Nodulation and Growth of Trifolium Subterraneum L. CY. Mount Barker in Agar Culture

Abstract

The presumptive effect of root exudates on the course of nodulation of Trifolium subterraneum L. cv. Mount Barker in agar culture was investigated by means of the preplanting technique. The technique was also re-examined with a view to its use for the bloassay of substances influencing nodule formation. Preplanting was found to remove unidentified nitrogenous compounds from the agar media. It was also found that some of the data obtained are subject to observer effects. The environmental conditions and the type of agar used to prepare the root media have large and significant effects on the number of nodules formed, but the effect of preplanting is slight and varies in direction with the type of agar. There is no acceptable evidence that any of these factors affects the interval between inocualtion and initiation of nodulation. Plant yield was affected in a highly significant manner by the environmental conditions but responses to the type of agar and preplanting was confined to plants grown in the glasshouse. It was concluded that further physiological investigations are required before chemical fractionation of the root exudate of this species is warranted.