Performance of some Phalaris accessions under irigation in south-eastern Queensland

Abstract

The productivity and seasonal growth pattern of sixteen accessions of Phalaris (including introductions, breeding lines and cultivars of Phalaris aquatica, and hybrids between P. aquatica and either P. arundinacea or P. canariensis) was assessed under irrigation in two field cutting experiments in south-eastern Queensland. The quantity and quality of forage produced was measured when grasses were fertilized with 300 kg N ha-1 year-1 or grown in association with white clover (Trifolium repens cv. Ladino) over 2-year periods. Siro 1146 was the highest yielding accession, producing 13.25 and 17.20 t ha-1 year-1 over 2-year periods in Experiments 1 and 2, respectively. It outyielded cv. Australian in summer and autumn and matched it in winter and spring. No other line had higher total yields over the 2-year periods than cv. Australian, but P. aquatica CPI 14279 and P aquatica x P. arundinacea (allopolyploid) were more productive in summer, and an American synthetic accession (API) was more productive in spring. Grass yields were higher when fertilized with nitrogen than when grown in association with white clover. White clover yields were negatively correlated with associated grass yields. Combined grass and legume yields of the mixtures were equivalent to those of the nitrogen-fertilized monoculture treatments in only 1 year from each experiment. All lines maintained levels of nitrogen above 1.0% throughout the experimental periods, with Australian having the highest levels.