Changes in mean character and uniformity ofLolium (perenne + multiflorum)var. ‘Grasslands Manawa' during seed increase

Evaluation of cocksfoot (Dactylis glomerata L.)

“…The lack of shift in overall mean, but increase in between-line variance with advancing generations of 'Apanui', contrasts with the results of Rumball (1970) for 'Manawa' short-rotation ryegrass, seed production of which is carried out under the same general certification system. Rumball found that for all characters including growth notes, but with the exception of flowering date, which became earlier, conforming with results for other species, there was a shift with advancing generations towards an Italian ryegrass type, as opposed to a perennial type.…”

“…However, these results usually refer to reproductive characteristics of such characters as cyanogenic contcnt. In 'Manawa' ryegrass Rumball (1970) found a consistent shift toward Italian ryegrass characteristics, including higher winter growth. The Italian type has a clear superiority in growth in the first winter, so it dominates the seeding stand.…”

“…There has been concern (for example Rumball 1970) that genetic shifts in populations may occur during generations of seed increase, particularly where such increase occurs in an environment different from that under which a cultivar has been bred, as is the case for 'Apanui' cocksfoot. The relative amounts of seed produced by different genotypes making up a synthetic may vary with the environment (Stanford et al 1960), as may the pollen contribution of the genotypes.…”

“…Recorded genetic shifts in forage species have usually involved reproductive characters. It has been suggested that early-flowering genotypes contribute disproportion8~ely to total seed yield (Dovrat et al 1968), causing ,t shift toward early flowering (Taylor et al 1966;~tanford et al 1962;Rumball 1970). …”

Effects of density and management on components of floret production inLolium(multiflorum lam.xperennel.) ‘grasslands manawa’ ryegrass

“…Rumball (1970) has demonstrated such changes during seed multiplication of Lolium (multiflorum Lam. X perenne L.) 'Grasslands Manawa' ryegrass, indicating a trend away from L. perenne characters towards those of L. multifiorum.…”