scholarly journals Design, Modeling, and Implementation of an Environmental Control Chamber

Author(s):  
◽  
Aaron Matarese
Weed Science ◽  
1979 ◽  
Vol 27 (3) ◽  
pp. 336-342 ◽  
Author(s):  
D. S. Murray ◽  
J. E. Street ◽  
J. K. Soteres ◽  
G. A. Buchanan

Environmental control chamber experiments showed that cotton (Gossypium hirsutumL. ‘Stoneville 213′) and soybean [Glycine max(L.) Merr. ‘Bragg’] root and shoot growth were reduced when treated with increasing rates of dinitramine (N4,N4-diethyl-α,α,α-tri-fluoro-3,5-dinitrotoluene-2,4-diamine), profluralin [N-(cyclopropylmethyl)-α,αα-trifluoro-2,6-dinitro-N-propyl-p-toluidine], and trifluralin (α,α,α-trifluoro-2,6-dintrio-N,N-dipropyl-p-toluidine). Viusal root ratings, dry root weights, and fresh and dry herbage weights were used to evaluate plant response to herbicide treatments in environmental chambers. The order of increasing GR50values for cotton on two soils and with all response measurements, except dry root weights on one soil, was trifluralin, dinitramine, and profluralin. The order of increasing GR50values for soybeans on two soils and with all response measurements was dinitramine, trifluralin, and profluralin.


1981 ◽  
Vol 39 (4) ◽  
pp. 135-137
Author(s):  
H. F. Vermaas ◽  
T. Rypstra ◽  
J. Forrer ◽  
A. F. Steyn

1966 ◽  
Vol 46 (1) ◽  
pp. 17-26 ◽  
Author(s):  
F. W. Calder ◽  
L. B. MacLeod

Alfalfa plants were grown in the greenhouse and harvested by three systems: (1) as one hay crop, (2) as two hay crops, and (3) as a hay crop followed by two pasture cuts. The cutting systems were arranged factorially with three levels of potassium fertilization: no potassium, 200 lb K per acre, and 300 lb K per acre. After hardening and freezing in an environmental control chamber, plants which were harvested only once had the best recovery, the most etiolated regrowth, and the highest percent of total available carbohydrates (TAG) in the roots. Plants harvested only once also had the largest root weight but the lowest yield of harvested herbage. One crop harvested at early bloom followed by two pasture cuts produced the second highest herbage yield, the lowest root yield, the lowest percentage of total available carbohydrates in roots, the highest percent K and P in the tissue, the lowest yield of etiolated regrowth, and the poorest recovery after freezing.Plants which received 200 and 300 lb K per acre were not significantly different in most criteria measured but gave higher yields than the plants which did not receive additional K. Etiolated regrowth, percent TAG in the roots, and recovery rating were better for plants fertilized with K. The plants which recovered best after the cold treatment were those fertilized with K and allowed to reach full bloom following the first hay-cut.


Author(s):  
K.C. Newton

Thermal effects in lens regulator systems have become a major problem with the extension of electron microscope resolution capabilities below 5 Angstrom units. Larger columns with immersion lenses and increased accelerating potentials have made solutions more difficult by increasing the power being handled. Environmental control, component choice, and wiring design provide answers, however. Figure 1 indicates with broken lines where thermal problems develop in regulator systemsExtensive environmental control is required in the sampling and reference networks. In each case, stability better than I ppm/min. is required. Components with thermal coefficients satisfactory for these applications without environmental control are either not available or priced prohibitively.


2019 ◽  
Author(s):  
Marko J. Spasojevic ◽  
Sören Weber1

Stable carbon (C) and nitrogen (N) isotopes in plants are important indicators of plant water use efficiency and N acquisition strategies. While often regarded as being under environmental control, there is growing evidence that evolutionary history may also shape variation in stable isotope ratios (δ13C and δ15N) among plant species. Here we examined patterns of foliar δ13C and δ15N in alpine tundra for 59 species in 20 plant families. To assess the importance of environmental controls and evolutionary history, we examined if average δ13C and δ15N predictably differed among habitat types, if individual species exhibited intraspecific trait variation (ITV) in δ13C and δ15N, and if there were a significant phylogenetic signal in δ13C and δ15N. We found that variation among habitat types in both δ13C and δ15N mirrored well-known patterns of water and nitrogen limitation. Conversely, we also found that 40% of species exhibited no ITV in δ13C and 35% of species exhibited no ITV in δ15N, suggesting that some species are under stronger evolutionary control. However, we only found a modest signal of phylogenetic conservatism in δ13C and no phylogenetic signal in δ15N suggesting that shared ancestry is a weaker driver of tundra wide variation in stable isotopes. Together, our results suggest that both evolutionary history and local environmental conditions play a role in determining variation in δ13C and δ15N and that considering both factors can help with interpreting isotope patterns in nature and with predicting which species may be able to respond to rapidly changing environmental conditions.


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