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The committee has been quite active since the 2001 AOAC Meeting and Exposition. Five collaboratives in various stages are progressing toward committee approval. First was the Alternative Methanol Extraction Procedure for Method 2001.12; on June 13 a conference call was held to discuss and ratify Method 2002.04, Gravimetric Determination of Amylase Treated Neutral Detergent Fiber in Feeds Using Refluxing Beakers or Crucibles. Currently the committee is processing the following collaboratives: IC-017, Crude Fat, Diethyl Ether Extraction in Feed, Cereal Grain, and Forage (Randall/Soxtec/Submersion Method); IC28 Crude Fat, Hexane Extraction in Feed, Cereal Grain, and Forage (Randall/Soxtec/Submersion Method); and IC29, Determination by Liquid Chromatography of Urea in Certain Liquid Fertilizers Containing Substantial Amounts of Water-Soluble Urea-Formaldehyde Reaction Products and in Aqueous Urea Solutions. The goal is to have all reviews completed, reviews by the 2 designated OMB members, and the committee vote set for September at the Committee meeting in Los Angeles.

Information is lacking on the precision of atmometers and empirical models used to estimate turfgrass evapotranspiration (ET). Experiments were conducted to evaluate the precision of black Bellani plates, a class A evaporation pan, and the Penman-Monteith empirical model for estimating ET of 'Mustang' tall fescue (Festuca arundinacea Schreb.), 'Meyer' zoysiagrass (Zoysia japonica Steud.), 'Prairie' buffalograss [Buchloe dactyloides (Nutt.) Engelm.], and 'Midlawn' bermudagrass [Cynodon dactylon (L.) Pers. x transvaalensis Burtt-Davy] under well-watered conditions. Tall fescue was mowed once weekly at 6.5 cm, and warm-season grasses were mowed at 4.5 cm twice weekly. Diurnal ET was measured between June and September in 1993 and 1994 using weighing lysimeters and the water balance method. Evaporation from atmometers was measured during the hour that turfgrass ET was determined, and Penman-Monteith-estimated ET was calculated for the same time period. Black Bellani plate evaporation was correlated most closely with measured turf ET (R 2 = 0.73), followed by class A pan evaporation (R 2 = 0.67), and Penman-Monteith-estimated ET (R 2 = 0.60). Ranking of grasses for mean daily ET was tall fescue (6.8 mm d -1 ) > zoysiagrass (5.6 mm d -1 ) > buffalograss (5.1 mm d -1 ) = bermudagrass (5.0 mm d -1 ). The black Bellani plate provides the most precise estimate of turfgrass ET under well-watered conditions.

Specific problems in plant selection for the midwest vary widely because of large differences in climate, soils, and urbanization. A project was started in 1984 to identify and evaluate worthy landscape plants for use in Kansas and other areas of the midwest. As of 1991, 40 species and cultivars have been planted in six locations throughout Kansas. Data collected for four years include survival, height, stem diameter, foliage quality, and overall quality. The results of the first two completed segments of this study (1984 and 1985) are presented.

Chloroplast thylakoids isolated from bean (Phaseolus vulgaris L.) leaves have been used as a model system to identify heat-induced changes in membrane protein structure. Susceptibility of SDS gel electrophoresis bands to trypsin digestion was used as an assay for altered structure of proteins comprising the bands. Both reversible and irreversible alternations in membrane protein structure have been observed as a result of exposure to 35 or 45°C for varying time periods.

This paper defines several solution properties that alter the effects of heat on isolated chloroplast thylakoid membranes. Isolated bean (Phaseolus vulgaris L.) «Oregon 1604» thylakoids in various milieus were exposed to 25 or 45 °C, and the repercussion(s) of heat were determined. Raffinose (0.4-0.5 M) wass lightly more thermostabilizing than 2 M sucrose as evidenced by an amelioration of the: (i) heat-induced decline in electron transport, (ii) heat-induced alteration in the susceptibility of thylakoid polypeptides to trypsin digestion, and (iii) heat-induced decline in the maximum fluorescence transient measured at 685 nm...

Degree-day modeling applications in turfgrass management have recently seen increased interest. The predictive capacity of any degree day model is dependent on an accurate determination of the basal growth temperatures for the species under consideration. The objective of this study was to determine basal growth temperatures and growth rate constants for eight warm season turfgrasses (five species). Sprigs from bermudagrass [Cynodon dactylon (L.) Pers. cv. Arizona Common and C. dactylon lc C. transvaalensis Burtt Davey cv. Midiron], buffalograss [Buchloe dactyloides (Nutt.) Engelm. cv. Kansas Common and Texoka], zoysiagrass (Zoysia japonica Steudel cv. Meyer), St. Augustinegrass [Stenotaphrum secundatum (Walter) Kuntze cv. Raleigh and Floratam], and centipedegrass [Eremochloa ophiuroides (Munro) Hackel, cv. Common] were grown at temperatures ranging from 5 to 30°C in a controlled environment chamber under 14-h photoperiods. Chamber temperature was decreased in a step-wise fashion to the next temperature after two leaves were fully expanded. Leaf growth rates at each temperature were calculated and expressed as millimeters per day. Base temperature and growth rate constants for each turfgrass were calculated with segmented nonlinear regression analysis. Base temperatures for the eight tested cultivars ranged from 0 to 13°C. Interspecific and intraspecific differences for basal growth temperature were found, indicating that degree-day model application accuracy is dependent on proper determination of target species and cultivar basal growth temperature. Joint Contribution of Kansas Agric. Exp. Stn. Contribution No. 95-393-J and Nebraska Agric. Res. Div. Journal Series No. 11054.

A system for the digital analysis of photographic prints of turfgrass plots is being developed. The 3-year-old turfgrass plots included Meyer zoysiagrass, Midlawn bermudagrass, Prairie buffalograss and Mustang tall fescue. The plots were photographed by a camera with a small dual bubble level on the camera back and a 28-mm-wide angle lens. Photographs were digitized with flatbed scanners. The images can then be analyzed in a variety of ways. For example, a series of photographs were taken from mid-Sept. through late Oct 1995 and spectral analysis of the resultant digital images were made. The initial RGB (red-greenblue) format of the images was converted to HSI (hue-saturation-intensity) for analysis. The results indicate, obviously, that hue changed from 104 (i.e., green) to 75.7 degrees (i.e., brownish) between the beginning and end of Oct. 1995. Similarly, intensity changed from ≈0.12 to ≈0.16 during the same time period, indicating that the images became darker over time. These phenomena were observed in all four species examined. However, the saturation value evoked a significant species * date interaction. The three warm-season species showed a decrease in saturation, while Mustang had no significant decrease during Oct. Spectral as well as textural analysis are likely the two most useful techniques in the digital analysis of turfgrass plots. Examples of both will be presented.

A relatively accurate estimate of turfgrass evapotranspiration (ET) using environmental parameters readily obtainable from a local weather station would be of benefit to golf course superintendents, landscape managers, and homeowners. The Penman–Monteith model is clearly a poorer estimate than that obtained by Bellani plates or spheres. It has been suggested that, while the Penman–Monteith model is good in the drier climate of the southwestern United States, other models may be of greater practicable utility in climates such as are common in Kansas. Thus, other models have been evaluated for their suitability as turfgrass ET estimates in Kansas-like climates. Turfgrass ET was measured via lysimeters in 1992–94. Specifically, measurements were taken on three tall fescue varieties mowed at 6.35 or 7.62 cm, and zoysiagrass and perennial ryegrass mowed at 2.54 cm. Evaporation from black Bellani plates was measured simultaneously. These evaporation and ET rates were compared to those estimated by various empirical models whose data came from a weather station located within 31 m of the Bellani plates and lysimeters. Empirical models included temperature methods (e.g., FAO-24 Blaney–Criddle), radiation methods (e.g., Jensen–Haise, Hargreaves–Samani), combination equations (e.g., Priestly–Taylor, Penman), and variants. The best model(s) determined from these comparisons will likely become the method(s) of choice for estimating turfgrass ET in Kansas.

Two systems of relay-intercropping muskmelons (Cucumis melo L.) with Scotch pine (Pinus sylvestris L.) Christmas trees using black plastic mulch and drip irrigation were evaluated for their potential to improve cash return. Returns ranged from a high of $26,200/ha for plastic mulch-drip irrigation and a selling price of $l.00/melon to a low of $6900/ha for bare ground-drip irrigation and a selling price of $0.40/melon. The benefit- cost index ranged from 24 to 3.4, depending on the system evaluated. Pine growth apparently was impeded by plastic mulch; however, increased yields of melons grown under plastic mulch may offset the slight decrease in pine growth. Christmas tree production is a common enterprise in many parts of the United States, especially in the northeastern and Great Lakes regions (Chapman and Wray, 1979; Dickson and Winch, 1976). Consumers generally pre- fer to purchase locally grown trees (Hildebrandt et al., 1989). In many instances, Christmas tree production is relegated to marginal land, and few additional inputs are used. It may take 6 to IO years to produce a marketable 1.8- to 2.4- m-tall Scotch pine Christmas tree (Behlen, 1978; Davenport and Walters, 1970). Produc- ers receive no cash return from their invest- ments during this time. Cut-your-own Christmas trees may be a component of a large retail horticultural op- eration, especially near urban or suburban populationcenters. Producing such along-term crop on high-value land requires a steady cash flow to ensure a profitable operation. The purpose of this study was to determine if an intensive crop production system using plastic mulches, drip irrigation, and relay-intercropped

Digitized photographic images of turf plots composed of bermudagrass, buffalo grass, tall fescue, and zoysiagrass were taken at a height of about 150 cm with a 28-mm lens. Fast Fourier transforms of these images were performed, and a radial plot of the power spectrum was obtained from each image. Hurst plots (log frequency vs. log intensity) were used to subtract “background” from the power spectra, so peaks would be more evident. The peak of the power spectrum occurs at the average spacing between leaves (more precisely, between areas of the canopy that reflects a significant amount of light) and defines the characteristic dimension. Zoysiagrass had the lowest characteristic dimension, while tall fescue had the highest. The width of the power spectrum is indicative of the variability of the characteristic dimension within the canopy. The minimum characteristic dimension (occurring at the highest frequency) was less than 1.7 cm, whereas all the other species had about the same minimum characteristic dimension of ≈1.9 cm. The maximum characteristic dimension was greatest for fescue (6.9 cm), followed by buffalo grass (3.8 cm), bermudagrass (3.3 cm), and zoysiagrass (2.8 cm). These results indicate that the characteristic dimension can be a useful tool for discriminating between turfgrass species in digitized images.

Photographs of turfgrass canopies were taken throughout Spring, Summer, and Fall 1997 at a height of 1.3 m using a 28-mm lens and film sensitive to either visible or infrared light. The species evaluated were warm-season Bermudagrass, buffalograss, zoysiagrass, and cool-season tall fescue. Color spectra of digitized photographs were obtained by first separating the hue, saturation, and intensity components of the color photo into separate 8-bit (256 gray levels) files. Calculations were then made on the basis of those color components. The infrared photos were scanned as 8-bit files without conversion. Greenup was indicated by a decrease in the frequency of hues between 0 and 50° (reds, browns, and yellows) and an increase in the frequency of hues between 50 and 100° (green and yellow-green). It is well-known that canopy reflectance in the green wavelengths is primarily a function of chlorophyll density, whereas reflectance of near-infrared radiation is indicative more of cell structure. More near-infrared radiation is reflected from leaf surfaces than is green radiation, and less infrared is absorbed by internal leaf structures than is visible radiation. Thus, it is possible to approximate canopy leaf area ratios by using both visible and near-infrared photographic measurements. Quantitative changes in visible and near-infrared canopy reflectances, leaf area ratios, and other morphometric parameters will be presented as a function of time of the year and species. The results demonstrate the utility of using this relatively inexpensive procedure to obtain quantitative measurements as a substitute for, or in conjunction with, subjective visual ratings of turfgrass plots.

Evapotranspiration from tall fescue, perennial ryegrass and zoysiagrass turfs during the summers of 1992-3 was compared to evapotranspiration estimates from an evaporation pan, a black Bellani plate, and several empirical combination models, Actual measurement of turf water use was made with small weighing lysimeters. Soil was maintained at field capacity. Data were collected on 51 dates between June and September. Tall fescue was clipped weekly at 7.6 cm whereas ryegrass and zoysiagrass were clipped 3 times weekly at 2.5 cm, Although differences between the grass species existed, in general the rankings of estimate precision were Bellani plate > evaporation pan > empirical models when compared with measured evapotranspiration rates.

Scanning electron micrographs of grape berry surfaces, which resemble mountainscapes, contain a wealth of structural information. A typical statistical characterization of features such as root mean square peak-to-peak spacings, peak density, etc., is readily performed on these images. However, a much richer base of information is accessible by analyzing the images with fractal geometry. Fractal box dimension is a quantitative measure of surface roughness, and varies with the contour at which it is determined in both cultivars `Foch' and `Perlette', suggesting that the surfaces are multifractal structures. Fourier spectral analyses of the surfaces produce a similar conclusion. Thus, the unambiguous quantitative resolution of cultivars on the basis of their wax surface structure looks promising, but requires further work.

The prediction of which species will do well in various microclimates is of obvious interest to horticulturists as well as homeowners. To this end, the following 5 species of trees and shrubs where planted at 5 disparate sites across Kansas in spring 1985 and growth and environment measured for the 4 following years: Phellodendron amurense, Acer rubrum, Acer platanoides `Greenlace', Quercus acutissima, and Cercocarpus montanus. Preliminary analysis of trunk diameter growth vs. environment indicates few simple relationships and several rather complex relationships. Rather simplistic linear relationships (growth vs. a single environmental parameter) are largely meaningless, and often misleading. For instance, growth of Q. acutissima was negatively correlated with the highest maximum temperature prior to the growing season and positively correlated with the lowest minimum temperature prior to the growing season. More complex, and reasonable, relationships will be presented.

The following model simulates hourly temperature fluctuations at 6 Kansas stations: \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[T_{h}=\frac{(T_{x}-T_{n})}{2}\left[\mathrm{exp}\left(\frac{0.693h}{DL_{M}}\right)-1\right]+T_{n};{\ }0{\leq}h{\leq}DL_{M}\] \end{document} \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[T_{h}=\frac{(T_{x}-T_{n})}{2}\left[1+\mathrm{sin}\frac{{\pi}(h-DL_{M})}{2(23-DL_{M})}\right]+T_{n};{\ }DL_{M}{\leq}h{\leq}23\] \end{document} where h = time (hours after sunrise), DLM = 20.6 - 0.6 * daylength (DL), Th = temperature at time h, and TX and Tn = maximum and minimum temperature, respectively. Required inputs are daily TX and Tn and site latitude (for the calculation of DL). Whereas other models have been derived by fitting equations to chronological temperatures, this model was derived by daily fitting of hourly temperatures sorted by amplitude. Errors from this model are generally lower, and less seasonally biased, than those from other models tested.

Peach [Prunus persica, (L.) Batsch] seedling growing in irrigated soil showed strong diurnal variations in totalwater potential, turgor potential, and stomatal resistance. A significant positive correlation existed between turgor potential and total water potential while osmotic potential remained fairly constant. There appeared to be no rapid, diurnal osmotic adjustment to maintain constant turgor, although there may have been some slight, long-term osmotic adjustment over the 2-week experimental period. When turgor approached zero, a depression of osmotic potential due to water loss through transpiration maintained turgor above zero. Stomatal resistance remained low throughout the day, even though total water potential dropped below –16 bars and turgor potential was below 2 bars. Stomatal resistance was negatively correlated with irradiance level but not with turgor potential.

Possibilities to account for the mechanism of freeze-thaw injury to isolated protoplasts of Spinacia oleracea L. cv. Winter Bloomsdale were investigated. A freeze-thaw cycle to −3.9 C resulted in 80% lysis of the protoplasts. At −3.9 C, protoplasts are exposed to the equivalent of a 2.1 osmolal solution. Isolated protoplasts behave as ideal osmometers in the range of concentrations tested (0.35 to 2.75 osmolal), arguing against a minimum critical volume as a mechanism of injury. Average protoplast volume after a freeze-thaw cycle was not greatly different than the volume before freezing, arguing against an irreversible influx of solutes while frozen. A wide variety of sugars and sugar alcohols, none of which was freely permeant, were capable of protecting against injury which occurred when protoplasts were frozen in salt solutions. The extent of injury was also dependent upon the type of monovalent ions present, with Li = Na > K = Rb = Cs and Cl ≥ Br > I, in order of decreasing protoplast survival. Osmotic conditions encountered during a freeze-thaw cycle were established at room temperature by exposing protoplasts to high salt concentrations and then diluting the osmoticum. Injury occurred only after dilution of the osmoticum and was correlated with the expansion of the plasma membrane. Injury observed in frozen-thawed protoplasts was correlated with the increase in surface area the plasma membrane should have undergone during thawing, supporting the contention that contraction of the plasma membrane during freezing and its expansion during thawing are two interacting lesions which cause protoplast lysis during a freezethaw cycle.

Pregerminated snapdragon seed was damaged to different extents by low-temperature storage for 4 or 8 days in 3 hydrophilic gels or deionized water. Poststorage viability and vigor decreased as a result of storage, but for apparently different reasons. Medium pH was correlated with poststorage vigor, whereas the gas-exchange capacity of the storage media was correlated with poststorage viability. Seed germination and radicle elongation within the gel was also stimulated when the gas-exchange capacity of the storage medium was increased. Enzymatic generation of oxygen within the gel increased both seed germination and radicle elongation, which suggests that the oxygen diffusion rate specifically was limiting these phenomena.

The influence of root and shoot pruning on the growth of transplanted 3-year-old Ilex crenata ‘Convexa’ × I. crenata ‘Stokes’ was determined under various backfill regimes. Root pruning reduced shoot dry weight increment 24% but only reduced root dry weight increment 6%. Root pruning caused water deficits to develop which can quantitatively account for the reduced shoot growth. Shoot pruning reduced root dry weight increment without influencing shoot dry weight increment. Adjustments of the means for altered tissue water content caused by shoot pruning resulted in decreased root and shoot dry weight increment. Root and shoot pruning influenced plant growth directly — by influencing growth mediating processes, and indirectly — by influencing plant water relations. Root growth was influenced primarily by growth mediating processes while shoot growth responded to both growth mediating processes and plant water relations.

The possibility that low cellular concentration of sucrose was limiting the expression of hardiness in young roots of Pyracantha coccinea Roem. ‘Lalandii’ Dipp. was investigated. While the sucrose content of young roots increased four-fold following exposure to 4°C, the highest concentration was not higher than that found in non-acclimated mature roots. Attempts to increase hardiness by incubating young roots on sucrose solutions were unsuccessful. However, intracellular sucrose concentrations were not significantly increased by this treatment. Cytochrome oxidase incorporated into a membrane fraction containing plasmalemma vesicles isolated from Pyracantha young roots or from tissue capable of acclimation (Hedera helix L. ‘Thorndale’ callus cultures) was used as a probe for architectural alterations of this membrane following exposure to 4° and 5°. The apparent first order rate constant of the cytochrome oxidase reaction was used to indicate membrane fluidity. Above the Arrhenius discontinuity, membrane fluidity in both species was greatest when plants were grown at 4° or 5°. However, below the Arrhenius discontinuity fluidity remained greater in ivy callus grown at 5°, but not in Pyracantha young roots exposed to 4°. Altered properties of the membrane surface, inferred from the second order rate constant, were observed only in plasmalemma of young roots. Several possibilities to account for the lack of young root hardiness are presented.

Kinetics of inhibition of cyanide-insensitive O 2 uptake by n -propyl gallate (PG) and salicylhydroxamic acid (SHAM) were determined in fresh slices from ethylene-treated tubers of Solanum tuberosum `Norchip9 and with mitochondria and lipoxygenase (EC 1.13.11.12) isolated from these tubers. PG and SHAM appeared to be inhibiting at identical sites in mitochondria but at disparate sites in slices. The apparent K I for SHAM was similar in mitochondria and slices. However, the apparent K I for PG in mitochondria was about 40-fold lower than the K I for PG inhibition of lipoxygenase activity. The amount of lipoxygenase associated with mitochondria increased when tubers were treated with ethylene. PG, but not SHAM, inhibited aging-induced development of cyanide-insensitive respiration. The latter two phenomena are in accord with the hypothesis that lipid metabolism is required for the development of the alternative pathway.

Kinetic parameters of 3-(3, 4-dichlorophenyl)-1, 1-dimethyl urea (DCMU)-induced inhibition of electron transport in chloroplast thylakoids isolated from Phaseolus vulgaris L. cv. Oregon 1604 were determined from analysis of a convergent, parallel electrical circuit. Through this analogue, the apparent affinity of the purported binding site for DCMU (K1) and the relative amount of DCMU-insensitive electron transport (vmax1/vo) were obtained using a reiterative non-linear least squares curve-fitting procedure. Exposure of thylakoids to heat caused a gradual increase in K1 (or decrease in the affinity of the thylakoid for DCMU) with an apparent activation energy of 134 kJ mol−1. Tryptic susceptibility of a protein region regulating K1 also decreased gradually with exposure to 45°C, suggesting that the heat-induced increase in K1 might be due to a protein conformational change. On the other hand, thylakoid exposure to 45°C resulted in a rapid (

A reexamination of the data of Farrant and Woolgar ( Cryobiology , 9 , 9–15 (1972)) demonstrates that human erythrocytes exhibit osmometric behavior as predicted from the Boyle-Van't Hoff law when suspended in sodium chloride solutions as high as 3.5 osmolal. A Boyle-Van't Hoff plot is linear with r = 0.998. However, 24% of the water in isotonic red blood cells appears to be osmotically-inactive, although nearly 75% of this apparent non-osmotic water can be accounted for by the water of hydration of hemoglobin. These facts have direct significance to hypotheses concerning hemolysis as well as to the modeling of osmometric events which occur at sub-zero temperatures.

Equal average container temperatures during prolonged periods of low outside air temperatures were achieved by unheated structures covered with either a double-layer of clear polyethylene or a double-layer with the inner layer translucent and the exterior clear polyethylene. Single-layer structures were less effective, with clear polyethylene affording more protection than translucent. Excessively high mid-day temperatures in both the single- and double-layer clear houses increased the probability of desiccation injury and affected the quality of the nursery stock. Fluctuations of air temperatures below 0°C were most rapid in the clear houses, and appear to depend greatly on the relative humidity, which affects the thermal conductivity of the air. Container temperature fluctuations were similar whether the container soil water was frozen or unfrozen. The best covering tested thus far appears to be a double-layer with the interior translucent and the exterior clear polyethylene. This covering moderates low container temperatures, high mid-day temperatures, desiccation problems, rapid temperature fluctuations and concomitant management problems.

The process of ice formation in media at container capacity was followed by sectioning the frozen medium and determining solute content in each sample using sodium fluorescein as a tracer. H2O apparently moved from the bottom and central interior regions of the container medium to the sides of the container. The phase in which movement occurred is unknown. Fluorescein moved down from the top and central interior regions to the bottom and sides of the container. The final distribution of fluorescein should indicate the location of the majority of liquid H2O due to the exclusion of solutes by ice. In the partially frozen state the greatest amount of liquid water therefore occurs near the container sides – a region normally occupied by a large proportion of the root system.

Root hardiness of numerous woody ornamentals was determined after artificial acclimation. In the species tested, the killing temperatures of young roots ranged from -3° to -11°C while that of mature roots ranged from -8° to -23°. The relative hardiness of young roots was not necessarily indicative of the relative hardiness of mature roots.

Seedlings of ‘Halford’ peach [Prunus persica (L.) Batsch] maintained in a growth chamber and exposed to leaf water deficits as low as – 38 bars exhibited slight osmotic adjustment before turgor potential reached zero. This adjustment was inadequate to maintain high turgor potential, which decreased until reaching zero at a total leaf water potential of ca. —20 bars. Stomatal conductance was linearly related to total leaf water potential and independent of the average turgor potential of the leaf.

A modification of the ninhydrin method of evaluating injury was made by expressing the release of ninhydrin-reactive compounds following freezing as a percentage of the potential release. This method eliminates a laborious weighing procedure and also eliminates variability due to differences in endogeneous concentrations of ninhydrin-reactive compounds in roots. The technique correlated well with survival of Pyracantha coccinea Roem. cv. Lalandii Dipp. roots and stems 3 weeks after freezing, and lends itself to studies requiring large numbers of viability determinations using relatively small sample sizes.

Cyanide-resistant O(2) consumption can be stimulated by either treating whole white potato tubers (Norchip) with ethylene, in the presence of 100% O(2), or aging slices obtained from untreated potato tubers. A comparison of alternative pathway activity elicited by either treatment was undertaken. The proportion of electrons flowing through the alternative path in the presence of intermediate concentrations of KCN and at various concentrations of salicylhydroxamic acid was identical in both cases. However, the respiration of slices from ethylene-treated tubers was in every case stimulated by KCN, whereas the aged slices never exhibited this phenomenon. Furthermore, the metabolism of d-[U-(14)C]glucose was several hundred times greater in aged slices than in fresh slices from C(2)H(4)-treated tubers. These results, along with the respiratory kinetics of aged slices from ethylene-treated tubers, suggest that aged slices and fresh slices from ethylene-treated tubers are biochemically dissimilar.

Reaction kinetics of the reduction of O2 by cytochrome oxidase follow essentially the same rate equation as that proposed for the oxidation of cytochrome c. However, the apparent second order rate constant varies with the oxidase concentration. The redox level of cytochrome c at the steady state was found to be essentially temperature-independent. Currently recognized pathways (or mechanisms) of electron transport from cytochrome c to O2 do not predict, and cannot account for the occurrence of these phenomena.