GREATER LEAF CONDUCTANCE OF WELL-WATERED VA MYCORRHIZAL ROSE PLANTS IS NOT RELATED TO PHOSPHORUS NUTRITION

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  • *Washington State University College of Agriculture Scientific paper No. 7356.

SUMMARY

Plants of Rosa hybrida L. cv. ‘Samantha’, grown with high or low phosphorus (P) fertilization, were inoculated with Glomus intraradices Schenck & Smith, G. deserticola Trappe, Bloss & Menge, or left non-mycorrhizal. All plants except the low-P non-mycorrhizal group had similar tissue dry weights, leaf and root surface areas, growth ratios, stomatal characteristics and P contents. The higher rate of P fertilization increased plant dry weight three-fold and leaf area four-fold in non-mycorrhizal plants, but had no effect on growth characteristics of mycorrhizal plants except for a depression of colonization levels. Under well-watered conditions (75–90% and 45–50% relative soil water content, θ), low-P mycorrhizal plants displayed greater leaf conductance (g) than both high-P mycorrhizal and non-mycorrhizal plants. Leaf water potential (Ψ) was similar in colonized and uncolonized roses. Fungal species did not differ significantly in their influence on Ψ or g.

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