Bridging upland-irrigated rice (Oryza sativa L.) gene pools via anther culture

Conventional rice breeding has met with limited success in trying to combine gene pools of japonica and indica subspecies. Hybridization of these two subspecies often results in high levels of spikelet sterility in the F1. To avoid this problem anther culture was explored as a tool to incorporate desirable traits from upland (japonica sensu lato) to irrigated (indica) rice. Progenies of four upland x irrigated crosses were produced through both anther culture and single seed descent breeding methods. Field performances of progenies derived from these two methods were evaluated at two rice-growing locations, Bagua (Peru) and Palmira (Colombia). Comparisons were made between breeding methods, F1- and F2-derived doubled haploids, and for random and selected populations, in terms of means, variances, and proportion of favorable recombinant lines for eight traits. These traits included: spikelet sterility, days to maturity, leaf pubescence, number of grains per panicle, number of panicles per square meter, 1000-grain weight, plant height, and endosperm dispersion.;Single seed descent progenies had higher population means than doubled haploid progenies for leaf pubescence, 1000-grain weight, and plant height. Lower spikelet sterility was also observed in the populations resulting from the single seed descent method. No consistent differences between the two breeding methods were detected in terms of variances for the traits studied. Proportion of progenies with various combinations of desirable traits was higher in single seed descent populations. Doubled haploid progenies derived from the F1 had lower spikelet sterility and higher 1000-grain weight than those derived from the F2. Selection in the F2 prior to the production of doubled haploid lines was effective in increasing the proportion of lines for leaf pubescence and plant height as compared to random selection in the F2. However, lines derived from selected F2 plants did not have a higher proportion of desirable traits than those derived from the F1. These results suggest that the F1 is the generation of choice for deriving doubled haploid lines through anther culture in upland x irrigated rice crosses.