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

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.

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.

Seasonal changes in photosynthetic rate and pigment content in two populations of the monotypic Balkan serpentine endemic Halacsya sendtneri

2015 ◽  
Vol 63 (2) ◽  
pp. 167 ◽  
Author(s):  
Dražen D. Vicić ◽  
Milovan M. Stoiljković ◽  
Marko S. Sabovljević ◽  
Branka M. Stevanović
Keyword(s):  
Photosynthetic Rate ◽  
Photosynthetic Activity ◽  
Balkan Peninsula ◽  
Summer Period ◽  
Spring Period ◽  
Leaf Chlorophyll ◽  
Steep Decline ◽  
Microclimate Conditions ◽  
Two Populations

Halacsya sendtneri (Boiss.) Dörfl. is an obligate serpentine palaeoendemic of the Balkan Peninsula. It is able to maintain a favourable magnesium : calcium (Mg : Ca) ratio throughout its root and shoot, and grow in serpentine habitats with different microclimate conditions. Seasonal variation of leaf chlorophyll and carotenoid contents showed a steep decline right after the spring period, which was most probably caused by the drought imposed on the plants on the shallow serpentine soil. However, the in situ photosynthetic rate remained stable throughout the spring and summer period. Prolonged photosynthetic activity enables this species an investment into root development and sustainable survival in the harsh soils of the habitats it occupies.

Continuous in Situ Recording of the Photosynthetic Activity of Antarctic Lichens—established Methods and a New Approach

1991 ◽  
Vol 23 (3) ◽  
pp. 253-265 ◽  
Author(s):  
B. Schroeter ◽  
L. Kappen ◽  
C. Moldaenke
Keyword(s):  
Water Content ◽  
Photosynthetic Rate ◽  
Photosynthetic Activity ◽  
Dark Respiration ◽  
South Shetland Islands ◽  
Fibre Optics ◽  
Fluorescence Response ◽  
Gravimetric Water Content ◽  
Thallus Water Content

AbstractA new method is described that records the periods of photosynthetic and respiratory activity in lichen thalli in situ by measuring the actinic chlorophyll fluorescence response of the photobiont. The technique is based on a pulse amplitude modulation fluorometer that was specially developed for continuous and unattended measurements in the Antarctic. In Livingston Island, South Shetland Islands, the periods of metabolic activity of Usnea antarctica were recorded simultaneously with the microclimatic parameter in its natural environment. In one series of diurnal measurements the fluorescence response signal was treated as a qualitative on/off signal for photosynthetic activity. In a parallel series the diurnal courses of net photosynthesis and dark respiration of rain-moistened thalli of U. antarctica were measured by means of a CO2/H2O porometer together with gravimetric water content determination. Both methods showed marked coincidence from low water content to water saturation of the thalli. In the laboratory both the actinic fluorescence response and the photosynthetic rate as a function of thallus water content were investigated in Caloplaca regalis. In the laboratory experiments the CO2 exchange cuvette contained a balance for gravimetric water content control as well as the glass-fibre optics of the fluorescence analysis equipment. The experiments revealed a quantitative relationship between actinic fluorescence and photosynthetic rate within the range of optimum to limiting low thallus water content. The method described is suitable for measurements of lichen activity in field microclimate studies and should allow continuous unattended year-round measurements of lichen activity, which are needed in remote regions such as Antarctica.

scholarly journals Effect of Supplementary Light Intensity on Quality of Grafted Tomato Seedlings and Expression of Two Photosynthetic Genes and Proteins

Agronomy ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 339 ◽  
Author(s):  
Hao Wei ◽  
Jin Zhao ◽  
Jiangtao Hu ◽  
Byoung Ryong Jeong
Keyword(s):  
Light Intensity ◽  
Dry Weight ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Natural Lighting ◽  
Tomato Seedlings ◽  
Photosynthetic Genes ◽  
Supplemental Lighting

Lower quality and longer production periods of grafted seedlings, especially grafted plug seedlings of fruit vegetables, may result from insufficient amounts of light, particularly in rainy seasons and winter. Supplemental artificial lighting may be a feasible solution to such problems. This study was conducted to evaluate light intensity’s influence on the quality of grafted tomato seedlings, ‘Super Sunload’ and ‘Super Dotaerang’ were grafted onto the ‘B-Blocking’ rootstock. To improve their quality, grafted seedlings were moved to a glasshouse and grown for 10 days. The glasshouse had a combination of natural lighting from the sun and supplemental lighting from LEDs (W1R2B2) for 16 h/day. Light intensity of natural lighting was 490 μmol·m−2·s−1 photosynthetic photon flux density (PPFD) and that of supplemental lighting was 50, 100, or 150 μmol·m−2·s−1 PPFD. The culture environment had 30/25 °C day/night temperatures, 70% ± 5% relative humidity (RH), and a natural photoperiod of 14 h as well. Compared with quality of seedlings in supplemental lighting of 50 μmol·m−2·s−1 PPFD, that of seedlings in supplement lighting of 100 or 150 μmol·m−2·s−1 PPFD improved significantly. With increasing light intensity, diameter, fresh weight, and dry weight, which were used to measure shoot growth, greatly improved. Leaf area, leaf thickness, and root biomass were also greater. However, for quality of seedlings, no significant differences were discovered between supplement lighting of 100 μmol·m−2·s−1 PPFD and supplement lighting of 150 μmol·m−2·s−1 PPFD. Expressions of PsaA and PsbA (two photosynthetic genes) as well as the corresponding proteins increased significantly in supplement lightning of 100 and 150 μmol·m−2·s−1 PPFD, especially in 100 μmol·m−2·s−1 PPFD. Overall, considering quality and expressions of two photosynthetic genes and proteins, supplemental light of 100 μmol·m−2·s−1 PPFD (W1R2B1) would be the best choice to cultivate grafted tomato seedlings.

Characteristics, Features of Development, Regional and Sectoral Determinants of High-tech Business in Russia

2017 ◽  
pp. 142-154 ◽  
Author(s):  
A. Yusupova ◽  
S. Khalimova
Keyword(s):  
Regression Analysis ◽  
Performance Indicators ◽  
Sustainability Assessment ◽  
Business Development ◽  
High Tech ◽  
Assessment Data ◽  
High Tech Sector ◽  
Fast Growing ◽  
High Level

The paper deals with the research devoted to characteristics of high tech business development in Russia. Companies’ performance indicators have been analyzed with the help of regression analysis and author’s scheme of leadership stability and sustainability assessment. Data provided by Russia’s Fast Growing High-Tech Companies’ National Rating (TechUp) during 2012-2016 were used. The results have revealed that the high tech sector is characterized by high level of uncertainty. Limited number of regions and sectors which form the basis for high tech business have been defined. Relationship between innovation activity’s indicators and export potential is determined.

scholarly journals Wheat, Rye, and Barley Genomes Can Associate during Meiosis in Newly Synthesized Trigeneric Hybrids

Plants ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 113
Author(s):  
María-Dolores Rey ◽  
Carmen Ramírez ◽  
Azahara C. Martín
Keyword(s):  
Chromosome Segregation ◽  
Genome Duplication ◽  
Triticum Turgidum ◽  
Aegilops Tauschii ◽  
Genomic In Situ Hybridization ◽  
Hordeum Chilense ◽  
Genomic Constitution ◽  
Chromosome Associations ◽  
High Level

Polyploidization, or whole genome duplication (WGD), has an important role in evolution and speciation. One of the biggest challenges faced by a new polyploid is meiosis, in particular, discriminating between multiple related chromosomes so that only homologs recombine to ensure regular chromosome segregation and fertility. Here, we report the production of two new hybrids formed by the genomes of species from three different genera: a hybrid between Aegilops tauschii (DD), Hordeum chilense (HchHch), and Secale cereale (RR) with the haploid genomic constitution HchDR (n = 7× = 21); and a hybrid between Triticum turgidum spp. durum (AABB), H. chilense, and S. cereale with the constitution ABHchR (n = 7× = 28). We used genomic in situ hybridization and immunolocalization of key meiotic proteins to establish the chromosome composition of the new hybrids and to study their meiotic behavior. Interestingly, there were multiple chromosome associations at metaphase I in both hybrids. A high level of crossover (CO) formation was observed in HchDR, which shows the possibility of meiotic recombination between the different genomes. We succeeded in the duplication of the ABHchR genome, and several amphiploids, AABBHchHchRR, were obtained and characterized. These results indicate that recombination between the genera of three economically important crops is possible.

scholarly journals Effect of Pre-Harvest Supplemental UV-A/Blue and Red/Blue LED Lighting on Lettuce Growth and Nutritional Quality

Horticulturae ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 80
Author(s):  
Triston Hooks ◽  
Joseph Masabni ◽  
Ling Sun ◽  
Genhua Niu
Keyword(s):  
Blue Light ◽  
Nutritional Quality ◽  
Uv Light ◽  
Ultra Violet ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Daily Light Integral ◽  
Lettuce Growth ◽  
Supplemental Lighting

Blue light and ultra-violet (UV) light have been shown to influence plant growth, morphology, and quality. In this study, we investigated the effects of pre-harvest supplemental lighting using UV-A and blue (UV-A/Blue) light and red and blue (RB) light on growth and nutritional quality of lettuce grown hydroponically in two greenhouse experiments. The RB spectrum was applied pre-harvest for two days or nights, while the UV-A/Blue spectrum was applied pre-harvest for two or four days or nights. All pre-harvest supplemental lighting treatments had a same duration of 12 h with a photon flux density (PFD) of 171 μmol m−2 s−1. Results of both experiments showed that pre-harvest supplemental lighting using UV A/Blue or RB light can increase the growth and nutritional quality of lettuce grown hydroponically. The enhancement of lettuce growth and nutritional quality by the pre-harvest supplemental lighting was more effective under low daily light integral (DLI) compared to a high DLI and tended to be more effective when applied during the night, regardless of spectrum.

Some observations on rock weathering, Cumberland Peninsula, Baffin Island

1979 ◽  
Vol 16 (5) ◽  
pp. 977-983 ◽  
Author(s):  
Stephen H. Waits
Keyword(s):  
Salt Crystallization ◽  
Rock Weathering ◽  
Baffin Island ◽  
Significant Modification ◽  
Bedrock Weathering ◽  
Arctic Conditions ◽  
Selective Preservation ◽  
Mechanical Weathering ◽  
High Level

A variety of bedrock weathering features—both modern and remnant—including surface grus, polygonal cracks, siliceous glaze, tors, weathering pits, and tafoni typify upland outcrops on the Cumberland Peninsula. Tor ridges are particularly prevalent and at lower elevations they show significant modification and streamlining by flowing ice. On summit areas at elevations above 750 m, however, remnant corestones are preserved in situ, suggesting selective preservation of upland surfaces. Bedrock structure and composition, topographic position, and intensity of process strongly influence tor development. Weathering pits are common on high level, open summit surfaces where weathering occurs in response to both climate and continued removal of derived debris. Pit enlargement through lateral undercutting has been favoured by accumulation of protective bottom residua, mechanical weathering, and the presence of exfoliation crusts. It is postulated that salt crystallization plays a role in outcrop microweathering under present upland arctic conditions.

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