Evaluation of variability, heritability and genetic advance in relation to seed yield and its attributing traits in rice (Oryza sativa L.)

Introduction

Rice (Oryza sativa L., 2n= 24), belongs to the family Poaceae (Graminae) is the most important food crop of the developing world. Rice is the staple food of more than half of the world's population. It is especially important crop of Asia, where more than 90% of world rice is grown and consumed, where more than half of world's people live. Rice is regarded as important cereal crop for its potential to provide food security to the increasing world population (Kaur et al., 2016) [5] . Among the rice growing countries in the world, India has the largest area under rice crop and ranks second in production next to China. The total global area under rice cultivation in 2020-21 is Area: 164.19 m ha, production is 756 mt and productivity: 32.89 q/ha and in India Area: 45.07 mha, production: 122.27 mt and productivity: 27.13 q/ha. In UP it is cultivated with an area of 5.68 million hectares with annual production of 15.52 million tonnes. It is widely grown in South-East Asia where largest population resides. Rice farming is about 10,000 year old and largest single use of land for producing food. Rice fields covers 11% of Earth's entire arable land. Two rice species are important cereals for human nutrition. The grain is a caryopsis in which the single seed is fused with the wall which is the pericarp of the ripened ovary forming the grain which is the seed. Rice is rich in nutrients and contains a number of vitamins and minerals. Genetic variability serves as the fundamental asset for plant breeders seeking to enhance plant performance. This variability within a population arises from genetic diversity, environmental influences, and the interaction between genetics and the environment. The presence of genetic variability in crop germplasm assists in efficiently selecting highyielding, well adapted crop plants which can be utilized either by directly introducing it as a new variety or by incorporating it as one of the parents in breeding programs aimed at developing improved crop varieties. An insight into the magnitude of genetic variability present in the gene pool of a crop species is of utmost importance to a plant breeder for starting a judicious plant-breeding program.

Materials and Methods

The materials were collected for the present investigation consisted of 58 diverse strains of Rice (Oryza sativa L., 2n=24) from the Department of Genetics and Plant Breeding, SVPUAT, Meerut and Pantnagar University. Randomized Block Design (RBD) with three replications were used to grown all the 58 genotypes. The length of the rows was kept 3.0 meter and spacing between R × R 30 cm and P × P 10 cm. five competitive plants were selected randomly from each entry in each replication and were tagged for recording detailed field observations later on the data on yield and its components were recorded on these randomly selected plants except days to 50% flowering and days to maturity which were recorded on the plot basis. The experimental data were subjected to statistical analysis as following standard statistical procedure described Panse and Sukhatme (1969) [7] to assess component of variance and coefficient of variation. Heritability -Allard (1960) [1] and genetic advance -Johnson et al. (1955) [4] .

Results and Discussion

The importance of variance was investigated using the analysis of variance across 58 distinct Oryza sativa germplasm. The data was displayed in Table 1. For all 10 traits studied, including days to 50% flowering, days to maturity, plant height, no. of productive tillers, panicle length, grain per panicle, 1000 seed weight, biological yield, harvest index and grain yield per plant the RBD analysis of variance revealed extremely significant differences between the materials used in this study. For these qualities, the phenotypic coefficient of variance was higher than the genotypic coefficient of variation Harvest index ((24.27%) and (25.58%), grain yield/plant (21.92%) and (19.80%), and grain per panicle (20.15%) and (17.20%) all had significant GCV and PCV. Nayak et al. (2016) [6] Moderate GCV and PCV observed in no. of productive tillers (18.00%) and (14.97%), biological yield (16.90%) and (15.17%), 1000 seed weight (12.01%) and (6.67%). These observations are in accordance with Chandra et al. (2009) [3] , Sravan et al. (2012) [13] , Shankar et al. (2016) [11] , PCV and GCV levels that are high and moderate suggest that these features can yet improve genotypes. It's worth noting that, for all of the qualities tested, PCV estimations were often not significantly higher than their corresponding GCV indicating that, in the manifestation of these traits, environment affect not much and additive gene effects, implying that genotypes can be improved and chosen for these characteristics The findings on heredity in general for seed yield and attributing factors found that heritability estimates ranged from 26.08% (panicle length) to 89.98% (harvest index). The character number of harvest index 89.98%) had the highest heritability in the broad sense, followed by grain yield/plant (81.58%), biological yield (80.56%). Moderate heritability in the broad sense is observed in days to 50% flowering (74.35%) followed by grain per panicle (72.85%) and plant height (72.85%) panicle length was estimated to have a low heritability in a wide sense (26.08%). It is in confirmation with the results of earlier workers Prasad et al. (2011) [8] , Babu et al. (2012) [2] , Nayak et al. (2016) [6] , Reddy et al. (2013) [9] . The genetic advance was arbitrarily divided into three categories: high GA (more than 20%), moderate GA (10-20%), and low GA (less than 10%). (below 10 percent). harvest index (47.42%), grain yield/plant (36.84%),grain per panicle (30.24%), biological yield (28.04%), no. of productive tiller (25.65%) all had high expected GA (>20%) days to 50% flowering (17.22%) followed by plant hieght (10.19%) and days to maturity (10.19%) had a moderate GA (10-20%), although 1000 seed weight (7.63%) and panicle length (3.74%) estimation had a low GA in percent age of mean (10). For harvest index, grain yield/plant, biological yield there was a high heritability combined with a high GA. As a result, for future enhancement of Oryza sativa genotypes, direct selection of germplasm can be done using these features. Prasad et al. (2011) [8] Sharma et al. (2013) [12] have all reported similar findings.

Conclusion

Variance analysis demonstrated that the current set of breeding material had considerable genetic variance, and research into genetic factors using these genotypes worth valuable results. The current research into variability, heritability, and genetic advance suggested that to improve the grain yield per plant these traits could be used directly.

References

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