Comparing the effectiveness of mycorrhizal inoculation and amendment with sugar beet, rock phosphate and Aspergillus niger to enhance field performance of the leguminous shrub Dorycnium pentaphyllum L.

Abstract

A field experiment was undertaken to evaluate the effectiveness of mycorrhizal inoculation with Glomus intraradices (Schenck & Smith) or Glomus deserticola (Trappe, Bloss. & Menge) and the addition of sugar beet (SB), rock phosphate and Aspergillus niger with respect to the establishment of Dorycnium pentaphyllum L. seedlings, in a semiarid Mediterranean area, and the improvement of the physical-chemical, biochemical and biological properties of the soil. Eighteen months after planting, amended soil had higher available phosphorus and aggregate stability levels than control soil (165 and 157%, respectively). All assayed treatments had higher soil total carbohydrates and water soluble C values and enzyme activities (dehydrogenase, urease, acid phosphatase and β-glucosidase), and lower soil pH and bulk density than control soil. Biomass C and dehydrogenase, urease and β-glucosidase activities of the rhizosphere of G. deserticola-inoculated plants were higher than those of the rhizosphere of G. intraradices-inoculated plants. Mycorrhizal inoculation treatments stimulated significantly the production of shoot biomass, to a higher extent than the addition of the amendment alone to soil or the combined treatment. The highest levels of mycorrhizal colonisation and of foliar N and K were recorded in the seedlings inoculated with G. deserticola. The shoot biomass of G. deserticola-inoculated D. pentaphyllum plants was greater (about 219% with respect to control plants) than that of G. intraradices (about 116% with respect to control plants).