yield capacity often varies among cultivars based on environmental conditions (Mungra KD et al., 2011) [9] . Plant breeders have observed that different genotypes respond differently to environmental changes, prompting them to evaluate their genotypes for stability under various conditions. Breeders aim to develop varieties or hybrids with broad adaptability. Information on the adaptability and performance of genotypes across multiple years and locations is critical for national crop production policies. Characterizing breeding materials at various stages of genotypes development typically involves assessing their response to environmental changes and the stability of that response. For these measures to be valuable in a breeding program, they must be genetic, repeatable, and provide insights beyond yield alone (Casler MD and Hovin AW. 1984) [2] . Various methods have been proposed to describe and interpret the response of genotypes to environmental variation. These include approaches based on analysis of variance. The analysis of variance approach, developed and modified [Carlos TSD and Koranowski WJ (2003)] [1] , evaluations of genotype x environment interaction. Pearl millet is a crucial staple cereal for subsistence farmers in the semiarid tropics of Africa, as noted [Comstock RE, Moll RH (1963) [3] , and Ramanatha Rao and Toby Hodgkin (2002)] [11] . It serves as a primary source of energy and protein for millions in Africa and is recognized for its numerous nutritional and medicinal benefits (Yang X et al., 2012) [20] . Traditional crop genotypes that have been developed by farmers over many years through natural and human selection, adapting to local conditions. These distinct plant populations are named and maintained by farmers to fulfill their social, economic, cultural, and ecological needs (Worede M et al., 2000) [17] . The accomplishment of a breeding program aimed at yield improvement through phenotypic selection relies significantly on the nature and extent of variation in the available material, as well as the environmental influence on the expression of plant characters. Principal component analysis (PCA) is a critical method for reducing the complexity of observed variables into a smaller set of independent dimensions (Johnson RA and Wichern DW, 2007). General combining ability (GCA) provides an evaluation of a genotype's average performance, indicating its breeding value. Studies on combining ability are thus instrumental in identifying and excluding inferior genotypes from breeding programs. The objective of this study was to assess the productivity of 6 pearl millet genotypes, examine genetic parameters, and analyze the variation in yield and its component traits. This analysis aims to provide insights that could inform crop improvement strategies.

Materials and Methods

The experiment material for studied is 6 Genotypes of pearl millet (84A, 86M14, BJ 527, Dhana Shakthi, Bajra M4, MPMH 24M, ABV-04, 86M84, BAJRA 48 F/S, MOTI BAJRA, PB106M, TSFB-15-8). Selected genotypes of pearl millet and evaluated in this study (Table 1). This experiment was carried out at Field Experimental Centre at Department of Genetic and Plant Breeding, Sam Higginbottom University of Agriculture, Technology and Sciences Naini Prayagraj, Vindhyan Region Uttar Pradesh. During Kharif seasons 2023. The field trial was arranged in a Randomized Block Design with 3 replications. Studied Traits were as follow: Germination percentage (%), Plant Height at 30, 60 and 90 DAS (cm), Days to 50% Flowering, Leaf Blade Length, Width, Number of Leaves, Nodes, Productive tillers Panicle length, Width (cm), Seed Shape, Colour, 1000 Seed Weight (g), Seed Yield per Plant (g), Plot (g), Hectare (quintal) Biological Yield (g), Harvest Index (%) and Green Weight per Plant (g). Statistical investigation was imperiled to proper statistical analysis of Randomized Block Design with three replications. Means were associated at 0.05 level of significance by least significant different (L.S.D) test using (Mstat C. 1986) [8] . Genetic parameters were estimated rendering the formula given by (Robbinson HV. et al., 1951; Johanson HW. et al., 1951) [13,4 ] . ANOVA revealed the high significance of the differences between genotypes concerning the following traits: germination percent, plant height at different stages of growth (30, 60, and 90 cm), days to 50% flowering, number of leaves and nodes per plant, leaf blade length-width, number of productive tillers per plant, panicle length-width, test weight, and seed yield calculated by different methods (per plant, per plot, and per hectare). The magnitude of genotype variance for plant height at 90 cm was exceptionally high, with a mean square value of 18918.87 in comparison to the error with a mean square value of 6.45, indicating that this character is under strong genetic control (Kumar et al., 2023) [5] . Similarly, the productive tillers per plant also manifested highly significant genotypic variation, with a mean square value of 13.602, which postulates that this character is effectively selectable in breeding programs for yield improvement (Sharma and Singh. 2022) [15] . ANOVA table for seedling growth Parameters showed ANOVA showed that there was a significant effect of the genotype on all the parameters studied, among them the germination percentage and index, the length of seedlings, shoot and root length, dry weight, and seed vigor indices. The mean square of the genotype for seedling length is 18.09 versus an error mean square of 1.57, while genotypic differences have a profound impact on the initial growth stages, which are so important in establishing a healthy crop. The high variability for seed vigor indices, especially Seed Vigour Index II, was genotype mean square = 128704.4, which, together with the potential for early selection of genotypes for the trait early vigour-an important one in improving crop establishment under varied environmental conditions of the Vindhya region (Patel et al., 2022) [10] . These results indicate genotypes for growth and yield-attributing traits and for seedling traits. High variability in plant height, panicle characteristic, and seeds of yield metrics follows the high possibility of selection of these traits in order to gain adequate improvement in Pearl Millet breeding programs. Besides this, the marked genetic variability in seedling growth attributes indicates that early vigor is one of the most important characteristics which can provide a good establishment of proper crop under the prevailing climatic and soil conditions of the Vindhya region, thereby bringing about a better yield. The results are in tune with findings from other workers which have indicated the role of genetic variability in the improvement of crop attributes through the selection program (Singh et al., 2021) [16] .

Results and Discussion

Genetic Parameters

The Genetic parameters for field traits, including Genotypic Coefficient of Variation (GCV), Phenotypic Coefficient of Variation (PCV), Environmental Coefficient of Variation (ECV), Heritability, Genetic Advance, and Genetic Advance as a Percentage of Mean (GA as % of Mean).

Field Traits Germination %

The percent germination manifested moderate genetic variability, with GCV of 6.719%, somewhat lower than the PCV value of 7.014%. High heritability, 0.918, suggests that the variability manifested in the germplasm would be due to genetic causes. Genetic advance of 13.26% of the mean depicts a moderate possibility of improvement through selection. Breeding for higher germination percentage should hence be successful through selection based on phenotypic performance. Plant Height at Different Growth Stages [PH@30, PH@60, PH@90 cm] Plant height at different growth stages showed very high magnitude of GCV and PCV at 30, 60, and 90 cm. PH@60 and PH@90 cm had almost similar GCV estimate of 44.591% and PCV of 44.61%, respectively, and hence heritability was almost complete, 0.999. The percentage of the mean through GA was very high, 91.81%-91.82%, thus suggesting a great genetic potential through selective breeding to increase the plant height. This indicated that plant height is a highly heritable trait and a significant amount of genetic gain can be realized through selection on this trait.

Number of Leaves per Plant

The number of leaves per plant showed high genetic variability, as GCV accounted for 23.778%, while PCV was slightly higher, 24.49%. Heritability was high, 0.943, with a high GA percentage of the mean, 47.57%, indicating that selection can bring a considerable potential improvement in this character. This indicates that the number of leaves per plant can effectively be improved through selection.

Number of Nodes per Plant

Like the number of leaves, a high variability represented by GCV of 41.215% and a PCV of 42.27% was found in the number of nodes per plant. The heritability was 0.951 and the GA in terms of percentage of mean was 82.81%. This high heritability coupled with a high GA suggests that the number of nodes per plant is under strong genetic control, hence significant improvement could be achieved through selection. Yield and Associated Components Biological Yield (g), Harvest Index, Seed Yield /Plant, Seed Yield / Hectare, Green Weight /Plant Yield-associated attributes such as biomass yield, green weight per plant, and seed yield per hectare recorded a high range of heritability 0.94-0.999 with moderate to high GA as % of mean 74.48%-91.81%. These attributes have a comparatively major part of genetic control in them so far as selection for these traits is highly effective and would eventually pay off in terms of the overall crop yield.

Harvest Index

A low heritability value of 0.239 and a low GA as a percentage of the mean of 1.21% are recorded in the harvest index. This observation further suggests that this trait is more influenced by environmental parameters rather than genetic parameters, hence a less reliable criterion for selection.

Laboratory Traits

Seedling Length (cm), Shoot Length (cm), and Root Length (cm): These characters showed high genetic variability as revealed by GCV with a magnitude of 24.85%, 24.07%, and 44.73%, respectively. Heritability estimates for these characters fell within the range of 0.65 to 0.78, categorizing them from moderate to high heritability. The GA as percentage of mean varied from 39.81 to 79.97%. This implied that selection could be effectively applied for the improvement of these characters, and root length showed the maximum possibility for genetic improvement.

Dry Matter (gm) and Vigour Index (VI-I, VI-II)

Dry weight and vigour indices showed high heritability ranging from 0.76 to 0.86 with high genetic advance under selection, as would be evidenced from the parameter of 'GA as % of mean' which varies between 53.93% and 79.30%. These growth parameters are often regarded as very important indicators of seedling vigor and overall plant health, and this may clearly indicate a high heritability and thus good scope for improvement through selective breeding.

Evaluation of Genotypic and Phenotypic Correlations

Analysis: Pearl Millet (Pennisetum glaucum L.) Growth and Yield and Yield attributing Traits reveals significant relationships that are essential for breeding and selection programs. Present investigation was undertaken to find out the genotypic and phenotypic associations between different agronomic characters in pearl millet [Pennisetum glaucum L.]. Analysis was done to establish the association among seed yield with other growth attributes to understand the important traits that most contribute to yield performance under prevailing environmental conditions of the Vindhyan Region in Uttar Pradesh. Some key traits studied for their associations included germination percentage, plant height at different stages of growth, the number of leaves per plant, and nodes per plant including the length and width of its leaf blade in relation to seed yield per hectare. Highly significant positive associations were observed among various traits including plant height at different stages of growth, number of leaves per plant, and seed yield per hectare. There is, for example, a very strong positive correlation between PH@ 60 and SY/Ha that was reported at r = 0.652, genotypic, which should indicate that at this stage of growth, taller plants tend to produce higher yields. Another one is NL/P, which also correlated well with seed yield, r = 0.7541 (genotypic level), hence the higher the leaves per plant, the better the tendency for yielding more seeds. Interestingly, Number of Productive Tillers per Plant also presented a high positive correlation with seed yield, followed by Panicle Length, and thus these traits could be used as potential selection criteria in breeding programs for yield improvement. Other important traits like Harvest Index and Panicle Width did not show significant association with yield, and thus they contributed little to seed yield directly under the studied conditions. Genotypic and phenotypic correlation analysis of Pearl Millet traits came up with important topographies, informing future breeding objectives toward the improvement in yield performance. The strong positive correlation between plant height at different growth stages and seed yield points to the fact that plant height may be an important key trait for indirect selection in breeding programs. The high magnitude of genotypic correlation estimated between plant height at 60 cm and seed yield (r = 0.652) suggests that selection of taller plants at an early stage of growth may result in increased overall yields, probably because of an association with enhanced biomass accumulation and effective distribution of assimilates. Similarly, Number of Leaves /Plant and Number of Nodes /Plant showed a positive association with seed yield, indicating their importance as life-history determinants of reproductive success. This result is consistent with previous studies that highlight a strong vegetative growth as essential to maximize the yield potential in cereals (Yadav et al., 2017) [19] . Positive correlations between PL and seed yield further support the role of panicle architecture in yield determination, with longer panicles offering more space for seed development, hence resulting in higher grain production (Kumar and Sharma, 2021) [6] . By contrast, the non-significant association between harvest index and seed yield indicates that partitioning dry matter between vegetative and reproductive organs might not be a reliable index of selection. It thus provides an implication that HI, though normally considered a critical yield component, plays its role in an environmentally specific way, or even its role is masked by other more influential traits under certain conditions.

Conclusion

The study concluded that field and lab traits have varying degrees of genetic control and environmental influence. Field traits like Germination Percentage (%), Plant Height @30 (cm), Plant Height @60 (cm), and Plant Height @90 (cm) show high heritability and significant genetic advances, indicating potential for selection and improvement. Lab traits like Germination percentage and Germination Index have moderate GCV but lower heritability. Root Length and Dry Weight show high GCV and heritability, suggesting strong genetic control. Seedling Length and Shoot Length show moderate to high heritability with substantial genetic advances. Seed Vigour Index II is a promising target for breeding programs. On the basis of performance, Seed Yield is highest in BAJRA M4 and lowest in 84A, with BAJRA M4 also having the highest cost benefit ratio. In terms of seedling growth, BJ 527 exhibits the maximum performance, while 86 M14 shows the minimum and correlation analysis shows significant positively among all the characters. These characters may be given due consideration during selection for crop improvement.

Acknowledgement

AcknowledgementThis is part of the author's post-graduate thesis work at Sam Higginbottom University of Agriculture Technology and Sciences, Department of Genetics and Plant Breeding, Field Experimental Centre. The author is highly grateful for the research services provided by Dr. Prashant Kumar Rai, Assistant Director of Seed Farm, Sam Higginbottom University of Agriculture Technology and Sciences, Prayagraj, Uttar Pradesh.

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