Normal CO2 Concentration Research Articles

The Effect of Leaf Water Potential, Leaf Temperature and Light Intensity on Leaf Diffusion Resistance and the Transpiration of Leaves of Malus sylvestris

AbstractThe relationship between leaf resistance to water vapour diffusion and each of the factors leaf water potential, light intensity and leaf temperature was determined for leaves on seedling apple trees (Malus sylvestris Mill. cv. Granny Smith) in the laboratory. Leaf cuticular resistance was also determined and transpiration was measured on attached leaves for a range of conditions.Leaf resistance was shown to be independent of water potential until potential fell below — 19 bars after which leaf resistance increased rapidly. Exposure of leaves to CO2‐free air extended the range for which resistance was independent of water potential to — 30 bars.The light requirement for minimum leaf resistance was 10 to 20 W m−2 and at light intensities exceeding these, leaf resistance was unaffected by light intensity.Optimum leaf temperature for minimum diffusion resistance was 23 ± 2°C. The rate of change measured in leaf resistance in leaves given a sudden change in leaf temperature increased as the magnitude of the temperature change increased. For a sudden change of 1°C in leaf temperature, diffusion resistance changed at a rate of 0.01 s cm−1 min−1 whilst for a 9°C leaf temperature change, diffusion resistance changed at a rate of 0.1 s cm−1 min−1.Cuticular resistance of these leaves was 125 s cm−1 which is very high compared with resistances for open stomata of 1.5 to 4 s cm−1 and 30 to 35 s cm−1 for stomata closed in the dark.Transpiration was measured in attached apple leaves enclosed in a leaf chamber and exposed to a range of conditions of leaf temperature and ambient water vapour density. Peak transpiration of approximately 5 × 10−6 g cm−2 s−1 occurred at a vapour density gradient from the leaf to the air of 12 to 14 g m−3 after which transpiration declined due presumably to increased stomatal resistance. Leaves in CO2‐free air attained a peak transpiration of 11 × 10−6 g cm−2 s−1 due to lower values of leaf resistance in CO2 free air. Transpiration then declined in these leaves due to development of an internal leaf resistance (of up to 2 s cm−1). The internal resistance was masked in leaves at normal CO2 concentrations by the increase in stomatal resistance.

Studies on the Carbon Dioxide Environment for Plant Growth. VI

In the course of investigations on photosynthesistranpiration-CO2 concentration relations, cyclic changes of transpiration rate with approximately 30 minute periods were found under conditions of 0.75 cal⋅cm-2⋅ min-1 light intensity, 25°C air temperature and 65% relative humidity in normal CO2 concentration of air. The amplitude of oscillation was affected by wind speed and increased with increase of wind speed. The average transpiration rate increased with increase of wind speed and showed the maximum value at 150 cm·sec-1 wind speed.In high CO2 concentration, the period and the amplitude of oscillation became longer and narrower respectively and the cyclic changes disappeared at about 3, 000 ppm, but when air temperature was raised to 30°C, the cyclic changes continued up to 20, 000 ppm.The average transpiration rate reduced with increase of CO2 concentration and showed minimum value at about 1, 000 ppm. Over that concentration, the transpiration rate increased up to approximately 20, 000 ppm, and also in darkness, the transpiration rate increased over 1, 000 ppm. This phenomenon depended on air temperature, i.e., the depression of transpiration rate disappeared when air temperature was raised to 35°C. Similar phenomena were observed on pet-sai (Brassica pekinensis PUPR), cabbage (Brassica oleraces L., var. capitata L.), turnip (Brassica ropa var. Mana) and radish (Raphanus sativus L.) .The causes of increase of the transpiration rate in high CO2 concentration were not clarified, but the transpiration rate was reduced by spraying ABA solution on the plants. This means that CO2 causes the stomata to open again in high CO2 concentration.

Light Intensity During Leaf Growth Affects Chlorophyll Concentration and CO2 Assimilation of a Soybean Chlorophyll Mutant1

An evaluation was made of leaf diffusive resistance and chlorophyll concentrations of dark green (normal) and pale green (chlorophyll deficient) phenotypes of a soybean [Glycine max (L.) Merrill] mutant when grown 10‐ and 30‐klux light intensities. When grown at the 10‐klux intensity the two leaf types had similar mesophyll and total CO2 diffusive resistances and similar net photosynthetic rates per unit leaf area at normal ambient CO2 concentrations (e.g., 300 µl/liter). Chloropyhll concentration of the pale green leaf was one‐fourth that of the dark green leaf. On a chlorophyll basis, rate of CO2 fixation was four times faster in the pale green type than in the dark green type. The similarity in net photosynthetic rates per unit leaf area of the two phenotypes when grown at the 10‐klux light intensity was the result of (1) similar CO2 diffusive resistances and (2) the ability of the photosynthetic apparatus of the pale green leaf to fix CO2 as rapidly as that of the dark green leaf, in spite of a much lower amount of chlorophyll.When grown at the 30‐klux light intensity, chlorophyll concentration of the pale green phenotype progressively declined, to one‐tenth the amount at the 10‐klux intensity. Chlorophyll concentration of the dark green phenotype was not significantly affected by light intensity. Photosynthesis of the pale green leaf grown at the 30‐klux intensity became CO2 saturated at concentrations well below 300 µl/liter. Therefore, light intensity during leaf growth strongly influenced the relative CO2 assimilation rates of the dark green and pale green phenotypes.

EFFECT OF LIGHT AND GROWTH SUBSTANCES ON FLOWERING OF IRIS × HOLLANDICA CV. WEDGWOOD

SUMMARY In the winter period with prevailing low light intensities and short days, the forcing of Iris “Wedgwood” can easily result in flower bud abortion (bud blast). Consequently a high proportion of plants fail to produce flowers. To elucidate the cause of bud blast, plants were subjected to various treatments —12CO2, 14CO2, growth substances — in the period of rapid stem elongation about two weeks before flowering. Plants grown under weak illumination and normal CO2 concentration (leading to 57% flowering) were compared with plants grown under strong illumination at low CO2 concentration (leading to 100% flowering). As the dry weight of whole plants of both these groups was almost the same at flowering, bud blast under low illumination cannot simply be attributed to a lack of recent photosynthetic products. The distribution pattern of photosynthates appears to be changed. It is suggested that a hormone imbalance plays a role in the distribution pattern and consequently in bud blast, since injections of cytokinins, such as N6-benzylaminopurine, zeatin, and kinetin, during dark treatment can increase the flowering proportion.

MODERATE‐TERM WATER STRESSES AND ASSOCIATED CHANGES IN SOME PHOTOSYNTHETIC PARAMETERS IN COTTON

SUMMARYCotton plants (Gossypium hirsutum L., var Deltapine smoothleaf) were subjected to 1‐ or 2‐week periods of mild water stress using an osmotic soil cell. The treatments were severe enough to affect seriously several photosynthetic parameters, while good night‐time recovery of plant water‐potential minimized effects on development and leaf expansion.Most measurements were made soon after rewatering, owing to very high stomatal resistances in the stressed plants. The stressed plants had lower rates of potential photosynthesis and lower rates of actual photosynthesis (at normal ambient CO2 concentrations) than the controls. Both stomatal and intracellular resistances and the corresponding ‘photosynthetic limitations’ were greater in the stressed plants than the controls. Most of these parameters showed fairly complete recovery 24 hours after rewatering. Parallel changes were observed in the activities of carbonic anhydrase, ribulosediphosphate carboxylase and 14C fixation by leaf slices, all of which were lower in the stressed plants.Although activities of all the processes studied showed parallel changes, there was evidence that the major factor causing reduced photosynthesis in the stressed plants was stomatal closure. There was some evidence that the photosynthetic system adjusted itself to water stress over the periods studied.

Changes in Transpiration, Net Carbon Dioxide Assimilation and Leaf Water Potential Resulting from Application of Hydrostatic Pressure to Roots of Intact Pepper Plants

AbstractHydrostatic pressures varying from 0 to 6.0 bar were applied to roots of intact Capsicum annuum L. cv. California Wonder plants growing in nutrient solution and the rates of transpiration, and net CO2 assimilation, apparent compensation point and leaf water potential measured.Increasing the pressure on the roots of plants with roots in solution with either ‐0.5 or ‐5.0 bar osmotic potential with 1 bar increments resulted in a decrease in transpiration. With the application of 1 or 2 bar pressure the rate of transpiration returned to near or above the original rate. An application of 3 or 4 bar pressure reduced the rate of transpiration of all plants. The transpiration of plants with roots in solution with ‐0.5 bar osmotic potential remained at the reduced rate for as long as these pressures were maintained. The transpiration of plants with roots in solution with ‐5.0 bar was only temporarily suppressed at these pressures. Changing the applied pressure from 3 or 4 bar to 0 resulted in a rapid increase in transpiration which lasted approximately 15 minutes. This was followed by a decrease in transpiration to a rate lower than before the pressure was applied. The pattern of response was similar for plants at low or high light intensity or at normal or low CO2 concentrations. When leaf diffusive resistance was 6.0 s cm−1 or greater, changes in net CO2 assimilation were similar to those of transpiration. The apparent CO2 compensation point increased as pressure was applied and decreased with a release in pressure. Leaf water potential increased with an increase in pressure and decreased with a decrease in pressure. The changes in leaf water potential were frequently but not always proportional to changes in pressure.It is postulated that the respouses noted were due to changes in resistance to flow of water from xylem terminals through the mesophyll cells and stomatal cavities to the atmosphere.

Die Wirkung monochromatischen Lichts auf die extracellul�re Glykols�ure-Ausscheidung und die Lichtatmung bei der Blaualge Anacystis nidulans

The algae were grown under normal air conditions in a low light intensity (400 lux) and measured in the normal CO2-concentration (0.03 Vol. %). After an illumination period we observed a CO2 gush which is dependent on the temperature and wavelength used during the measurements. At +20°C a CO2 gush occurs only in the blue and far red regions. At +35°C, on the other hand, a CO2 outburst appears over the whole spectrum. The magnitude of the CO2 gush varies with the wavelength used during the light period. On this basis we have measured an action spectrum of photorespiration which is identical with the action spectrum of photosynthetic CO2 uptake.

Photosynthetic activity of vegetable plants and its horticultural significance

After-effect of low-CO2 experience upon the growth and physiology for tomato and cucumber plants was examined by means of isotopic tracers under controlled conditions.The fixation of 14CO2 at normal CO2 concentration, was decreased slightly in the tomato plants which had been kept for 2 hours in an atmosphere containing 80ppm CO2. Such an after-effect of low-CO2 experience for tomato could be brought out only when the plants had been placed under conditions of low CO2 concentration and a certain degree of light intensity. On the other hand, cucumber plants had no after-effect of low-CO2 experience, although total activity of 14C fixed into the plants was clearly decreased at very low CO2 concentration.A downward translocation of 14C-assimilates to the roots was restricted more significantly in cucumber than that in tomato at 80ppm CO2 in the light. A considerable restriction for translocation of assimilates from leaves into the roots was observed in cucumber plant during normal photosynthesis in the light.CO2 compensation concentration which is reached in a closed system containing the plants at 20, 000 lux was 38±2ppm CO2 for tomato and 65±4ppm CO2 for cucumber. The amounts of CO2 evoluted into CO2-free air through the respiration were also higher in cucumber.Tomato plants which had been kept at 80ppm CO2 for 2 hours had lower value of respiratory activity in the roots. In addition, low-CO2 experience caused a considerable decrease in the uptake of phosphorus through the tomato roots.Tomato plants placed in an atmosphere containing 80ppm CO2 for 1 hour in every morning during 2 weeks resulted in the marked decrease in dry weight of root, and considerable decrease in net assimilation rate.

Adaptations of the Photosynthetic Mechanism of Sugar Maple (Acer saccharum) Seedlings Grown in Various Light Intensities

AbstractSugar maple (Acer saccharum Marsh.) seedlings were grown in a nursery for three years in 13, 25, 45 and 100 per cent of full daylight. During the third year of growth, the rates of their apparent photosynthesis and respiration were measured periodically with an infra‐red gas analyzer at various light intensities and normal CO2 concentration. In addition, the rates of apparent photosynthesis of a single attached leaf of the same seedlings were measured at saturating light intensity, hut varying CO2 concentrations.An increase in the light intensity in which seedlings were grown had no effect on their height or mean leaf area, hut resulted in thicker leaves, an increase in the total leaf area per seedling due to an increase in the number of leaves, an increase in the dry weight especially of roots and a decrease in the chlorophyll content of leaves.Throughout the growing season seedlings grown in full daylight, as compared with those grown in lower light intensities, had the lowest rates of apparent photosynthesis measured at standard conditions (21,600 lux light intensity and 300 ul/l of CO2), when this was expressed per unit leaf area, hut the highest rates on a per seedling basis. Thus dry matter production attained at the end of the growing season correlated positively with the photosynthetic rate per seedling, but not per unit leaf area. The rates of apparent photosynthesis of seedlings grown at lower light intensities were more responsive to changes in light intensity or CO2 concentration than those of seedlings grown in full daylight intensity.

Effects of Light Intensity and Carbon Dioxide Concentration on Photosynthetic Rate of Soybean1

Photosynthetic response curves to CO2 concentration and light intensity were determined for the soybean varieties ‘Hark’ and ‘Chippewa‐64’.At light intensities above 5,380 lux, the photosynthetic rates of both varieties were limited by the CO2 concentration of the surrounding atmosphere within the range investigated (270 to 1670 ppm).At normal atmospheric CO2 concentration (300 ppm), photosynthesis of both varieties was light saturated at about 21,530 lux. At a CO2 concentration of 1670 ppm, photosynthesis was not light saturated in either variety at the highest light intensity tested (75,350 lux).The photosynthetic rate of the variety Hark was higher than that of the variety Chippewa‐64 at 45 of the 48 combinations of light intensity and CO2 concentration tested.

Studies on the carbon dioxide environment for plant growth. I

The present study was undertaken to determine the effect of atmospheric CO2 concentrations on the growth, flowering and fruit setting of eggplant.Cultivar of eggplant, “Senryo”, grown in polyvinyl plastic growth chambers were treated with CO2 at 4 levels of concentrations, 200, 300 (normal air), 900 and 3, 000ppm, for 8 hours daily from April 1 to June 30, 1964. Above normal CO2 concentrations were obtained by regulation of the flow rate of air and CO2 from cylinder at inlet to the chambers. The chamber used for below normal CO2 was sealed off and air in the chamber was recirculated through the air conditioner and maintained about 200ppm.1) Differences in growth and appearance of the plants grown under the normal and the above normal levels of CO2 were apparent within 20 days. At the end of treatment, marked increases in fresh and dry weights, number of leaves and leaf area were observed as the CO2 concentrations increased, but there was little effect on plant height. In the 3, 000ppm chamber, fresh and dry weight yields of plant were increased about 1.5-1.6 times as compared to that in the 300ppm chamber. Similarly, leaf area in the 3, 000ppm chamber was about 1.2 times as compared to that in the 300ppm chamber, and this consisted of both expansion in leaf size and increase in number of leaves per plant. Moreover, CO2 enrichment enhanced net assimilation rate. NAR in the 3, 000ppm chamber doubled as compared with that in the 300ppm chamber. This was a similar result to that. obtained with swiss chard in a previous report.2) As CO2 concentrations increased, number of flowers increased, while the ratio of the abnormal short or moderate styled flower to the normal long styled flower decreased. Similarly, percentage of fruit set per flower opened and the total yield of fruit increased. Fresh and dry weight yields of fruit in the 3, 000ppm chamber were 2, 271g and 135.9g, respectively, compared to 734.5g and 58.1 g in the 300ppm chamber.3) Content of chlorophyll, nitrogen, phosphorus and potassium in leaves were not significantly affected by CO2 concentrations, while their amounts per plant increased as the CO2 concentrations were raised.

Studies on the carbon dioxide environment for plant growth. II

The present study was undertaken to determine the effect of atmospheric CO2 concentrations on the growth, flowering and fruit setting of eggplant.Cultivar of eggplant, “Senryo”, grown in polyvinyl plastic growth chambers were treated with CO2 at 4 levels of concentrations, 200, 300 (normal air), 900 and 3, 000ppm, for 8 hours daily from April 1 to June 30, 1964. Above normal CO2 concentrations were obtained by regulation of the flow rate of air and CO2 from cylinder at inlet to the chambers. The chamber used for below normal CO2 was sealed off and air in the chamber was recirculated through the air conditioner and maintained about 200ppm.1) Differences in growth and appearance of the plants grown under the normal and the above normal levels of CO2 were apparent within 20 days. At the end of treatment, marked increases in fresh and dry weights, number of leaves and leaf area were observed as the CO2 concentrations increased, but there was little effect on plant height. In the 3, 000ppm chamber, fresh and dry weight yields of plant were increased about 1.5-1.6 times as compared to that in the 300ppm chamber. Similarly, leaf area in the 3, 000ppm chamber was about 1.2 times as compared to that in the 300ppm chamber, and this consisted of both expansion in leaf size and increase in number of leaves per plant. Moreover, CO2 enrichment enhanced net assimilation rate. NAR in the 3, 000ppm chamber doubled as compared with that in the 300ppm chamber. This was a similar result to that. obtained with swiss chard in a previous report.2) As CO2 concentrations increased, number of flowers increased, while the ratio of the abnormal short or moderate styled flower to the normal long styled flower decreased. Similarly, percentage of fruit set per flower opened and the total yield of fruit increased. Fresh and dry weight yields of fruit in the 3, 000ppm chamber were 2, 271g and 135.9g, respectively, compared to 734.5g and 58.1 g in the 300ppm chamber.3) Content of chlorophyll, nitrogen, phosphorus and potassium in leaves were not significantly affected by CO2 concentrations, while their amounts per plant increased as the CO2 concentrations were raised.

Tissue carbon dioxide concentrations in rats during acute respiratory acidosis.

Tissue carbon dioxide concentrations were measured in rats following exposure of the intact animals to 10% or 30% Co2 in oxygen for time intervals from 5 minutes to 2.5 hours. The rats were sacrificed by decapitation. The average normal Co2 concentrations in skeletal muscle, heart and brain were 13.2, 18.6 and 15.1 mm/kg of wet tissue, respectively. The tissue Co2 increased at about the same rate, relative to normal concentration, in each of the three tissues, the concentration approximately doubling in the first 35 minutes on 30% Co2. The skeletal muscle Co2 concentration on 30% Co2 followed a single exponential curve in which the rate constant was 0.036 min.-1. Tissue Co2 capacity curves and data on the rate of Co2 loss post mortem are presented. The barium-soluble Co2 fraction of Conway and Fearon was found to increase in skeletal muscle from 9.4 to 14.6 mm/kg wet tissue when rats had been on 30% Co2 for 1 hour. Even in control rats this fraction showed a large variability and may have little physiological significance. Submitted on April 23, 1959