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Gamba grass (Andropogon gayanus Kunth.) seed persistence and germination temperature tolerance

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Bebawi, F. F., Campbell, S. D. and Mayer, R. J. (2018) Gamba grass (Andropogon gayanus Kunth.) seed persistence and germination temperature tolerance. The Rangeland Journal, 40 . pp. 463-472.

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Article Link: https://doi.org/10.1071/RJ17125

Publisher URL: https://www.publish.csiro.au/paper/RJ17125


Gamba grass (Andropogon gayanus Kunth.) is a highly invasive, naturalised Weed of National Significance in Australia due to its economic, environmental and social impacts. It outcompetes native pastures and fuels intense fires in northern Australian rangelands. To aid management of current infestations and to better understand its potential distribution, this study determined the germination response of gamba grass under a range of constant (13°C−48°C) and alternating (11/7°C–52/42°C) temperature regimes and quantified the potential longevity of soil seed banks. The effect of different soil types, levels of pasture cover and burial depths on seed longevity was investigated in the Dry Tropics of northern Queensland.Germination of gamba grass occurred under a wide range of both constant (17°C−39°C) and alternating day/night temperatures (16/12°C–47/39°C), although the level of germination declined at the lower and higher temperature ranges. At the cooler temperatures, seed viability was not affected, but seeds went into a state of dormancy. The highest level of seed viability was recorded at the lowest constant temperature regime (13°C) and at the two lowest alternating temperatures (11/7°C and 16/12°C). A gradual but variable decline in viability occurred thereafter with increasing temperatures. At the higher temperature range (e.g. constant temperatures of 39°C−43°C and alternating temperatures of 47/39°C) both dormancy and loss of seed viability were occurring, but once alternating and constant temperatures reached above 47/39°C and 43°C all seeds were rendered unviable after 9 and 6 weeks respectively.In the Dry Tropics of northern Queensland, viability of seeds was <1% after 12 months and nil after 24 months, irrespective of soil type or vegetation cover. However, burial depth had a significant effect, with surface located seeds exhibiting a faster rate of decline in germination and viability than seeds buried below ground (i.e. 2.5–10 cm). These findings have implications for the duration of control/eradication programs (i.e. seed persistence) and also suggest that gamba grass has the potential to greatly expand its current distribution into the relatively cooler southern latitude areas of Australia.

Item Type:Article
Business groups:Animal Science
Keywords:burial depth, dormancy, soil type, temperature regimes, vegetation cover, viability.
Subjects:Science > Invasive Species > Plants > Eradication and containment
Science > Invasive Species > Plants > Weed ecology
Agriculture > Agriculture (General) > Soils. Soil science
Plant culture > Seeds. Seed technology
Animal culture > Rangelands. Range management. Grazing
Live Archive:12 Feb 2019 02:58
Last Modified:03 Sep 2021 16:44

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