Comparison and Evaluation Methods for the Removal of Ethylene and Other Hydrocarbons from Air for Biological Studies

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mentioning

confidence: 99%

Effects of Carbon Dioxide on Ethylene Production and Action in Intact Sunflower Plants

Dhawan¹,

Bassi²,

Spencer³

1981

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“…All systems were allowed to equilibrate for 20 h, and an open air flow system was used in all experiments (12). The 70% relative humidity was maintained by passing the hydrocarbon-purified (12) air through a gas washing bottle containing water and was immersed in a water bath at constant temperature 16 ± 0.2°C.…”

Section: Methodsmentioning

confidence: 99%

“…The 70% relative humidity was maintained by passing the hydrocarbon-purified (12) air through a gas washing bottle containing water and was immersed in a water bath at constant temperature 16 ± 0.2°C. The flow rates of the air entering the chambers were maintained at 10 mL min-' and were monitored by a Gasmet flowmeter calibrated against a bubble meter.…”

Section: Methodsmentioning

confidence: 99%

“…uous flow system for detection of ethylene was developed in this laboratory (5,12), and it has been used with both intact shoots and excised segments of leaves or seedlings (7). It was found that intact shoots of sunflower, soybean and tomato seedlings in a flow-through open system produce less ethylene than the corresponding excised leaf segments in a closed system (7).…”

mentioning

confidence: 99%

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Ethylene Production by Attached Leaves or Intact Shoots of Tobacco Cultivars Differing in Their Speed of Yellowing during Curing

Alejar¹,

Visser²,

Spencer³

1988

Using an open air flow system, differences in the yellowing rate of leaves during curing were assessed in relation to ethylene production by shoots of intact seedlings or attached mature leaves of 60 day old tobacco (Nicotiana tabaum L.) plants. The rate of ethylene evolution from the leaves of the fast yellowing cultivars was significantly higher than in the slow yellowing ones. The same differences were obtained with shoots of intact seedlings. The findings suggest that it is possible to use ethylene production by seedlings as a selection criterion in screening for genotypic differences in the rate of yellowing. The (e.g. 3, 4, 17). An open continuous flow system for detection of ethylene was developed in this laboratory (5, 12), and it has been used with both intact shoots and excised segments of leaves or seedlings (7). It was found that intact shoots of sunflower, soybean and tomato seedlings in a flow-through open system produce less ethylene than the corresponding excised leaf segments in a closed system (7). To date, there has been no report on ethylene measurements from single attached leaves incubated in an open system. In the present work, shoots or single leaves of intact plants were used for measurements of ethylene production.It is known that C02 affects the rate of ethylene evolution from tissues (6,11,16), presumably acting on the conversion of ACC4 to ethylene (16,19). However, there has been no report on the effect of CO2 on the possible differences in ethylene production among tissues at different stages of development. This paper also reports on the C02-induced ethylene production in relation to the previously mentioned tobacco varietal differences. MATERIALS AND METHODSThe attainment of a bright yellow color is important for the marketability oftobacco. Curing accelerates yellowing and many other aspects of senescence typical of detached leaves. Reduction of curing time is economically important. Ethylene and ethylene releasing chemicals have been used to attain a bright yellow color and reduce curing time of tobacco leaves (1). The time required for yellowing during flue-curing differs among Philippine tobacco cultivars, ranging from 35 to 60 h (15). This study assesses the possible relationship between rates of ethylene production in tobacco leaves and the known speeds of yellowing of the leaves during flue-curing.The role of ethylene as an initiator of senescence is well documented for flowers and fruits (1,4,18,20), but evidence for a similar role in foliar senescence is lacking (14,20,21). Although some workers propose that a rise in ethylene production triggers senescence in leaves (4,13,17,18) Plant Material and Culture. Four cultivars of tobacco (Nicotiana tabacum L.) were used in this study, Coker 86, WR-5, Coker 258, and NCBY, certified seeds of which were obtained from the Philippine Tobacco Research and Training Center, Ilocos Norte, Philippines. The first two cultivars exhibit a slow yellowing (SY) behavior during flue-curing and the latter two are fast yellowing (FY)...

“…Much progress has been made in development of techniques for ethylene analysis; it is now possible to determine a fraction of a nanoliter of ethylene with gas chromatography. Even smaller amounts of ethylene in air can be determined by collection of the ethylene on an adsorbent before gas chromatographic analysis (5,6).…”

mentioning

confidence: 99%

A Cuvette Design for Measurement of Ethylene Production and Carbon Dioxide Exchange by Intact Shoots under Controlled Environmental Conditions

Bassi¹,

Spencer²

1979

Self Cite

A cuvette is described for simultaneous measurement of ethylene production and CO2 fixation by intact shoots under controOed enviromental conditions. This design overcomes potential problems associated with closed systems conventionaUly used for studies on ethylene production, allowing accurate determination of rates of ethylene production in plants exposed to different environmental conditions. There has been considerable interest in recent years in studying the roles of ethylene in different stages of plant growth and development (1). Many plant responses can be elicited by very low concentrations of ethylene. Much progress has been made in development of techniques for ethylene analysis; it is now possible to determine a fraction of a nanoliter of ethylene with gas chromatography. Even smaller amounts of ethylene in air can be determined by collection of the ethylene on an adsorbent before gas chromatographic analysis (5,6).However, little work has been done to improve the experimental techniques for studies of ethylene evolution from plants. Most studies are done using closed systems (e.g. 7, 8, 11, 15 12,13,15). The tissue produces ethylene continuously and is exposed to constantly changing ethylene concentrations. Also, hydrocarbon contaminants are present in room air and in most commercially available gases, including compressed air and CO2. Thus, even in the few studies done using continuous flow systems, there has been inadequate control over hydrocarbons. We have recently reported (6) an efficient method for removing hydrocarbons from an air stream through the use of metal catalysts at high temperatures. In addition to the problem associated with contamination of the air stream, a cuvette recently described (5) does not provide for selective sealing of the shoot, adequate air circulation, and temperature control.To our knowledge, no hydrocarbon-free cuvette has been de- ' We wish to thank the National Research Council of Canada for Grant A-1451 to MSS in aid of this research.signed for accurate measurement of ethylene production from intact plant shoots. The cuvettes used for CO2 exchange studies invariably rely on rubber and plastics and hence are of little use for ethylene studies. Even in CO2 exchange studies, the variation in ethylene concentration could lead to erroneous conclusions. In this paper, we describe a cuvette that allows simultaneous measurement of CO2 exchange and ethylene production by intact shoots of plants under controlled environments.The cuvette (Fig. 1) We have tried "O" rings ofdifferent materials such as Neoprene, Viton, and natural rubber, but they were all found to contaminate the air stream with ethylene. For example, when a natural rubber gasket was used to seal the cuvette, it produced 4.74 nl/h ethylene when exposed to a balanced spectrum of light. The level of ethylene declined to 0.96 nl/h I h after the lights were switched off. Ethylene production completely subsided after 24 h, only to resume again when the lights were turned back on. Silicone rubber di...