Exposure of ferredoxin-dependent glutamate synthase (EC 1.4.7.1) mutants of Arabidopsis thaliana to photorespiratory conditions resulted in the accumulation of NH(4) (+) and the inhibition of photosynthesis. However, upon transfer from 2% O(2), 350 microliters per liter CO(2), to 21% O(2), 350 microliters per liter CO(2), net photosynthesis declined at a slower rate in methionine sulfoximine tr...

Previous studies suggest that the radiative effects of atmospheric aerosols (reducing total radiation while increasing the diffuse fraction) can enhance terrestrial productivity. Here, simulations using a regional climate/terrestrial biosphere model suggest that atmospheric aerosols could also enhance terrestrial photosynthesis and transpiration through an interaction between solar radiation, l...

Coupled land surface and terrestrial ecosystem models are used to simulate energy and carbon fluxes over winter wheat at the Ponca City, Oklahoma, Ameriflux site. The terrestrial ecosystem model consists of photosynthesis and respiration (autotrophic and heterotrophic) sub-modules, which uses canopy temperature, soil moisture, and soil temperature simulated by the land surface scheme. The photo...

We examined the effects of elevated CO2 concentration ([CO2]) on leaf demography, late-season photosynthesis and leaf N resorption of overstory sweetgum (Liquidambar styraciflua L.) trees in the Duke Forest Free Air CO2 Enrichment (FACE) experiment. Sun and shade leaves were subdivided into early leaves (formed in the overwintering bud) and late leaves (formed during the growing season). Overal...

Soybean plants (Glycine max var. Ransom) were grown at light intensities of 850 and 250 mueinsteins m(-2) sec(-1) of photosynthetically active radiation. A group of plants was shifted from each environment into the other environment 24 hours before the beginning of the experiment. Net photosynthetic rates and stomatal conductances were measured at 2,000 and 100 mueinsteins m(-2) sec(-1) photosy...

We tested for a tradeoff across species between plant maximum photosynthetic rate and the ability to maintain photosynthesis under adverse conditions in the unfavorable season. Such a trade-off would be consistent with the observed trade-off between maximum speed and endurance in athletes and some animals that has been explained by cost-benefit theory. This trend would have importance for the g...

Potential increases in plant productivity in response to increasing atmospheric CO(2) concentration are likely to be constrained by nutrient limitations. However, the interactive effects of nitrogen nutrition and CO(2) concentration on growth are difficult to define because both factors affect several aspects of growth, including photosynthesis, respiration, and leaf area. By expressing growth ...

1. By using EDTA in reaction mixtures it was possible to determine the activity of sucrose phosphate synthetase in freshly prepared leaf extracts without the complications caused by sucrose phosphatase. 2. EDTA was found also to increase the activity of sucrose phosphate synthetase by as much as 100%. 3. High sucrose phosphate synthetase activities were found in leaf preparations in which sucro...

Four-week-old French Colombard plants rooted from green cuttings were inoculated with 0, 1,000, 2,000, 4,000, or 8,000 Meloidogyne incognita second-stage juveniles and maintained at 25 C night and 30 C day. Leaf area and dry weight and the rates of photosynthesis, stomatal conductance, and internal leaf CO concentration were measured at intervals up to 59 days after inoculation. Nematode stress...

Four-week-old French Colombard plants rooted from green cuttings were inoculated with 0, 1,000, 2,000, 4,000, or 8,000 Meloidogyne incognita second-stage juveniles and maintained at 25 C night and 30 C day. Leaf area and dry weight and the rates of photosynthesis, stomatal conductance, and internal leaf COs concentrat ion were measured at intervals up to 59 days after inoculation. Nematode stre...