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Zhu Y.,University of Adelaide | Taylor C.,Future Farming Systems Research | Sommer K.,Future Farming Systems Research | Wilkinson K.,University of Adelaide | Wirthensohn M.,University of Adelaide
Acta Horticulturae | Year: 2014

The effects of deficit irrigation on almond fatty acid and tocopherol levels were studied in a field trial. Mature almond trees were subjected to three levels of deficit irrigation (85, 70 and 55%), compared to control (100%) and over-irrigation (120%). Two deficit strategies were used: regulated deficit irrigation (RDI) and sustained deficit irrigation (SDI). Results from two harvest years showed moderate deficit irrigation (85% RDI and 85% SDI) had no negative impacts on almond kernel lipid content. Moderate to severe deficiency, 70 and 55% had variable impacts on lipids. USFA and SFA fluctuated under the treatments and no fatty acid was resistant to water deficiency. γ-Tocopherol levels were relatively stable under deficit irrigation but not α, β-tocopherol and α-tocotrienol. The variation between years indicated climate has an effect on almond fruit development. We concluded it is feasible to irrigate almond trees using less water than the normal requirement, without the loss of kernel nutrition quality.

Lopresti J.,Future Farming Systems Research | Goodwin I.,Future Farming Systems Research | Golding J.,Australian Department of Primary Industries and Fisheries | Holford P.,University of Western Sydney | McGlasson B.,University of Western Sydney
Acta Horticulturae | Year: 2015

Variation in soluble solids concentration (SSC) in fruit within a tree can significantly reduce the proportion of harvested peach and nectarine that meets consumer requirements. Accumulation of SSC during fruit growth may be influenced by cell number and size in mesocarp tissue. The relationship between sucrose, the major component of SSC, and both cell size and number was investigated in Prunus persica 'Summer Flare 26' nectarine. Variation in sucrose concentration within, and between fruit, was partly explained by cell size as measured by cell area or cell number per fixed area of tissue. This correlation was consistent within fruit categorised as ripe and unripe. Sucrose concentration was moderately correlated to cell number per fixed area in small and medium-sized fruit but not in large fruit. Total sucrose content in fruit within three positions in a tree was strongly correlated to total cell number but the relationship was mediated by cell size, particularly in fruit from the middle and bottom of the tree. Sink size (i.e., total cell number) and sink activity (i.e., cell size), were able to explain 77% of variation in sucrose content between fruit within a single tree. Further anatomical studies on a larger fruit population are being conducted to confirm these findings. © 2015 ISHS.

Devadas R.,University of Vic | Jones S.D.,University of Vic | Fitzgerald G.J.,Grains Innovation Park | Mccauley I.,Future Farming Systems Research | And 5 more authors.
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2010

Water and Nitrogen (N) are critical inputs for crop production. Remote sensing data collected from multiple scales, including ground-based, aerial, and satellite, can be used for the formulation of an efficient and cost effective algorithm for the detection of N and water stress. Formulation and validation of such techniques require continuous acquisition of ground based spectral data over the canopy enabling field measurements to coincide exactly with aerial and satellite observations. In this context, a wireless sensor in situ network was developed and this paper describes the results of the first phase of the experiment along with the details of sensor development and instrumentation set up. The sensor network was established based on different spatial sampling strategies and each sensor collected spectral data in seven narrow wavebands (470, 550, 670, 700, 720, 750, 790 nm) critical for monitoring crop growth. Spectral measurements recorded at required intervals (up to 30 seconds) were relayed through a multi-hop wireless network to a base computer at the field site. These data were then accessed by the remote sensing centre computing system through broad band internet. Comparison of the data from the WSN and an industry standard ground based hyperspectral radiometer indicated that there were no significant differences in the spectral measurements for all the wavebands except for 790nm. Combining sensor and wireless technologies provides a robust means of aerial and satellite data calibration and an enhanced understanding of issues of variations in the scale for the effective water and nutrient management in wheat.

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