Rapid generation advance technique in the study of photoperiod sensitivity inheritance of early maturity genotype ULR368 and RD6 rice varieties for out season evaluation

Abstract

Several studies of genetic inheritance of the photoperiod sensitivity trait in rice had been investigated. The evaluation of photoperiod sensitivity in rice was necessary to assessed in the normal growing season (wet season) due to off-season evaluation (dry season) was discrepancies, especially in the inheritance genetic studies. The evaluation was done once time per year. Therefore, the objectives of this study were to evaluate the inheritance of photoperiod sensitivity in indigenous rice ULR368, insensitive and early maturity, and the cultivated medium-sensitive variety RD6 using rapid generation advance (RGA) technique that it controlled under short daylength and to evaluated the possibility of RGA technique in photoperiod-sensitivity inheritance evaluation and variety selection in breeding program. The day to flowering in F₁ generation and the ratio of F₂ population were evaluated using RGA techniques with less than 10 hours daylength/day. The result found that RGA technique was suitable for photoperiod sensitivity inheritance study between ULR368 and RD6 populations. The results were able to clearly identify photoperiod and non-photoperiod genotypes. In F₂ population, they were evaluated during January to April that dry season (long daylength) using RGA technique and found that 191 plants were sensitive to photoperiod, and 177 were insensitive to photoperiod with the ratio of 9:7. The result indicated that photoperiod sensitivity was controlled by two dominant complementary genes with epistasis interaction. In addition, 150 plants were identified as insensitive to photoperiod and early maturity genotypes. So, the RGA technique could be used to assess gene expression for the photosensitive in dry season or off-season and can be separated the early maturity and medium-photoperiod sensitive genotypes. This technique can be used as a tool to shorten the assessment time in photoperiod sensitivity trait in rice breeding program.