Cooperative Research Centre

About: Cooperative Research Centre is a based out in . It is known for research contribution in the topics: Population & Sea ice. The organization has 7633 authors who have published 8607 publications receiving 429721 citations.

Grana stacking and protection of Photosystem II in thylakoid membranes of higher plant leaves under sustained high irradiance: An hypothesis

Abstract: We propose yet another function for the unique appressed thylakoids of grana stacks of higher plants, namely that during prolonged high light, the non-functional, photoinhibited PS II centres accumulate as D1 protein degradation is prevented and may act as dissipative conduits to protect other functional PS II centres. The need for this photoprotective mechanism to prevent high D1 protein turnover under excess photons in higher plants, especially those grown in shade, is due to conflicting demands between efficient use of low irradiance and protection from periodic exposure to excessive irradiance.

Characterization of Iron–Polyphenol Nanoparticles Synthesized by Three Plant Extracts and Their Fenton Oxidation of Azo Dye

Abstract: In this paper, iron–polyphenol nanoparticles (Fe–P NPs) were synthesized using the extracts obtained from Australian native plant leaves, these being Eucalyptus tereticornis, Melaleuca nesophila, and Rosemarinus officinalis. The Fe–P NPs synthesized from the extracts were characterized using scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results show that the reaction between iron ions and polyphenols can form complex nanoparticles with sizes ranging from 50 to 80 nm, the surface of which presents organic characters. The synthesized nanoparticles were then utilized as a Fenton-like catalyst for decolorization of acid black 194 in solution. The batch experiments showed that 100% of acid black was decolorized, and over 87% total organic carbon (TOC) was removed. In addition, removal of acid black 194 fitted well to the pseudo-first-order model. Compared with the conventional Fenton reaction, the Fento...

Photosynthetic temperature responses of Eucalyptus globulus and Eucalyptus nitens.

Abstract: Steady-state photosynthetic responses to leaf temperature of 4-year-old Eucalyptus globulus Labill. and E. nitens (Deane and Maiden) Maiden trees were measured between 10 and 35 degrees C at approximately monthly intervals from early spring to midwinter. The photosynthetic temperature optimum of recently expanded leaves in the sun canopy was linearly related to the average temperature of the preceding week during the 9-month measurement period. The optimum temperature for net photosynthesis of E. globulus increased from 17 to 23 degrees C as the mean daily temperature increased from 7 to 16 degrees C. Similarly, the optimum temperature for net photosynthesis of E. nitens increased from 14 to 20 degrees C as the mean daily temperature increased from 7 to 19 degrees C. The temperature for maximum photosynthetic response of E. globulus and E. nitens was similar at each measurement time, but the photosynthetic performance of E. nitens was less sensitive to temperatures above and below this optimum than that of E. globulus. In December, the apical shoots of branches of E. globulus had a net photosynthetic temperature optimum of between 10 and 15 degrees C. The corresponding values for expanding leaves, fully expanded leaves from the current year's growth, and fully expanded leaves from the previous year's growth were 15, 20 and 20-25 degrees C, respectively. In a second experiment, E. globulus clones taken from four mother plants originating from climatically dissimilar locations within Tasmania were acclimated at day/night temperatures of 10/15, 18/23 and 25/30 degrees C in temperature-controlled greenhouses. Another set of clones was acclimated in a shadehouse where temperatures ranged between 10 and 25 degrees C and with a mean daily temperature of approximately 15 degrees C. Plants grown at 25/30 degrees C had significantly lower net photosynthetic rates when measured at 10 and 20 degrees C than plants grown at lower temperatures. Plants grown at 10/15 degrees C had significantly lower net photosynthetic rates when measured at 30 degrees C than plants grown at higher temperatures. Plants grown at the ambient conditions prevailing in midautumn in Hobart had significantly higher net photosynthetic rates at 20 degrees C than plants raised in the greenhouses and were equal best performers at 10 and 30 degrees C. A comparison of the light response curves of the plants showed that the maximum rate of net photosynthesis was affected by the growth temperature, whereas the apparent quantum efficiency remained unchanged. There were no significant differences in the photosynthetic temperature responses of the four genotypes derived from climatically dissimilar locations within Tasmania. A comparison of temperature response models for E. globulus indicated that incomplete acclimation (defined by a slope value of less than 1 for the linear relationship between the temperature optimum for photosynthesis and the growth temperature) generally resulted in a greater daily carbon uptake than complete acclimation (slope value of 1).

Factors regulating the contributions of fixed nitrogen by pasture and crop legumes to different farming systems of eastern Australia

Abstract: On-farm and experimental measures of the proportion (%Ndfa) and amounts of N2 fixed were undertaken for 158 pastures either based on annual legume species (annual medics, clovers or vetch), or lucerne (alfalfa), and 170 winter pulse crops (chickpea, faba bean, field pea, lentil, lupin) over a 1200 km north-south transect of eastern Australia The average annual amounts of N2 fixed ranged from 30 to 160 kg shoot N fixed ha−1 yr−1 for annual pasture species, 37–128 kg N ha−1 yr−1 for lucerne, and 14 to 160 kg N ha−1 yr−1 by pulses These data have provided new insights into differences in factors controlling N2 fixation in the main agricultural systems Mean levels of %Ndfa were uniformly high (65–94%) for legumes growing at different locations under dryland (rainfed) conditions in the winter-dominant rainfall areas of the cereal-livestock belt of Victoria and southern New South Wales, and under irrigation in the main cotton-growing areas of northern New South Wales Consequently N2 fixation was primarily regulated by biomass production in these areas and both pasture and crop legumes fixed between 20 and 25 kg shoot N for every tonne of shoot dry matter (DM) produced Nitrogen fixation by legumes in the dryland systems of the summer-dominant rainfall regions of central and northern New South Wales on the other hand was greatly influenced by large variations in %Ndfa (0–81%) caused by yearly fluctuations in growing season (April–October) rainfall and common farmer practice which resulted in a build up of soil mineral-N prior to sowing The net result was a lower average reliance of legumes upon N2 fixation for growth (19–74%) and more variable relationships between N2 fixation and DM accumulation (9–16 kg shoot N fixed/t legume DM) Although pulses often fixed more N than pastures, legume-dominant pastures provided greater net inputs of fixed N, since a much larger fraction of the total plant N was removed when pulses were harvested for grain than was estimated to be removed or lost from grazed pastures Conclusions about the relative size of the contributions of fixed N to the N-economies of the different farming systems depended upon the inclusion or omission of an estimate of fixed N associated with the nodulated roots The net amounts of fixed N remaining after each year of either legume-based pasture or pulse crop were calculated to be sufficient to balance the N removed by at least one subsequent non-legume crop only when below-ground N components were included This has important implications for the interpretation of the results of previous N2 fixation studies undertaken in Australia and elsewhere in the world, which have either ignored or underestimated the N present in the nodulated root when evaluating the contributions of fixed N to rotations