Controlled environment chamber

Fig. 1. Elongation rate of stem intemode 12 (A), silks (A), leaf 8 ( ), and nodal roots (O) of maize at various water potentials. Elongation rates are the average per hour for 24 h of growth in a controlled environment chamber. Water potentials were measured in the growing region of each organ in the same plants. Samples were taken immediately after the growth period when the plants had been in the dark for the last 10 h. Each point is from a single plant. Modified from Westgate Boyer (1985a).

A survey of the environmental control and monitoring technology used in several experimental studies indicated significant limitations in experimental control capability. There are seven controlled-environment chambers or clean-room facilities in the United States for human exposure (community air pollution inhalation) from which studies have been reported. Another is under construction at the University of North Carolina in association with the epa at Chapel Hill. There are three chambers in Canada of similar design. 

Over 50 different pyridazin-3-ones were evaluated for biological activity in a wheat (Triticum aestivum L.) test system described previously (1). Briefly, seeds were germinated in 9-cm petri dishes on three layers of filter paper. Pyridazinones were dissolved in acetone and the filter papers were impregnated with 1 ml of acetone solution. After the soluent evaporated, 10 ml of distilled water were added to form an inhibitor concentration of 100 yM. Seeds were planted directly on the moist papers and germinated for 4 days in a controlled environment chamber on a 16-hr photoperiod with 27+lC day temperature and 21+lC night temperature. Light intensity from both fluorescent and incandescent bulbs was 28 klux at dish level. Lipids were extracted and recovered from 1 g of lyophilized shoot tissue, separated into membrane and non-membrane lipids, and analyzed by gas chromatography as described (1). 

Leaf discs (10 per treatment) were punched out with a 18-mm-dlameter cork borer Insecticide-treated discs were in a 0.008% (w/v) solution of carbaryl in acetone, and control discs were dipped in acetone alone and allowed to dry. One caterpillar was placed on each disc and held for 24 hr in a 1-oz creamer cup placed in a controlled-environment chamber (25 C, 16/8 hr llgbt/dark)... 

Growth of Seedlings. Cucumber (Cucumis sativus L., cv. Wisconsin SMR-IS) and soybean (Glycine max L. Merr., cv. Wayne) were grown in vermiculite and watered daily in a controlled environment chamber (26 2 C day, 21 2 C night) on a 12 hr photoperiod (eight 30-W cool-white fluorescent tubes plus four 25-W incandescent bulbs 200+foot-candles). The balanced nutrient solution of Frick and Mohr (H9), modified to include 1 g/1 Ca(N03)2 but without sucrose, succinic acid and kinetin, was applied on alternate days. 

In choosing a lamp for a controlled-environment chamber for growing plants, both the total energy emitted and the wavelength distribution of the photons should be considered. Tungsten lamps are comparatively poor sources of visible radiation because about 90% of their radiant energy is emitted in the IR—the actual amount depends on the operating temperature... 

Particle obsawation and manipulation were performed on the stage of a Digital Instruments (Santa Barbara, CA) Nanoscope III scanning force microscope mounted in a controlled environment chamber. The humidity was adjusted by introducing a controlled mixture of dry and humidified air. The RH in the chamber was continuously monitored with a BioForce... 

In a later study (13), a controlled environment chamber was used to identify direct and possible synergistic effects of SO, NO, and... 

A unique chemiluminescence photon-counting system, designed specifically for measurement of stress-enhanced polymer reactions, was used for the studies described here. This system Includes a miniature tensile stress device, a controlled environment chamber and a luminescence detection system and associated optics Integrated Into a single unit. 

Figure 3. Controlled Environment Chamber (CEEC) Showing IR Transfer Optics...

Spinach plants (Spinacia oleracea) used in this study were grown in a controlled environment chamber as previously described (5). 

Two reindeer (Rangifer tarandus) were placed in stalls located within controlled environment chambers, and 1(X) xCi HTO was injected into their jugular veins. Periodically, blood samples were inspected for radioactivity. This study of body-water volume and turnover was conducted using 12 different combinations of diet and temperature. A comparison of water-flux rate, as determined with HTO, to measured water input showed a linear relationship (Figure 48). The investigators (Cameron et aL, 1976) concluded that the tritium water dilution technique provided accurate determinations of total-body-water flux over the wide range of experimental conditions in reindeer. 

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