COMBINING ABILITY STUDIES ON YIELD AND YIELD COMPONENTS IN RICE GENOTYPES (Oryza sativa L.)

Abstract

Nigeria has a wide range of arable rice growing environments including the inland valleys. Despite being the largest rice producer in West Africa, Nigeria is still a rice deficit nation. One of the major constraints to rice production in the inland valleys of Nigeria is iron (Fe) toxicity. The understanding of the genetic basis of Fe tolerance mechanisms can provide useful information for the breeding of tolerant varieties. Based on the aforementioned, the research was conducted to study the general and specific combining ability for yield and its components and to estimate the gene action for seed yield and its components. Eight rice varieties were planted and crossed using incomplete diallel mating design to generate 28 hybrids which were evaluated along with the eight parents and two checks (Alhaji Baba and Ewodufagi) at Edozhigi during the 2017/2018 dry season. Data were collected on grain yield, days to 50% flowering, number of tillers, number of leaves, plant height, panicle length, number of seeds per panicle, panicle exertion, number of effective tillers, 1000 grain weight, first and second iron toxicity scores were subjected to diallel analysis of variance (ANOVA) for both parents and hybrids, using Statistical Analysis System (SAS) software package (2002). The results from the study are summarized as follows GCA and SCA mean squares were significant for most measured traits under iron toxicity hotspot, indicating importance of additive and non-additive gene action for controlling the traits. There was preponderance of additive gene effects over non-additive gene effects for all the traits measured indicating that additive gene action was more important in the inheritance of the traits under iron toxicity hotspot. FARO 52, SUAKOKO 8, CK-21 and CK-43 were good general combiners for grain yield under iron toxicity hot spot conditions.