Performance of diverse rice genotypes based on seed-set in interspecific hybrid production: Implications for plant breeders
Biotechnology Research Development Centre, Ebonyi State University, P.M.B. 053, Abakaliki, Nigeria; African Centre for Crop Improvement, University of KwaZulu-Natal, Pietermaritzburg, South Africa
Interspecific hybridization is an important technique used in improving rice populations by combining desired traits from different species. However, this could be difficult due to barriers to interspecific hybridization. The objective of this study was to determine the performance of different rice species based on seed set in an interspecific hybridization program. Five Oryza glaberrima genotypes and four interspecific inbred lines were used as female (seed) parents and two improved O. sativa and two interspecific inbred lines (NERICA 2 and NERICA 3) as male (pollen) parents to generate 36 cross combinations representing the North Carolina Design II mating scheme. Four groups of crosses were made: group A (O. glaberrima O. sativa), group B (O. glaberrima Interspecific), group C (Interspecific O. sativa) and group D (Interspecific Interspecific). Groups A and B had seed-set levels of about 10%. Group D had the highest seed-set level, with a mean of 19%. The least seed-set was for group C (6% seed-set). Overall, the study indicated a serious challenge in making interspecific hybrids, because only 11% of 8031 pollinations were successful in setting seed, compared with 45% within O. glaberrima and 70% within O. sativa crosses under similar conditions. Higher sterility was observed in backcrosses involving the O. glaberrima cytoplasm as compared with single crosses. The backcrosses involving O. glaberrima cytoplasm were completely sterile with no seed-set except with the CG 14 cytoplasm.
Oryza; Oryza glaberrima; Oryza sativa