THE BIOLOGY OF MYCORRHIZA IN THE ERICACEAE V. THE EFFECTS OF MYCORRHIZAL INFECTION, SOIL TYPE AND PARTIAL SOIL‐STERILIZATION (BY GAMMA‐IRRADIATION) ON GROWTH OF CRANBERRY (VACCINIUM MACROCARPON AIT.)

Abstract

Vaccinium macrocarpon was grown in open pots for 20 weeks on three heathland soils of decreasing fertility. Interactions between the effects of mycorrhizal infection, soil type and partial soil‐sterilization (by γ‐radiation) were studied by the calculation of various growth‐functions from fitted curves. Mycorrhizal infection increased whole‐plant dry weight and relative growth‐rate but decreased the root/shoot ratio of plants grown on two of the irradiated soils. These plants contained a greater percentage of nitrogen and had higher specific absorption rates for N than uninfected controls. The fertility of each soil was increased by partial sterilization. On one irradiated soil, mycorrhizal infection was without effect: all plants grew rapidly and had large specific absorption rates which were associated with a large net mineralization of NH4+‐N. Changes in the values of growth‐functions with time occurred in most treatments and were especially marked in plants grown on the irradiated soil with marked mineralization of NH4+‐N. The importance of these ontogenetic variations is considered in relation to other experiments on the response of higher plants to mycorrhizal infection. Copyright © 1975, Wiley Blackwell. All rights reserved