Characterization of Grain Quality Traits of Thai Highland Glutinous Rice Landraces

Glutinous rice is popularly consumed as a staple food, processed for the snack industry, and fermented for alcoholic beverages by people in the North and Northeast of Thailand. Cooking quality traits are an important factor used to select for consumption and utilization by farmers. The target outputs of future rice breeding programs should focus on developing rice varieties with superior grain quality, particularly in relation to their utilization. Therefore, this research aims to assess the morphological characteristics and cooking quality of four populations of Thai highland glutinous rice landraces: Pa Ai Khupe (PAKP4 and PAKP5) and Khao Hao (KH2 and KH5), comparing them to two elite varieties (RD4 and RD6). Additionally, it examines the partial nucleotide sequence of genes involved in amylopectin branch length, specifically SSII3, ISA3, and PUL3. The study illustrates that the four populations of glutinous rice landraces exhibit morphological variations between and within populations in plant type, and panicle exsertion. Variations in alkali spreading value, gel consistency, gelatinization temperature, amylose content, and seed elongation ratio were observed among and within the glutinous rice populations. PAKP5 and KH5 were classified as hard rice, similar to RD4. KH2 was classified as medium-hard texture after cooking, while PAKP4 was classified as soft rice after cooking, similar to RD6. The partial target sequences of the selected genes showed a similar nucleotide sequence among glutinous rice landraces. Therefore, further studies should focus on more nucleotide sequences of the selected genes and additional genes, as implications for marker-assisted selection in glutinous rice breeding programs. This study provides information to assist in breeding strategies for grain quality in Thai glutinous rice breeding programs.