Gramine in Barley Forage ‐ Effects of Genotype and Environment¹

Abstract

Consumption of reed canarygrass ( Phalaris arundinacea L.) containing about 2,000 μg dry wt or more of the indole alkaloid gramine can adversely affect ruminant performance. Because gramine occurs in barley ( Hordeum vulgare L.) leaves, 20 cultivars of barley and four races of Hordeum spontaneum Koch were analyzed for gramine and related alkaloids after growth in controlled environments (21/16 C, day/night) to the fourleaf stage. Shoot gramine levels ranged from <30 to >10,000 μg/dry wt; 10 ‘high‐gramme’ genotypes (six H. vulgare , four H. spontaneum ) contained at least 2,000 μg/g. Other indole alkaloids were absent or present only in trace amounts. Beginning at the two‐leaf stage, the high‐gramine barley cultivars ‘Arimar’ and ‘Maraini’ were grown for 2 weeks at 21/16 C and 30/25 C, with either adequate or limited water supply. Growth of both cultivars at the higher temperatures approximately doubled their gramine concentrations (to about 4,000 μg/g). Cyclic wilting, which resulted from limiting irrigation, did not greatly affect gramine concentrations. In a cool, spring, field planting at a loamy, non‐irrigated site, the gramine concentration in Arimar shoots was 1,700 μg/g at the three‐to‐four‐leaf stage, but fell to 200 μg/g at the six leaf stage. In a warm, summer, field planting at a sandy irrigated site, the gramine concentrations at both three‐to‐four and six‐leaf stages were ≥2,700 μg/g in Arimar and ≥4,500 μg/g in Maraini. Gramine merits attention as a potential anti‐quality factor in breeding programs for barley suited to grazing or other forage uses.