Abstract:

Ef-cd gene is a dominant earliness gene located on the short arm of rice chromosome 3. In order to promote application of Ef-cd gene in rice improvement, we studied the photosensitivity and effect of Ef-cd gene on main agronomic traits by using near isogenic lines harboring the gene and their recurrent receptor parents Minghui 63 (MH63), Shuhui 881 (SH881) and Shuhui 527 (SH527). At the same time, application potential of Ef-cd gene in developing early-maturing hybrid rice was evaluated through analysis of main agronomic traits and yield of F₁ combinations from the cross between the near isogenic lines of Ef-cd gene and CMS lines. The results showed that there was no significant difference of reduction of dates to heading in the same early-maturing lines between long-day and short-day conditions. Under natural long-day condition, there were significant differences in dates to heading and plant height between the early-maturing lines and their receptor parents, with 13–21 d earlier and 2.4–10.9 cm shorter in the early-maturing lines than in their receptor parents, respectively. However, there were no significant differences in panicles per plant, spike length, grain number per panicle, seed setting rate, and 1000-grain weight between the early-maturing lines and their receptor parents. It is assumd that Ef-cd gene is a photoperiod-insensitive dominant earliness gene and can significantly accelerate heading, markedly reduce plant height, but does not have significant effects on panicles per plant, spike length, grain number per panicle, seed setting rate, and 1000-grain weight of rice. Days to heading of the hybrid combinations of early-maturing line E527-5-5 with CMS lines G46A, G201A, and G203A were 13–17 d earlier than those of its receptor parent SH527 with the same CMS lines, however, yield of the early-maturing hybrid combinations was 5.8%–7.1% higher as compared with the control cultivar Shanyou 77 with the same mature period. It is also suggested that Ef-cd gene can advance late-maturing hybrid rice to head significantly earlier, and increase the yield of early-maturing hybrid rice with Ef-cd gene. Therefore, Ef-cd gene may have promising application potential in developing early-maturing and high-yielding hybrid rice.

Key words: Rice, Earliness, Near isogenic line, Gene effect