Early detection of non-visible sprouting in barley seed using rapid viscosity analysis

Export of grain for malting markets requires viable seed that can withstand storage and shipping conditions. Malting barley is selected for rapid germination. However, barley from the Canadian prairies has minimal dormancy, leading to high risk of sprouting. The goal of this study was to assess the suitability of rapid viscosity analysis (RVA) to detect early non-visible sprouting. Cultivars Harrington (for North America), Alexis (Europe) and CDC Dolly (Western Canada feed barley with low alpha-amylase enzyme activity) were greenhouse grown in Saskatoon, Saskatchewan, and treated in a growth chamber at 12 combinations of t emperature (5 to 22°C) and relative humidity (RH; 60 to 95%) for 1 to 9 d at each of two growth stages, physiological or harvest maturity. Harvested seed from treated plants was measured by RVA, alpha-amylase activity, and germination tests. High RVA final viscosity values (> 150) indicated zero sprouting; RVA < 100 and alpha-amylase values > 125 nmol CU h-1 were associated with sprouting. Alexis sprouted more readily than Harrington and CDC Dolly. More than 3 d at 7.5 to 10°C and > 70% RH induced sprouting at harvest maturity. Future research is needed to further refine the RVA cut-off value on a cultivar basis for identifying problem seed. However, in the meantime, these findings can be used by breeding programs to screen genotypes for improved dormancy and by industry to detect barley viability problems prior to storage or transit.