Genetic improving of North Sumatra upland red rice through mutation breeding

Local rice is still widely found and is an asset of genetic resources in the supply of adaptive high yielding varieties, so its development is still being pursued. One kind of upland rice in North Sumatra that is widely planted by the community is the upland red rice, in addition to having advantages both as a staple food and health functions for the body. They usually adapted well to a specific environment where they grow largely, having good aroma and eating quality, but they have some weakness such very long growth duration, susceptible to lodging, unresponsive to fertilizer, and low yield. This research was conducted from April 2016 until June 2017 aimed to improve the genetic of local red rice of North Sumatra (Sigambiri merah) especially related to plant age to be more early and dwarf/semi dwarf posture through mutation breeding (induced mutations). To obtain the optimum dosage, rice seeds were irradiated with gamma rays Co-60 doses of 0, 100, 200, 300, 400, 500, 600, 700, 800, 900, and 1000 Gy at the Center for Isotope and Radiation Application - National Nuclear Energy Agency (CIRA - BATAN), Jakarta. Planting of M1 and M2 was conducted at BPTP of North Sumatra. The observation of seedlings growth percentage, plant height and root length in the nursery phase, and percentage of grain void in M1 plants obtained irradiation doses of 200-300 Gy is an effective dose in produce genetic diversity. This is also seen in the population of M2 plants resulting from irradiation of 200 Gy resulted in an extensive number of chlorophyll mutations with 8 different types of mutations of 8 types, namely albina, xhanta, viridis, tigrina, spotting leaf, alboviridis, marginata, and striata. It also produces a wide genetic diversity in high plant character variables, number of productive tillers and harvest age. From the result of selection conducted on M2 population obtained mutant early maturity candidates as many as 69 candidates with mutation frequency of 1.09 %. The seedling plants and dwarf /semi dwarf posture will certainly be very useful as initial plant material in red rice varieties improvement in future plant breeding programs. (author)