Post-flowering tillering in contrasting light environments of two New Zealand perennial ryegrass cultivars with different perennation strategies

Post-flowering tillering responses of 'Ellett' and 'Grasslands Ruanui' pere nnial ryegrass (Lolium perenne L.) cultivars after inflorescence production were studied at INRA, Lusignan in France, at near ambient light (absence o f light competition, control treatment) and under shading (low-light intens ity and low red-far red ratio). A dense sward containing inflorescence bear ing plants of both perennial ryegrass cultivars at ambient light was cut to a height of 50 mm above ground level after which the light treatments were imposed. Forty-five days later, data were collected on the number of tille rs per plant, the number of new tillers per original tiller and the dry wei ght of vegetative and reproductive tillers. Regardless of light treatment, cv. 'Ellett' had fewer tillers per plant, higher weight per tiller and a hi gher proportion of reproductive tillers than did cv. 'Grasslands Ruanui'. N umber of tillers per plant and number of new tillers per tiller were consis tently reduced under shade compared with the control treatment for both cul tivars. When shaded, weight of reproductive tillers of cvs 'Ellett' and 'Gr asslands Ruanui' were 40% and 43%, respectively, less than the control, whe reas vegetative tiller weight did not change. In addition, differences betw een cultivars in the tillering strategy after flowering seem to be unaffect ed by the light environment. Thus, field observations regarding tillering o f cvs 'Ellett' and 'Grasslands Ruanui' were consistent with current results suggesting different grazing managements are needed after flowering to opt imize the replacement of tillers for both cultivars.