Effect of gamma irradiation on the 2-acetyl-1-pyrroline content during growth of Thai black glutinous rice (Upland rice)

2-acetyl-1-pyrroline (2AP) is the characteristic compound for the fragrant rice. 2AP accumulation in rice can be affected by environmental factors such as salinity, drought stress and solar intensity. In this study, the accumulation of 2AP content during growth of Thai black glutinous rice (Upland rice) was investigated. Furthermore, we also investigated the effect of gamma irradiation on plant growth, grain weight and 2AP content of irradiated rice, compared to non-irradiated rice. The results revealed that 2AP was accumulated in shoots and roots of rice. The highest 2AP content in roots was found in seedling stage I and about 2-fold higher when compared with 2AP in shoots at the same stage. After seedling stage I, the 2AP content of roots decreased and was lower than 2AP content of shoots. The results indicated that 2AP content may be migrated from roots in seedling stage I into other part of rice after this stage. When rice grains were subjected to ¹³⁷Cs gamma irradiation, shoot length, 2AP content and grain weight of irradiated rice was investigated and compared with non-irradiated rice. Shoot length of irradiated rice was higher than non-irradiated rice at low gamma dose, while the high gamma dose inhibited the shoot length of irradiated rice. The trend of 2AP content in shoots and roots of irradiated rice in some gamma doses were higher than non-irradiated rice. Moreover, the 2AP content of shorter irradiated rice shoots seems to be higher than of longer-irradiated rice shoots. The gamma ray caused the reduction of grain weight in irradiated rice, while the 2AP content in grain of irradiated rice was higher than non-irradiated rice. This report suggests that the gamma irradiation technique cloud induce the growth of rice and improve the 2AP content in rice.