CHARACTERIZATION OF BARLEY SILAGE - MATURITY RELATIONSHIPS FOR CENTRAL ALBERTA

Production of high-quality whole-plant barley (Hordeum vulgare L.) silage requires an understanding of the relationships among whole-plant percent dry matter (WPDM), whole-plant yield parameters reflecting both whole plant and kernel maturity, grain-to-straw ratio (harvest index) and in vitro digestible organic matter (IVDOM) over the grain-filling period. Eight six-row, standard-type barley cultivars, representative of the range of maturity and stature of cultivars recommended for grain production in Alberta, were grown at Lacombe. Alberta during 1983 and 1984. Seven weekly whole-plant harvests were carried out on each cultivar beginning at heading. Fresh and dry weights on whole-plant and kernel fractions at each harvest allowed calculation of the essential parameters. Regression analyses were used to determine whether several production-related response variables could be predicted from variables such as WPDM, days after heading and cumulative growing degree days (DD) greater than 5-degrees-C after heading. All cultivars exhibited similar trends with DD after heading for these relationships over two years of very different climatic conditions. IVDOM did not vary (P > 0.05) during the growing seasons indicating that IVDOM content cannot be a criterion for determining harvest date. Other relationships indicated that if whole-plant harvest occurred at 30% WPDM it would precede the time of maximum whole-plant yield and grain maturity by 160 and 208 DD, respectively, resulting in a loss in potential whole-plant yield of about 17%. Cultivars which produce more herbage but are too late maturing for grain production could be used to offset this yield loss and there may be a place in barley breeding programs for late-maturing, tall, strong-strawed cultivars specifically for silage production. For harvest index, a large difference (8 %) between years indicated that a simple relationship between harvest index and DD was not adequate to routinely predict grain content in barley silage.