A RELATIONSHIP BETWEEN HEADING DATE AND INVITRO TILLERING PROPENSITY IN PERENNIAL RYEGRASS (LOLIUM-PERENNE L)

In vitro tillers of over 1000 genotypes from nine contrasting Lolium perenne cultivars were cultured on various media containing the synthetic cytokinin, 6-benzylaminopurine (BAP), in order to determine the effect on tillering. The cultures were assessed after seven weeks for survival. tiller production, size and vigour. Added auxins 2,4-dichlorophenoxyacetic acid (2,4-D) and alpha-napthaleneacetic acid (NAA) had no consistent beneficial effects. A significant relationship was found between in vitro tiller production and cultivar heading date. Genotypes of early-heading, less persistent cultivars produced more tillers than genotypes from late heading more persistent cultivars. This was consistent with the generally higher in vitro tiller production in the biennial species Lolium multiflorum cultured on similar media.