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MISCELLANEOUS PUBLICATION 1271, U.S. DEPARTMENT OF AGRICULTURE 



growth curve of dry matter production in Towns- 

 ville stylo was similar to that of other annual 

 pasture species. Confirmation of this was obtained 

 by Fisher (18) who found that, under favorable 

 conditions, mean growth rates and dry matter 

 production of Townsville stylo were about the 

 same as those of subterranean clover. Townsville 

 stylo, a self-regenerating species, germinates at 

 the end of the dry season. The vertical taproot 

 of the plant penetrates the soil rapidly, but shoot 

 growth initially is slow. Early in the wet season 

 lateral shoots develop, and their growth rate in- 

 creases. By February in northern Australia, the 

 leaf canopy fully intercepts the light, and, from 

 then on, the growth rate is high until maturation 

 and senescence in the early part of the winter 

 dry season. Cameron described flowering behavior 

 (11, 12). 



Loch and Humphreys (20) defoliated Towns- 

 ville stylo at floral initiation, flower appearance, 

 and advanced flowering. Defoliation at each of 

 the three stages reduced seed production in com- 

 parison with no cutting; the reduction being 

 more marked the later the stage of cutting. Un- 

 like the prostrate subterranean clover, which 

 branches and produces more inflorescences when 

 cut or grazed before flowering, Townsville stylo 

 has an erect habit and its buds are more vulner- 

 able to cutting or grazing. Defoliation of Towns- 

 ville stylo also reduced the number of florets that 

 set seed. This was due perhaps in part to later 

 flowering as a result of cutting, and consequently 

 to maturation of seed during falling temperatures 

 and intensities of radiation (20). 



Defoliation did not affect the growth rate sig- 

 nificantly, stem and inflorescence growth were 

 reduced, but leaf growth rate was increased. 



Management Of Annual Communities 



Smith's (4.1) defoliation experiments indicated 

 that decapitation during the period of elonga- 

 tion promoted tillering and seed setting in barley 

 grass. These results were confirmed by the graz- 

 ing experiments of Robards and Leigh (32) and 

 Burt (9). In another experiment, Smith (43, U) 

 had a series of plots grazed until mid-August, 

 the onset of stem elongation, and then imposed, 

 among others, the following differential treat- 

 ments in both 1962 and 1963: 



1. No grazing after mid-August (late winter). 



2. Grazed for an additional month that is until 

 mid-September (early spring). 



3. Cut as for silage — October 4, 1962, and Oc- 

 tober' 22, 1963. 



4. Cut as for hay— October 16, 1962, and Oc- 

 tober 30, 1963. 



Seed yields from plots grazed in September, 

 that is, during a period of rapid stem elonga- 

 tion, were higher than from plots cut for silage 

 or for hay in October. Yields from grazed plots 

 were no lower and in two instances were higher 

 than from plots not grazed after the onset of the 

 reproductive stage. The highest yields of viable 

 seed were recorded also from plots grazed during 

 stem elongation. 



Cutting for hay at seed formation in October re- 

 duced yields of seed to a greater extent than 

 cutting at flowering for silage. Results for all 

 treatments were similar in 1962 and 1963. 



In 1963 some plots were oversown with sub- 

 terranean clover and, in the presence of clover, 

 less seed was produced by barley grass on all 

 treatments. 



In the year following the last application of 

 treatments, oversown plots cut previously for 

 silage or hay, and particularly those cut late for 

 hay, had less barley grass and more clover than 

 grazed plots. Seed yields of clover were highest 

 on plots cut for grass hay or silage in the previous 

 2 years, that is, on those plots yielding the least 

 barley grass. On grazed plots, inflorescences of 

 barley grass were closer to the ground than on 

 other treatments, presumably because of the 

 shorter vegetative stage and earlier floral initia- 

 tion in axillary tillers. Seed heads close to the 

 ground are less likely to be injurious to grazing 

 animals than the erect inflorescences normal in 

 lightly grazed barley grass. 



Late mowing offers some scope for reducing 

 the proportion of other annual grasses, except 

 perhaps the early maturing Yulpia spp. but al- 

 lows ingress of other annuals, such as capeweed 

 and erodium. 



In a drier environment in southwestern New 

 South Wales, Robards and Leigh (32) found that 

 the critical months for grazing barley grass were 

 August and September — as in Smith's experiment, 

 the period of stem elongation. The highest yields 

 of dry matter were from plots grazed ever}- 



