Factors causing variable seed quality in rye and triticale

In seed production of rye kernels frequently do not meet the minimum requirements for germination under laboratory conditions due to mechanical seed deterioration, preharvest sprouting and heavy infection with snow mold. Some triticale lots contain too many foreign cereal grains because triticale often follows wheat in the rotation. Additionally, snow mold infection causes abnormal seedling development, but chemical seed dressing can increase seed germination. Swiss seed companies are obliged to maintain supplementary multiplication surfaces of both grain species to serve the demand of the market. As seed quality is unknown until harvest, expenses of transport, cleaning and seed testing arise. We examined germination under laboratory conditions as the proportion of normally developed seedlings in samples of the rye varieties Matador and Palazzo and of the triticale variety Cosinus. Samples were taken in the field before harvest, after threshing, after pre-cleaning and at the end of the cleaning process. Grain moisture content of the samples was measured. The results revealed that grains of rye with moisture contents at harvest below 14% as well as above 16% showed reduced germination due to mechanical seed deterioration. Low grain moisture contents were measured in 2011 when the whole vegetation period was dry.For grains of the triticale variety Cosinus, only untreated seeds of lots with severe snow mold infections did not meet the minimum germination rate of 80%. As elimination of wheat kernels in the cleaning process is not efficient, farmers have to avoid wheat as preceding crop and must clean the thresher thoroughly between uses.