Susceptibility to Preharvest Sprouting of Chilean and Australian Elite Cultivars of Common Wheat

One of the main factors that negatively affect common wheat (Triticum aestivum L.) grain quality is preharvest sprouting (PHS). In some regions of Chile and Australia, PHS can result in economic losses from lower yields and flour quality as a consequence of grains exposed to rain prior to harvest. Twenty-three Chilean common wheat cultivars were characterized in two locations (central and southern Chile) using the falling number (FN) method, standard germination test, and visual sprouting for PHS screening in two experimental seasons (2013-2014 and 2014-2015). Similarly, 20 Australian wheat cultivars were compared in six seasons using germination index (GI) at harvest ripeness. In the Chilean study, there were high positive (GI and sprouting score [SS]) and negative (FNwet samples and SS) correlations between the PHS tests, suggesting that they are appropriate tools to differentiate the PHS response among the common wheat genotypes studied. There was a strong phenological stage and genotypic effect on PHS variation, and while most cultivars showed intermediate or susceptible PHS phenotype, 'Konde', 'Kumpa', and 'Swindy' exhibited PHS resistance. Likewise, the germination index of Australian cultivars ranged from high to intermediate. The effect of temperature on PHS susceptibility was investigated by comparing varieties in open field conditions and under polyethylene covers in Chile or by using different times of sowing in Australia. In both experiments, a positive correlation between temperature and susceptibility to PHS was observed, which was more pronounced in cultivars with intermediate PHS resistance.