Effect of storage temperature on storage efficacy, germination and physical characters of some paddy rice cultivars during different storage periods

Postharvest loss is a serious problem in rice, and the loss during storage period can account for the majority of the postharvest loss. Traditional methods of storing paddy rice are vulnerable to insect and fungal infestations, leading to a considerable deterioration in rice quality. Here we focus on low-temperature storage to improve the storage efficacy of rice. Laboratory experiments were conducted to appraise the effects of storage temperature (traditional, cold and freeze storage) and period (6, 12, 18 and 24 months) on the storage efficacy such as pest and fungal infestations, germination success and physical quality of rice grains, using 11 paddy rice cultivars. Insect and fungal infestations significantly increased whereas germination success and rice quality were reduced, with increasing storage periods. Traditional storage of rice grains resulted in the highest levels of insect and fungal infestations caused by rice weevil, Alternaria sp., Nigrospora oryzae and Fusarium spp., while germination success and rice quality were relatively low. In contrast, cold storage satisfactorily lowered insect and fungal infestations while maximizing 1000-grain weight, germination success, hulling, milling and head rice. Although freeze storage of rice grains minimized the infestation levels, the other efficacy indices were inferior to those of cold storage. The impacts of the storage temperature and period were complicated depending on rice cultivars, which suggested that a further improvement of efficacy was possible by choosing the best cultivar suitable for storage. It is concluded that the cold storage (5°C) can achieve the best storage efficacy to preserve the rice grains quality when storage period is up to 24 months.