Heterosis and gene action study of agronomic traits in diploid and autotetraploid rice

The quest of changing and improving the heredity of crop plants is a never ending process. An autotetraploid indica/japonica hybrid combines the advantages of polyploidy and heterosis between indica and japonica and seems to have stronger potential vigor in rice breeding than diploid rice does. In the present experiment it was revealed that traits like panicle length, number of grains per panicle, and grain length seemed to be predominantly influenced by an additive type of gene action, while remaining traits were found to be influenced by non-additive genetic effects. Diploid material represented greater negative genetic effects as compared with autotetraploid material except for grain length and seed-setting rate for which both types of plant material preformed equivalently. Genotypic environment interaction effects were also more pronounced in diploid rice hybrids as compared with their autotetraploid counterparts. Autotetraploid hybrids demonstrated highly significant heterosis over a better parent for most traits as compared with diploid hybrids. Autotetraploid plant materials studied here may be adaptable to various locations for yield trait. Also, the autotetraploid cross-combination Guanglu'ai 4×Jackson may be utilized in autotetraploid rice hybrid breeding owing to its better performance over that of others. The idea of better performance of polyploids over diploids might come to be true after consideration of research findings compiled in the present research.