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.