Identifying rice grains with premium nutritional quality among on-farm germplasm in the highlands of Northern Thailand

Local rice varieties with premium nutritional quality grains are beneficial to consumers, and their genetic traits may be deployed in breeding programmes for many purposes. This study explores grain quality characteristics with health implications of rice germplasm maintained and used by farmers in the highlands of Northern Thailand. Concentrations of iron (Fe), zinc (Zn), phenols and anthocyanin and anti-oxidative capacity were determined in the caryopsis without husk of 77 samples of rice seed collected from farmers. Entries with the highest grain quality characteristics identified were grown together with four standard check varieties at two different elevations in a farmer’s field at Mae Wang District of Chiang Mai province (800 m above mean sea level), as well as in pots at Chiang Mai University (CMU) (330 m above mean sea level). The grain quality characteristics were determined at maturity, separately for 10 individual plants grown at CMU. A wide variation in all the grain quality characteristics was found among samples grown in the farmer’s field. There were approximately twofold differences in the lowest and highest Fe and Zn concentrations, especially high variation in contents of phenols and anthocyanin and anti-oxidative capacity found in grain with purple pericarp. The top entries identified from the farmer’s seed had significantly higher anthocyanin concentration and anti-oxidative capacity than the check varieties when grown together at Mae Wang and CMU, in spite of the strong locality-specific effects on these characteristics. Further variation was found in the grain quality characteristics within each of the selected farmer’s seed samples. Quality improvement could thus be made by either eliminating the poorest performing lines or development of single-seed descent lines from the top-performing plants. The desirable genetic traits can also be used in breeding programme for improvement of grain yield as well as cooking and nutritional quality.