Nutrient and water relations of mycorrhizal white clover

Abstract

Growth of uninoculated and Glomus fasciculatum s.1. inoculated white clover was evaluated under three water regimes (approximately 30%, 60% and 90% of field capacity, respectively), combined with four nutritional treatments: Long Ashton nutrient solution without P, the same with 30 ppm P added as mono-calcium phosphate (MCP), phosphate only, either as MCP or as tri-calcium phosphate (MCP). Plants were harvested after 72 days growth, and shoot dry weight, leaf area, root length and dry weight, and mycorrhizal infection determined. At the lowest water regime growth was very restricted; infection however improved both survival and shoot dry weight. At the intermediate water regime uninoculated plants grew moderately well only if supplemented with MCP; the higher water regime further increased shoot dry weight of MCP supplemented plants. Mycorrhizal status greatly improved the ratio dry matter produced/water unit given, at all nutritional treatments. Since also at the higher water regime mycorrhizal plants grew better than nonmycorrhizal ones, it is suggested that, under the experimental conditions, the improvement in water utilization was primarily mediated by improved nutritional status.