Diverse Grain-Filling Dynamics Affect Harvest Management of Forage Barley and Triticale Cultivars

Harvest time for small-grain forage is impacted by changes in yield, dry matter concentration (DMC) and forage quality during grain-filling. Little information exists for hulless and two-rowed barley (Hordeum vulgare L.) and triticale (X Triticosecale Wittmack) grown in Alberta. Two barley and two triticale cultivars were grown at three planting dates and two locations over 2 yr at Lacombe, AB, Canada. Forage was harvested five times after boot stage at 7-and 10-d intervals for barley and triticale, respectively. Relationships were developed by regressing variables with growing degree days (GDD) after the boot stage for triticale cultivars, combined, and each barley cultivar ('Falcon' and 'Gadsby'). Comparisons were made at GDD positions. Triticale out-yielded and dried slower than barley and had higher DMC for 560 GDD after the boot stage; Gadsby out-yielded Falcon. The soft dough stage (DS 85) indicated optimum yield, 93% of relative dry matter yield (RDMY) at less than 400 g kg(-1) DMC for barley and triticale, but occurred at 400 and 500 GDD after the boot stage, respectively. Triticale had lower in vitro true digestibility (IVTD) and higher fiber levels than barley at boot stage; but triticale IVTD decreased slower than barley and Falcon declined faster than Gadsby. Starch accumulated more rapidly for Gadsby than Falcon, while triticale increased slowly initially, then rapidly later in the grain filling period. Delaying harvest by 100 GDD for triticale compared to barley (both at DS 85) resulted in the higher triticale yield, while allowing more starch to accumulate.