Tillering in tussock grasses in relation to defoliation and apical bud removal
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Authors: J. H. Richards, R. J. Mueller, and J. J. Mott
Date: 1988
Journal: Annals of Botany
Volume: 62
Number:
Pages: 173-179
Summary of Methods: Experiments with five caespitose grass species from temperate and tropical environments showed that the number of lateral shoots (tillers) which emerged following defoliation was not increased by leaving a greater residual leaf area. Increased availability of photosynthate was effective, however, in increasing the rate of growth and degree of flowering of new lateral shoots in one tropical species, Panicum maximum. In two temperate Agropyron tussock grasses, decapitation did not stimulate lateral shoot growth. This indicated that apical dominance was not a factor preventing growth of lateral buds just prior to inflorescence emergence on the parent tillers. However, defoliation, where both terminal buds and foliage was removed from the parent tillers stimulated lateral bud growth. In contrast to the temperate species, lateral bud growth was stimulated by both decapitation and defoliation in the three tropical species. These results strongly suggest that lack of carbon resources in defoliated tillers does not limit the stimulation of daughter tillers in these three specie at the morphological stage when the treatments were applied.
Article Summary / Main Points: None
Vegetation Types:
MLRA Ecoregions:
Agrovoc Control Words: Riparian zones Rangelands Wildlife
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: agropyron spicatum, agropyron desertorum, heteropogon contortus, panicum maximum, themeda triandra, crested wheatgrass, bluebunch wheatgrass, black speargrass, green panic grass, kangaroo grass, apical dominance, regrowth, tolerance, photosynthate allocat
Annotation: The experiment on the tropical-savanna species Heteropogon contortus, Panicum maximum and Themeda triandra, was conducted in Queensland Australia. The experiment on Agropyron species was conducted in the field in Utah. 3 treatments were (control, defoliation, and decapitation) were applied in a random design in each experiment. In the defoliation treatment (cutting height 7-10 cm), terminal buds and more than 85% of green blade sheaths and stems were removed. This treatment simulated the intensity and pattern of defoliation observed on these tussock grass species following moderate to heavy grazing by cattle. In the decapitation treatment, the apical bud was dissected from all tillers on plants assigned that treatment, but green leaf and stem tissues of each tiller were left intact. Date of treatment was June 1-8, 1994 for Agropyron species; January 13, 1986 for P. maximum; February 12-14, 1986 for T. triandra and H. contortus.
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