Chemical Manipulation of Grass Seed Crops

Abstract

The seed yield potential established at anthesis in grass seed crops is usually 5-10 times greater than actual seed yields realised at harvest. Losses in seed yield between anthesis and harvest result primarily from the death of fertile tillers and poor seed site utilisation. Lodging has been identified as one of the most important factors reducing seed yields, and the use of growth retardants has significantly increased seed yield in perennial ryegrass and tall fescue. The effects of the growth retardant paclobutrazol on the growth, development and seed yield of perennial ryegrass (Lolium perenne) are presented and discussed. Little is known of the effects of leaf and stem diseases on grass seed yields. Recent research has found that fungicide application can substantially increase seed yield in perennial ryegrass through delaying senescence of leaf tissue. Increased leaf area duration is associated with a reduction in seed abortion, resulting in more seeds per spikelet at harvest. The possibilities for fungicide use in the crop are discussed. Keywords: Seed production, grasses, fertile tillers, seed abortion, growth retardants, paclobutrazol, fungicide, senescence.