I identifying new sources of variation in wheat germplasm for grain traits and Pre-Harvest Sprouting Tolerance.

Abstract

Abstract Pre-harvest sprouting (PHS) in cereal crops is associated with an anticipated loss of seed dormancy in the mature seed. PHS susceptibility depends on genotype and environmental (moisture, temperature) conditions. At present, many commercial elite wheat genotypes are prone to PHS and it has become a serious issue for food security. In cereal-growing areas of word, pre-harvest sprouting is a main limitation to the production of high-quality grains resulting in huge economic losses. Hence, pre-harvest sprouting resistant genotypes are necessary to avoid losses in wheat yield and quality. Therefore, this field study was conducted at EMBRAPA Passo Fundo, Brazil to find wheat cultivars more resistant to preharvest sprouting, in six Brazilian wheat cultivars in four replicates and to establish the best sampling time and germination assay temperature to screen for germination index indicative of PHS resistance in wheat cultivars. In each plot spikes were sampled at 25d, 32d, 38d and 45d post anthesis and a germination assay carried out at two temperatures, 10oC and 25oC. Results for germination index showed that among all cultivars BRS Parrudo and BR 18 were highly susceptible to PHS, while BRS 179, Quartzo and BRS 177 show intermediate resistance to PHS and Frontana was most resistant to pre-harvest sprouting. It was also observed that at 10oC wheat cultivars were less dormant and more susceptible to PHS while, at 25oC wheat cultivars were more dormant and less susceptible to PHS. It was also observed that germination index percentage was increased gradually when delaying sampling time from 25 d to 38 d post anthesis. The cultivar range in GI at 38 DPA was much narrower at 10oC (55.8-69.8%) than at 25oC (29.3-64.5%) (Where dormancy expresses) indicating that the more sensitive screen for distinguishing between the cultivars for GI and resistance to pre-harvest sprouting was at 25oC. Therefore, it is recommended that PHS resistant cultivar Frontana should be grown for preventing preharvest sprouting. Under low temperature, repeated rain and high humidity conditions the prompt crop harvest is generally recommend to avoid any risk of preharvest sprouting.