Detection of pre-harvest sprouting in rice seeds by using¹H-NMR

Pre-harvest sprouting (PHS) is a serious source of costly yield and grade losses for producers. Unreleased test lines of cereals should be screened for resistance to PHS. However, screening large numbers of test lines is relatively time-consuming or expensive. In this study, nuclear magnetic resonance (NMR) was used to characterize PHS as a nondestructive method. The water content in the rice grains of 'TC65' and 'Notched' gradually decreased until 21 days after pollination (DAP). After 21 DAP, the water content in both lines remained constant. In PHS at this time, none of the 'TC65' seeds germinated while 15% of the 'Notched' seeds had germinated. At 14 DAP when PHS was not confirmed, NMR spin-spin relaxation time (T₂) in 'TC65' and 'Notched' seeds were about 40 ms and 20 ms, respectively. These results indicated that the T ₂ is effective to screen resistance to PHS at early stage. In addition, T₂s in germinating seeds linearly increased to 165 ms as germination advanced during 10-day treatment period. On the contrary, T ₂s in nongerminating seeds were about 20 ms and they remained constant during the treatment period. Thus, ¹H-NMR relaxation times were measured as a way to screen both resistance to PHS and germination process.