Rhizosphere and endophytic colonisation of ryegrass and sweet corn roots by the isolate Trichoderma atroviride LU132 at different soil pHs

Abstract

The colonisation of plant roots by biological control agents is dependent on abiotic factors, one of the most important being soil pH. The rhizosphere and endophytic colonisation of ryegrass and sweet corn roots by the biological control agent Trichoderma atroviride LU132 were assessed in a pot experiment with non-sterile soil at three different pHs (5.5, 6.5 and 7.5). T. atroviride LU132 colonised the roots of both plants regardless of the soil pH with 1.13-1.47 × 10⁶ CFU/g of dry rhizosphere soil (DRS) for ryegrass and 1.36-3.50×10⁵ CFU/g DRS for sweet corn. T. atroviride LU132 was able to colonise both plants endophytically, regardless of soil pH. However, the isolate was recovered from entire ryegrass roots but only from the upper parts of sweet corn roots. These experiments demonstrated that T. atroviride LU132 colonised the rhizosphere and roots within a soil pH range common to most NZ soils, which is a desirable trait for biological control agents.