Abstract
Background and objectiveInvestigation on genetic variability and correlation study between yield and its components of genotypes on rice may increase the opportunity to exploit its potential which will help meet the demand of high grain yield and nutrition supply. The current study aimed to determine correlation and path coefficients between twenty-two Egyptian and exotic rice genotypes to establish selection criteria which might help to develop genotypes for high yielding.Materials and methodsTwenty-two Egyptian and exotic rice genotypes were evaluated through seven agronomic traits. Agronomic data were collected during the two successive rice growing seasons, 2017 and 2018. The matrix of phenotypic correlations was estimated and analyzed into direct and indirect effects through path coefficient analysis.ResultsResults showed that grain yield per plant had a high positive and significant correlation (p ≤ 0.01) with panicle number per plant, full grain number per panicle, and 1000 grain weight, 0.791**, 0.670**, and0.766**, respectively. As expected, there was a negative correlation (p ≤ 0.05) between days to heading and panicle number per plant (r = – 0.496*) and with1000 grain weight (r = – 0.433*). Path coefficient analysis showed that despite high positive and significant correlation (p ≤ 0.01) between grain yield per plant and many variables, a small number of these correlations was verified to have a relationship of cause and effect. Variables with positive and significant correlation and with a high direct effect on grain yield per plant were 1000 grain weight (0.5107 direct effects) followed by panicle number per plant (0.4003), and full grain number per panicle (0.3028).ConclusionThe three traits (1000 grain weight, panicle number per plant, and full grain number per panicle) are the most important variables for use in grain yield per plant assessment programs as selection indices because they have positive and significant correlations and direct and/or indirect effect on the correlation value of the increased rice grain yield production. Hence, for increasing grain yield, the direct selection of genotypes based on positively correlated traits will be more fruitful while planning any rice breeding program to achieve higher grain yield in rice.
Highlights
Rice (Oryza sativa L.) is an important staple food worldwide
Our results suggest that full-grain number and panicle number per plant and with 1000 grain weight are important yield-related traits and could be considered as selection criteria to increase rice grain yield
The correlation among traits under study indicated that the short period to heading will provide more time to increase the number of panicle per plant and 1000 grain weight, and full-grain number per panicle will be improved by increasing of panicle length or panicle number per plant, as well as any increase in panicle number per plant will cause an increase in 1000 grain weight which leads to improvement of the final grain yield which was correlated positively to yield traits
Summary
Rice (Oryza sativa L.) is an important staple food worldwide. About half of the world’s population depends on rice for their survival. Considering the growing population, the primary goal of plant breeders will always be towards improving grain yield in the strategic food crops. Plant breeders used agricultural path analysis to help identify useful features as selection criteria for improving crop yields (Milligan et al, 1990). The objective of this study was to (i) discover association among different agronomic traits in Egyptian and exotic rice genotypes for developing new cultivars, (ii) assess the direct and indirect effects of some agronomic traits on grain yield of rice, (iii) define selection criteria for grain yield improvement, and (iv) save time and resources during selection processes. The current study aimed to determine correlation and path coefficients between twenty-two Egyptian and exotic rice genotypes to establish selection criteria which might help to develop genotypes for high yielding
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