scholarly journals Methomyl Injury to Carbon Exchange Rates and Related Processes in Cotton

2017 ◽  
Author(s):  
C.E. Salem ◽  
J.T. Cothren ◽  
C.R. Benedict
Keyword(s):  
Exchange Rate ◽  
Chlorophyll Fluorescence ◽  
Stomatal Conductance ◽  
Carbon Exchange ◽  
Rubisco Activity ◽  
Bisphosphate Carboxylase ◽  
Chlorophyll Fluorescence Parameter ◽  
Fluorescence Parameter ◽  
Time Courses ◽  
Induced Changes

AbstractSome insecticides have the potential to cause varying levels of phytotoxicity. This study examined 1) the time courses of photosynthetic injury in cotton (Gossypium hirsutisms L.) leaves treated with methomyl [S-methyl-N-[(methyl carbamoyl)oxy]-thioacetimidate] and 2) the relationships between carbon exchange rate (CER), stomatal conductance, the chlorophyll fluorescence parameter FX/FP, and ribulose-1,5-bisphosphate carboxylase/ oxygenase (rubisco) activity. Plots were sprayed with either 0 or 0.84 kg methomyl·ha-1 when cotton was in mid-reproductive growth. Starting on the day of spraying, CER, stomatal conductance, FX/FP, and rubisco activity were measured daily for five consecutive days [4, 28, 52, 76 and 100 hours after spraying (HAS)]. In methomyl-treated leaves, CER decreased within hours after spraying, reached their lowest point at 28 HAS in experiment I and 76 HAS in experiment II, then recovered near-control levels by 100 HAS. At their lowest points, CER of methomyl-treated leaves decreased from 20 to 50% compared to controls. Stomatal conductance, FX/FP, and rubisco activity followed similar patterns to CER. Stomatal conductance was more closely related to CER than were FX/FP and rubisco activity. Chlorophyll fluorescence recovered more quickly than did CER. Rubisco activity did not decrease till after CER. From the parameters measured in this study, stomatal conductance appeared to be the major factor influencing methomyl-induced changes in CER, although all three parameters may be involved in the process of CER change.AbbreviationsCERcarbon exchange raterubiscoribulose-1,5-bisphosphate carboxylase/ oxygenaseDATdays after treatmentHAShours after spraying

scholarly journals Chlorophyll Fluorescence Parameters and Antioxidant Defense System Can Display Salt Tolerance of Salt Acclimated Sweet Pepper Plants Treated with Chitosan and Plant Growth Promoting Rhizobacteria

Agronomy ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1180 ◽  
Author(s):  
Muneera D. F. ALKahtani ◽  
Kotb A. Attia ◽  
Yaser M. Hafez ◽  
Naeem Khan ◽  
Ahmed M. Eid ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Plant Growth ◽  
Plant Growth Promoting Rhizobacteria ◽  
Sweet Pepper ◽  
Fruit Yield ◽  
Chlorophyll Fluorescence Parameter ◽  
Fluorescence Parameter ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Pepper Plants

Salinity stress deleteriously affects the growth and yield of many plants. Plant growth promoting rhizobacteria (PGPR) and chitosan both play an important role in combating salinity stress and improving plant growth under adverse environmental conditions. The present study aimed to evaluate the impacts of PGPR and chitosan on the growth of sweet pepper plant grown under different salinity regimes. For this purpose, two pot experiments were conducted in 2019 and 2020 to evaluate the role of PGPR (Bacillus thuringiensis MH161336 106–8 CFU/cm3) applied as seed treatment and foliar application of chitosan (30 mg dm−3) on sweet pepper plants (cv. Yolo Wonder) under two salinity concentrations (34 and 68 mM). Our findings revealed that, the chlorophyll fluorescence parameter (Fv/Fm ratio), chlorophyll a and b concentrations, relative water content (RWC), and fruit yield characters were negatively affected and significantly reduced under salinity conditions. The higher concentration was more harmful. Nevertheless, electrolyte leakage, lipid peroxidation, hydrogen peroxide (H2O2), and superoxide (O2−) significantly increased in stressed plants. However, the application of B. thuringiensis and chitosan led to improved plant growth and resulted in a significant increase in RWC, chlorophyll content, chlorophyll fluorescence parameter (Fv/Fm ratio), and fruit yield. Conversely, lipid peroxidation, electrolyte leakage, O2−, and H2O2 were significantly reduced in stressed plants. Also, B. thuringiensis and chitosan application regulated the proline accumulation and enzyme activity, as well as increased the number of fruit plant−1, fruit fresh weight plant−1, and total fruit yield of sweet pepper grown under saline conditions.

Chlorophyll fluorescence screening of Arabidopsis thaliana for CO2 sensitive photorespiration and photoinhibition mutants

2009 ◽  
Vol 36 (11) ◽  
pp. 867 ◽  
Author(s):  
Murray R. Badger ◽  
Hossein Fallahi ◽  
Sarah Kaines ◽  
Shunichi Takahashi
Keyword(s):  
Arabidopsis Thaliana ◽  
Chlorophyll Fluorescence ◽  
Fluorescence Imaging ◽  
High Throughput ◽  
Rapid Decline ◽  
Arabidopsis Mutants ◽  
High Co2 ◽  
Chlorophyll Fluorescence Parameter ◽  
Low Co2 ◽  
Fluorescence Parameter

Exposure of Arabidopsis thaliana (L.) photorespiration mutants to air leads to a rapid decline in the Fv/Fm chlorophyll fluorescence parameter, reflecting a decline in PSII function and an onset of photoinhibition. This paper demonstrates that chlorophyll fluorescence imaging of Fv/Fm can be used as an easy and efficient means of detecting Arabidopsis mutants that are impaired in various aspects of photorespiration. This screen was developed to be sensitive and high throughput by the use of exposure to zero CO2 conditions and the use of array grids of 1-week-old Arabidopsis seedlings as the starting material for imaging. Using this procedure, we screened ~25 000 chemically mutagenised M2 Arabidopsis seeds and recovered photorespiration phenotypes (reduction in Fv/Fm at low CO2) at a frequency of ~4 per 1000 seeds. In addition, we also recovered mutants that showed reduced Fv/Fm at high CO2. Of this group, we detected a novel ‘reverse photorespiration’ phenotype that showed a high CO2 dependent reduction in Fv/Fm. This chlorophyll fluorescence screening technique promises to reveal novel mutants associated with photorespiration and photoinhibition.

Effects of Water Stress on Carbon Exchange Rate and Activities of Photosynthetic Enzymes in Leaves of Sugarcane (Saccharum Sp.)

1996 ◽  
Vol 23 (6) ◽  
pp. 719 ◽  
Author(s):  
YC Du ◽  
Y Kawamitsu ◽  
A Nose ◽  
S Hiyane ◽  
S Murayama ◽  
...  
Keyword(s):  
Exchange Rate ◽  
Water Stress ◽  
Stomatal Closure ◽  
Total Soluble Protein ◽  
Carbon Exchange ◽  
Bisphosphate Carboxylase ◽  
Pyruvate Orthophosphate Dikinase ◽  
Photosynthetic Enzymes ◽  
Orthophosphate Dikinase ◽  
Saccharum Sp

The responses of carbon exchange rate (CER), stomatal conductance (gs), activities of phosphoenolpyruvate carboxylase (PEPcase), NADP malic enzyme (NADP-ME), ribulose-1,5- bisphosphate carboxylase (Rubisco), fructose-1,6-bisphosphatase (FBPase) and pyruvate, orthophosphate dikinase (PPDK), and contents of chlorophyll (Chl) and total soluble protein (Tsp) in leaves of sugar cane (Saccharum sp. cv. NiF4) to gradually developed water stress were investigated. The initial inhibitions of CER, gs, activities of the photosynthetic enzymes and contents of Chl and Tsp were observed from leaf water potentials (Ψw) of -0.37 MPa. During water stress, CER and gs, decreased in a non-linear way, activities of the five enzymes and contents of Chl and Tsp decreased linearly with decreasing leaf Ψw. The changes of gs the photosynthetic enzymes, Chl and Tsp were highly related to the changes of CER. The decline in CER during water stress was caused by both stomatal and non- stomatal limitations. Above leaf �w of -0.85 MPa, the decline in CER was caused by stomatal closure, below -0.85 MPa, the decline in CER was caused by non-stornatal limitation. Among non-stomatal components, PPDK activities decreased 9.1 times during water stress, much more than other enzymes which decreased from 2 to 4 times. Measured PPDK activities were only a little higher than the corresponding CER values at various leaf Ψw suggesting that PPDK is very likely to be the limiting enzyme to photosynthesis under water stress.

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