Studies on awns in polyploid rice (Oryza sativa L.) and preliminary cross experiments of a special awnless tetraploid rice

Abstract

Awns are an important genetic character of rice (Oryza sativa L.) and almost all awnless diploid varieties will change into awned varieties after polyploidization. In order to increase the understanding of awns and promote the development of polyploid rice breeding, the effect of polyploidization on awns was investigated and the development and distribution characteristics have been summarized. Furthermore, cross experiments were made between a special awnless tetraploid rice and two awned tetraploid rice. The results showed that the awns of polyploid rice initially emerged at the pistil–stamina formation stage and there was a stable corresponding relationship between awn development and other organs or development characteristics. Polyploidization had a great effect on awns. Awn length was considerably affected when diploid rice was doubled to polyploid. However, the degree of change varied between varieties. The F1 hybrids between awnless and awned tetraploid rice in this research were all partial awn types and showed that the larger the mean, maximum awn length and the percentage of awned spikelets (PAS) of their awned parents, then the larger these of their F1 hybrids. But different cross combinations showed some variation. The F2 generations were still all partially awned and awnless type was not found. And the awn length and PAS of the plants developing from awned grains were significantly greater than that of the plants developing from awnless ones. This showed that the awn character of a grain could affect the plants developing from this grain. The results laid the foundation of further research of awn inheritance.