Track 1-04

Description

Complete summer dormancy is associated with plant senescence in late spring-summer even though soil moisture is non-limiting. The trait is well understood in exotic temperate grasses for persistence in environments which experience frequent summer droughts (Annicchiarico et al. 2011). However, the trait appears to be uncommon in Australian native grasses (Culvenor 2009). The C3 native perennial grass, Elymus scaber, is broadly adapted across a wide range of climatic zones and soil types in south eastern Australia (Johnston et al. 2001) and has been described as displaying strong summer dormancy (Mitchell et al. 2001). However, the reports of dormancy were not tested under conditions of non-limiting soil moisture. Therefore the dormancy aspect of its growth habit over summer may be confused with drought avoidance, causing leaf senescence in response to drying soil.

This study tested the hypothesis that E. scaber exhibits traits consistent with complete summer dormancy, by placing a range of populations of the species under three irrigation regimes (after Norton et al. 2006). For E. scaber to demonstrate complete summer dormancy, it would show no new growth over summer irrespective of the irrigation treatment.

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Summer Dormancy Expression in the Australian Native Grass Elymus scaber

Complete summer dormancy is associated with plant senescence in late spring-summer even though soil moisture is non-limiting. The trait is well understood in exotic temperate grasses for persistence in environments which experience frequent summer droughts (Annicchiarico et al. 2011). However, the trait appears to be uncommon in Australian native grasses (Culvenor 2009). The C3 native perennial grass, Elymus scaber, is broadly adapted across a wide range of climatic zones and soil types in south eastern Australia (Johnston et al. 2001) and has been described as displaying strong summer dormancy (Mitchell et al. 2001). However, the reports of dormancy were not tested under conditions of non-limiting soil moisture. Therefore the dormancy aspect of its growth habit over summer may be confused with drought avoidance, causing leaf senescence in response to drying soil.

This study tested the hypothesis that E. scaber exhibits traits consistent with complete summer dormancy, by placing a range of populations of the species under three irrigation regimes (after Norton et al. 2006). For E. scaber to demonstrate complete summer dormancy, it would show no new growth over summer irrespective of the irrigation treatment.