scholarly journals Auxin Applications Affect Posttransplant CO2 Exchange Rate and Growth of Bare-rooted Vinca [Catharanthus roseus (L.) G. Don] Seedlings

1999 ◽  
Vol 124 (3) ◽  
pp. 234-238 ◽  
Author(s):  
Marc van Iersel
Keyword(s):  
Exchange Rate ◽  
Catharanthus Roseus ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Dry Mass ◽  
Co2 Exchange ◽  
Naphthaleneacetic Acid ◽  
Negative Effects ◽  
Transplant Shock ◽  
Whole Plant

Uprooting and transplanting seedlings can cause root damage, which may reduce water and nutrient uptake. Initiation of new roots and rapid elongation of existing roots may help minimize the negative effects of transplant shock. In this study, seedlings with four true leaves were transplanted into diatomaceous earth and the plants were transferred to a growth chamber, where they were treated with NAA (0, 0.025, 0.25, and 2.5 mg·L-1; 36 mL/plant). The effects of drenches with various amounts of 1-naphthaleneacetic acid (NAA) on the posttransplant CO2 exchange rate of vinca [Catharanthus roseus (L.) G. Don] were quantified. Whole-plant CO2 exchange rate of the plants was measured once every 20 minutes for a 28 day period. Seedlings treated with 0.025 or 0.25 mg·L-1 recovered from transplant shock more quickly than plants in the 0 and 2.5 mg·L-1 treatments. Naphthaleneacetic acid drenches containing 0.025 or 0.25 mg·L-1 increased whole-plant net photosynthesis (Pnet) from 10 days, dark respiration (Rdark) from 12 days, and carbon use efficiency (CUE) from 11 days after transplanting until the end of the experiment. The increase in CUE seems to have been the result of the larger size of the plants in these two treatments, and thus an indirect effect of the NAA applications. These differences in CO2 metabolism among the treatments resulted in a 46% dry mass increase in the 0.025 mg·L-1 treatment compared to the control, but shoot-root ratio was not affected. The highest rate of NAA (2.5 mg·L-1) was slightly phytotoxic and reduced the growth rate of the plants.

Influence of temperature on net CO2 exchange in roses

1991 ◽  
Vol 71 (1) ◽  
pp. 235-243 ◽  
Author(s):  
J. Jiao ◽  
M. J. Tsujita ◽  
B. Grodzinski
Keyword(s):  
Dark Respiration ◽  
Net Photosynthesis ◽  
Co2 Exchange ◽  
Effect Of Temperature ◽  
Flower Bud ◽  
Temperature Range ◽  
Whole Plant ◽  
Optimal Temperature Range ◽  
Influence Of Temperature On ◽  
Whole Plants

The effect of temperature on net CO2 exchange of source and sink tissues of the flowering shoots and of whole plants was examined using single-stemmed Samantha roses. At all stages of shoot development, the optimal temperature range for whole-plant carbon (C) gain at saturating irradiance and ambient CO2 level was between 20° and 25 °C, narrower than the temperature range for optimal leaf net photosynthesis. Dark respiration increased more dramatically than photosynthesis with temperatures between 15 and 35 °C. At 25 °C, C loss due to respiration from the flower bud at colour bud stage accounted for 45% of the C loss of the flowering shoot. At low irradiance levels (e.g. 200 μmol m−2 s−1) whole-plant net photosynthesis was greater at 16° than at 22 °C because of a greater reduction in respiration. Lowering the night temperature from 27 to 17 °C also increased daily C gain due to a reduction in the C lost at night. Whole-plant net photosynthesis of plants grown and measured at enriched (1000 ± 100 μL L−1) CO2 was greater than that of plants grown and measured at ambient (350 ± 50 μL L−1) level at temperatures between 15° and 35 °C. Furthermore, the optimal temperatures for whole-plant net photosynthesis in CO2 enrichment was higher than at ambient CO2 level. Key words: Dark respiration, net photosynthesis, Rosa hybrida, temperature

Temperature Response of Whole-plant CO2 Exchange Rates of Magnolia (Magnolia grandiflora L.)

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 511d-511
Author(s):  
Marc W. van Iersel ◽  
Orville M. Lindstrom
Keyword(s):  
Dark Respiration ◽  
Temperature Response ◽  
Net Photosynthesis ◽  
Co2 Exchange ◽  
Limiting Factor ◽  
Response Curves ◽  
Gross Photosynthesis ◽  
Temperature Range ◽  
Whole Plant ◽  
Increasing Temperature

Photosynthesis and respiration temperature-response curves are useful in predicting the ability of plants to perform under different environmental conditions. Whole crop CO2 exchange of two groups of magnolia `Greenback' plants was measured over a 26 °C temperature range. Net photosynthesis (Pnet) increased from 2 to 17% C and decreased again at higher temperatures. The Q10 for Pnet decreased from ≈4 at 6 °C to 0.5 at 24 °C. The decrease in Pnet at temperatures over 17 °C was caused by a rapid increase in dark respiration (Rdark) with increasing temperature. The Q10 for Rdark was estimated by fitting an exponential curve to data, resulting in a temperature-independent Q10 of 2.8. Gross photosynthesis (Pgross), estimated as the sum of Rdark and Pnet, increased over the entire temperature range (up to 25 °C). The Q10 for Pgross decreased with increasing temperature, but remained higher than 1. The data suggest that high respiration rates may be the limiting factor for growth of magnolia exposed to high temperatures, since it may result in a net carbon loss from the plants. At temperatures below 5 °C, both Pnet and Rdark become low and the net CO2 exchange of the plants would be expected to be minimal.

scholarly journals 155 Fertilizer Concentration Affects Whole Plant CO2 Exchange and Growth of Subirrigated Pansies

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 416D-416
Author(s):  
Marc van Iersel ◽  
Jong-Goo Kang
Keyword(s):  
Root System ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Co2 Exchange ◽  
Bedding Plants ◽  
Whole Plant ◽  
Growing Medium ◽  
Wide Range ◽  
K Deficiency ◽  
Plant Photosynthesis

Subirrigation is an economically attractive irrigation method for producing bedding plants. Because excess fertilizer salts are not leached from the growing medium, salts can accumulate in the growing medium. Fertilizer guidelines developed for overhead irrigation may not be appropriate for subirrigation systems. Our objective was to quantify the effect of the fertilizer concentration (N at 0, 135, 285, and 440 mg·L–1) on whole-plant CO2 exchange and growth of subirrigated pansies. Whole plant CO2 exchange rate (net photosynthesis and dark respiration) was measured once every 10 min for 31 days. Whole-plant photosynthesis, dark respiration, and carbon use efficiency increased during the experiment. Fertilizer concentration started to affect the growth rate of the plants after approximately 7 days. Maximum photosynthesis and growth were achieved with N at about 280 mg·L–1 in the fertilizer solution [electrical conductivity = 2 dS·m–1]. Growth was reduced by ≈10% when the plants were fertilized with N at 135 and 440 mg·L–1 compared to 280 mg·L–1. Growth of plants watered without any fertilizer was greatly reduced, and plants showed symptoms of N and K deficiency. The size of the root system decreased and the shoot: root ratio increased with increasing fertilizer concentration, but the size of the root system was adequate in all treatments. These results indicate that subirrigated pansies can tolerate a wide range of fertilizer concentrations with relatively little effect on plant growth.

Optimizing aerial environments for greenhouse rose production utilizing whole-plant net CO2 exchange data

1991 ◽  
Vol 71 (1) ◽  
pp. 253-261 ◽  
Author(s):  
J. Jiao ◽  
M. J. Tsujita ◽  
B. Grodzinski
Keyword(s):  
Dark Respiration ◽  
Net Photosynthesis ◽  
Co2 Exchange ◽  
Day Length ◽  
Daily Growth ◽  
Relative Contribution ◽  
Whole Plant ◽  
Nondestructive Measurements ◽  
Environment Modelling ◽  
Exchange Data

A daily growth model was developed for Samantha roses based on nondestructive measurements of whole-plant net CO2 exchange rate (NCER) under various aerial environmental conditions. Irradiance, CO2 concentration, and temperature accounted for 70, 20, and 5%, respectively, of the variance in whole-plant net photosynthesis explainable by a second-order polynomial model (R2 = 0.86). The predicted optimal temperatures for whole-plant net photosynthesis increased from 19 to 24 °C with increasing irradiance from 100 to 1200 μmol m−2 s−1 and CO2 concentration from 350 to 1500 μL L−1. Dark respiration rate increased exponentially with temperature and could be predicted by the Arrhenius equation. Even though respiratory carbon (C) loss at night increased linearly with daytime C gain, daily C gain (AC) was still proportional to daytime net photosynthesis. The relative contribution of irradiance (100–1200 μmol m−2s−1), day length (8–16 h), CO2 concentration (350–1500 μL L−1), day temperature (15–30 °C), and night temperature (15–25 °C) to plant daily growth was 64, 31, 4, 0.3, and 0.7%, respectively. Key words: Carbon balance, environment, modelling, photosynthesis, respiration, Rosa hybrida

Influence of radiation and CO2 enrichment on whole plant net CO2 exchange in roses

1991 ◽  
Vol 71 (1) ◽  
pp. 245-252 ◽  
Author(s):  
J. Jiao ◽  
M. J. Tsujita ◽  
B. Grodzinski
Keyword(s):  
Exchange Rate ◽  
Radiant Energy ◽  
Co2 Enrichment ◽  
Co2 Exchange ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Carbon Gain ◽  
Flower Bud ◽  
Whole Plant ◽  
Bud Size

At three stages of flowering shoot development, varying the irradiance and CO2 levels had a similar effect on the whole-plant net CO2 exchange rate (NCER) of Samantha rose plants. At 22 °C, the NCER was saturated at 1000 μmol m−2 s−1 photosynthetically active radiation (PAR). The duration of the light period was also important in determining daily carbon (C) gain. When roses were exposed to a constant daily radiant energy dose of 17.6 μmol m−2 provided either as a 12-h irradiation interval at 410 μmol m−2 s−1 PAR or 24 h of irradiation at 204 μmol m−2 s−1 PAR, the plants exposed to 24 h of continuous irradiation at the lower photon flux density retained 80% more C. Under saturating irradiance, the net photosynthetic rate at an enriched (1000 μL L−1) CO2 level was almost double that at ambient (350 μL L−1) CO2. However, plants grown at ambient and enriched CO2 levels had similar whole-plant NCERs when compared at the same assay CO2 level. Under CO2 enrichment the flower stem was longer and thicker but the flower bud size at harvest was not significantly different to that of roses grown at the ambient CO2 level. Key words: CO2 enrichment, daily carbon gain, net CO2 exchange rate, radiation, Rosa hybrida

The ecology of Ramalina menziesii. VI. Laboratory responses of net CO2 exchange to moisture, temperature, and light

1987 ◽  
Vol 65 (1) ◽  
pp. 182-191 ◽  
Author(s):  
U. Matthes-Sears ◽  
T. H. Nash III ◽  
D. W. Larson
Keyword(s):  
Dark Respiration ◽  
Net Photosynthesis ◽  
Co2 Exchange ◽  
Response Curves ◽  
Central California ◽  
Photosynthetic Rates ◽  
Chlorophyll Contents ◽  
The Mean ◽  
The Difference ◽  
Thallus Water Content

The response of net CO2 exchange to thallus water content, thallus temperature, and photosynthetically active radiation was measured in the laboratory for two morphologically different forms of Ramalina menziesii collected from a coastal and an inland habitat in central California. Equations describing the response curves are fitted to the data and compared statistically for the two sites during two seasons. Significant differences were present for all responses both in summer and winter but were more pronounced for net photosynthesis than for dark respiration. The main differences between the two forms were in the absolute rates of net photosynthesis; a maximum of 6.2 was measured for the inland form but only 3.6 mg∙g−1∙h−1 for the coastal form. Chlorophyll contents were also different between the two forms, indicating that chlorophyll is the likely cause for the difference in net photosynthetic rates. Net photosynthetic rates were higher at low temperatures during winter than during summer, but otherwise seasonal variations in the gas exchange responses were relatively minor. Both forms of the lichen are light saturated at quantum fluxes greater than 200 μE∙m−2∙s−1. Both show an optimum temperature for maximum CO2 exchange at 25 °C, well above the mean operating temperature of R. menziesii in the field.

scholarly journals Physiological Responses of Cowpea (Vigna unguiculata) Under Irrigation With Saline Water and Biostimulant Treatment

2018 ◽  
Vol 10 (12) ◽  
pp. 24
Author(s):  
Leonardo Vieira de Sousa ◽  
Rayanne Maria Paula Ribeiro ◽  
Manoel Galdino dos Santos ◽  
Fernando Sarmento de Oliveira ◽  
Hugo Ferreira ◽  
...  
Keyword(s):  
Vigna Unguiculata ◽  
Saline Water ◽  
Net Photosynthesis ◽  
Co2 Concentration ◽  
Dry Mass ◽  
Saline Stress ◽  
Stress Effect ◽  
Negative Effects ◽  
Shoot Height ◽  
Cowpea Cultivars

Cowpea (Vigna unguiculata) is one of the world’s main crops, and it is a fundamental source of protein for semiarid regions population. In these regions, the use of high salts concentration water in irrigation systems is one of the major factors that contributes to reduced cowpea yield. One way to alleviate the negative effects of salinity is through the biostimulants application, which is a product that has beneficial substances to the plants metabolism. The aim of this study was to evaluate the application of biostimulant in cowpea cultivars under irrigation with saline water. The study was carried out in the Agrarian Sciences Center, of the Department of Agronomic and Forest Sciences of the Federal Rural University of the Semi-Arid, in the city of Mossoró, RN. The experimental design was completely randomized, with four replications. The treatments were arranged in 5 × 2 × 2 factorial scheme, with five doses of biostimulant (0, 15, 30, 45 and 60 mL L-1), two electrical conductivities of the irrigation water (0.5 and 5.0 dS m-1), and two cowpea cultivars (IPA-206 and BRS Guariba). The evaluated characteristics were: chlorophyll content index, stomatal conductance, net photosynthesis, internal CO2 concentration, transpiration rate, shoot height, stem diameter and shoot dry mass. The biostimulant application was not efficient in attenuating the salinity stress effect on the development of cowpea cultivars. The higher biostimulant concentrations along with the use of saline water increased the negative effects of salinity on the cowpea plants physiology. There was no difference between the cultivars regarding the tolerance to saline stress and the application of biostimulant.

scholarly journals Uso da subirrigação para imposição de estresse hídrico em sistema semi-contínuo para medição de CO2

2015 ◽  
Vol 21 (2) ◽  
pp. 235 ◽  
Author(s):  
Rhuanito Soranz Ferrarezi ◽  
Marc W. Van Iersel ◽  
Roberto Testezlaf
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Plant Growth ◽  
Net Photosynthesis ◽  
Dry Mass ◽  
Co2 Exchange ◽  
Carbon Gain ◽  
Growth Responses ◽  
Shoot Height ◽  
Soil Moisture Sensors

The objectives of this work were to evaluate the effects of distinct moisture contents to trigger subirrigation on salvia photosynthesis and plant growth, and to verify the feasibility of subirrigation use in water stress imposition research in this crop. We evaluated two substrate volumetric water contents (VWC) as treatments (0.2 and 0.4 m3 m-3) to trigger subirrigation, with 4 replications. Each replication was composed of 10 plants. An automated semi-continuous multi-chamber crop CO2-exchange system was used, with capacitance soil moisture sensors for continuous moisture monitoring. Manual subirrigation with nutrient solution was performed when VWC dropped below the thresholds. In both treatments, the values of net photosynthesis, daily carbon gain and carbon use efficiency reduced over time, from 2 to 1.1 μmol s-1 from 2.2 to 1 μmol d-1 from 0.7 to 0.45 mol mol-1, respectively, in both soil moisture treatments. Total shoot dry mass (p=0.0129), shoot height in the tip of the highest flower (p<0.0001) and total leaf area (p=0.0007) were statistically higher at 0.4 m3 m-3 treatment. The subirrigation system was not efficient to impose water stress, due to excessive variation on VWC values after each irrigation event in both treatments. Higher soil moisture promoted positive plant growth responses in salvia cultivated by subirrigation.

scholarly journals Nutrient Solution Concentration Affects Whole-plant CO2 Exchange and Growth of Subirrigated Pansy

2002 ◽  
Vol 127 (3) ◽  
pp. 423-429 ◽  
Author(s):  
Marc W. van Iersel ◽  
Jong-Goo Kang
Keyword(s):  
Plant Growth ◽  
Exchange Rates ◽  
Leaf Area ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Gross Photosynthesis ◽  
Whole Plant ◽  
Wide Range ◽  
Shoot To Root Ratio ◽  
Fertilizer Solution

To determine the effect of fertilizer concentration on plant growth and physiology, whole-plant C exchange rates of pansies (Viola ×wittrockiana Gams.) subirrigated with one of four fertilizer concentrations were measured over 30 days. Plants were watered with fertilizer solutions with an electrical conductivity (EC) of 0.15, 1.0, 2.0, or 3.0 dS·m-1 (N at 0, 135, 290, or 440 mg·L-1, respectively). Plants watered with a fertilizer solution with an EC of 2 dS·m-1 had the highest shoot dry weight (DW), shoot to root ratio, leaf area, leaf area ratio (LAR), and cumulative C gain at the end of the experiment compared to those watered with a solution with a higher or lower EC. Shoot tissue concentrations of N, P, K, S, Ca, Fe, Na, and Zn increased linearly with increasing fertilizer concentration. A close correlation between final DW of the plants and the measured cumulative C gain (CCG) (r2 = 0.98) indicated that the C exchange rates were good indicators of plant growth. There were quadratic relationships between fertilizer EC and gross photosynthesis, net photosynthesis, and dark respiration, starting at 13, 12, and 6 days after transplanting, respectively. Although plants fertilized with a fertilizer solution with an EC of 2 dS·m-1 had the highest C exchange rates, the final differences in shoot DW and CCG among ECs of 1.0, 2.0, and 3.0 dS·m-1 were small and it appears that pansies can be grown successfully with a wide range of fertilizer concentrations. Plants with a high LAR also had higher DW, suggesting that increased growth was caused largely by increased light interception. A detrimental effect of high fertilizer concentrations was that it resulted in a decrease in root DW and a large increase in shoot to root ratio.

scholarly journals Medium-incorporated PEG-8000 Reduces Elongation, Growth, and Whole-canopy Carbon Dioxide Exchange of Marigold

HortScience ◽  
2006 ◽  
Vol 41 (1) ◽  
pp. 124-130 ◽  
Author(s):  
Stephanie E. Burnett ◽  
Marc W. van Iersel ◽  
Paul A. Thomas
Keyword(s):  
Carbon Dioxide ◽  
Polyethylene Glycol ◽  
Dark Respiration ◽  
Net Photosynthesis ◽  
Carbon Dioxide Exchange ◽  
Seedling Height ◽  
Tagetes Patula ◽  
Whole Plant ◽  
Growing Medium ◽  
Peg 8000

French marigold (Tagetes patula L. `Boy Orange') was grown in a peat-based growing medium containing different rates (0, 15, 20, 30, 42, or 50 g·L–1) of polyethylene glycol 8000 (PEG-8000) to determine if PEG-8000 would reduce seedling height. Only 28% to 55% of seedlings treated with 62, 72, or 83 g·L–1 of PEG-8000 survived, and these treatments would be commercially unacceptable. Marigolds treated with the remaining concentrations of PEG-8000 had shorter hypocotyls, and were up to 38% shorter than nontreated controls at harvest. Marigold cotyledon water (ψw), osmotic (ψs), and turgor (ψp) potentials were significantly reduced by PEG-8000, and ψp was close to zero for all PEG-treated seedlings 18 days after seeding. Whole-plant net photosynthesis, whole-plant dark respiration, and net photosynthesis/leaf area ratios were reduced by PEG-8000, while specific respiration of seedlings treated with PEG-8000 increased. Marigolds treated with concentrations greater than 30 g·L–1 of PEG-8000 had net photosynthesis rates that were close to zero. Fourteen days after transplanting, PEG-treated marigolds were still shorter than nontreated seedlings and they flowered up to 5 days later. Concentrations of PEG from 15 to 30 g·L–1 reduced elongation of marigold seedlings without negatively affecting germination, survival, or plant quality. It appears that marigold seedlings were shorter because of reduced leaf ψp and reductions in net photosynthesis.

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