Vesicular–Arbuscular Mycorrhizal Development and Growth Response of Rough Lemon in Soil and Soilless Media: Effect of Phosphorus Source

Abstract

Abstract Vesicular–arbuscular mycorrhizal (VAM) development of Glomus intraradices Schenck & Smith and growth response of container-grown rough lemon (Citrus jambhiri Lush.) were compared in a phosphorus-deficient (2 μg P/g) sand-soil and peat-perlite, soilless mix, both fertilized with 3 levels of superphosphate (SP) and rock phosphate (RP). Mycorrhizal development and growth response were affected primarily by initial P availability in the media. In both soil and peat-perlite, VAM formation was greatest at 8 μg available P/g medium and maximum growth responses occurred over a range of 4 to 8 μg P/g medium. Available P from SP greater than 20 μg P/g medium inhibited mycorrhizal colonization and eliminated growth response. Less VAM development in peat-based media compared to soil suggested an effect of organic matter. In peat-perlite, moderate levels of colonization and a growth response equal to that of nonmycorrhizal plants grown in soilless media with high levels of available P were attained if RP was used to provide a low but sustained level of available P. In soilless media, mycorrhizae prevented P-induced, copper-deficiency symptoms in rough lemon.