Sustained growth and increased tolerance to glyphosate observed in a C3 perennial weed, quackgrass (Elytrigia repens), grown at elevated carbon dioxide

2000 ◽  
Vol 27 (2) ◽  
pp. 159 ◽  
Author(s):  
Lewis H. Ziska ◽  
John R. Teasdale

Although the response of crop plants to rising atmospheric carbon dioxide concentration ([CO2]) has been well characterized, little is known concerning the long-term growth and/or photosynthetic response of peren-nial weeds. The growth and photosynthetic characteristics of three cohorts of a perennial C3 weedy species, quack-grass (Elytrigia repens (L.) Nevski) were examined at ~380 µmol mol−1 (ambient) and 720 µmol mol−1 (elevated) [CO2] in temperature-controlled greenhouses during 1998 and early 1999. Different cohorts were used to assess the sensitivity of growth, photosynthesis and glyphosate tolerance to elevated [CO2] for different stages in the life cycle of quackgrass. For the ‘old’ cohort, planted on Day of Year (DOY) 187, elevated [CO2] resulted in a consistent stim-ulation of single leaf photosynthesis, vegetative and whole plant biomass relative to the ambient [CO2] condition over a 231-d period. Data from the ‘intermediate’ (DOY 268) and ‘young’ cohorts (DOY 350) indicated that the stimula-tion of biomass at the elevated [CO2] was time-dependent. To determine if the observed stimulation of growth at ele-vated [CO2] altered tolerance to chemical weed control, glyphosate [(N-phosphonomethyl)glycine] was applied to each cohort and each [CO2] treatment at rates of 0 (control) and 2.24 kg ai ha−1 (sprayed). Tolerance was determined by following the growth and slope of each cohort at the growth [CO2] treatment for a 28-d period following glyphosate application. For the young cohort, [CO2] had no affect on glyphosate tolerance; however, an application rate of 2.24 kg ai ha−1, reduced but did not eliminate growth for the intermediate and old cohorts grown at elevated [CO2]. The basis for increased glyphosate tolerance at elevated [CO2] for these cohorts was unclear, but was not related to plant size at the time of glyphosate application. Data from this experiment indicate that sustained stimula-tion of photosynthesis and growth in perennial weeds could occur as atmospheric [CO2] increases, with a reduction in chemical control effectiveness and potential increases in weed/crop competition.

2013 ◽  
Vol 40 (2) ◽  
pp. 101 ◽  
Author(s):  
Alexander A. T. Johnson

Roughly half of the Earth’s seven billion people rely on rice as their primary source of food. The milled grain of rice, often referred to as polished or white rice, serves as a rich source of energy but is low in protein and several essential micronutrients such as iron and zinc. As a result, billions of people in rice-based countries suffer the debilitating effects of protein-energy and micronutrient malnutrition with symptoms including iron-deficiency anaemia, growth retardation and blindness. By 2050, the Earth’s atmospheric carbon dioxide concentration ([CO2]) is expected to reach 550 μmol mol–1, representing a 70% increase from today’s concentration of 392 μmol mol–1. The impacts of elevated [CO2] on plant growth will likely include agronomically useful traits such as increased biomass, yield and water-use efficiency. However, increased plant productivity is likely to be accompanied by decreased protein and micronutrient mineral concentrations of cereal grain. This review focuses on the effects of carbon dioxide-enrichment on rice physiology and nutritional composition and proposes increased activity of the Strategy II iron uptake pathway as a promising method to maintain or increase iron and zinc concentrations in rice grain, and perhaps cereal grain in general, under elevated [CO2].


2018 ◽  
Author(s):  
Oscar A. Douglas-Gallardo ◽  
Cristián Gabriel Sánchez ◽  
Esteban Vöhringer-Martinez

<div> <div> <div> <p>Nowadays, the search of efficient methods able to reduce the high atmospheric carbon dioxide concentration has turned into a very dynamic research area. Several environmental problems have been closely associated with the high atmospheric level of this greenhouse gas. Here, a novel system based on the use of surface-functionalized silicon quantum dots (sf -SiQDs) is theoretically proposed as a versatile device to bind carbon dioxide. Within this approach, carbon dioxide trapping is modulated by a photoinduced charge redistribution between the capping molecule and the silicon quantum dots (SiQDs). Chemical and electronic properties of the proposed SiQDs have been studied with Density Functional Theory (DFT) and Density Functional Tight-Binding (DFTB) approach along with a Time-Dependent model based on the DFTB (TD-DFTB) framework. To the best of our knowledge, this is the first report that proposes and explores the potential application of a versatile and friendly device based on the use of sf -SiQDs for photochemically activated carbon dioxide fixation. </p> </div> </div> </div>


It is known that past periods of high atmospheric carbon dioxide concentration are associated with poor carbonate preservation in the deep-ocean sedimentary record. Bottom water can become more aggressive towards carbonate sediments during such periods. To interpret the sedimentary record more exactly, and to predict future atmospheric carbon dioxide levels, it is necessary to know the rate of solution of carbonate for a given degree of bottom-water undersaturation. In parts of the Atlantic Ocean, turbidite sedimentation mechanisms have emplaced carbonate-rich material in contact with undersaturated bottom water. The time of the emplacement event can be determined from natural radionuclide distributions, and the degree of carbonate dissolution in this time can be measured. This provides a direct measurement of dissolution rate from a natural sediment surface at a known degree of undersaturation. The range of applicability of the method is explored with a mathematical model, and field data from a 5430 m depth Atlantic site are presented.


1964 ◽  
Vol 44 (1) ◽  
pp. 87-95 ◽  
Author(s):  
F. G. Proudfoot

A total of 9360 eggs was used in two series of experiments to study the effect of pre-incubation treatments on hatchability, egg weight, and chick weight. These treatments involved plastic packaging, alterations in atmospheric carbon dioxide, temperature, humidity, and time during the pre-incubation stage.Hatchability was maintained at a higher level when eggs were enclosed in plastic film during the pre-incubation period. There was also evidence that plastic packaging was more beneficial when eggs were held at adverse temperatures. Temperatures from 50 to 66° F did not appear to have a detrimental effect on hatchability when eggs were held for short storage periods. An increase in the carbon dioxide concentration in the egg storage environment depressed hatchability.Long pre-incubation holding periods tended to decrease egg weight at setting time and at the 18th day of incubation but appeared to increase chick weight. Temperatures ranging from 50 to 64° F had little effect on egg and chick weights. High humidity levels increased egg weight (when eggs were not enclosed in plastic packages) but this weight difference disappeared during incubation.


2017 ◽  
pp. 185-188
Author(s):  
András Tamás ◽  
Ágnes Törő ◽  
Tamás Rátonyi ◽  
Endre Harsányi

The atmospheric concentration of carbon dioxide increases from decade to decade in increasing pace. In 1957, atmospheric carbon dioxide levels were around 315 ppm, while in 2012 it amounted to 394.49 ppm concentration. In parallel, the global temperature is rising,which is projected to average 1.5–4.5 °C. The carbon dioxide concentration is a key factor – in interaction with the light – affects the plant's photosynthesis. Among the various factors significant interactions prevail: environmental factors affect - the growth and the development of plants, leaf area size and composition, the function of the photosynthetic apparatus, the duration of growing season.


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