scholarly journals Nitrogen Shortage in a Tomato Crop; Scaling up from Effects on Electron-Transport Rate to Plant Productivity

1999 ◽  
Vol 54 (9-10) ◽  
pp. 840-848 ◽  
Author(s):  
Ad H. C. M. Schapendonk ◽  
Oijen ◽  
Sander C. Pot ◽  
Riki Van den Boogaard ◽  
Jeremy Harbinson
Keyword(s):  
Electron Transport ◽  
Simulation Model ◽  
Tomato Plant ◽  
Electron Transport Rate ◽  
Photosynthetic Apparatus ◽  
Plant Productivity ◽  
Scaling Up ◽  
Nitrogen Supply ◽  
Nitrogen Partitioning ◽  
Tomato Crop

Optimization of nitrogen supply in a tomato plant is stepwise assessed, from chloroplast characteristics to whole crop performance. Experiments are reported in which important key processes are quantified in relation to the nitrogen content of leaves. Interactions of N effects with leaf aging and canopy light distribution are analyzed. A simulation model that integrates this knowledge is constructed. The results of three nitrogen partitioning scenarios for Rubisco suggest that optimization of the distribution of Rubisco between leaf layers is less important for plant productivity than within-leaf optimization of the photosynthetic apparatus

scholarly journals Different Sensitivity Levels of the Photosynthetic Apparatus in Zea mays L. and Sorghum bicolor L. under Salt Stress

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1469
Author(s):  
Martin A. Stefanov ◽  
Georgi D. Rashkov ◽  
Ekaterina K. Yotsova ◽  
Preslava B. Borisova ◽  
Anelia G. Dobrikova ◽  
...  
Keyword(s):  
Zea Mays ◽  
Electron Transport ◽  
Sorghum Bicolor ◽  
Zea Mays L ◽  
Electron Transport Rate ◽  
Photosynthetic Apparatus ◽  
Pigment Content ◽  
Transport Rate ◽  
Stress Markers ◽  
Sorghum Bicolor L

The impacts of different NaCl concentrations (0–250 mM) on the photosynthesis of new hybrid lines of maize (Zea mays L. Kerala) and sorghum (Sorghum bicolor L. Shamal) were investigated. Salt-induced changes in the functions of photosynthetic apparatus were assessed using chlorophyll a fluorescence (PAM and OJIP test) and P700 photooxidation. Greater differences between the studied species in response to salinization were observed at 150 mM and 200 mM NaCl. The data revealed the stronger influence of maize in comparison to sorghum on the amount of closed PSII centers (1-qp) and their efficiency (Φexc), as well as on the effective quantum yield of the photochemical energy conversion of PSII (ΦPSII). Changes in the effective antenna size of PSII (ABS/RC), the electron flux per active reaction center (REo/RC) and the electron transport flux further QA (ETo/RC) were also registered. These changes in primary PSII photochemistry influenced the electron transport rate (ETR) and photosynthetic rate (parameter RFd), with the impacts being stronger in maize than sorghum. Moreover, the lowering of the electron transport rate from QA to the PSI end electron acceptors (REo/RC) and the probability of their reduction (φRo) altered the PSI photochemical activity, which influenced photooxidation of P700 and its decay kinetics. The pigment content and stress markers of oxidative damage were also determined. The data revealed a better salt tolerance of sorghum than maize, associated with the structural alterations in the photosynthetic membranes and the stimulation of the cyclic electron flow around PSI at higher NaCl concentrations. The relationships between the decreased pigment content, increased levels of stress markers and different inhibition levels of the function of both photosystems are discussed.

Investigation on the Photosynthetic Membranes of Spruce Needles in Relation to the Occurrence of Novel Forest Decline I. The Photosynthetic Electron Transport

1988 ◽  
Vol 43 (7-8) ◽  
pp. 581-588 ◽  
Author(s):  
Bernhard Dietz ◽  
Iris Moors ◽  
Ute Flammersfeld ◽  
Wolfgang Rühle ◽  
Aloysius Wild
Keyword(s):  
Electron Transport ◽  
Electron Transport Rate ◽  
Membrane Damage ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Electron Transport ◽  
Transport Rate ◽  
Electron Microscopic ◽  
Transport Pathway ◽  
Natural Habitats ◽  
Electron Transport Chains

The investigations described here were carried out in the context of our research project on the physiological, biochemical, and cytomorphological characterization of spruce trees growing in natural habitats and showing damage of varying intensity. Here we report on specific aspects of the photosynthetic apparatus. The aim of the measurements was to analyze whether or not the activity of the photosynthetic electron transport pathway is affected in damaged trees. The investigations were carried out on a 20 to 25-year-old spruce plantation in the Hunsrück mountains and on an 80-year-old spruce plantation in the Westerwald mountains. The photosynthetic electron transport rate was determined by photoreduction of 2,6-dichlorophenolindophenol. A decrease of the electron transport rate was shown in the damaged spruce trees in comparison to the apparently healthy trees. The investigation of the water splitting enzyme system - determined in the Hillreaction by feeding in electrons by means of diphenylcarbazide - indicates that the electron transport on the oxidizing side of photosystem II is impaired. The results imply that the photosynthetic electron transport chains in the thylakoid membranes of the spruce chloroplasts are sites of early injurious effects. This is in agreement with the electron microscopic analyses which show consistently that early damage occurs especially at the cellular membranes. This membrane damage is apparent even in the green needles of damaged spruce trees.

scholarly journals Flavodiiron proteins act as safety valve for electrons in Physcomitrella patens

2016 ◽  
Vol 113 (43) ◽  
pp. 12322-12327 ◽  
Author(s):  
Caterina Gerotto ◽  
Alessandro Alboresi ◽  
Andrea Meneghesso ◽  
Martina Jokel ◽  
Marjaana Suorsa ◽  
...  
Keyword(s):  
Electron Transport ◽  
Photosystem I ◽  
Physcomitrella Patens ◽  
Safety Valve ◽  
Cell Metabolism ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Electron Transport ◽  
Flowering Plants ◽  
Knock Out ◽  
Electron Sink

Photosynthetic organisms support cell metabolism by harvesting sunlight to fuel the photosynthetic electron transport. The flow of excitation energy and electrons in the photosynthetic apparatus needs to be continuously modulated to respond to dynamics of environmental conditions, and Flavodiiron (FLV) proteins are seminal components of this regulatory machinery in cyanobacteria. FLVs were lost during evolution by flowering plants, but are still present in nonvascular plants such as Physcomitrella patens. We generated P. patens mutants depleted in FLV proteins, showing their function as an electron sink downstream of photosystem I for the first seconds after a change in light intensity. flv knock-out plants showed impaired growth and photosystem I photoinhibition when exposed to fluctuating light, demonstrating FLV’s biological role as a safety valve from excess electrons on illumination changes. The lack of FLVs was partially compensated for by an increased cyclic electron transport, suggesting that in flowering plants, the FLV’s role was taken by other alternative electron routes.

scholarly journals Updating the steady state model of C4 photosynthesis

2021 ◽  
Author(s):  
Susanne von Caemmerer
Keyword(s):  
Steady State ◽  
Electron Transport ◽  
Electron Transport Rate ◽  
Transport Rate ◽  
Initial Slope ◽  
Carboxylase Activity ◽  
Quantitative Correlation ◽  
Steady State Model ◽  
State Models

AbstractC4 plants play a key role in world agriculture. For example, C4 crops such as maize and sorghum are major contributors to both first and third world food production and the C4 grasses sugarcane; miscanthus and switchgrass are major plant sources of bioenergy. In the challenge to manipulate and enhance C4 photosynthesis, steady state models of leaf photosynthesis provide and important tool for gas exchange analysis and thought experiments that can explore photosynthetic pathway changes. Here the C4 photosynthetic model by von Caemmerer and Furbank (1999) has been updated with new kinetic parameterisation and temperature dependencies added. The parameterisation was derived from experiments on the C4 monocot, Setaria viridis, which for the first time provides a cohesive parametrisation. Mesophyll conductance and its temperature dependence have also been included, as this is an important step in the quantitative correlation between the initial slope of the CO2 response curve of CO2 assimilation and in vitro PEP carboxylase activity. Furthermore, the equations for chloroplast electron transport have been updated to include cyclic electron transport flow and equations have been added to calculate electron transport rate from measured CO2 assimilation rates.HighlightThe C4 photosynthesis model by von Caemmerer and Furbank (1999) has been updated. It now includes temperature dependencies and equations to calculate electron transport rate from measured CO2 assimilation rates.

scholarly journals Mefenpyr-diethyl as a safener for haloxyfop-methyl in bahiagrass

2021 ◽  
Author(s):  
Roque de Carvalho Dias ◽  
Leandro Bianchi ◽  
Vitor Muller Anunciato ◽  
Leandro Tropaldi ◽  
Paulo Vinicius da Silva ◽  
...  
Keyword(s):  
Electron Transport ◽  
Protective Effect ◽  
Plant Height ◽  
Electron Transport Rate ◽  
Transport Rate ◽  
Low Doses ◽  
Protective Response ◽  
Randomized Design ◽  
Dry Biomass ◽  
Completely Randomized Design

Abstract Mefenpyr-diethyl is a foliar-acting safener of the pyrazoline chemical group, and after its absorption, the metabolization and detoxification of herbicides occur in treated plants. Studies have demonstrated the protective effect of this safener for the herbicide fenoxaprop-P-ethyl in grass. Thus, this work aimed to evaluate whether a tank mixture of mefenpyr-diethyl has a protective response to haloxyfop-methyl in non-perennial bahiagrass. The experiment had a completely randomized design and was carried out in a greenhouse, using five replications with a 10x2 factorial scheme and ten doses of haloxyfop-methyl (0.00, 0.24, 0.49, 0.97, 1.95, 3.90, 7.79, 15.59, 31.28, and 62.35 g a.i. ha-1) in the presence or absence of a tank mixture of mefenpyr-diethyl (50 g a.i. ha-1). Phytotoxicity and electron transport rate (ETR) were evaluated at 7, 14, 21, and 28 days after application (DAA), in addition to plant height and dry biomass at 28 DAA. In general, phytotoxicity increased due to the higher levels of the herbicide haloxyfop-methyl. The application of mefenpyr-diethyl, in turn, provided lower levels of phytotoxicity, as well as lower reductions in ETR, height, and dry biomass when compared to untreated plants. These results show the safener action of a tank mixture of mefenpyr-diethyl on low doses of haloxyfop-methyl in non-perennial bahiagrass.

scholarly journals The Effect of Magnetic Water for Chemical Fertilizer in Tomato Plant

2014 ◽  
Vol 11 (2) ◽  
pp. 958-961
Author(s):  
Baghdad Science Journal
Keyword(s):  
Tomato Plant ◽  
Tomato Fruit ◽  
Fruit Size ◽  
Water System ◽  
Chemical Fertilizer ◽  
Chemical Fertilizers ◽  
Tomato Crop ◽  
Magnetized Water ◽  
Magnetic Water

The research aims to find ways to minimize the use of quantities of chemical fertilizers in agriculture in order to get to an environment that is free of contaminants. Magnetized water technology used in the experience of planting seeds of tomatoes Thomson type to obtain a higher efficiency to absorb fertilizer NRK in the protected environment of the period from February to June. Magnetized water system used locally made levels Gaues (4800,2500,1500) concentrations of 50 to 100% for each level and the rate of (4) replicates, and results indicated that the severity of the magnet (4800 Gaues) and a concentration of 50% gave the highest percentage of tomato fruit size and intensity ( 1500 Gaues) and a concentration of 100% did not give any increase in the proportion of tomatoes or fruit size, but did not give three levels increase in the amount of tomato crop.

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