Interaction of soil type and temperature on the survival of Rhizobium leguminosarum bv. viciae

Abstract

Field pea (Pisum sativum) production depends on effective nodulation by Rhizobium leguminosarum bv. viciae (R.I. viciae). The requirement to re-introduce these rhizobia with each pea crop depends on their ability to survive in cropping soils, season to season. The survival of R.I. viciae, in response to soil desiccation at ambient room temperatures, or at 30°C, and to intermittent exposure of the desiccated soil to 50°C (3 h on 3 consecutive days), was measured in soils of differing texture, pH (CaCl 2) and total exchangeable cations (tec). The soils were collected mostly from the cropping regions of south-western Australia. Survival of native strains in air-dried soil sampled from pea crops varied with soil pH. They were often not detected when pH was < 4.6, but usually exceeded 10 2g −1 soil above pH 4.9. Survival of R.I. viciae SU391 inoculated into sterile soil, following desiccation, was adversely affected by low tec (particularly exchangeable Mg), low soil pH and elevated soil temperature. Soil pH and Mg content were useful for estimating soil desiccation and high temperature effects on the survival of SU391, and may be used to predict the need for inoculating pea with R.I. viciae.