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1	Superoptimal CO2 Reduces Seed Yield in Wheat Grotenhuis, Timothy P. 01 May 1996 (has links) Although projected terrestrial CO2 levels will not reach 1000 μmol moI-1 (0.1%) for many decades, CO2 levels in growth chambers and greenhouses routinely exceed that concentration. CO2 levels in life support systems in space can exceed 10,000 μmol moI-1 (1%) CO2. Numerous studies have examined CO2 effects up to 1000 μmol mol-1, but theoretical and some experimental evidence indicates that the beneficial effects of CO2 continue past 1000 μmol mol-1 and are near-optimal for wheat at about 1200 μmol mol-1. We studied the effects of near-optimal and superoptimal CO2 levels (>1200 μmol mol-1) on yield of two cultivars of hydroponically grown wheat in 12 trials. Increasing CO2 from suboptimal to near-optimal (350 to 1200 μmol mol-1) increased vegetative growth by 25% and seed yield by 15% in both cultivars. Yield increases were primarily the result of an increased number of heads m-2. Further elevation of CO2 to 2500 μmol mol-1reduced seed yield by 22% in cv. 'Veery-10' and by 15% in cv. 'USU-Apogee'. Superoptimal CO2 did not decrease the number of heads m-2, but reduced seeds per head by 10% and mass per seed by 11%. CO2 toxicity occurred over a wide range of light levels. Subsequent trials revealed that superoptimal CO2 in the 2 weeks before and after anthesis mimicked the effect of constant superoptimal CO2. Furthermore, near-optimal CO2 in the 2 weeks before and after anthesis mimicked the effect of constant near-optimal CO2. Nutrient concentration of leaves and heads was not affected by CO2. The yield decreases may be a response mediated by ethylene. superoptimal CO2 seed yield wheat Plant Sciences
2	Effects of Air vs. Air+Soil Heating During a Simulated Heat Wave on White Oak (Quercus alba) and Black Oak (Quercus velutina) Lightle, Nicole E. 22 August 2013 (has links) No description available. Ecology Environmental Science Forestry Physiology Plant Sciences Plant Biology Urban Forestry acute heat heat stress heat wave extreame weather soil heating superoptimal temperature root zone temperature global climate change white oak black oak Quercus forest mortality thermotolerance photosynthesis root respiration ABA

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Superoptimal CO2 Reduces Seed Yield in Wheat

Effects of Air vs. Air+Soil Heating During a Simulated Heat Wave on White Oak (Quercus alba) and Black Oak (Quercus velutina)