Comparison of different methods for phenotyping preharvest sprouting in white-grained wheat

The objective of this study was to identify a suitable method for phenotyping preharvest sprouting (PHS) resistance in white bread wheat. Forty doubled-haploid (DH) lines derived from a cross between two whitegrained spring wheats (Triticum aestivum L.) cultivar Argent (nondormant) and wheat breeding line W98616 (dormant) were evaluated for germination frequency, Falling Number (FN), and alpha-amylase activity in dry and water-imbibed seeds and spikes. The alpha-amylase activity in dry seeds or spikes did not differ significantly between parent lines or lines of the DH population. Wetting of seeds or spikes for two days caused a fiveto sevenfold increase in cc-amylase activity but only in Argent and the nondormant subgroup (49-100% germination) of the DH lines. A positive association (r = 0.60***) was detected between germination frequency and alpha-amylase activity in imbibed seeds and spikes. Germination frequency could not be correlated to FN or alpha-amylase activity in dry-harvested seeds. FN showed a strong correlation (r = -0.83***) to alpha-amylase activity in the dry-harvested seeds but could not be correlated to alpha-amylase activity in the imbibed seeds. The germination test was the most reliable method for measuring PHS resistance because seed dormancy provides potential resistance to PHS, whereas high a-amylase activity may occur in grains without causing PHS.