The Grassland Society of Southern Australia Inc offers a student study bursary valued at $1000 to provide financial assistance to final year students studying an agricultural related undergraduate course. Apply for your Student Bursary today - 2010 applications close 30th April. You or one of yur parents must be a current financial member to apply2009 Student BursaryTravis Moodie – winner of the 2009 Joyce Gillespie student bursary I’m currently in my final year of a Bachelor of Animal Science and Management at the University of 2008 Student Bursary RecipentsCongratulations to Erin Mayall from University of Melbourne and Ryan Bateman from University of Adelaide
Student research abstract
The effect of nitrogen and gibberellic acid on the winter growth of Barberia hybrid ryegrass
By Erin Mayall
Erin was a Bachelor of Agriculture student at the Dookie Campus of the University of Melbourne in 2008 and completed her final year industry project with Heritage Seeds at their “Shrublands” Research Station at Howlong, NSW.
The cooler temperatures experienced during the winter months still restrict the growth of ryegrasses. As such, the limited supply of pasture feed over this
period can pose significant production and financial challenges for pasture-dependent producers. Thus, there is a need to increase pasture dry matter
through the winter months when low soil temperatures limit pasture growth.
The application of gibberellic acid, in conjunction with nitrogen, is a relatively new
approach being tested by both producers and researchers. Evidence suggests that when correctly applied, and provided there are no other limiting soil or environmental factors, pasture growth can be increased. To date, no research has specifically
examined the effects of gibberellic acid and urea on the winter production of Barberia ryegrass.
Barberia ryegrass
Barberia is a tetraploid hybrid ryegrass cultivar, which has more perennial properties than Italian ryegrass in its breeding. It is described as a mid-late flowering cultivar and is commonly used in short- to medium-term pastures in the Goulburn Valley. Barberia is a Heritage Seeds product marketed as a ‘long-rotation ryegrass’.
Plant growth processes are regulated by plant hormones and the phytohormone, gibberellic acid (GA), regulates many important aspects of plant growth and development, including germination, growth, stem elongation and flowering.
Experimental design
My trial investigated the effects of both applied nitrogen and exogenous applications of GA on the growth and development of Barberia ryegrass during winter. Nitrogen was applied as urea and GA was applied as a foliar spray (ProGibb® SG, a product of Sumitomo Chemical Australia). The experimental design was a 2 x 4 fully-randomised factorial layout replicated four times, with the two factors being GA applied at two rates (0 and 20 g/ha) and nitrogen (N) applied as urea at four rates (0, 50, 100 and 200 kg N/ha). The experimental site was initially irrigated, scarified and
topdressed with 100 kg/ha of mono-ammonium phosphate; two days after a second irrigation in mid-April 2008, the experimental plots (6 m x 1.5 m) were sown with 25 kg/ha of Barberia ryegrass. Prior to application of the treatments in late June, the trial
site was soil sampled at 0-20 cm and 20-40 cm depths and the bulked soil samples analysed for their available nitrogen contents. Ryegrass growth was measured in
mid-June (pre-treatment), late- July and mid-August using a plot forage harvester set at a cutting height of 5 cm.
Results
The results from this trial showed that prior to the application of the treatments, the
soil nitrate-N levels were low (8.3 and 9.4 mg/kg for the 0-20 and 20- 40 cm horizons, respectively). Additionally, there were no significant (P>0.05) differences in ryegrass dry matter yields in mid- June (site mean: 0.12 t/ha) between the designated GA and N treatment plots. One month after the application of GA and urea (i.e. late July), the dry matter yields of Barberia ryegrass showed significant but independent responses to both the GA (1.18 t/ ha compared with 1.02 t/ha for the control; LSD5% = 0.13) and N (0.83, 0.96, 1.17 and 1.47 t/ha for 0, 50, 100 and 200 kg N/ha, respectively; LSD5% = 0.18). The regrowth measured in mid- August showed only a significant
(P<0.05) response to the highest rate of N (0.99, 0.94, 1.10 and 1.36 t/ha for 0, 50, 100 and 200 kg N/ ha, respectively; LSD5% = 0.22) and a significant (P<0.05) decrease to the GA (0.97 t/ha compared with 1.22 t/ha for the control; LSD5% =
0.16). The visual differences in growth coincided with a yellowing of ryegrass treated with both GA and the low and nil rates of urea. These observations suggest that these plants may have been nitrogen deficient; tissue testing would have
confirmed this possibility.
In conclusion
Applying GA to ryegrass pastures, provided there are no limiting soil nutrients,
particularly of nitrogen, is a strategy that producers could adopt to increase the dry matter production of their winter ryegrass pastures without the need to apply fertiliser nitrogen. Depending on the soil type, fertiliser history and pasture management of each paddock, together with the availability of water and the financial circumstances of each farm enterprise, the value of GA applications may differ from paddock to paddock and farm to farm. It is recommended that GA only be applied to ryegrass
pastures, provided there are adequate supplies of nutrients within the soil, and adequate water available either as rainfall or irrigation water, to achieve the
extra growth and ensure an economic return for the producer.Abstracts from Previous RecipentsThe effect of low staple strength on farm wool profitabilityby Fiona Frawley, 2006 Joyce Gillespie Bursary recipient This abstract summarises the research Fiona undertook for her Honours year in Agriculture and Commerce at The University of Melbourne last year.Australia produces 98% of the world’s fine wool and quality fine wool attracts price premiums at auction. Fine wool, however, can be more susceptible to breakage because of low staple strength or ‘tender’ wool. Tender wool receives price discounts that range from 3 to 30%, which greatly impacts on farm wool income. Producers first need to determine if staple strength is a problem in their wool clip by estimating the income forgone as a result of strength discounts before evaluating management strategies for overcoming tender wool. This study examined industry and a case-study farm data to determine if poor staple strength is a problem in south western Victoria. These data showed that almost one third of all wool sold had poor staple strengths.
In these years, the profits from wool of sound strength was almost double that from tender wool. However, in years when wool prices and discounts were low, the profit differences from strong and tender wool were marginal, and had little effect on final profits. Strategies to reduce tender wool however add to the production costs. It was estimated that to increase the staple strength of the wool of breeding ewes by 5 N/ktex costs $3.29/head. In years of high prices, this cost is outweighed by the increased returns (for example, $8.98/ewe in 2001-02, and $7.09/ewe in 2002-03) but in years of lower wool prices, it decreased profits.
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