The persistence of five cultivars of phalaris after cutting during reproductive development in spring

Abstract

Cultivars of phalaris (Phalaris aquatica L.) were cut at various stages of development between the vegetative state and anthesis, or fortnightly during spring, to determine the effects on subsequent regeneration and persistence. The treatments were applied for 2 years to plants growing on a 200 mm grid at two field sites in the A.C.T. Most of the effects were established in the first year, in which late spring and summer were dry and hot. At a site which was irrigated during the first spring, there was little effect of a single cut at each stage of development. However, autumn regeneration of plants cut again after 14 days or cut frequently was affected. At a less fertile site which was not irrigated, and where dormancy was interrupted during summer in the first year, reductions in autumn regeneration growth of greater than 50% were observed in plants cut once at the early stem elongation and early boot stages. Most plants observed to be dead in autumn at the second site had been cut at the early boot stage. When cut at earlier stages of development, most plants which subsequently died had been cut twice. Unlike a previous study under artificial conditions, differences in autumn regeneration between a reputedly persistent cultivar (cv. Australian) and newer cultivars were not large, probably due to only small differences in synchrony of reproductive stem development occurring under the competitive spring growth conditions of this study. However, higher rates of tillering and tiller survival by cv. Australian observed after cutting prior to stem elongation should reduce its susceptibility to damage during spring. Avoidance of repeated heavy grazing of phalaris during spring, or sudden heavy grazing of tall stands in the stem elongation phase, is recommended to enhance persistence should seasonal factors become unfavourable for tiller survival.