Relationships between yield and quality parameters of malting barley (Hordeum vulgare L.) and phenological and meteorological data

In this study, phenological and meteorological data have been used to interpret variations in a time series of regional average yields and quality parameters of malting barley (Hordeum vulgare L ). The analyses were focused mainly on the grain filling period. Duration and occurrence of this development stage showed remarkable differences from year to year, as heading varied over more than four weeks and yellow ripeness over two weeks in the investigation period from 1974 to 1996. Yields above average were achieved only in years when grain filling duration exceeded 42 d. Protein concentrations below 10.5 % and grading percentages over 90 % required at least 44 d of grain filling. Temperature had the strongest influence on the length of grain filling, even though the calculated Growing Degree Days (base temperature 3 degreesC) were not absolutely constant. Mean daily temperature and relative air humidity were the best estimators with respect to grain yield. An optimum temperature range was found between 14 and 18 degreesC. Assuming a linear relationship, yield reductions between 4.1 and 5.7 % have been calculated for every 1 degreesC increase of the mean daily temperature. Relative air humidity was the best single estimator for grain protein concentration. The results of this study suggest that relative humidity during grain filling can be a more suitable parameter to describe drought stress effects than precipitation amounts from heading to yellow ripeness or from January 1 to yellow ripeness.