A comparison of root competition and shoot competition between Dactylis glomerata and Holcus lanatus

Abstract

Dactvlis glomerata and Holcus lanatus were grown together in boxes with either full competition, root competition only, shoot competition only or no competition between them. The boxes were either fertilized (150 kg ha^'N, 100 kg ha"'K, 80 kg ha" ' P) or not fertilized. The experiment was continued for 13 months, and a total of six cuts were taken.H. lanatus was more competitive than D. glomerata throughout the experiment, though the efTect declined after flowering during the second growing season. The effects of root competition were generally much greater than those of shoot competition and tended to increase during the first year. However, the effects of root competition declined, relative to shoot competition, after flowering in the second growing season.Fertilizer applications slightly increased the root competitive ability of //. lanatus relative to D. glomerata but slightly reduced its shoot competitive ability.

The nature of competition between perennial ryegrass and white clover

“…In both these studies no reversal of dominance of root competition after defoliation was observed. This may have been due to the fact that in the above studies the two species in competition were either both grasses (Remison and Snaydon, 1980) or both clovers (Scott and Lowther, 1980) and there may not have been large differences in the response of root growth to defoliation, shoot growth rates or canopy height and disposition, while in ihe present study there were large differences in the above attributes between the two species.…”

“…Numerous studies on Ihe nature of competition between species and populations of pasture plants (Donald, 1958;Rhodes, 1968;Snaydon, 1971;Eagles, 1972;Remison and Snaydon, 1980;Scott and Lowther, 1980), crops and weeds (Aspinail. 1960;Idris and Milthorpe, 1966), and cereaUcgume mixtures (Martin and Snaydon, 1982) have shown that the effects of root competition are usually greater than those of shoot competition, at least during the first few months after planting.…”

Nutrient stress, host plant quality and herbivore performance of a leaf-mining fly on grass

“…Because H. lanatus normally occurs on soils of moderate to low fertility (Remison and Snaydon 1980) we suspected that the plants of high nutrient treatments are possibly subjected to a stress situation due to a nutrient overdose. Therefore we formulated two specific hypotheses about the treatments a priori.…”

“…Optimal growth occurs in moist conditions; it grows well in very wet conditions and can survive moderate periods of drought (Watt 1978). H. lanatus occurs on soils of moderate to low fertility, but fertilisation appears to improve its competitive ability (Remison and Snaydon 1980). A. nigripes is an oligophagous miner that infests grasses from the tribes Glycerieae, Aveneae and Agrosteaea (Spencer 1990).…”

Influence of nitrogen on competition between purple nutsedge, maize and soybean

“…Previous studies on the nature of competition between crops and weeds (Remison and Snaydon 1980, Scott and Lowther 1980, Martin and Snaydon 1982, Martin and Field 1984, Kannangara and Field 1985, Bozsa and Oliver 1990, Satorre and Snaydon 1992, Qasem and Hill 1994 have shown that root competition has a greater effect on the relative performance of the species than does shoot competition. The present results are supportive of these studies.…”