Abstract

Sangyod Phatthalung rice is a local rice that possesses high nutritional value and has a potential to be developed to be an economic rice variety for southern region production. However, previous research found that Sangyod Phatthalung rice has a dormancy period around 8 - 10 weeks. This could affect the utilization of this variety in breeding program as well as in commercial production. So, the aim of this experiment was to study the method of breaking seed dormancy of Sangyod Phatthalung rice. There were 7 treatments; 1) control (no dormancy breaking), 2) using scarifier by passing the seed through scarifier 3 times, 3) using scarifier by passing the seed through scarifier 5 times, 4) drying in a hot-air oven at 50°C for 3 days, 5) drying at 50°C for 5 days, 6) drying at 50°C for 7 days, and 7) soaking in 1M nitric acid for 24 hours. Another experiment was conducted to determine the effect of storage relative humidity (RH) on the release of seed dormancy. The newly harvested seeds were stored in hematic jars controlling relative humidity at 30, 60, and 90% at 25°C for 12 weeks. Seed dormancy and germination were recorded at 2-month intervals. The results showed that the 6 methods used in this study could not satisfactorily overcome seed dormancy of Sangyod Phatthalung rice. Drying at 50°C for 7 days gave 16% seed germination higher than other treatments. For the release of seed dormancy under different storage relative humidity, it was found that the seed stored at 30%RH 25°C had after-ripening period for 8 weeks whereby the germination percentage was higher than 80%. Seed stored at 60 and 90%RH showed the after-ripening period around 10 and 12 weeks, respectively.