Publication Date

1985

Location

Kyoto Japan

Description

In order to appreciate how population regulation of grass varieties occur in sward conditions, seven varieties of Rhodes grass were sown at four densities and grown with four cuttings during the first year, and records were taken of the density of surviving genets, the density of tillers, the mean genet weight and the mean tiller weight. During the experiment the two density-dependent processes of population regulation were observed, viz, density­dependent mortality of genets and density-dependent tillering of surviving genets. As results of these processes, tiller density converged towards a value characteristic of the variety but nearly free from influence of the initial sowing density at the end of the year. At that time, heritability estimates were high for the tiller density and the mean tiller weight in contrast with those for the genet density, the mean genet weight and the mean tiller number per genet, and high negative genetic correlation was observed between the tiller density and the mean tiller weight. The results suggest that the tiller is an important unit of population regulation in sward conditions, which is characteristic of the variety.

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Population Regulations of Rhode grass (Chloris gayana) Varieties in Sward Conditions

Kyoto Japan

In order to appreciate how population regulation of grass varieties occur in sward conditions, seven varieties of Rhodes grass were sown at four densities and grown with four cuttings during the first year, and records were taken of the density of surviving genets, the density of tillers, the mean genet weight and the mean tiller weight. During the experiment the two density-dependent processes of population regulation were observed, viz, density­dependent mortality of genets and density-dependent tillering of surviving genets. As results of these processes, tiller density converged towards a value characteristic of the variety but nearly free from influence of the initial sowing density at the end of the year. At that time, heritability estimates were high for the tiller density and the mean tiller weight in contrast with those for the genet density, the mean genet weight and the mean tiller number per genet, and high negative genetic correlation was observed between the tiller density and the mean tiller weight. The results suggest that the tiller is an important unit of population regulation in sward conditions, which is characteristic of the variety.