Abstract
Pre-harvest sprouting (PHS) in wheat causes devastating damage to the quality of wheat flour owing to the degradation of seed starch during germination. In this study, we investigated whether nuclear magnetic resonance (NMR) relaxation times (T_1, T_2) could be used to characterize PHS in wheat (Triticum aestivum L.) cultivars, 'Shirogane-Komugi' (sprouting susceptible), 'Norin61' (sprouting resistant) and 'Chikugoizumu'(intermediate type). The PHS rate of 'Shirogane-Komugi' markedly increased to about 65% at 28 DAP while PHS rate of 'Norin61' was almost zero at the stage. The water contents in the wheat seeds of the three cultivars were not significantly different during ripening stages. T_2 values of long fraction in 'Shirogane-Komugi' were about 130 ms and those of 'Chikugoizumi' indicated around 75 ms at 28 DAP. On the other hand, those of 'Norin61' decreased and was about 60 ms at 28 DAP. T_2 values of long fraction of all of the three cultivars markedly decreased to less than 1 ms at 42 DAP. These results suggested that free water in 'Shirogane-Komugi', 'Chikugoizumi' and 'Norin61' seeds was maintained until 28, 21 and 14 DAP, respectively. The PHS sensitive cultivar, 'Shirogane-Komugi' kept free water 14 days longer than the resistant one. Therefore, NMR relaxation time, especially, T_2 is effective for early screening of pre-harvest sprouting characteristics.
