No abstract

Seasonal variations in taxane concentrations in Taxus canadensis Marsh. (Canada yew) were measured at 15 sampling dates from September 2004 to September 2005 by clipping 3-year-old shoots from the same 15 plants. Four age classes of needles and stems were separated and individually weighed and analyzed for the three major taxanes in T. canadensis: 10-deacetylbaccatin III (10-DAB III), 9-dihydro-13-acetylbaccatin III (9-DHAB III), and paclitaxel (PAC). The dry weight fraction of each foliage age class decreased with increasing age; that is, proportionately more young than old foliage (current > current + 1 year > current + 2 year) was present in a 3-year-old stem. The ratio of needle:stem dry weight also decreased with increasing foliage age. Taxane concentrations varied widely, depending on the tissue, its age, and time of year. Peak concentrations were observed for a short period at the end of the growing season (August-September). The lowest taxane levels were found during the period of active growth: April through July. PAC and 9-DHAB III concentrations were higher in needles, but young stems contained the highest amounts of 10-DAB III. Levels of all three taxanes were higher in young than in old stems, likely due to increasing amounts of taxane-poor stem wood. Composite taxane concentrations were calculated for 3-year-old foliage from the component needle and stem weights and taxane analyses. It is suggested that summer harvesting between April and July (the low point in annual taxane levels) yields the poorest quality biomass, and harvesting from August onward is preferable.

Two experiments in black spruce (Picea mariana (Mill.) BSP) seedling seed orchards were established to determine if a stem injection of paclobutrazol (2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl) could be used as an adjunct treatment to increase the efficacy of stem injections of gibberellins A4 and A7 (GA4/7). Trees received a single injection of GA4/7 and (or) paclobutrazol shortly after vegetative bud burst. There was a dose-dependent but nonlinear increase in the production of cones of both sexes in response to stem injections of either GA4/7 or paclobutrazol. The optimum rate of GA4/7 for stimulating pollen-cone production was 3.3 mg, whereas the most seed cones were induced on trees receiving 11 mg. The sex ratio (number of seed cones/number of pollen cones) increased with the rate of GA4/7 applied. Injecting paclobutrazol also promoted cones of both sexes equally, resulting in sex ratios comparable with that of the control trees. Treatments did not affect the total numbers of buds (vegetative, latent, and cone) produced. Seed- and pollen-cone buds occurred in positions that would have otherwise developed vegetatively and become latent, respectively. The mechanisms whereby paclobutrazol could affect flowering in black spruce are discussed. The use of paclobutrazol as an adjunct to GA4/7 treatments in black spruce seedling seed orchards appears effective, practical, and safe.

The Great Australian Bight Research Program (the Program) has been a 4-year, $20 million research collaboration involving BP, CSIRO, the South Australian Research and Development Institute (SARDI), the University of Adelaide and Flinders University. The Program is generating a whole-of-system understanding of the environment (physical and biological), economic and social values of the region and providing a public information source for all to use. It is one of the few whole-of-system studies ever undertaken in Australian waters and is the first large-scale, integrated study of the Great Australian Bight. Considered prospective for oil and gas, the region is also one of Australia’s most valuable marine ecosystems; supporting globally significant populations of seabirds, marine mammals and diverse and highly endemic benthic assemblages, as well as important fishing, aquaculture and ecotourism industries. The goal of the Program was to obtain information and understanding to better inform the balance of human activity and sustainability in the region. The Program involved more than 100 of Australia’s leading scientists organised around seven themes: Oceanography, Pelagic ecosystem and environmental drivers, Benthic biodiversity, Ecology of iconic species and apex predators, Petroleum geology and geochemistry, Socioeconomic analysis, and Integration and modelling. Through the multidisciplinary approach, supported by two Marine National Facility research voyages in 2013 and 2015 and use of the Integrated Marine Observing System facilities and datasets, the Program is building the first integrated model of the biological and physical systems of the Great Australian Bight.