Tolerance of Five Cool‐Season Perennial Grasses to Selected Herbicides
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Emergence and survival of the seedlings of warm-season native perennial grasses Aristida ramosa R.Br., Bothriochloa macra (Steud.) S . T. Blake, Dichanthium sericeum (R.Br.) Camus, Sporobolus elongatus R.Br., Eragvostis leptostachya Steud. and Chloris truncata R.Br. and the cool-season species Stipa variabilis Hughes and Danthonia linkii Kunth were studied in both native pastures and sown monospecific plots on the north- west slopes of New South Wales. The most favourable period for the successful emergence and establishment of warm-season grasses was from mid summer to early autumn. Cool-season native perennial grasses established best from seedlings that appeared from mid autumn to late winter. Few seedlings were observed to germinate in spring, probably as a result of large variations in temperature, low minimum temperatures or intra and interspecific competition. Seedlings growing in native pasture spent long periods in the vegetative phase compared to the early flowering of seedlings in the sown plots. In the pasture studied only two seedlings flowered over 700 days after emergence, and many others after persisting for up to 2 years died without producing seed. These findings indicate that the seedlings in these native pastures were under considerable stress and that the adult populations of the species examined were relatively stable and little recruitment occurred.

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A method to differentiate summer-dormant from summer-active tall fescue and orchardgrass accessions at germination stage

Australian Journal of Agricultural Research ◽

10.1071/ar08084 ◽

2008 ◽

Vol 59 (12) ◽

pp. 1092 ◽

Cited By ~ 8

Author(s):

Dariusz P. Malinowski ◽

David P. Belesky ◽

Betty A. Kramp ◽

Joyce Ruckle ◽

Jaime Kigel ◽

...

Keyword(s):

Tall Fescue ◽

Weather Conditions ◽

Perennial Grasses ◽

Cool Season ◽

Instantaneous Rate ◽

Validation Test ◽

Cultivar Development ◽

Summer Dormancy ◽

Mediterranean Origin ◽

Dactylis Glomerata L

Summer-dormant, cool-season perennial grasses are being used in place of traditional, summer-active cultivars for high-quality winter forage. One reason for this change is the ability of cultivars with summer-dormant attributes to tolerate increasing annual temperature, decreasing precipitation, and repeated severe summer droughts. The mechanism of summer dormancy is still not understood in detail. Cultivar development for summer dormancy typically is conducted under field conditions in environments where summer-active types do not survive summer weather conditions. We developed a method based on germination responses to photoperiod to differentiate summer-dormant from summer-active types of tall fescue [Lolium arundinaceum (Schreb.) S. J. Darbyshire] and orchardgrass (Dactylis glomerata L.). Seed of cultivars with known summer dormancy characteristics was germinated at a constant temperature of 24°C under a range of photoperiods (0–24 h) for 14 days. Total germination, modelled cumulative germination, instantaneous rate of germination, and relative germination (to that in the dark) were analysed. Germination of summer-dormant orchardgrass was similar in the dark and short photoperiods (4–12 h), but it was inhibited by a photoperiod longer than 12 h. Germination of summer-active orchardgrass was promoted by any photoperiod compared with the control (0 h). Short photoperiods (4–12 h) promoted germination of summer-dormant tall fescue, while long photoperiods (>12 h) inhibited germination compared with germination in the dark. Summer-active types of tall fescue did not respond to photoperiod, regardless of length. A validation test using two Mediterranean origin cultivars of orchardgrass with contrasting summer dormancy characteristics and experimental lines of Mediterranean origin tall fescue with known expression of summer dormancy characteristics supported the use of seed germination analysis to differentiate among lines for this trait.

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