Investigations into the effects of elevated carbon dioxide and drought on the growth and physiology of carpet weed (Galenia pubescens Eckl. & Zeyh.)

The present study aimed to examine the interactive effects of elevated atmospheric CO2 concentration and drought stress on the growth and some of the physiological processes of Galenia pubescens. Photosynthetic rate of plants increased under elevated CO2 concentration, however drought caused significant reduction in net photosynthetic rate by (45% in 400 ppm CO2) and (27% in 700 ppm CO2) after five days simulating the drought treatment when compared with well-watered plants. Plants grown under elevated CO2 level and well-watered produced a greater biomass (17.5 ± 0.5 g per plant) compared to the plants which were grown under the ambient CO2 concentration

Impacts of elevated atmospheric CO₂ on nutrient content of important food crops.

One of the many ways that climate change may affect human health is by altering the nutrient content of food crops. However, previous attempts to study the effects of increased atmospheric CO2 on crop nutrition have been limited by small sample sizes and/or artificial growing conditions. Here we present data from a meta-analysis of the nutritional contents of the edible portions of 41 cultivars of six major crop species grown using free-air CO2 enrichment (FACE) technology to expose crops to ambient and elevated CO2 concentrations in otherwise normal field cultivation conditions. This data, collected across three continents, represents over ten times more data on the nutrient content of crops grown in FACE experiments than was previously available. We expect it to be deeply useful to future studies, such as efforts to understand the impacts of elevated atmospheric CO2 on crop macro- and micronutrient concentrations, or attempts to alleviate harmful effects of these changes for the billions of people who depend on these crops for essential nutrients

Annual ryegrass (Lolium rigidum Gaud) competition altered wheat grain quality: a study under elevated atmospheric CO2 levels and drought conditions

Annual ryegrass is one of the most serious, costly weeds of winter cropping systems in Australia. To determine whether its competition-mediated plant defence mechanisms effect on wheat grain quality, wheat (cv. Yitpi) and annual ryegrass were grown under two levels of CO (400 ppm; (a[CO]) vs 700 ppm; (e[CO]), two levels of water (well-watered vs drought) and two types of competition (wheat only; (W), and wheat × annual ryegrass; (W × R) with four replicates. The competition × [CO] interaction had a significant effect on wheat grain protein content, where it was increased in W × R under both e[CO] (+17%) and a[CO] (+21%). Grain yield, total grain reducing power and phenolic content were significantly affected by [CO] × drought × competition. In a summary, annual ryegrass competition significantly altered the wheat grain quality under both [CO] levels (depending on the soil water level), while also decreasing the grain yield

Impacts of elevated atmospheric CO2 on nutrient content of important food crops

One of the many ways that climate change may affect human health is by altering the nutrient content of food crops. However, previous attempts to study the effects of increased atmospheric CO2 on crop nutrition have been limited by small sample sizes and/or artificial growing conditions. Here we present data from a meta-analysis of the nutritional contents of the edible portions of 41 cultivars of six major crop species grown using free-air CO2 enrichment (FACE) technology to expose crops to ambient and elevated CO2 concentrations in otherwise normal field cultivation conditions. This data, collected across three continents, represents over ten times more data on the nutrient content of crops grown in FACE experiments than was previously available. We expect it to be deeply useful to future studies, such as efforts to understand the impacts of elevated atmospheric CO2 on crop macro- and micronutrient concentrations, or attempts to alleviate harmful effects of these changes for the billions of people who depend on these crops for essential nutrients

Wheat grain quality dynamics under elevated atmospheric CO2 concentration in Mediterranean climate conditions

© 2013 Dr. Nimesha D. FernandoSince 1959, carbon dioxide concentration [CO2] in the atmosphere increased from 315 µmol mol-1 to approximately 389 µmol mol-1 by 2009 in a rate of 1.5 µmol mol-1 per year. Within the next 50 years, atmospheric [CO2] will likely to rise to 550 µmol mol-1. Carbon dioxide is a greenhouse gas and a major factor that contributes to global warming. In parallel, global temperature is predicted to increase by an average of 1.5-4.5 ºC with more frequent occurrences of extreme climatic events such as heat waves and/or drought by the mid of this century. There is a limited understanding on the impact of elevated atmospheric [CO2] (e[CO2]) on wheat grain quality in semi-arid and Mediterranean cropping systems. The research reported in this thesis investigated the effects of e[CO2] on wheat grain physical, chemical, flour rheological properties under two main climate conditions: semi-arid and Mediterranean which represent the water-limited “mega-environment 4”, larger wheat grown area in the world as defined for wheat (Braun et al., 1996). The experiments were carried out using state art technology of free- air CO2 enrichment (FACE) facilities located in Walpeup and Horsham, Victoria, Australia. (See thesis for full abstract

Factors affecting seed germination of feather fingergrass (Chloris virgata)

Laboratory experiments were carried out to determine the effect of several environmental factors on seed germination of feather fingergrass, one of the most significant emerging weeds in warm regions of the world. Seed germination occurred over a broad range of temperatures (17/7, 25/10, and 30/20 C), but germination being highest at alternating temperatures of 30/20 C under both 12 h light/12 h dark and 24 h dark conditions. Although seed germination was favored by light, some seeds were capable of germinating in the dark. Increasing salt stress decreased seed germination until complete inhibition was reached at 250-mM sodium chloride. Germination decreased from 64 to 0.7% as osmotic potential decreased from 0 to -0.4 MPa, and was completely inhibited at -0.6 MPa. Higher seed germination (>73%) was observed in the range of pH 6.4 to 8 than the other tested pH levels. Heat shock had a significant effect on seed germination. Germination of seeds placed at 130 C for 5 min was completely inhibited for both dry and presoaked seeds. The results of this study will help to develop protocols for managing feather fingergrass, and to thus avoid its establishment as a troublesome weed in economically important cropping regions

Rising atmospheric CO2 concentration affects mineral nutrient and protein concentration of wheat grain

Wheat (Triticum aestivum L. cv. Yitpi) was grown in the Australian Grains Free-Air Carbon dioxide Enrichment (AGFACE) facility under current ambient [CO2] (384 μmol mol -1) and elevated [CO2] (550 μmol mol -1) in combination with two different times of sowing (TOS) to investigate the interactive effect of [CO2] and grain filling conditions on wheat grain quality. Grains were sampled at harvest maturity and their protein and mineral nutrient (Ca, S, Zn and Fe) concentrations were measured. Protein concentration of the grain was decreased by 12.7% at elevated [CO2] and the largest reduction in grain protein was observed at the later TOS (TOS 2). Concentration of grain S, Ca, Fe and Zn were also significantly decreased at elevated [CO2]. Most of the grain mineral nutrient concentrations were significantly increased at the TOS 2 suggesting that rising temperature together with increased water stress are likely to offset some of the negative effects of elevated [CO2] on grain mineral concentrations

Glyphosate resistance of C3 and C4 weeds under rising atmospheric CO2

The present paper reviews current knowledge on how changes of plant metabolism under elevated COconcentrations (e[CO]) can affect the development of the glyphosate resistance of Cand Cweeds. Among the chemical herbicides, glyphosate, which is a non-selective and post-emergence herbicide, is currently the most widely used herbicide in global agriculture. As a consequence, glyphosate resistant weeds, particularly in major field crops, are a widespread problem and are becoming a significant challenge to future global food production. Of particular interest here it is known that the biochemical processes involved in photosynthetic pathways of Cand Cplants are different, which may have relevance to their competitive development under changing environmental conditions. It has already been shown that plant anatomical, morphological, and physiological changes under e[CO] can be different, based on (i) the plant’s functional group, (ii) the available soil nutrients, and (iii) the governing water status. In this respect, Cspecies are likely to have a major developmental advantage under a COrich atmosphere, by being able to capitalize on the overall stimulatory effect of e[CO]. For example, many tropical weed grass species fix COfrom the atmosphere via the Cphotosynthetic pathway, which is a complex anatomical and biochemical variant of the Cpathway. Thus, based on our current knowledge of COfixing, it would appear obvious that the development of a glyphosate-resistant mechanism would be easier under an e[CO] in Cweeds which have a simpler photosynthetic pathway, than for Cweeds. However, notwithstanding this logical argument, a better understanding of the biochemical, genetic, and molecular measures by which plants develop glyphosate resistance and how e[CO] affects these measures will be important before attempting to innovate sustainable technology to manage the glyphosate-resistant evolution of weeds under e[CO]. Such information will be of essential in managing weed control by herbicide use, and to thus ensure an increase in global food production in the event of increased atmospheric [CO] levels

Building suitable restoration approaches in the Brownfields

Human activity has, in the recent past resulted in substantial changes in land cover, ecosystem health, and the ability of affected ecosystems to return to their original state. This necessitates further human intervention to recreate the systems functions than the present. Earlier restoration activities have not been documented extensively. This hinders our efforts to identify approaches that might support further work. "From abstract