scholarly journals Daily Variations of Photosynthetic Efficiency of Greenhouse Tomato Plants during Winter and Spring

2000 ◽  
Vol 125 (2) ◽  
pp. 235-241 ◽  
Author(s):  
O. Ayari ◽  
M. Dorais ◽  
A. Gosselin
Keyword(s):  
Photosynthetic Efficiency ◽  
Photosynthetic Activity ◽  
Photon Flux ◽  
Tomato Plants ◽  
Greenhouse Tomato ◽  
Northern Latitudes ◽  
Protective Strategy ◽  
Growing Conditions ◽  
Source Limitation

Daily and seasonal variations of photosynthetic activity, chlorophyll a (Chl-a) fluorescence and foliar carbohydrate content were studied in situ on greenhouse tomato (Lycopersicon esculentum Mill. `Trust') plants grown under CO2 enrichment and supplemental lighting. The objective of this study was to assess the effect of seasonal variation of the photosynthetic photon flux (PPF) on photosynthetic efficiency of tomato plants and to determine the presence or absence of photosynthetic down-regulation under greenhouse growing conditions prevailing in northern latitudes. During winter, the fifth and the tenth leaves of tomato plants showed low, constant daily photosynthetic activity suggesting a source limitation under low PPF. In winter, the ratio of variable to maximum Chl-a fluorescence in dark adapted state (Fv/Fm) remained constant during the day indicating no photoinhibition occurred. In February, an increase in photosynthetic activity was followed by a decline during March, April, and May accompanied by an increase in sucrose and daily starch concentrations and constant but high hexose level. This accumulation was a long-term response to high PPF and CO2 enrichment which would be caused by a sink limitation. Thus, in spring we observed an in situ downregulation of photosynthesis. The ratio Fv/Fm decreased in spring compared to winter in response to increasing PPF. The daily decline of Fv/Fm was observed particularly as a midday depression followed by a recovery towards the end of the day. This indicated that tomato leaves were subject to a reversible inhibition in spring. Fv/Fm was lower in March than in April and May even though PPF was higher in April and May than in March. These results suggest that tomato plants develop an adaptive and protective strategy as PPF increases in spring.

Échanges gazeux de la tomate de serre cultivée sous éclairage d’appoint

1993 ◽  
Vol 73 (2) ◽  
pp. 577-585 ◽  
Author(s):  
Martine Dorais ◽  
Josée Charbonneau ◽  
André Gosselin
Keyword(s):  
Regression Analysis ◽  
Photosynthetic Rate ◽  
Transpiration Rate ◽  
Photosynthetic Activity ◽  
Photon Flux ◽  
Tomato Seedlings ◽  
Échanges Gazeux ◽  
Supplemental Lighting ◽  
High Level

This study reports on in situ gas-exchange measurements in tomatoes grown under a sequential intercropping system with supplemental lighting provided by high-pressure sodium-vapour lamps. A supplemental photosynthetic photon flux (PPF) of 150 μmol m−2 s−1 significantly increased the amount of light energy penetrating the canopy of intercropped tomato seedlings. During the day, the supplemental 150 μmol m−2 s−1 light regime increased the photosynthetic rate of leaves 5 and 10 by 67%, while at night the increases were 93 and 12%, respectively. Regression analysis of the photosynthetic rate of leaves 5 and 10 as a function of PPF received accounts for 58 and 45% of the variation, respectively. Hierarchical analysis demonstrated a significant linear relationship between PPF received during the day and photosynthetic activity of leaves 5 and 10 accounting for 46 and 28%, respectively, of the variance in the model. Regression analysis of the photosynthetic activity as a function of PPF received at night accounts for 41 and 32%, respectively, of the variation in the photosynthetic rate of leaves 5 and 10. Using a high level of supplemental lighting during the day or at night had no significant effect on stomatic conductance or on the transpiration rate of leaves. Key words: Stomatal conductance, photosynthetic photo flux, Lycopersicon esculentum, photosynthesis, transpiration rate

Photosynthetic activity of spring wheat depending on the conditions of water supply

2020 ◽  
Author(s):  
I.I. Seregina ◽  
◽  
I.G. Makarskaya
Keyword(s):  
Water Supply ◽  
Spring Wheat ◽  
Sodium Selenite ◽  
Photosynthetic Activity ◽  
Wheat Variety ◽  
Sharp Decrease ◽  
Soil Culture ◽  
Growing Conditions ◽  
Spring Wheat Variety ◽  
Excessive Water

Abstract:In model experiments in soil culture, the effect of different methods of treatment with sodium selenite on the photosynthetic activity of spring wheat variety Zlata was studied under extreme growing conditions. Under drought conditions, the inhibition of the growth of the photosynthetic surface of spring wheat plants was revealed. Under conditions of excessive water supply, a sharp decrease in the area of the assimilating surface of wheat plants was observed. The positive effect of sodium selenite solution on the photosynthetic activity of spring wheat plants was established with insufficient and excessive water supply to wheat plants.

scholarly journals Digitization and Visualization of Greenhouse Tomato Plants in Indoor Environments

Sensors ◽  
2015 ◽  
Vol 15 (2) ◽  
pp. 4019-4051 ◽  
Author(s):  
Dawei Li ◽  
Lihong Xu ◽  
Chengxiang Tan ◽  
Erik Goodman ◽  
Daichang Fu ◽  
...  
Keyword(s):  
Indoor Environments ◽  
Tomato Plants ◽  
Greenhouse Tomato

scholarly journals In Situ Estimation of Carbon Balance of In Vitro Sweetpotato and Tomato Plantlets Cultured with Varying Initial Sucrose Concentrations in the Medium

2002 ◽  
Vol 127 (6) ◽  
pp. 963-970 ◽  
Author(s):  
Chieri Kubota ◽  
Makiko Ezawa ◽  
Toyoki Kozai ◽  
Sandra B. Wilson
Keyword(s):  
Carbon Balance ◽  
Ipomoea Batatas ◽  
Dry Weight ◽  
Photon Flux ◽  
Sugar Uptake ◽  
Relative Contribution ◽  
Carbon Balances ◽  
Species Specific

The effects of initial sucrose (suc) concentrations in the medium (S0) on the carbon balance and growth of sweetpotato [Ipomoea batatas (L.) Lam. `Beniazuma'] and tomato (Lycopersicon esculentum Mill. `HanaQueen') plantlets were studied under controlled environmental conditions. Plantlets were cultured with 0, 7.5, 15, or 30 g·L-1 of S0 under high photosynthetic photon flux (160 to 200 μmol·m-2·s-1) and CO2 enriched (1400 to 2050 μmol·mol-1) conditions. Net photosynthetic rate per leaf area (Pl) decreased and dry weight per plantlet (Wd) increased with increasing S0, but did not differ significantly between S0 of 7.5 to 30 g·L-1 for sweetpotato or 15 to 30 g·L-1 for tomato. Carbon influxes and effluxes of the plantlets by metabolism of medium suc and/or photosynthesis, and respiration were estimated based on measurements of in situ and steady state CO2 exchange rates and sugar uptake during culture. At S0 from 7.5 to 30 g·L-1, photosynthesis was responsible for 82% to 92% and 60% to 67% of carbohydrate assimilation for sweetpotato and tomato, respectively. Estimated carbon balances of plantlets based on the estimated and actual increases of moles of carbon in plant tissue demonstrated that in situ estimation of carbon balance was reasonably accurate for sweetpotato at S0 of 0 to 15 g·L-1 and for tomato at S0 of 0 g·L-1 and that the actual contribution of photosynthesis for tomato at high S0 might be lower than the values estimated in the present experiment. Results showed that initial suc concentration affected the relative contribution of photosynthesis on their carbon balances and that the responses were species specific. The failure of validation at S0 in a range specific to each species suggested the need for further study on carbon metabolism of in vitro plantlets cultured with sugar in the medium.

scholarly journals Acclimation of Photosynthetic Activity of Zantedeschia `Best Gold' in Response to Temperature and Photosynthetic Photon Flux

2002 ◽  
Vol 127 (2) ◽  
pp. 290-296 ◽  
Author(s):  
Keith A. Funnell ◽  
Errol W. Hewett ◽  
Julie A. Plummer ◽  
Ian J. Warrington
Keyword(s):  
Quantum Yield ◽  
Leaf Area ◽  
Photosynthetic Rate ◽  
Photosynthetic Activity ◽  
Natural Habitat ◽  
Photon Flux ◽  
Photosynthetic Photon Flux ◽  
Leaf Area Expansion ◽  
Response To Temperature ◽  
Area Expansion

Photosynthetic activity of individual leaves of Zantedeschia Spreng. `Best Gold' aff. Z. pentlandii (Wats.) Wittm. [syn. Richardia pentlandii Wats.] (`Best Gold'), were quantified with leaf expansion and diurnally, under a range of temperature and photosynthetic photon flux (PPF) regimes. Predictive models incorporating PPF, day temperature, and percentage leaf area expansion accounted for 78% and 81% of variation in net photosynthetic rate (Pn) before, and postattainment of, 75% maximum leaf area, respectively. Minimal changes in Pn occurred during the photoperiod when environmental conditions were stable. Maximum Pn (10.9μmol·m-2·s-1 or 13.3 μmol·g-1·s-1) occurred for plants grown under high PPF (694 μmol·m-2·s-1) and day temperature (28 °C). Acclimation of Pn was less than complete, with any gain through a greater light-saturated photosynthetic rate (Pmax) at high PPF also resulting in a reduction in quantum yield. Similarly, any gain in acclimation through increased quantum yield under low PPF occurred concurrently with reduced Pmax. It was concluded that Zantedeschia `Best Gold' is a shade tolerant selection, adapted to optimize photosynthetic rate under the climate of its natural habitat, by not having obligate adaptation to sun or shade habitats.

scholarly journals Automatic Wheat Ear Counting Using Thermal Imagery

2019 ◽  
Vol 11 (7) ◽  
pp. 751 ◽  
Author(s):  
Jose Fernandez-Gallego ◽  
Ma. Buchaillot ◽  
Nieves Aparicio Gutiérrez ◽  
María Nieto-Taladriz ◽  
José Araus ◽  
...  
Keyword(s):  
Pipeline System ◽  
Counting System ◽  
Thermal Images ◽  
Manual Counting ◽  
Rgb Images ◽  
Growing Conditions ◽  
The Relationship ◽  
Comparability Of Results ◽  
Automatic Pipeline

Ear density is one of the most important agronomical yield components in wheat. Ear counting is time-consuming and tedious as it is most often conducted manually in field conditions. Moreover, different sampling techniques are often used resulting in a lack of standard protocol, which may eventually affect inter-comparability of results. Thermal sensors capture crop canopy features with more contrast than RGB sensors for image segmentation and classification tasks. An automatic thermal ear counting system is proposed to count the number of ears using zenithal/nadir thermal images acquired from a moderately high resolution handheld thermal camera. Three experimental sites under different growing conditions in Spain were used on a set of 24 varieties of durum wheat for this study. The automatic pipeline system developed uses contrast enhancement and filter techniques to segment image regions detected as ears. The approach is based on the temperature differential between the ears and the rest of the canopy, given that ears usually have higher temperatures due to their lower transpiration rates. Thermal images were acquired, together with RGB images and in situ (i.e., directly in the plot) visual ear counting from the same plot segment for validation purposes. The relationship between the thermal counting values and the in situ visual counting was fairly weak (R2 = 0.40), which highlights the difficulties in estimating ear density from one single image-perspective. However, the results show that the automatic thermal ear counting system performed quite well in counting the ears that do appear in the thermal images, exhibiting high correlations with the manual image-based counts from both thermal and RGB images in the sub-plot validation ring (R2 = 0.75–0.84). Automatic ear counting also exhibited high correlation with the manual counting from thermal images when considering the complete image (R2 = 0.80). The results also show a high correlation between the thermal and the RGB manual counting using the validation ring (R2 = 0.83). Methodological requirements and potential limitations of the technique are discussed.

scholarly journals Application of Trichoderma harzianum, 6-Pentyl-α-pyrone and Plant Biopolymer Formulations Modulate Plant Metabolism and Fruit Quality of Plum Tomatoes

Plants ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 771 ◽  
Author(s):  
Petronia Carillo ◽  
Sheridan L. Woo ◽  
Ernesto Comite ◽  
Christophe El-Nakhel ◽  
Youssef Rouphael ◽  
...  
Keyword(s):  
Trichoderma Harzianum ◽  
Total Yield ◽  
Plant Metabolism ◽  
Tomato Plants ◽  
Beneficial Effects ◽  
Greenhouse Tomato ◽  
Solanum Lycopersicum L ◽  
Functional Quality ◽  
Stimulate Plant Growth

Many Trichoderma are successfully used to improve agriculture productivity due to their capacity for biocontrol and to stimulate plant growth and tolerance to abiotic stress. This research elucidates the effect of applications with Trichoderma harzianum strain T22 (T22), or biopolymer (BP) alone or in combination (BP + T22 or BP + 6-pentyl-α-pyrone (6PP); a Trichoderma secondary metabolite) on the crop performance, nutritional and functional quality of greenhouse tomato (Solanum lycopersicum L. cultivar Pixel). T22 elicited significant increases in total yield (+40.1%) compared to untreated tomato. The content of lycopene, an important antioxidant compound in tomatoes, significantly increased upon treatment with T22 (+ 49%), BP + T22 (+ 40%) and BP + 6PP (+ 52%) compared to the control. T22 treatments significantly increased the content of asparagine (+37%), GABA (+87%) and MEA (+102%) over the control; whereas BP alone strongly increased GABA (+105%) and MEA (+85%). The synthesis of these compounds implies that tomato plants are able to reuse the photorespiratory amino acids and ammonium for producing useful metabolites and reduce the pressure of photorespiration on plant metabolism, thus optimizing photosynthesis and growth. Finally, these metabolites exert many beneficial effects for human health, thus enhancing the premium quality of plum tomatoes.

Diurnal gross photosynthetic patterns and potential seasonal CO2 assimilation in Cladonia stellaris and Cladonia rangiferina

1983 ◽  
Vol 61 (3) ◽  
pp. 642-655 ◽  
Author(s):  
Thomas J. Moser ◽  
Thomas H. Nash III ◽  
Steven O. Link
Keyword(s):  
Photosynthetic Activity ◽  
Growing Season ◽  
Early Morning ◽  
Co2 Assimilation ◽  
Atmospheric Moisture ◽  
Growing Seasons ◽  
Late Evening ◽  
Summer Rain ◽  
Cladonia Rangiferina

The daily, in situ gross photosynthetic patterns of Cladonia stellaris (Opiz.) Pouz. & Vězda. and Cladonia rangiferina (L.) Wigg. were monitored during portions of the 1977, 1978, and 1979 growing seasons at Anaktuvuk Pass, Alaska. Photosynthetic activity in both species closely paralleled atmospheric moisture status, where peak photosynthetic rates were attained during or following sporadic summer rain. In addition, thallus absorption of moisture during extended periods of high atmospheric water vapor content gave rise to short periods of minimal photosynthetic activity. During late evening and early morning hours moistened thalli exhibited minimal or no photosynthetic activity, coinciding with consistent attenuation in solar radiation during these periods. Photosynthetic activity was not homogeneous throughout the thallus. The greatest activity occurred in the apical regions and decreased progressively into the basal regions. The apical 10-mm regions of C. stellaris and C. rangiferina thalli accounted for approximately 50% of their photosynthetic capabilities. The potential gross CO2 assimilation of the apical 10-mm regions over 72 days of the 1978 growing season was estimated at approximately 35 g CO2∙m−2 and 16 g CO2∙m−2 for C. stellaris and C. rangiferina, respectively.

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