This paper describes an innovative method, commonly referred to as
‘spider mapping’, that allows pasture biomass and related data to
be collected over large areas in a timely and efficient manner. Spider mapping
was developed initially to collect data to allow calibration and validation of
a spatial and temporal pasture growth model operating across Queensland on a 5
km grid basis. Two field officers made over 220 000 estimates and collected
about 1300 samples of pasture biomass between January 1994 and August 1995. A
number of selected biomass samples were analysed for nitrogen, phosphorus and
carbon content. In addition, data were also collected on foliage projective
cover and tree basal area for a range of woodland communities and both
variables compared with mean long-term Normalised Difference Vegetation Index
values derived from a time series of National Oceanographic and Atmospheric
Administration satellite imagery. Both variables were strongly related to the
satellite data with overstorey foliage projective cover having the strongest
non-linear correlation (r2
= 0.91). The method described here is currently being used in related
work in the rangelands of New South Wales, South Australia, Western Australia
and the Northern Territory.
Sucrose is the dominant accumulated carbohydrate in the wheat plant until approximately 4 weeks before harvesting, when starch takes this position. Starch is the dominant carbohydrate in the grain. Total reducing sugars are never accumulated in large amounts in any portion of the plant. The mature mottled grain contains significantly more starch and less protein than the unmottled. The developing grain from an area known to produce mottled wheat is always higher in starch and lower in protein when compared with grain from an unmottled area. Irrespective of variety and whether the grain is mottled or not, starch extracted from the mature grain contains 22.4 per cent. amylose, and there appear to be no major differences between the starches extracted from the respective grains. It is probable that while the ratio of amylose to amylopectin is set by heredity, the molecular size of these components varies as starch is laid down in the developing grain.
Ascorbic acid at a concentration of 10−3 M was a more effective pro‐oxidant in the presence of low copper concentrations than at high concentrations, particularly in the initial stages of oxidation or in the lower pH range (5·5–4·7). This suggested a much more complex role for ascorbic acid than that of copperreducing agent. Reaction of the ascorbic acid radical with oxygen and consequent formation of free HO' radicals was considered to be the most likely initiation reaction resulting from the oxidation of ascorbic acid to dehydroascorbic acid by copper. Dehydroascorbic acid was also found to be an effective pro‐oxidant in the presence of copper.
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