Selection of Advanced Lines for High Grain Anthocyanin Content and Photoperiod Insensitivity in F4 and F5 Generations Between Pi-ei-su 1 and Pathum Thani 1 Rice Varieties

Abstract

Pi-ei-su 1 (PES1) is a sticky purple rice variety, which was selected from an indigenous rice variety in the highland of northern Thailand with a black pericarp and high grain anthocyanin content. However, PES1 is a photoperiod sensitive and low yield variety. The growing season is limited to one a year. To improve these agronomic characters, PES1 was crossed to Pathum Thani 1 (PTT1), a modern variety with the photoperiod insensitivity trait and high yield. The objectives of this experiment were to evaluate and select advanced lines with a black pericarp, high anthocyanin content, and high grain yield in F₄ and F₅ generations. The initial trial was conducted during the off-season in experimental pots. All F₄ hybrid plants exhibited a black pericarp, flowering between 91-132 days. Fifteen plants that exhibited flowering closely to the PTT1 parent and higher yield than the PEZ1 parent were selected for evaluation of their characteristics in the F₅ generation. In the F₅ generation, fifteen plants were grown under field conditions. PES1 and PTT1 parents yielded at 11.5 and 41.0 g/plant, respectively, while fifteen hybrid lines yielded between parental boundaries. The hybrid lines flowered within 96 to 106 days, which was close to the PTT1 parent. Six advanced lines produced higher anthocyanin content and yield than the PES1 parent. The amylose content of non-glutinous advanced lines at 12.9% to 15.4%. These advanced lines will be used as a genetic material for further improvement of premium quality rice varieties.