Do VA mycorrhizae enhance transpiration by affecting host phosphorus content?

Abstract

The prevailing indication in the literature is that enhancement of transpiration by vesicular‐arbuscular (VA) mycorrhizae is usually mediated by improved host phosphorus nutrition. The present experiments were conducted to investigate this in mycorrhizal Rosa hybrida L. ‘Samantha’ plants. In growth room and greenhouse studies, roses colonized by either a native or an exotic VA mycorrhizal fungus had greater transpiration rates than nonmycorrhizal rose plants of similar size and phosphorus content, under similar conditions. This mycorrhizal effect on transpiration was observed throughout a range of soil water potential. Whether or not plants were mycorrhizal, phosphorus content was not correlated with transpiration rate on an individual leaf basis.