Centre for Plant & Water Science - Central Queensland University

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Centre for Plant & Water Science 2008 Annual Report STABILISATION OF RAIL FORMATIONS USING NATIVE VEGETATION SUMMARY Presence of woody vegetation in the vicinity of rail tracks is known to improve stability of rail formation in cracking clayey soils (Potter and Cameron 2005). This concept was tested at Banana, central Queensland, by establishing over 100 native species on either side of the rail track (Fig 1.). The established trial is being maintained and will be monitored when funded by the Rail CRC. During 2008, more than 65% of the established species have survived and produced appreciable amount of plant canopy (Fig 1.). Although equal number of seedlings was planted in each plot, some species have produced denser canopies than the others. Some coastal species that lacked frost tolerance have died and this area has been covered with local grasses. Some species are performing very well and have produced seeds. We plan to study changes in plant diversity, as the new seedlings are recruited from the seeds. We also plan to compare hydraulic properties of planted (perennial vegetation) and unplanted (annual vegetation) areas to delineate the effects of perennial vegetation on rail track stability. This information will finally help minimise maintenance costs of rail tracks as well as providing ecological sustainability to rail tracks. Fig 1. The Experimental site in 2007 (top) and in 2008 (bottom) PROJECT STAFF Principal Investigator: Co-Principal Investigator: Others: FUNDING CRC Rail INCOME $1,142 Associate Professor N. Ashwath Dr Don Cameron (UniSA) Darryl Nissen (QR), Ajay Sharma 45
Centre for Plant & Water Science 2008 Annual Report EXPLORING THE RESPONSE OF SOME VEGETABLE SPECIES TO OXYGATION SUMMARY Various trials, with and without plants, evaluated a number of aspects of oxygation. Four species including pak choy, beetroot, shallot, and dwarf bean were studied in a pot experiment to examine their response to oxygation. The results showed that except for shallot, the other vegetables did not show significant increase in yield or yield components due to oxygation. The effect of pipe size, water cross sectional area, the geometry of joiners, and non-ionic surfactant at various concentrations on air flow rate distribution along a 20 m lateral line was also studied to understand uniformity of supply within a field situation. The response of pak choy, beetroot, shallot, and dwarf bean grown in 26 L pots to oxygation was studied. For each species, the experiment was laid out as a Completely Randomized Block Design (CRBD), replicated four times with two treatments, irrigation with aerated water by means of air injector venturi or control. In addition to the crop yield, soil oxygen concentration, soil respiration rate, leaf chlorophyll concentration, photosynthetically active radiation, transpiration rate, stomatal conductance and photosynthesis rate for aerated and non-aerated treatments were measured during the growing season. Aerated shallots in contrast to control ones showed significant higher performance in terms of leaf chlorophyll concentration, soil respiration rate, leaf length, leaf count and leaf weight per unit area at 5% level of confidence. The other vegetable species did not show significant response to oxygation. Production of aerenchyma and/or shallow roots might be responsible for lack of response in the other species. Three pipe sizes of 13 mm, 19 mm, and 25 mm and two types of pot emitters of 0.52 mm 2 (1.2 L h -1 ) and 1.25 mm 2 (4 L h -1 ) water cross sectional area along with symmetric and asymmetric joiners spaced at 50 cm intervals on 20 m long recirculating pipes were tested. Generally, distribution of air flow rates in all trials was non-uniform. The closer the emitter to the venturi, the higher the air flow rate. The result of paired t-test performed on the air flow rates for a 19 mm pipe with asymmetric joiners indicated that the cross sectional area of the emitters had no significant effect on the air flow rate distribution at 5% level of confidence. By means of the same test, it was revealed that asymmetric joiners in contrast to symmetric ones cause significantly higher air flow rates along the pipe line regardless of the pipe size. Furthermore, with symmetric joiners, the smaller the pipe size, the higher will be the average of the air flow rate along the pipe; this trend was reversed if asymmetric joiners are used in the line. Application of a non-ionic surfactant (BS 1000) at 20, 35, 50, 65, 80, and 100 ppm concentrations in a non-recirculating partially open-end 20 m pipe of 19 mm ID with asymmetric joiners and 4 L h -1 pot drippers resulted in enhanced air flow rate uniformity, where the minimum surfactant concentration for yielding the highest air flow rate uniformity (CUC=80%) was 65 ppm. PROJECT STAFF Principal Investigator: Manouchehr Torabi Co-Principal Investigator: Prof David Midmore Others: Dr Surya Bhattarai & Dr Xinming Chen FUNDING Cotton CRC, CQUniversity INCOME $4,497 46
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Centre for Plant & Water Science - Central Queensland University

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