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Australian Journal of Botany Australian Journal of Botany Society
Southern hemisphere botanical ecosystems
RESEARCH ARTICLE

Impact of heat on seed germination of three perennial grasses in the semiarid region in Central Argentina

Alicia G. Kin A B , Carla E. Suárez A , Claudia C. Chirino A , Patricia L. Ávila A and Ernesto F. A. Morici A
+ Author Affiliations
- Author Affiliations

A Facultad de Agronomía, Universidad Nacional de La Pampa, CC 300, 6300, Santa Rosa, La Pampa, Argentina.

B Corresponding author. Email: kin@agro.unlpam.edu.ar

Australian Journal of Botany 64(5) 451-455 https://doi.org/10.1071/BT15238
Submitted: 31 October 2014  Accepted: 12 July 2016   Published: 5 August 2016

Abstract

Fire is an important factor affecting the viability and germination of seeds in the soil seed bank. We evaluated the effects of heat on germination and seed viability of three native perennials winter grasses of central Argentina. Seeds of two palatable grasses Piptochaetium napostaense (Speg.) Hack, Nassella tenuis (Phil.) Barkworth and a non-palatable Jarava ichu Ruiz & Pav. were exposed to different heat shock treatments resulting from a combination of temperature: 70, 90, 120, 140 and 170°C and three exposure times (5, 10 or 20 min) and a control (no heat) treatment. All control treatments had a high percentage of seed viability (>97%). Germination of P. napostaense was not affected by mild heat shock (70 and 90°C) but it was sensitive to higher temperatures: no seeds survived the exposure to 140 and 170°C. Seeds of this species have awns that facilitate the burring of seeds in the soil, which can reduce fire exposure. N. tenuis and J. ichu were less sensitive to heat. High heat shock reduced seed germination but not seed viability. These experiments show that seeds of P. napostaense, the target species for management on these grasslands, were the most sensitive to heat treatments. Our results show that heat shock can have a negative effect on the soil seed bank of P. napostaense (palatable and dominant species), but does not have significant effects on J. ichu seeds (unpalatable species). Thus, we suggest that the current management recommendations for the use of controlled fire to promote palatable species may not be optimal for these species.

Additional keywords: grasslands, fire ecology, Poaceae.


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