Publication Date
1985
Location
Kyoto Japan
Description
Heavy grazing by cattle, resulting from various practices to intensify carrying capacity, is reducing the abundance of the dominant Kangaroo grass (Themeda australis) in Australia's tropical and subtropical savannas. The objective of this study was to find whether morphological and/or physiological factors were the cause oflow tolerance of T. australis to heavy grazing. Themeda australis was compared in a glasshouse experiment, with buff el grass ( Cenchrus ciliaris), a successful introduction from Africa and known to be grazing tolerant. Half the plants were subjected to frequent close defoliation and their regrowth was compared with infrequently defoliated plants. The species differed markedly in ability to cope with frequent defoliation. Shoot regrowth was severely depressed in T. australis but unaltered in C. ciliaris for frequently compared with infrequently defoliated plants. A combination of morphological and physiological factors were involved in the differences including capacity to from nodal tillers, photosynthetic capacity of initial leaf growth following defoliation, resource allocation and rates of leaf initiation. It is concluded that the T. australis is not adapted to cope with frequent close defoliation. Higher grazing pressures may be tolerated by the species if a grazing regime is used that maximizes rest periods.
Citation
Hodgkinson, K C.; Mott, J J.; and Ludlow, M M., "Coping with Grazing: A Comparison of Two Savanna Grasses Differing in Tolerance to Defoliation" (1985). IGC Proceedings (1985-2023). 11.
(URL: https://uknowledge.uky.edu/igc/1985/ses11/11)
Included in
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Coping with Grazing: A Comparison of Two Savanna Grasses Differing in Tolerance to Defoliation
Kyoto Japan
Heavy grazing by cattle, resulting from various practices to intensify carrying capacity, is reducing the abundance of the dominant Kangaroo grass (Themeda australis) in Australia's tropical and subtropical savannas. The objective of this study was to find whether morphological and/or physiological factors were the cause oflow tolerance of T. australis to heavy grazing. Themeda australis was compared in a glasshouse experiment, with buff el grass ( Cenchrus ciliaris), a successful introduction from Africa and known to be grazing tolerant. Half the plants were subjected to frequent close defoliation and their regrowth was compared with infrequently defoliated plants. The species differed markedly in ability to cope with frequent defoliation. Shoot regrowth was severely depressed in T. australis but unaltered in C. ciliaris for frequently compared with infrequently defoliated plants. A combination of morphological and physiological factors were involved in the differences including capacity to from nodal tillers, photosynthetic capacity of initial leaf growth following defoliation, resource allocation and rates of leaf initiation. It is concluded that the T. australis is not adapted to cope with frequent close defoliation. Higher grazing pressures may be tolerated by the species if a grazing regime is used that maximizes rest periods.
