Abstract:
Rice (Oryza sativa L.) is the dietary staple food in Sri Lanka and the major livelihood of farmers since
ancient times. After harvesting rice, storage is done as a postharvest operation to prolong the shelf life and commercial value. Gelatinization temperature and amylose content are the most important
physicochemical properties that influence the cooking and eating characteristics of rice. Knowing
those properties is important in the processing, handling, and storage of rice. This study was carried
out to evaluate the several physicochemical properties of rice grains of selected improved and
traditional rice varieties harvested in three seasons (2021 Yala, 2021/22 Maha, and 2022 Yala).
Twelve rice varieties, including traditional (Pachchaperumal, Herathbanda, Madathawalu,
Suduheenati) and improved (Bg 352, Bg 360, Bg 366, Bg 374, Bg 450, At 362, At 311, Ld 253) were
cultivated and harvested at the Rice Research and Development Institute, Bathalagoda, Sri Lanka.
The gelatinization temperature was determined based on the alkali spreading score, and the amylose
content was determined according to the iodine binding procedure. All the tested parameters had
significant (p<0.05) variations among rice varieties within and among seasons. The most rice
varieties harvested in all three seasons, except for suduheenati in 2021 Yala and 2021/22 Maha
showed an intermediate gelatinization temperature (70–74 ℃). At 362, rice variety in all three
seasons showed low gelatinization temperature of 55-69 ℃. No variety was found with a high
gelatinization temperature (>74 ℃). High amylose content was observed in most varieties except for
At 311 in the 2021/22 Maha and 2022 Yala seasons. The traditional rice variety Herathbanda
showed high amylose content within the 31-35% range for three seasons. Grain elongation varied
significantly (p<0.05) in the 2021/22 Maha season, and there was no significant (p>0.05) difference
between the 2021 and 2022 Yala seasons. Bg 450 rice variety showed a higher grain elongation ratio
(71.25%) in the 2021/22 Maha season compared to the 2021 Yala and 2022 Yala seasons. The lowest
grain elongation ratio was observed in Bg 374 in 2021 Yala and 2021/22 Maha (31.27% and 30.54%
respectively). Herathbanda showed a lower grain elongation ratio (21.79%) in 2022 Yala. The
resulting information can be utilized in planning postharvest practices and selecting suitable rice
varieties for commercial cultivation in Sri Lanka
