Water‐soluble carbohydrates in perennial ryegrass breeding

Water‐soluble carbohydrate (WSC) contents of the early heading perennial ryegrass cultivar Aurora and five late heading cultivars were assessed in samples from spaced plants cut five times in 1982. Aurora had the highest overall WSC content. Majestic and Aberystwyth S23 had the lowest while Perma, Melle and Ba 9795 were intermediate. Samples from F1 and F2 spaced plants derived from crosses between Aurora and the five late heading cultivars were also analysed for WSC contents and heading dates were recorded. As expected, heading date behaved as a polygenic character controlled mainly by additive gene effects. However, WSC contents behaved in a more complex way with evidence of non‐additive gene effects comprising dominance, overdominance (heterosis) and epistasis. It was concluded that by crossing contrasting cultivars, significant improvements in WSC content could be achieved, which may be more stable than those obtained by within‐cultivar selection.