scholarly journals Photosynthetic Response of Carrots to Varying Irradiances, CO2 Concentrations, Moisture, and Nutrition

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1145D-1146
Author(s):  
Rajasekaran R. Lada ◽  
F. Christine Pettipas ◽  
Steve Kyei-Boahen ◽  
Robert Gordon ◽  
Tess Astatkie
Keyword(s):  
Leaf Gas Exchange ◽  
Environmental Parameters ◽  
Nutrient Concentrations ◽  
Photosynthetic Parameters ◽  
Gas Exchange Parameters ◽  
Moisture Regimes ◽  
Use Efficiency ◽  
Yield Responses ◽  
Red Core ◽  
Exchange Parameters

Genotypes and environmental parameters interactively act on plants and modify their yield responses through modifying photosynthetic processes. In order to optimize yield, it is critical to understand the photosynthetic behavior of the crop as altered by genotypes and environment. Leaf gas exchange parameters of carrot (Daucus carota L.) cultivars Cascade, Carson, Oranza, and Red Core Chantenay (RCC) were examined in response to various irradiances, fertility levels, moisture regimes, and to elevated CO2 concentrations. Leaf net photosynthetic rate (PN), stomatal conductance (gs), and transpiration rate (E) were measured. Cultivars responded similarly to increasing PAR and CO2 concentrations and did not differ in photosynthetic parameters. Increasing PAR from 100 to 1000 μmol·m-2·s-1 increased PN, which did not reach saturation. The gs and E increased to a peak between 600 and 800 μmol·m-2·s-1, then rapidly declined, resulting in a sharp increase in water use efficiency (WUE). Increasing CO2 concentrations from 50 to 1050 μmol·mol-1 increased PN until saturation at 650 μmol·mol-1. The gs and E increased to a peak at 350 μmol·mol-1 and then declined. WUE increased linearly with increasing CO2. Carrots exposed to drought over a period of 5 days decreased PN and E. The PN decrease was cultivar specific. Nutrient concentrations of 0 to 400 ppm gave a similar pattern of decrease for PN, E, and gs. Treatment of 50 ppm had the highest PN, E, and gs. The WUE generally increased with increasing nutrient concentration.

scholarly journals A Field Study on the Influence of Verticillium dahliae and Pratylenchus penetrans on Gas Exchange of Potato

Plant Disease ◽  
2007 ◽  
Vol 91 (12) ◽  
pp. 1531-1535 ◽  
Author(s):  
Ibrahim A. M. Saeed ◽  
Ann E. MacGuidwin ◽  
Douglas I. Rouse ◽  
Chris Malek
Keyword(s):  
Gas Exchange ◽  
Verticillium Dahliae ◽  
Field Experiments ◽  
Leaf Gas Exchange ◽  
Pratylenchus Penetrans ◽  
Gas Exchange Parameters ◽  
Pathogen Control ◽  
Use Efficiency ◽  
The Impact ◽  
Exchange Parameters

Field experiments were conducted for three consecutive years to study the effects of low populations of Verticillium dahliae and Pratylenchus penetrans on leaf gas exchange of Russet Burbank potato. Treatments were P. penetrans, V. dahliae, the combination of the nematode with the fungus, and a no-pathogen control. Gas exchange was measured nondestructively on young, fully expanded, asymptomatic leaves one to three times per week starting the ninth week after planting. Infection with either pathogen alone had little or no effect on leaf gas exchange parameters. However, co-infection by both pathogens resulted in reduced leaf light use efficiency (mole of CO2 fixed per mole of photon), lower leaf stomatal conductance, lower leaf water use efficiency (mole of CO2 fixed per mole of water used), and increased intercellular CO2 compared with the no-pathogen control. These effects, additive relative to the impact of each pathogen alone, were first observed 9 weeks after inoculation in the first 2 years of the study and 15 weeks after inoculation in the third year.

scholarly journals (430) Leaf Gas Exchange of Carrots in Response to Increasing Leaf Temperatures

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1075D-1075
Author(s):  
F. Christine Pettipas ◽  
Rajasekaran R. Lada ◽  
Robert Gordon ◽  
Tess Astatkie
Keyword(s):  
Gas Exchange ◽  
Global Climate ◽  
Leaf Gas Exchange ◽  
Great Influence ◽  
Photosynthetic Parameters ◽  
Moderate Increase ◽  
Gas Exchange Parameters ◽  
Response To Temperature ◽  
Increasing Temperature ◽  
Red Core

Increasing temperature as a result of global climate change is expected to exert a great influence on agricultural crops, possibly through effects on photosynthesis. Response to temperature of leaf gas exchange parameters of carrot (Daucus carota L. var. sativus) cultivars Cascade, Carson, Oranza, and Red Core Chantenay (RCC) were examined in a controlled growth room experiment. Leaf net photosynthetic rate (PN), stomatal conductance (gs), and transpiration rate (E) were measured at temperatures ranging from 15 to 35 °C at 370 μmol·mol-1 (CO2) and 450±20 μmol·m-2·s-1 PAR. The cultivars responded similarly to increasing temperature and did not differ in most photosynthetic parameters except gs. The PN increased between 20 and 30 °C, thereafter increasing only slightly to 35 °C. On average, increasing temperature from 20 to 30 °C increased PN by 69%. Carboxylation efficiencies (Ca/Ci ratio) ranged from 1.12–2.33 mmol·mol-1 while maximum PN were 3.25, 3.90, 5.49, 4.19 μmol·m-2·s-1 for Carson, RCC, Cascade, and Oranza, respectively. The E did not reach maximum at 35 °C while gs peaked at 30 °C and then decreased by 93% at 35 °C. The water use efficiency (WUE) decreased with an increase in temperature due to increases in both PN and E. The results indicate that increasing temperatures above the seasonal average (<20 °C) increases both PN and E up to 30–35 °C. An increase in photosynthesis due to an increase in temperature is expected to hasten growth. Carrots may be able to withstand a moderate increase in temperature.

scholarly journals Growth and Photosynthetic Response of Two Persimmon Rootstocks (Diospyros kaki and D. virginiana) under Different Salinity Levels

2014 ◽  
Vol 42 (2) ◽  
pp. 386-391 ◽  
Author(s):  
Meral INCESU ◽  
Berken CIMEN ◽  
Turgut YESILOGLU ◽  
Bilge YILMAZ
Keyword(s):  
Gas Exchange ◽  
Leaf Gas Exchange ◽  
Chlorophyll Concentration ◽  
Dry Mass ◽  
Diospyros Kaki ◽  
Gas Exchange Parameters ◽  
Leaf Chlorophyll ◽  
Salinity Levels ◽  
Leaf Chlorophyll Concentration ◽  
Exchange Parameters

Salinity continues to be a major factor in reduced crop productivity and profit in many arid and semiarid regions. Seedlings of Diospyros kaki Thunb. and D. virginiana L. are commonly used as rootstock in persimmon cultivation. In this study we have evaluated the effects of different salinity levels on photosynthetic capacity and plant development of D. kaki and D. virginiana. Salinity was provided by adding 50 mM, 75 mM and 100 mM NaCl to nutrient solution. In order to determine the effects of different salinity levels on plant growth, leaf number, plant height, shoot and root dry mass were recorded. Besides leaf Na, Cl, K and Ca concentrations were determined. Also leaf chlorophyll concentration, chlorophyll fluorescence (Fv’/Fm’) and leaf gas exchange parameters including leaf net photosynthetic rate (PN), stomatal conductance (gS), leaf transpiration rate (E), and CO2 substomatal concentration (Ci) were investigated. Significant decrease of leaf number, shoot length and plant dry mass by increasing salinity levels was observed in both rootstocks. D. virginiana was less affected in terms of plant growth under salinity stress. Leaf chlorophyll concentration reduction was higher in the leaves of D. kaki in comparison to D. virginiana in 100 mM NaCl treatment. By increasing salinity levels PN, gS and E markedly decreased in both rootstocks and D. kaki was more affected from salinity in terms of leaf gas exchange parameters. In addition there was no significant difference but slight decreases were recorded in leaf chlorophyll fluorescences of both rootstocks.

scholarly journals Gas exchange efficiency in Cocoa – Spanish elm agroforestry system in the northwest Antioquia, Colombia

2020 ◽  
Vol 73 (3) ◽  
pp. 9283-9291
Author(s):  
Juan Pablo Gómez-Yarce ◽  
Edna Rocío Mompotes-Largo ◽  
Aníbal López-Castro ◽  
Juan David Hernández-Arredondo ◽  
Oscar De Jesús Córdoba-Gaona
Keyword(s):  
Gas Exchange ◽  
Environmental Conditions ◽  
Block Design ◽  
Area Under The Curve ◽  
Agroforestry System ◽  
Agroforestry Systems ◽  
Cordia Alliodora ◽  
Gas Exchange Parameters ◽  
Use Efficiency ◽  
Exchange Parameters

The cultivation of cocoa (Theobroma cacao L.) under agroforestry systems, generates beneficial environmental conditions for cocoa crop physiology. An experiment was conducted to evaluate the effect of shade trees (Spanish elm trees - Cordia alliodora (Ruiz & Pavon) Oken) planted along with cocoa (clone CCN51) under an agroforestry system on cocoa’s gas exchange parameters regarding the reduction of the light intensity over the cocoa-leaf canopy. The experiment was developed in the Centro de Investigación el Nus - Agrosavia, located in the municipality of San Roque, Antioquia. The experimental design used was a randomized complete block design for the cocoa planting distances from the first row of Spanish elm trees interfacing with the cocoa plantation (4 m, 7 m, 10 m, 13 m). The statistical analysis was performed by estimating the area under the curve (AUC) of each variable, using the trapezoid equation of the statistical environment SAS® 9.4, an analysis of variances was performed to determine if there were statistical differences between treatments, and Tukey’s test at 5% probability was used to estimated statistical differences between means. There were significant differences in the treatments regarding the net photosynthetic rate (A), stomatal conductance (gs), and transpiration rate (E). The highest values of gas exchange parameters were found in the plants located 13 m from elm trees, while the lowest values were presented at 4 m. Plants at 7 m and 10 m always showed intermediate values for all gas exchange parameters. In the same sense, plants at 13 m had a higher radiation use efficiency (RUE) compared to plants at 4 m. The arboreal component modified the environmental conditions on cocoa trees regarding its distribution, generating a differential response to the physiological behavior of cocoa plants.

Effects of Exogenous Nitric Oxide on the Photosynthesis of Taxus chinensis var. Mairei Seedings

2011 ◽  
Vol 356-360 ◽  
pp. 2774-2777
Author(s):  
De Wen Li ◽  
Mei Lan Li ◽  
Xiao Xue Wei
Keyword(s):  
Nitric Oxide ◽  
Taxus Chinensis ◽  
Chlorophyll B ◽  
Total Chlorophyll ◽  
Gas Exchange Parameters ◽  
No Donor ◽  
Chlorophyll Contents ◽  
Use Efficiency ◽  
Exogenous Nitric Oxide ◽  
Exchange Parameters

In the study, the gas exchange parameters and chlorophyll contents of the leaves of Taxus chinensis var. mairei exposed to exogenous nitric oxide (NO) were determined. The seedlings were treated with sodium nitroprusside (SNP), a NO donor, at 5 different concentrations ranging from 0 mM to 1 mM. The experiment was conducted under controlled conditions in laboratory. The result showed that the 1 mM SNP increased the net photosynthetic rate (PN) of Taxus chinensis var. mairei slightly; however, other SNP treatments decreased PN. The water use efficiency (WUE) was increased by exogenous NO, while the stomata conductance (Gs) and the transpiration rate (E) were decreased. The concentrations of chlorophyll a, chlorophyll b, carotenoid and total chlorophyll exhibited 0.1 mM> 0.01 mM> 1 mM > 0 mM > 0.5 mM after 10 days of SNP treatments. The experiment proved that at suitable concentrations of exogenous NO signals increased the photosynthesis, and suggested that the SNP treatment might promote the growth of the Taxus chinensis var. mairei seedlings.

Effects of substrate acidity and UV-B radiation on photosynthesis of radishes

2011 ◽  
Vol 6 (4) ◽  
pp. 624-631
Author(s):  
Irena Januskaitiene
Keyword(s):  
Gas Exchange ◽  
Water Use ◽  
Raphanus Sativus ◽  
Net Photosynthesis ◽  
Enzymatic Reactions ◽  
Growth Substrate ◽  
Gas Exchange Parameters ◽  
Raphanus Sativus L ◽  
Use Efficiency ◽  
Exchange Parameters

AbstractThe aim of this study was to assess the combined effect of substrate acidity (pH 4.8; pH 3.8) and 1 kJm−2d−1 UV-B radiation on photosynthesis and growth of radishes (Raphanus sativus L.). Radishes were sown in a neutral pH 6.5 peat substrate. When the second true leaf unfolded, the growth substrate was acidified using different concentration of H2SO4 and exposed to UV-B radiation for a period of ten days. Gas exchange parameters were measured with the LI-6400 portable photosynthesis system. Content of chlorophyll was evaluated spectrophotometrically. The results showed that the greatest inhibition of net photosynthesis was observed when radishes were grown in an acidified pH 3.8 substrate. The decrease of the photosynthesis of radish plants treated with both investigated factors (substrate acidity and UV-B) were lower compared to the effect of substrate acidity alone. UV-B radiation stimulated both enzymatic reactions of photosynthesis and water use efficiency of radish plants grown in acidified peat substrates. Also, investigated factors had higher impact on biomass of tuber than biomass of foliage.

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