Study of Combining Ability And Heterosis of Rice (Oryza Sativa L.) in Rainfed Ecosystem
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Date
2003
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Birsa Agricultural University, Ranchi
Abstract
Enhanced rice production during the past two decades is the result of development of semi-dwarf, high yielding and photoperiod-insensitive varieties Now it is a matter of concern that the yield level of high yielding dwarf varieties of rice is getting plateaued in the areas of assured irrigation, which account for more than 75% of rice production. This warrants search for and adoption of innovative breeding approaches to further raise the ceiling of genetic yield to elevate the yield potential of semi-dwarf varieties, exploitation of hybrid vigour has been considered to be the most potent approach
Combining ability studies are useful in classifying parental lines in terms of their hybrid performance. Among different methods adopted the line x tester analysis has been recommended for early evaluation of parents, because of its simplicity in both experimentation and analysis (Dhillon, 1975). Such studies in rice are useful in assessing the heterotic ability of parents and thus aid in selecting parents which when crossed would give to more desirable segregates for increased yielding ability.
Thus, using this model present investigation was carried out with 15 lines x 3 testers. The total of 45 crosses were made during kharif 2001 and the crossed seed were again grown in kharif 2002. The data were recorded for 15 quantitative characters, which was further utilized in analyzing various genetic parameters.
The analysis of variance revealed highly significant differences among the genotypes for almost all the characters except grain yield per panicle. This indicates the inherent genetic variability among all the genotypes (parents as well as crosses) for all the characters.
High estimates of heritability (broad sense) along with moderate genetic advance for the characters days of panicle emergence, days to maturity, plant height, number of grains per panicle, 1000 grain weight, grain yield per plant and harvest index were observed. The similar results were also observed by Singh and Choudhary (1996), Most of the crosses showed positive heterosis over mid-parent and better parent for grain yield per panicle, 1000 grain weight.