Assessment of Genetic Diversity in 62 Maize Genotypes for Yield and Yield Accredited Traits

Author: Anusha G.*, Bhadru D., Vanisri S., Usha Rani G., Mallaiah B. and Sridhar V.

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Abstract

Genetic diversity is an essential element for the development of new inbred lines of maize because it has pivotal importance for hybrid combinations in maize breeding. The present experiment was carried out to determine the genetic diversity of 62 maize genotypes by using D2 cluster analysis. Analysis of variance revealed the existence of significant variability among the genotypes. The sixty-two maize genotypes were grouped into five clusters i.e., I, II, III which comprised 28, 23, and 9 genotypes respectively. Whereas cluster IV and cluster V are solitary clusters. Cluster I (312.76) exhibited the highest intra-cluster distance. The highest inter-cluster distance of 9470.22 was found between cluster III (MGC-13, GP-111, MGC-68, GP-215, PFSR-151, BML-13, MGC-39, MGC-90 and MGC-109) and cluster V (BML-30F). The genotypes included in clusters III and V exhibited high genetic diversity along with high per se performance, suggesting the utilization of these genotypes for future maize improvement programs.

Keywords

Maize, Genetic diversity, Variability, Cluster analysis

Conclusion

The results revealed the existence of highly significant differences among maize for grain yield and yield-related traits and 62 maize genotypes were classified into five groups based on the torcher method. The development of hybrids between identified divergent clusters III and V could yield heterotic hybrids. The genotype BML-30F was identified as high yielding and divergent genotype based on cluster analysis and per se performance.

References

INTRODUCTION Maize (Zea mays L.) is the third most important cereal crop after wheat and rice in the world, contributing to food security and income in tropical and sub-tropical environments. It is a versatile crop grown over a range of agro-climatic zones due to its wider adaptability. Globally Maize occupies an area of 193.7 million hectares with a production of 1147.7 million tonnes and productivity of 5.75 tonnes per hectare (FAO STAT 2020). In India maize is cultivated in an area of 9.89million hectares with a production of 31.65 million tonnes and productivity of 31.99quintals per hectare (INDIA STAT, 2020-2021). The demand for maize global production as a source of food, forage, oil, and biofuel is increasing for the ever-increasing world human population. However, the number of maize landraces decreases in farmers’ fields over time, threatening the availability of genetic resources for the future. The assessment of diversity among the maize germplasm is important for identifying parental lines for successful breeding programs and hybrid development (Mengistu, 2021; Soliman et al., 2021). Genetic diversity may arise due to geographical separation or genetical barriers to crossability or due to different patterns of evolution. Thus, the study of diversity in inbreds of different origins may either complement or highlight new features of variation in the maize breeding program. The significance of genetically diverse genotypes as a source of obtaining transgressive segregants with desirable combinations has been reported by several researchers (Singh and Narayanan 2013; Hassan et al., 2018). As a cross-pollinated crop, maize has maintained heterozygous balance under open population and exhibits heterosis in recombinants, particularly when inbreds differing for many genes affecting yield or some other characters of importance are used as parents. Inbred lines derived from the diverse genetic base were found to be more productive than crosses of inbred lines derived from closely related stocks (Moll et al., 1965; Vasal, 1998; Uday Kumar et al., 2013). To develop high-yielding hybrids in maize, inbred lines need to be evaluated for their genetic diversity which is important for planning an effective hybrid breeding program as genetically diverse parents are known to produce high heterotic effects (Matin et al., 2017). Further, the study of genetic divergence in the maize inbreds will help to ascertain the real potential value of the genotype. Characterization of morphological variability allows the breeder to identify accessions with desirable characters and avoid duplication of accessions in available germplasm collection and their utilization in varietal improvement programs. Various biometrical techniques dealing with the genetic analysis of important characteristics guided the plant breeders in identifying the best genotypes for diverse environments. The estimation of genetic diversity through biometrical procedures such as Mahalanobis’s D2 statistics has made it possible to select genetically diverse parents for a breeding program. It also measures the degree of divergence and determines the relative proportion of each of the component characters to the total divergence. Therefore, in view of the above context, the present investigation was undertaken to assess the extent of genetic diversity in 62 maize inbred lines which will help to select prospective parents to develop superior hybrids MATERIAL AND METHODS The present research work was undertaken at Maize Research Center (MRC), Rajendranagar, Hyderabad (27.2046°N, 77.4977°E) during Rabi, 2020-2021. A total of 62 maize genotypes (Table 1) were evaluated for yield and yield traits in a Randomized Block Design with two replications. Each entry was sown in two rows of 4min length and followed a spacing of 0.6m × 0.2m between row to row and plant to plant respectively. The standard agronomic management practices and plant protection measures were followed throughout the crop growing period to maintain proper plant stand. The observations for various characteristics like days to maturity, plant height (cm), ear height (cm), ear length (cm), ear girth (cm), kernel rows per ear, number of kernels per row, and 100-seed weight (g) were recorded on five randomly selected plants from each plot. Whereas, the characters i.e., days to 50 percent tasseling, days to 50 percent silking, and grain yield per plant were recorded on a plot basis. Data were subjected to analysis of Mahalanobis’ D2-statistics (Mahalanobis, 1936), and intra-cluster and inter-cluster distance, cluster mean and contribution of each trait to the divergence were estimated as suggested by Singh and Chaudhary (1985). Clustering of genotypes was done by using Tocher’s method (Rao, 1952). The cluster distance was estimated by the formula given by Singh and Chaudhary (1977). RESULTS AND DISCUSSION Cluster analysis. The analysis of variance revealed significant differences among the 62 inbred lines for all the eleven characters, indicating the existence of sufficient genetic variability among the tested genotypes (Table 2). These findings are in accordance with those reported by Matin et al., (2017); Mounika et al. (2018). The sixty-two maize genotypes were grouped into 5 clusters based on various agro-morphological characters (Table 3 and Fig. 1). Cluster I comprised 28 genotypes, cluster II consisted of 23 genotypes, clusters III included 9 genotypes, and the remaining two clusters IV and V are the solitary clusters having only one inbred line indicating the uniqueness of the genotypes included in those clusters when compared to the other genotypes in the present study. Similar results pertaining to a grouping of maize germplasm were reported by Ivy et al. (2007); Talukder et al. (2012); Kumari et al. (2017). Average intra and inter-cluster distance. The highest intra-cluster distance was observed in cluster I (312.76) followed by cluster III (268.68) and cluster II (261.91). The intra-cluster distance was not observed in clusters IV and V as these clusters had only one genotype each (Table 4 and Fig. 2). These results are in accordance with the findings reported by Singh et al. (2005); Patil et al. (2017). The highest intra-cluster distance indicated the presence of significant genetic diversity between the genotypes which were grouped together in those clusters. Hence, there is a great possibility for the exchange of genes among genotypes within these clusters. With regard to inter-cluster distance, cluster III and cluster V were found to be most diverse with each other as the distance between them was9470.22, which denotes that the crossing between these genotypes would provide good segregation for selection. The lowest inter-cluster distance was observed between clusters IV and V (461.48) which indicates that the genotypes included in those clusters were not very distant, but could not be grouped together based on these traits. Cluster means showed a wide range of variation for 11 characters (Table 5). Cluster I exhibited the highest mean value for plant height and ear height, cluster II had the highest mean value for days to 50 percent silking and cluster III showed the highest mean value for days to 50 percent tasseling and days to maturity. Cluster IV had the highest mean value for ear length and the number of kernels rows per ear and cluster V showed the highest mean value for ear girth, the number of kernels per row, 100 seed weight, and grain yield (kg/ha). Cluster IV and V contained one genotype each, which exhibited the highest mean value for most of the yield-related traits. Thus these genotypes can be further used to improve the grain yield in future maize breeding programs. Most of the studies have reported that cluster analysis is found to be effective to classify the genotypes under different environmental conditions and helpful for the selection of superior parents for hybrid breeding programs (Al-Naggar et al., 2020; Bhatti et al., 2020 ; Khalid et al., 2020).

How to cite this article

Anusha G., Bhadru D., Vanisri S., Usha Rani G., Mallaiah B. and Sridhar V. (2022). Assessment of Genetic Diversity in 62 Maize Genotypes for Yield and Yield Accredited Traits. Biological Forum – An International Journal, 14(2a): 261-265.