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There is widespread belief among the scientific community that anthropogenic-driven climate change is occurring and that it poses a serious global threat. Atmospheric concentrations of the three most important long-lived greenhouse gases (GHG) have

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amount of N applied for the accounting of N 2 O emissions from agricultural soils ( IPCC, 1997 ). Greenhouse gas emission variations found in the literature are due to a variety of factors ( Mosier et al., 1996 ; Smith et al., 2003 ) including crop, soil

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Abstract

Exhaust gases from a turbine fired with natural gas were used for heating and CO2 enrichment in a double-layered, polyethylene-covered greenhouse. The exhaust gases were passed between the inner and outer layers of the greenhouse covering. The warm inner layer supplied the heating requirements and acted as a selectively permeable membrane (patent pending). This resulted in greenhouse CO2 levels from 1200 to 3000 ppm, but kept the NO2 found in the exhaust gas below toxic levels. This system resulted in significantly greater yields of marketable tomatoes (Lycopersicon esculentum Mill.) as well as substantially reduced heating costs.

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The effect of drought on the growth and gas exchange of six bedding plant species—agastache [Agastache urticifolia (Benth.) O. Kuntze `Honeybee Blue'], dusty miller (Cineraria maritima L. `Silverdusty'), petunia (Petunia ×hybrida `Wave Purple'), plumbago (Plumbago auriculata Lam. `Escapade'), ornamental pepper (Capsicum annuum L. `Black Pearl'), and vinca [Catharanthus roseus (L.) G. Don `Titan']—was quantified under greenhouse conditions. Seeds were sown in January and seedlings were grown in the greenhouse until 18 Apr., when two irrigation treatments—drought (D, ≈18% volumetric moisture content at reirrigation) and control (C, ≈25% volumetric moisture content at reirrigation)—were initiated. Leaf net photosynthetic rate (Pn), stomatal conductance (gs), and transpiration (E) were determined in response to a range of substrate moisture content (from ≈5% to 30% by volume) and temperature (from 20 °C to 40 °C). Dry weight of agastache, ornamental pepper, and vinca was unaffected by drought, whereas that of other species was reduced. Leaf area of plumbago and height of plumbago and vinca were reduced by drought. As substrate moisture content decreased from 25% to 10%, Pn, E, and gs decreased linearly in all species except petunia and plumbago. Leaf net photosynthetic rate of all species declined as leaf temperature increased from 20 °C to 40 °C. In contrast, E of all species, except petunia, increased as temperature increased. Transpiration rate of petunia increased as temperature increased from 20 °C to 30 °C, and then decreased between 30 °C and 40 °C. Although petunia had the highest Pn among the tested species, its Pn and gs declined more rapidly compared with the other species as temperature increased from 20 °C to 40 °C or as substrate moisture content decreased, indicating that petunia was most sensitive to high temperature and drought.

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gas exchange rates provide hydroponic greenhouse growers with reference information useful to select EC levels that can increase the fruit quality while minimizing the potential yield reduction. Conclusions The photosynthetic and transpirational

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for heating greenhouse tomatoes. Using natural gas would restrict greenhouse tomato growers to locate their business near a network of underground supply lines or extend a costly supply line to their greenhouse location. Propane is a gaseous fuel much

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provide saturated light conditions necessary for plant growth and gas exchange measurements. Temperature and light conditions in the greenhouse were regulated using a reflective curtain and overhead fans. A variable number of healthy, fully expanded

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. Several best management practices have been developed for reducing emissions of CO 2 ( Paustian et al., 2000 ), CH 4 ( Mosier et al., 1998 ), and N 2 O ( Snyder et al., 2007 ) from agricultural production. Other programs such as Greenhouse Gas Reduction

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assessment is a tool that has been used to evaluate the environmental portion of the triple-bottom-line of products from cradle to grave or defined subsets of their life cycle. Greenhouse gas emissions and the subsequent CF have been reported for nursery crop

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,000 plus labor for a 24 × 75-ft greenhouse ( Lambe et al., 2012 ). To address the consumption of water and energy, the heat was provided by two gas furnaces (one would have been sufficient) with the venting organized such that the polyethylene tubes that

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