ENDOPHYTIC BACTERIAL SYSTEMS GOVERNING RED-CLOVER GROWTH AND DEVELOPMENT

Endophytic competent bacteria capable of promoting both beneficial and detrimental growth responses in red clover (Trifolium pratense L.) we re recovered from three adjacent areas of farmland each having a diffe rent cropping history - continuous red clover, continuous potatoes (So lanum tuberosum L.) or a 2 yr rotation of red clover and potatoes. The population composition of these rhizobacteria was altered by the vari ous crop sequences. The greatest instance of significant growth respon ses (beneficial or detrimental) occurred with those bacteria derived f rom the clover-potato soil, suggesting increased interactive 'competit ion' among bacterial populations at the 'interface' between different crop rotations. Whether bacterial strains promoted or inhibited growth appeared to depend on the cropping history and prior exposure of pre- bacterised clover plants to the natural microflora in the peat-based g rowing media. The interaction between bacterial colonists influenced p lant trait expression to the degree that some characteristics were com pletely masked. Improvements in plant growth were interpreted as an al lelopathic side-effect of the competition between endophytes for the s ame ecological niche, from which the plant inadvertently benefits.