Chinyere P. Anyanwu
Federal University of Technology, Nigeria
Chinyere P. Anyanwu has completed her PhD from the Department of Crop Science, University of Nigeria. She is a Senior Lecturer at the Department of Crop Science and Technology, Federal University of Technology, Owerri, Nigeria. She has more than 20 papers published in reputed journals and is a reviewer for many reputable journals. She has supervised more than 40 students’ research projects both at the graduate and undergraduate levels. She is currently working on the quality improvement of rice varieties grown and consumed in Nigeria.
Fifty – six hybrids seeds generated from an 8 x 8 Diallel reciprocal cross experiment during the 2007 growing season at the Teaching and Research Farm of the Federal University of Technology, Owerri, Nigeria were studied. Estimates of components of variance revealed higher variance due to general combining ability for grain length, grain width and grain length/ grain width ratio while variance due to specific combining ability was more important for inheritance of protein content in rice. Combining ability effects revealed that the parents CT 7127- 49 (0.0932) showed highest positive GCA effect for grain length while Fofifa 16 and IR57689-73 showed the highest and significant positive GCA effects of 0.1338 and 0.1233 for grain width. The cross of IR57689-73 x NERICA 1 (0.377) and IR5789-73 x Max (0.185) were the best specific combiners. Highest significant and positive GCA effects for grain length/ grain width ratio was recorded for WITA 4 (0.2169) making it the best general combiner while IR5789-73 and Fofifa 16 showed the highest significant negative GCA effects becoming poorest combiners. Fofifa 16 x NERICA 1 (0.433) showed highest positive and significant GCA effects followed by IR5789-73 x NERICA 1 (0.411), EMPASC 105 x NERICA 1(0.408), EMPASC 105 x Fofifa 16 (0.301) and WITA 4 x Max (0.274) indicating that these hybrids produced longer and finer grains than their parents. CT7127- 49 was the best general combiner for protein content. High and significant positive reciprocal effects were also observed indicating the role of maternal dosage in the inheritance of protein content in rice. The cross WITA 4 x NERICA 1 had positive SCA effect alongside with IR57689-73 x Fofifa 16, IR57689-73 x NERICA 1 and Fofifa 16 x NERICA 1 though both parents were poor combiners, indicating non-allelic interactions at the heterozygous loci. CT 7127-49 was the best general combiner for grain length and protein content. It could be utilized as a donor to breed for long grain varieties and for increasing protein content.
Keywords: General and specific combining ability, reciprocal effect, additive and dominance variance, maternal effect.