Selection of the persistent, seed-retaining cultivar, Australian II, within the gene pool of Phalaris aquatica L. cv. Australian

Abstract

Crosses were made between Australian and its seed-retaining, but inbred derivative, Uneta, to develop a vigorous, grazing-tolerant, seed-retaining phalaris cultivar similar to cv. Australian. Forty-two half-sib families from seed-retaining F ₂ plants were sown in replicated plots near Orange, NSW, Canberra, ACT, and Hamilton, Victoria, in 1993. These were compared with 9 different accessions of cv. Australian, 1 certified line of cv. Uneta (duplicated), and the winter-active cultivars, Holdfast, Sirosa and Sirolan. Heavy, continuous grazing by sheep was imposed at each site from autumn, 1994, a drought year at Canberra.

Seedling density was lower (Canberra site) and above-ground seedling dry weight (Canberra and Orange sites) was higher (P<0.05) in the winter-active group than in the Australian-type controls and half-sib families in 1993. At Canberra and Orange, the winter-active cultivars flowered about the same time as Australian and Uneta, but the half-sib families flowered 6–8 days later. The percentage of the ground surface occupied by phalaris tillers as estimated by point quadrats was similar in the families, Australian and Uneta during the winters of 1994 and 1995, but the families had denser stands in 1996. Swards of the winter-active cultivars were sparser (P<0.05) than those of the others, especially at Hamilton and Orange, but the winter-active cultivars yielded more, after a 6-week break from grazing, than the other lines at Canberra (P<0.05) and Hamilton (not significant) in 1995.

Based on these data, 8 half-sib families with high herbage yield and high ground cover in 1995 were selected. These families flowered 1 week later than Australian, and to correct this, a ninth, early flowering genotype was added to form a new cultivar, Australian II. The potential role of this cultivar as a drought hardy, strongly persistent, grazing tolerant, high ground cover, seed-retaining replacement for cv. Australian in cooler regions is discussed.