scispace - formally typeset
Search or ask a question

Showing papers in "Plant Physiology in 1951"


Journal ArticleDOI
TL;DR: During a study of the inactivation of IAA in aqueous solutions, it was frequently necessary to assay at one time many samples where the IAA concentrations were low, or where the degree of significance of small differences in concentrations between experimental unite required evaluation, so it was desirable to re-examine the ferric chloride-sulphuric acid procedure.
Abstract: The wide use of the auxin, indoleacetic acid, in physiological and biochemical experiments has promoted interest in methods for its colorimetrie estimation. Mitchell and Brunstetteb (1) have proposed both the nitrite and the ferric chloride-sulphuric acid tests for the quantitative estimation of indoleacetic acid (IAA) in aqueous solutions, basing their suggested procedures upon a study of optimal reaction conditions for these two reagents. According to them, the nitrite method is sensitive to 10 /tig. IAA/ml. and develops a red color that is stable after two hours. In several attempts to duplicate their nitrite method using solutions of IAA varying from 20 to 45 /tg./ml., we could not obtain a stable red color with IAA at the two hours proposed, or at any other time. A faint pink develops almost immediately which rapidly fades to orange or yellow, depending on IAA concentrations, within i hour. If the concentration of nitrite is reduced, the red color becomes sufficiently persistent to be read. Indole likewise gives a strong, relatively stable, red color in this test (cf. table II)?a reaction which is sometimes used as a qualitative test for indole (Nitroso-Indole reaction). Tang and Bonner (2) have modified the ferric chloride-sulphuric acid method for IAA, combining the iron and sulphuric acid as a single reagent to yield improved sensitivity. However, the color produced is also unstable, rapidly developing and then fading. We have found, as have these workers, that the fading color can be practically dealt with by adopting a standard time between addition of reagent and reading of absorbancy or transmittance. Both of the methods discussed above possess disadvantages, lacking either specificity, sensitivity, or stability of color complex formed. During a study of the inactivation of IAA in aqueous solutions, it was frequently necessary to assay at one time many samples where the IAA concentrations were low, or where the degree of significance of small differences in concentrations between experimental unite required evaluation. Hence, we considered it desirable 'to re-examine the ferric chloride-sulphuric acid procedure. Several alterations have been made which produce a more stable color, of increased specificity, which changes in density more rapidly with variation in IAA concentration. 1. The procedure of Tang and Bonner can be improved somewhat by reading at 15 minutes after addition of reagent (instead of 30 minutes as they suggest), since the transient color reaches a maximum at the former time. Maximum absorption was found to occur at 530 ???.

1,988 citations



Journal ArticleDOI
Paul J. Kramer1
TL;DR: This study was made in an effort to learn why saturating the soil with water causes almost immediate injury or death of many species of plants.
Abstract: This study was made in an effort to learn why saturating the soil with water causes almost immediate injury or death of many species of plants. While it has been shown that the deficient aeration accompanying flooding injures or kills the root systems, this fact does not explain why the shoots are injured so quickly. Injury is usually attributed to desiccation, caused by decreased water absorption through the injured roots; but this explanation seems inadequate. Plants can live for some days after the root systems are killed if the soil is kept saturated (11), and cut shoots can be preserved in good condition for many days in containers of water if the water is changed occasionally. Most species of plants can be grown fairly satisfactorily in shallow tanks of nutrient solution without forced aeration; but if the same species are grown in soil which is later flooded, the shoots are quickly injured. The injury of shoots cannot be caused entirely by injury to the roots as absorbing systems, because reduced absorption of water or of minerals cannot explain all of the symptoms observed in the shoots of flooded plants. Although wilting of leaves is often observed after flooding, this is not the only nor even the most characteristic symptom of injury. Among the conspicuous symptoms of flooding injury is yellowing and death of the leaves, beginning with the lower ones and progressing up the stem. This chlorosis superficially somewhat resembles nitrogen deficiency, but often develops within four to six days after flooding, much too soon to be caused by nitrogen deficiency. The middle leaves of tomato show epinastic curvature within twenty-four to forty-eight hours after the soil is flooded; and lumps of callus tissue develop along the stem, particularly at the water level. In many species adventitious roots develop at the soil surface or just below the water surface where the water level is above the soil surface.

201 citations


Journal ArticleDOI
TL;DR: The design of the growth chamber was investigated, particularly in regard to the most desirable thickness of the culture ex-Chlorella pyrenoidosa, to determine the conditions necessary to obtain maximum density, rate of growth, and efficiency of light utilization.
Abstract: Of the considerable body of literature variously concerned with the culture of algae there is relatively little work directed toward the particular problem of mass culture. Von Witsch (10, 11) grew Chlorella in vertical glass cylinders of 3 cm. diameter and studied effects of carbon dioxide provision and the composition of the medium on yield and rate of growth. He achieved yields which approached the following as maxima: 5.0 gm. dry weight per liter in 20 days; 6.68 gm. dry weight per liter in 38 days (figures from different experiments). Spoehr and co-workers (8) produced 10.69 kg. of dry Chlorella from 590 cultures grown in 5-gallon carboys under daylight illumination in a greenhouse. The cultures were harvested at 30 to 50 days ; the maximum yield achieved was about 4.0 gm. dry weight per liter. No attempt was made to investigate the factors limiting growth rate or yield. Ketchum, Lillick, and Redfield (4) studied growth and optimum yields in cultures illuminated by a jacketed neon tube immersed in eight liters of media contained in a pyrex bottle. Of a number of different unicellular algae examined Chlorella pyrenoidosa gave the highest density and daily yield, namely 0.74 gm. per liter maximum density and 0.065 gm. per liter per day maximum growth rate. If pushed to a stage of practical development, the mass culture of algae will become an engineering problem. Before any such stage is reached, however, the problem is essentially biological. The rates of growth obtained in the work cited above are lower by at least several orders of magnitude than the maximum growth rate of Chlorella of about sevenfold increase per day. The densities of population achieved are far below those obtained with other microorganisms in the fermentation industry. The biological problem is to determine the conditions necessary to obtain maximum density, rate of growth, and efficiency of light utilization. Sunlight appears to be the only feasible source of illumination for large scale mass culture. The initial experiments have been done, therefore, in a greenhouse under daylight illumination. Since the incident visible radiation per day varies from day to day such experiments must be self-contained, i.e., they must be designed to provide comparative data within any one experiment. As a starting point we chose to investigate the design of the growth chamber, particularly in regard to the most desirable thickness of the culture ex-

92 citations


Journal ArticleDOI
TL;DR: Early attempts to use higher plants for the biosynthesis of C14-labeled organic acids revealed that equilibrium in C14 distribution among the organic acids was not established even many hours after exposure to C1402, which suggested the possible importance of this acid as an early photosynthetic product.
Abstract: The importance of organic acids as photosynthetic intermediates, first suggested by Liebig, has been subject to speculation for over100 years. The free organic acids or their phosphate esters still are included in the most recent schemes for photosynthetic assimilation of carbon dioxide (8, 12). Recent advances in our knowledge of the path of carbon in photosynthesis have been described so adequately (3, 8, 9, 12), that any extensive review of the subject here is unwarranted. BENNET-CLARK (2) recently has reviewed the literature on the organic acids of plants. Our early attempts to use higher plants for the biosynthesis of C14-labeled organic acids (7) revealed that equilibrium in C14 distribution among the organic acids was not established even many hours after exposure to C1402. The observed concentration of C14 in malic acid suggested the possible importance of this acid as an early photosynthetic product. Accordingly, the distribution of C14 among several organic acids from plants supplied C1402 was investigated.

90 citations


Journal ArticleDOI
TL;DR: It is suggested that the auxin normally present in an organ is an important factor in delaying its abscissions, and that a decrease in this auxin precedes or accompanies abscission.
Abstract: It is a.common observation that a leaf stalk usually abscises shortly after the removal of its blade. La Rue (2) delayed this abscission of debladed leaf stalks by the application of indoleacetic acid to the stalk. Compounds related to indoleacetic acid also have delayed the premature abscission of leaves and fruits (1, 3). These observations suggest that the auxin normally present in an organ is an important factor in delaying its abscission, and that a decrease in this auxin precedes or accompanies abscission. To test these ideas, determinations were made of the auxin content of bean leaves of various ages. This paper presents the results of the auxin determinations and a discussion of their significance. The first trifoliate leaves of Black Valentine beans, grown in the greenhouse, were used in this investigation. In beans an abscission zone lies between the blade of each leaflet and the leaf stalk. Thus blades differ from stalks in relation to the leaflet abscission zone; tissues of the blade are distal to the zone and tissues of the stalk are proximal to the zone. Samples of blades and stalks were taken from the plants at each age studied, 15, 30, 40, 60, and 70 days after planting. At 15 days the leaves were immature, the blades only partially expanded. At 30 days the leaves were fully expanded. At 70 days the blades were turning yellow and showing other signs of approaching abscission. Each sample was treated in the following manner: Immediately after cutting it was weighed, put into a container, and frozen at -15? C. As soon as convenient it was dried in a lyophilizer. The dried material was ground through a 40-mesh screen in a Wiley Mill, and weighed. Each sample was put into a separate 250-ml. Erlenmeyer flask containing 100-ml. of freshly distilled cold ethyl ether, and the flask kept for two hours in a refrigerator at 0? C. The material was then filtered through No. 1 qualitative paper and the residue washed with three 2to 3-ml. portions of fresh ether. The ether extract thus obtained was evaporated to a few milliliters and with a pipette transferred to a small test tube where it was evaporated to dryness. A measured amount of 1?% agar was added to this dried extract, the mixture shaken vigorously for a few minutes, poured into a 10.8 ? 8 ? 1 mm. brass mold, and cut into 12 blocks. These blocks were placed on Avena

82 citations


Journal ArticleDOI
TL;DR: It was of interest to verify chemllically the identity of the active gas produced by the common green mold of citrus fruits, P. digitatum, which is a particularly promising organism for the study of the mechanism of ethylene formation.
Abstract: Experiments reported independently by BIALE (1) and MILLER, WINSTON, and FISHER (8) revealed that the common green mold of citrus fruits, P. digitatum, produces a physiologically active emanation whose effects on plant tissue are the same as those caused by ethylene gas. It was shown by the latter authors and by BIALE and SHEPHERD (3) that this fungus produces this emanation whether grown on its natural host or in culture, and PRATT (10) showed that production of the emanation does not depend on major nutrient components of the culture solution but does appear to be related to active growth and respiration of the culture. Production of the active gas by fungus-infected fruit has been further studied by ROHRBAUGH (12) and BIALE (2). Except for recent evidence of NICKERSON (9) that ethylene may be produced by Blastomyces dermatitidis and two other human pathogens, P. digitatum is the only fungus reported to have this activity. Biological testing of various other plant pathogens has given negative results (1, 14). Since P. digitatum is a particularly promising organism for the study of the mechanism of ethylene formation, it was of interest to verify chemllically the identity of the active gas produced.

73 citations


Journal ArticleDOI
TL;DR: Root growth of loblolly pine was measured under controlled conditions to find whether or not a definite and perhaps quantitative relationship to soil temperature and other factors could be shown.
Abstract: made under controlled conditions. Reed noted a marked reduction in root growth during the time when soil temperatures were lowest and also at times when the soil was driest. Turner's data also indicate this same general trend. It was, therefore, decided to measure root growth of loblolly pine under controlled conditions to find whether or not a definite and perhaps quantitative relationship to soil temperature and other factors could be shown. Materials and methods Two series of experiments were performed, the first during the spring and summer of 1941, the second during the winter of 1946. The seedlings need in 1941 were grown from seed collected in North Carolina in 1940, and the seedlings used in 1946 were grown from seed collected in Louisiana in 1945. The seedlings were grown in glass tubes about two inches in diameter and 18 inches long. These tubes were closed at the lower end with rubber stoppers and a layer of cinders placed over the stoppers. The tubes were then filled with a loamy greenhouse soil, which was kept wetted to field capacity. Although the soil was heated in an electric sterilizer before use, it still contained two species of small animals, a nematode and a collembolan. Neither seemed to be harmful; apparently they fed only on dead tissue sloughing off the roots. The collembolans may have aided in aeration by opening small passageways in the soil. The soil atmosphere in the tubes was analyzed with a Haldane apparatus and found to have approximately the same concentration of oxygen as the outside air. The concentration of carbon dioxide in the soil was somewhat higher than outside. The average amount was 1.0% and the maximum 2.88%. Cannon and Free (?) reported that for several species there was no detrimental effect on root growth of 20% or more carbon dioxide if oxygen were not deficient. Since the soil atmosphere normally contains more carbon dioxide than ordinary atmosphere and excesses from 0.2 to 5% are not unusual (28), it is believed that growth was not abnormally influenced by deficient oxygen or by an excess of carbon dioxide. 146

63 citations



Journal ArticleDOI
TL;DR: This is the first of a group of papers which will record investigations on nitrogen compounds and their metabolism in plants not only because of the intrinsic interest of nitrogen metabolism, but also because it had become so apparent that other vital phenomena would only be fully comprehended when their relations to nitrogen metabolism were revealed.
Abstract: This is the first of a group of papers which will record investigations on nitrogen compounds and their metabolism in plants. The work was undertaken not only because of the intrinsic interest of nitrogen metabolism, but even more because it had become so apparent that other vital phenomena would only be fully comprehended when their relations to nitrogen metabolism were revealed (26, and refs. there cited; 27). Plant respiration?long considered in terms only of carbohydrate breakdown?has recently been shown to include a moiety which varies concomitantly with protein synthesis and the metabolism of amino acids. This was especially true of the cells of the potato tuber (24), under the conditions which promote accumulation of salts. In another series of papers (for references see 21), the ability to accumulate salts, now somewhat generally conceded to be a property of active cells and dependent upon their aerobic respiration, has also been associated in a variety of ways with cells able to grow and to synthesize protein and with factors able to foster this process (22, 23, 24). For the particular case of the potato tuber, it was recognized that aerobic respiration, protein synthesis from the stored reserves of soluble nitrogen and the accumulation of anions (Br) and cations (K) varied pari passu under the influence of a wide range of conditions. Observations such as these led to the view that the energy of respiration was made available simultaneously for both salt accumulation and the protein synthesis with which it appeared to be linked. The necessary point of contact between the energy derived from aerobic respiration with the metabolism of nitrogen compounds and salt accumulation, promised, therefore, to be fundamental to the understanding of all of these processes. Prior to the work now to be described, some progress had been made by analytical methods which could fractionate the soluble nitrogen of the cells only into the amino-N and amide-N fractions (22). The total amide-N was further separable into glutamine-amide-N and asparagine-amide-N (25), and it became apparent that these two substances stood in quite different relationships to protein synthesis (26, and refs. there cited). Further-

59 citations


Journal ArticleDOI
TL;DR: Materials and methods Test plants were grown and used exactly as described previously and differences in the average percentage elongation of 15 sections growing in 25 ml.
Abstract: Materials and methods Test plants were grown and used exactly as described previously (8). The data are expressed as differences in the average percentage elongation of 15 sections growing in 25 ml. of the solution of the chemical and in distilled water: thus comparisons with previous tests can be made directly. All of the compounds were freshly prepared and carefully purified except a few which were Eastman White Label products crystallized from water until a satisfactory melting point was obtained. Experimental results and discussion


Journal ArticleDOI
TL;DR: It has only recently been demonstrated that the sensitivity of stornata to small changes in C02 concentration below normal is such that stomatal response to variations in light intensity could conceivably be due primarily to the effect of the latter on C 02 concentration within the leaf.
Abstract: The old hypothesis that light induces stomatal opening through its photosynthetic activity has been variously tested in a number of recent investigations. The results are strangely contradictory. First, reference may be made to tests based on the relative efficiency of different regions of the spectrum in promoting stomatal opening, though these tests are not very recent. The only systematic studies in which strictly quantitative methods have been used to equalize light intensity are those of Paetz (11), Sierp (15), and Harms (?). Paetz found that the order of activity was red light > blue > green, whereas Sierp and Harms found that red light was regularly the least active and that in most species green light was as active as blue. It has long been known that a reduction in the normal C02 content of the air tends to induce stomatal opening and an increase in CO2, up to a point, above normal has the opposite effect. It has, however, only recently been demonstrated (Heath, 7, 9) that the sensitivity of stornata to small changes in C02 concentration below normal is such that stomatal response to variations in light intensity could conceivably be due primarily to the effect of the latter on C02 concentration within the leaf. The only investigation in which measurement of photosynthesis rate has been combined with estimation of stomatal aperture is that of Wilson (18). Approaching the problem from various angles, he obtained results which seem quite opposed to the photosynthetic theory. Both in the behavior of plants in the open and under certain artificial conditions, stomatal opening and photosynthesis often showed no correlation, while complete absence of chlorophyll from leaves, including guard cells, did not entirely prevent stomatal response to light. On the other hand, regarding the long unsettled question of whether guard cells are capable of photosynthesis, the most

Journal ArticleDOI
TL;DR: Results of analyses undertaken with the possible catalytic role of one or more of the micronutrient metals: iron, manganese, copper, zinc, and molybdenum in the cellular activities of these cytoplasmic bodies are reported.
Abstract: An investigation of the extracellular reactions of chloroplasts in the light (4) and in the dark (5) has focused attention on the possible catalytic role of one or more of the micronutrient metals: iron, manganese, copper, zinc, and molybdenum in the cellular activities of these cytoplasmic bodies. The consideration of a possible participation of one or more of the micronutrient metals involves the knowledge of their relative distribution in the leaf and chloroplasts. This communication reports results of analyses undertaken with this purpose in view. Methods Sugar beet and chard plants were grown in a greenhouse in aerated nutrient solutions of the composition previously described (2), supplemented with the micronutrients B, Mn, Cu, Zn and Mo (1). Large leaves from plants approximately 12 wTeeks old were used for chemical analysis and the isolation of chloroplast fragments. The chloroplast fragments were prepared by trituration of the leaves in the cold without dilution in a "Vitajuicer" (3) and subsequent differential centrifugation as previously described (2), except that the final centrifugation was carried out in a Sorvall Type SS-1 centrifuge, for two hours in the cold, at the maximum speed corresponding to approximately 20,000 g. (A special test disclosed that the Vitajuicer could contribute only insignificant amounts of metal contamination to the analysis.) The chloroplast fragments were dried in an all-glass lyophilizer, and the dried material was kept in the cold in screw-capped bottles. The analyses of the whole leaves were made on samples of fresh leaves which were heated in the autoclave at 5 lbs. pressure for five minutes to stop enzymatic activity and were subsequently dried at 70? C. The dry material was ground in a porcelain mortar and redried at 70? C prior to analysis. The analytical determinations were made on aliquots of the ground leaves and of the lyophilized chloroplast fragments. Chlorophyll was measured as previously described (2). The total nitrogen, found by the micro-Kjeldahl method, in the trichloracetic acid precipitate of a water suspension of the dried material wTas designated as protein nitrogen and was multiplied by the factor 6.25 to give protein values. The metals were determined by the procedures of Parks et al. (15) modified as follows: in the preparation of the "ash solution" the hydrofluoric acid step was omitted and sulphuric acid was used in the perchloric acid digestion;

Journal ArticleDOI
TL;DR: Investigations of the activities of a number of benzoic acid derivatives have shown that the active compounds have one or both ortho positions occupied by electronegative atoms or groups, and it has been suggested that with these compounds the reaction takes place by a displacement of the electr onegative atom or group by the nucleophilic substrate.
Abstract: The substitution of atoms or groups in both ortho positions of phenoxyacetic, phenylacetic, phenylbutyric and indoleacetic acids causes the compounds to be ineffective in promoting the elongation of sections of Avena coleoptiles (9,15). The obvious interpretation is that these atoms or groups in the ortho position block a chemical reaction taking place at that point. Considerable evidence exists that electronegative atoms or groups attached to the benzene ring in phenoxyacetic and phenylacetic acids enhance the activity of these compounds, and this feature suggests that the substrate reacting at the ortho position is nucleophilic in nature (15). Bentley (2), however, has reported that 2,3,6-trichlorobenzoic acid is very effective in promoting the elongation of coleoptile sections, although both ortho positions are occupied by chlorine atoms. Investigations of the activities of a number of benzoic acid derivatives have shown that the active compounds have one or both ortho positions occupied by electronegative atoms or groups (9, 26), and it has been suggested that with these compounds the reaction takes place by a displacement of the electronegative atom or group by the nucleophilic substrate (9). One of the active derivatives of benzoic acid is 2,6-dichlorobenzoic acid. If such a substance does react at an ortho position by nucleophilic displacement of a chloride ion, then chemical analysis of the tissue and the solution in which growth has taken place should detect an increase in the amount of chloride ion. Such analyses wrere made and an increase in Cl~ was detected.

Journal ArticleDOI
TL;DR: No reports have been found in the literature on how long the seedling is dependent on the reserves in the cotyledons for successful establishment and later development.
Abstract: contained in the cotyledons on subsequent growth of the plants. Many investigations have dealt with the transformations which occur in the reserve food materials in seeds of crop plants as germination proceeds. Few studies, however, have been concerned with the rate of transfer of these foods to the seedling. No reports have been found in the literature on how long the seedling is dependent on the reserves in the cotyledons for successful establishment and later development. This information was desired for use in mineral nutrition studies on soybeans particularly where the effects of limiting levels of some of the major nutrients are being investigated. At starvation levels of nutrition, it was felt that the amount of a particular element supplied by the cotyledons may be sufficient to influence experimental procedure. Using semiquantitative, microchemical methods on freezing microtome sections of Manchu soybean seeds, Von Ohlen (12) followed the translocation of organic and inorganic substances from the cotyledons to the seedling during germination in the dark. His results show that oil moved out of the cotyledons more rapidly than the other main organic reserve, protein, and that among the mineral elements, potassium was translocated at a greater rate than phosphorus or magnesium. Holman (7) found that the fat content of Agat(e) soybeans had decreased 78%, 17 days after planting. The work of Miller (10) on sunflower probably gives the most complete data on the transformation and movement of foods in oilseed plants. The seedling material analyzed was grown under greenhouse conditions with natural light but at emergence the seedlings were transferred to a carbon dioxide-free atmosphere so that the seedlings were dependent upon the reserves of the cotyledons throughout the growing period. Miller's data show that hydration of the cotyledons was complete in 10 days, dry weight decreased gradu

Journal ArticleDOI
TL;DR: This investigation is essentially a collaboration between two laboratories bringing together problems in which each is interested and the use of S85 combined with autoradiographs of paper chromatograms is an obvious device to aid in the identification of the sulphur-containing amino acids.
Abstract: This investigation is essentially a collaboration between two laboratories bringing together problems in which each is interested. The Department of Agricultural Research of the American Smelting and Refining Company has long been interested in the problems of sulphur toxicity and sulphur metabolism in plants which are economically important. In the course of this work investigations have been made by the use of SS5. These have shown the general distribution of the isotope in the plant body. To some extent chemical procedures have been employed to identify in the protein hydrolysate specific sulphur-containing compounds, notably cystine and probably methionine (8, 9, and 10). It remained, however, necessary to obtain unequivocable evidence on the sulphur compounds into which the isotope had entered. In the Department of Botany at Rochester, investigations have been in progress since 1946 utilizing the techniques of paper chromatography to identify the free and combined amino acids in plants (2, 6, and 7). The sulphur-containing amino acids present rather special problems. Due to the small quantities commonly present and the poor reactivity of these substances with ninhydrin, they tend to be less easily detectable by the methods of paper chromatography than many of the other amino acids (1). Furthermore, as two-directional paper chromatograms are commonly carried out (i.e., using phenol : collidine-lutidine), the sulphur-containing amino acids tend to be obscured by others which are commonly present. Methionine sulphoxide occupies the same area as ?-amino butyric acid, a newly discovered free amino acid which is widely distributed (4, ?, and 7). Methionine itself is close to the leucines, and cystine can best be recognized if it is first converted to cysteic acid which occupies a position on the chromatograms well apart from other amino acids (1). In these circumstances the use of S85 combined with autoradiographs of paper chromatograms is an obvious device to aid in the identification of the sulphur-containing amino acids. In the laboratories of the American Smelting and Refining Company alfalfa plants were treated with S35 in the form of sulphate. The alfalfa

Journal ArticleDOI
TL;DR: The loblolly pine seedlings appeared to be more resistant to flooding injury than pond Pine seedlings, and both species made better growth in soil intermittently flooded for short periods than in soil maintained at field capacity or lower.
Abstract: Most crop and horticultural plants are seriously injured or even killed if the soil in which they are growing is flooded with water for an extended period of time. It generally is assumed that flooding is equally injurious to most species of forest trees and limits the natural distribution of many species to relatively well drained sites. It is supposed, for example, that pond pine occupies wet sites in the Atlantic Coastal Plain because its roots can survive flooding and the accompanying poor aeration better than the roots of loblolly pine or shortleaf pine. This view was not supported by the results of an experiment by Gaiser (1) who studied the effects of flooding on loblolly pine and pond pine seedlings grown in the greenhouse. The seedlings were planted in 5-quart oil cans filled with sandy soil. Holes were punched in the bottom of the cans and a layer of gravel was placed beneath the soil to facilitate drainage of the soil. Various periods of flooding, alternating with periods during which the soil was drained, were maintained for three months in the spring of 1948. The loblolly pine seedlings appeared to be more resistant to flooding injury than pond pine seedlings, and both species made better growth in soil intermittently flooded for short periods (two days out of nine) than in soil maintained at field capacity or lower. These results were so unexpected that a more extensive experiment was planned to study the effects of flooding.

Journal ArticleDOI
TL;DR: Mechanisms whereby synapsis and syngamy could extend their effects throughout the whole plant body are discussed.
Abstract: It is well known that the reproductive processes in plants are associated with pronounced changes of the physiology of the whole plant. In a series of papers, Murneek (19), Murneek and Wittwer (20, 21), Wittwer and Murneek (28) discussed mechanisms whereby synapsis and syngamy could extend their effects throughout the whole plant body. The increased knowledge about parthenocarpy has called attention to physiological distinctions between the processes of pollination and fertilization. The effect of pollination in leading to fruit development has been duplicated by use of synthetic growth substances (10). Fertilization is essential for embryo initiation and so far has not been replaced by treatment with any known substances. It is therefore of interest to know what effect pollination alone has on the metabolism of the flower.


Journal ArticleDOI
TL;DR: The basic features of the method consisted of jacketing the petiole of one primary leaf, immersing the blade in sugar solution and measuring the subsequent elongation of the plant occurring in the dark, which was used as an index to the effect of temperature on translocation of sugar.
Abstract: hydrate materials through petioles, will be influenced by temperature effects on numerous other processes occurring in various parts of the plant, such as respiration and assimilation, and the effect these processes have on concentration gradients between regions of export and import. Studies, therefore, in which the entire plant is subjected to different temperatures (4), although contributing much data of value, do not permit a clear analysis of the temperature effect on the process of translocation per se. In the present experiments, therefore, only the petiole temperature was varied, the rest of the plant in all treatments being maintained at a temperature of 20 ? Io C. Materials and methods The report by Weintraub and Brown (?) that stem elongation of ??aseolus vulgaris var. Black Valentine was directly proportional, within the range of 0 to .75 M, to the concentration of sugar supplied to the leaves suggested that this relationship could be used as a basis of approach for studying the effect of temperature on translocation of carbohydrates. If temperature has an effect on the rate of movement of sugar through the petiole then the amount of sugar reaching the growing tip will vary with temperature and the rate of elongation should vary accordingly. Stem elongation may then be used as an index to the effect of temperature on translocation of sugar. The basic features of the method, therefore, consisted of jacketing the petiole of one primary leaf, immersing the blade in sugar solution and measuring the subsequent elongation of the plant occurring in the dark. Seeds of Phaseolus vulgaris, variety Burpee's Stringless Greenpod (in

Journal ArticleDOI
TL;DR: A method of simultaneously preparing a large number of autoradiograms of entire plants, such that the intensity of the images is within limits proportional to the concentration of the radioactive material in the tissues derived from various applications of radio-phosphorus is presented.
Abstract: Favorable growth responses have recently been obtained with some phosphorus compounds applied as foliar sprays to vegetable crops, the objective being to supplement the usual supply of phosphorus absorbed by the roots (3). Preliminary studies utilizing a 25 millimolar solution of phosphoric acid enriched with small quantities of radioactive phosphorus indicated that the nutrient was absorbed by the leaves of a wide variety of crops and within a few hours translocated to -all plant parts, particularly to meristematic regions. A technique for making autoradiograms relating to root absorption and subsequent distribution of phosphorus in tomato fruit and leaves at various stages of development has been outlined (1). Suggestions for improving the quality of autoradiograms of biological materials have been described by BOYD (2). As a means of demonstrating the rapidity of absorption, translocation, and selective utilization of foliar applied nutrients, autoradiography offers a unique approach. The effects of chemical agents and variations in the external environment on nutrient absorption can readily be demonstrated. Autoradiograms provide one of the best means of obtaining indications of relative metabolic activities of various plant tissues since their accumulative capacities for many of the foliar applied nutrients is clearly revealed and located. Herein is presented a method of simultaneously preparing a large number of autoradiograms of entire plants, such that the intensity of the images is within limits proportional to the concentration of the radioactive material in the tissues derived from various applications of radio-phosphorus. Autoradiograms are included which illustrate some results obtained.

Journal ArticleDOI
TL;DR: It is noticed that light enhances, rather than inhibits, the auxin-induced growth, and this response was unexpected and of such great magnitude that it was considered desirable to investigate it more fully.
Abstract: In the first paper of this series (3), it was demonstrated that the auxininduced growth in length of sub-apical sections of etiolated pea stems -is greatly inhibited by light. This light-growth inhibition was subsequently (1, 2) interpreted in terms of a riboflavin-sensitized photoinactivation of indoleacetic acid (IAA). Such an interpretation derives support from the fact that light, concurrent with its inhibition of growth, increases the rate of disappearance of IAA from the external medium. In the course of similar experiments with stem sections of light-grown peas, we noticed that light enhances, rather than inhibits, the auxin-induced growth. This response was unexpected and of such great magnitude that it was considered desirable to investigate it more fully. The present paper describes the phenomenon in some detail and presents an explanation of it which seems consistent with all the facts at our disposal. The simple section growth test herein described may, incidentally, be of some use to those interested in utilizing green tissues for auxin or herbicide studies.

Journal ArticleDOI
TL;DR: This paper describes the second half of a series of tests of the photosynthetic theory of stomatal movement, which found that any agent that inhibits photosynthesis should prevent opening or cause closure in light?unless some other action prevents this.
Abstract: This paper describes the second half of a series of tests of the photosynthetic theory of stomatal movement. A corollary of this theory is that any agent that inhibits photosynthesis should prevent opening or cause closure in light?unless some other action prevents this. It has been reported that this relationship does not hold either in wilting or under the action of chloroform (Wilson, 14). The effects of these factors are investigated in the present paper. As before (11), stomatal aperture was measured by means of a modified porometer method, photosynthesis by infrared absorption, and, except in a few experiments, the leaf material all belonged to the same clone of Pelargonium zonale var. Barney.

Journal ArticleDOI
TL;DR: In this paper, the distribution of isotopic carbon in the carbohydrates of a bean plant allowed to photosynthesize in C1302 was investigated. But the results showed that the discrepancy between the two studies was due to a dilution of carbon atoms 3,4 by C1202 after the hexose was uniformly labeled.
Abstract: The rate at which assimilated carbon dioxide is distributed in the carbon atoms of plant sugars and other plant metabolites should provide indication of the interrelationships between the sugars and these substances after exposure of the plant to carbon dioxide in the light and in the dark. WOOD and BURR (9) were the first to determine the distribution of isotopic carbon in the carbohydrates of a bean plant allowed to photosynthesize in C1302. They found that sucrose had a higher C13 isotope content than the hexoses, dextrin or starch. They also noted that there was a difference in the C13 content in the various carbon atoms of the sugars. CALVIN and BENSON (2) have reported that during short period photosynthesis in C1402 sucrose was the only non-phosphorylated carbohydrate-containing label. The specific activity of carbon atoms 3,4 of the hydrolyzed sucrose was higher than carbon atoms 2,5 and 1,6. In some experiments, the specific activity of carbon atoms 2,5 was equal to carbon atoms 1,6 while in others they were unequal. Malic acid was predominantly carboxyl labeled. The distribution of label in alanine was somewhat similar to that of hexose. The carboxyl carbon having the highest specific activity, the beta carbon the least. GIBBs (3) reported that with a one-hour period of photosynthesis by barley plant in C1402, the distribution of label in the hexoses was the reverse of that published by the California workers (2), i.e., carbons 1,6 had the highest specific activity. Recently VITTORIO, KROTKOV, and REED (8) have shown that the discrepancy between the result in the two studies was due to a dilution of carbon atoms 3,4 by C1202 after the hexose was uniformly labeled. VARNER and BURRELL (7) found the same distribution of label within the carbon atoms of the soluble hexoses as in the glucose from starch isolated from Bryophyllum calycinum leaves which had photosynthesized for 30 minutes in C1402, carbon atoms 3,4 having the highest specific activity. Malic acid isolated from Bryophyllum leaves which had been exposed to C1402 in the dark for 2.5 hours was predominantly carboxyl labeled. The present work is concerned with the distribution of C14 in the glucose, fructose, sucrose, dextrin, starch, alanine, and malic acid of sunflower leaves I-Research carried out at Brookhaven National Laboratory under the auspices of the U. S. Atomic Energy Commission.

Journal ArticleDOI
TL;DR: In an attempt to elucidate the respiratory mechanism of the green alga, chlorella, several of the organic acids which are known to be intermediates in the aerobic path of carbohydrate metabolism in most animals and bacteria were supplied to Chlorella cells.
Abstract: In an attempt to elucidate the respiratory mechanism of the green alga, chlorella, several of the organic acids which are known to be intermediates in the aerobic path of carbohydrate metabolism in most animals and bacteria were supplied to chlorella cells. In a previous paper (9), the results of growth experiments were reported and there was some evidence of utilization of the acid intermediates for growth in the dark by chlorella. Since the organic acids supplied are assumed to enter the path of metabolism through the respiratory mechanism, the effects of the organic acids on the respiratory gas exchange {i.e., oxygen uptake and carbon dioxide evolution) were investigated. The results of this investigation are reported here.

Journal ArticleDOI
TL;DR: Determinations of soluble nutrients are of greater value as tissue tests than total analyses, which often obscure important variations in the nutrients concerned.
Abstract: Tissue tests applied to corn and various truck crops have afforded a convenient means of estimating the nutritional status of the plant. The application of suitable tissue tests to cotton should be of similar value. The determination of the portion of the plant to be used, the relation existing between the availability of certain elements and the accumulation of these elements in the sampling tissue, are among the problems which must be solved so that results obtained from tissue tests may be interpreted properly. Tissue tests developed at Purdue University are being used in diagnoses of nutrient deficiencies in corn (8, 12, 13, 14). According to Hoffer (8) the best time to make tests on corn is when the plants are well along in maturity. The value of information obtained late in the season is limited, however, by the fact that corrective measures cannot be taken until the following growing season. Carolus (1) employed quantitative tissue-testing methods using cabbage and potatoes as his experimental plants. He noted that a deficient supply of nitrogen was reflected in a high concentration of soluble phosphorus and a low concentration of soluble nitrate nitrogen in the experimental tissue. A reverse of the above situation was observed when phosphorus was the limiting element. A potassium deficiency resulted mainly in a low concentration of that element and in some cases was accompanied by increased amounts of soluble nitrate nitrogen. Magnesium deficiency was generally associated with a low concentration of nitrogen. Wolf and Ichisaka (16) drew similar conclusions as to the relationship existing between nitrogen and phosphorus. Emmert (5) utilized plant tissue tests as a guide in fertilizing tomatoes. He concludes that determinations of soluble nutrients are of greater value as tissue tests than total analyses, which often obscure important variations in the nutrients concerned.


Journal ArticleDOI
TL;DR: Oven-dried, midshoot leaves were available from the 1947 experiments on nutrient balance of tung and represented plants grown under a wide range of cations and of forms of nitrogen supply.
Abstract: Oven-dried, midshoot leaves were available from the 1947 experiments on nutrient balance of tung (10). These one year old seedlings had been grown in sand culture in a factorial experiment with three levels of Mg and ? (0.5, 2, and 4 millimoles/1.) and three ratios of nitrate ? to ammonium ? (all N03; f N03 to I NH4; \ N03 to \ NH4). In a supplementary experiment, the highest levels of ? and Mg of the main experiment were supplied with three levels of calcium (0.4, 2, and 5.7 millimoles/1.) in an all nitrate solution, and also in a \ N03 to \ NH4 solution. Thus the material represented plants grown under a wide range of cations and of forms of nitrogen supply.

Journal ArticleDOI
TL;DR: An increased respiration, a stimulated proliferation, and a considerable loss of carbohydrate are caused in the Jerusalem artichoke tuber by indoleacetic acid and other auxins.
Abstract: Many reports are available in the literature on the effects of 2,4-D on numerous physiological and biochemical processes. Among these are increased cell proliferation (5), increased respiration (20), increased carbohydrate depletion (17), decreased respiration of roots (27), decreased uptake of potassium by roots (18), decreased accumulation by the root system of KNO3 and KC1 (13), inhibition of lipase activity (9), inhibition of ascorbic acid oxidase (27), stimulation of phosphatase activity (15), stimulation of beta-amylase activity (22, 28), inhibition of alphaand beta-amylase activity (14), etc. Useful though these observations are for the understanding of auxin action, they do not tell us if these physiological changes are the specific reasons 2,4-D has such a high herbicidal activity. It would rather seem that these phenomena are not specific for 2,4-D but are caused as well by other auxins such as indoleacetic acid and naphthaleneacetic acid (for terminology see 22). Thus, an increased respiration, a stimulated proliferation, and a considerable loss of carbohydrate are caused in the Jerusalem artichoke tuber by indoleacetic acid (8). Increased phosphatase activity is found in Avena roots after treatment with indoleacetic acid and other auxins (4). Inhibition of amylase activity by indoleacetic acid and by a variety of other auxins has been demonstrated (26). Indoleacetic acid, though capable of affecting many reactions in a fashion similar to 2,4-D is definitely not an efficient herbicide. The clue to the solution of why 2,4-D displays such a high herbicidal activity appears to lie in a different direction. Rather than only asking: "What physiological changes does 2,4-D bring about?" it would appear to be more profitable to ask first: "In what fundamental aspect does 2,4-D differ from the other auxins?" The present paper will largely deal with this question.