scholarly journals Photosynthetic Performance of Guaranazeiro Plants as Affected by Glyphosate Application

2020 ◽  
Vol 12 (10) ◽  
pp. 287
Author(s):  
Bruna N. Leite ◽  
Karla Gabrielle D. Pinto ◽  
Victor Alexandre H. F. dos Santos ◽  
Marciel J. Ferreira ◽  
Sônia Maria F. Albertino
Keyword(s):  
Gas Exchange ◽  
Chlorophyll Content ◽  
Photosynthetic Performance ◽  
Productive Performance ◽  
Weed Species ◽  
Short Term ◽  
Paullinia Cupana ◽  
Process Gas ◽  
Quantum Efficiency Of Psii ◽  
Relative Chlorophyll Content

The unsuitable use of herbicides damages many cultures. In cases of high infestations and presence of aggressive weed species in guarana (Paullinia cupana) culture, glyphosate application is advisable, but its impact on guarana physiology is unknown. Therefore, leaf photosynthetic characteristics were measured with the aim of identifying if the photosynthetic performance of guaranazeiro plants is affected in response to glyphosate application. Three glyphosate doses (0 (control); 324 and 432 g a.i. ha-1) were applied to two guaranazeiro cultivars (BRS-Andirá and BRS-Maués) selected on the basis of productive performance. An analysis was made of the effects of these doses on characteristics that represent the photosynthetic process: gas exchange, maximum quantum efficiency of PSII, performance index and chlorophyll content. The application of glyphosate did not affect the short-term responses relative chlorophyll content (SPAD index) and light use (chlorophyll a fluorescence). After 168 h, there were changes only in gas exchange variables. The effects of glyphosate doses on gas exchange was different between guaranazeiro cultivars. The photosynthetic performance of the guaranazeiro seems to be tolerant to the effects of short-term of glyphosate application.

Seasonal photosynthesis and anthocyanin production in 10 broadleaf evergreen species

2007 ◽  
Vol 34 (12) ◽  
pp. 1072 ◽  
Author(s):  
Nicole M. Hughes ◽  
William K. Smith
Keyword(s):  
Gas Exchange ◽  
Chlorophyll Content ◽  
Chlorophyll A ◽  
Photosynthetic Capacity ◽  
Photosynthetic Performance ◽  
Evergreen Species ◽  
Maximum Light ◽  
Anthocyanin Pigments ◽  
Anthocyanin Production ◽  
Light Capture

Leaves of many evergreen species turn red when exposed to high sunlight during winter due to production of photoprotective anthocyanin pigments, while leaves of other species, lacking anthocyanin, remain green. Why some evergreen species synthesise anthocyanin pigments while others do not is currently unknown. Furthermore, the relative photosynthetic performance of anthocyanic (red) and acyanic (green) evergreens has yet to be described. Here we present seasonal ecophysiological data for five red and green broadleaf evergreen species. We hypothesise that species which synthesise anthocyanins in winter leaves correspond to those with the most drastic seasonal photosynthetic declines, as reduced energy sinks increase vulnerability to photoinhibition and need for photoprotection. Our results did not support this hypothesis, as gas exchange measurements showed no difference in mean seasonal photosynthetic capacity between red- and green-leafed species. Consistent with anthocyanin’s shading effect, red-leafed species had significantly higher chlorophyll content, lower chlorophyll a/b ratios, and higher maximum light capture efficiency of PSII (Fv/Fm) than green-leafed species during the winter, but not during the summer (when all leaves were green). We conclude that anthocyanin production during winter is likely not associated with diminished photosynthetic capacity, and may simply represent an alternative photoprotective strategy utilised by some species during winter.

scholarly journals Light spectrum affects growth and gas exchange of common dandelion and purple coneflower seedlings

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Donato Castronuovo ◽  
Adriano Sofo ◽  
Stella Lovelli ◽  
Vincenzo Candido ◽  
Antonio Scopa
Keyword(s):  
Gas Exchange ◽  
Chlorophyll Content ◽  
Experimental Period ◽  
Photosynthetic Performance ◽  
Controlled Environment ◽  
Artificial Light ◽  
Light Sources ◽  
Light Spectrum ◽  
Purple Coneflower ◽  
Common Dandelion

Artificial light, supplied by fluorescent lamps, has been effectively utilized in controlled- environment chambers for horticulture and floriculture nursery. This experiment aimed at investigating whether light-emitting diodes (LEDs) have the same effectiveness on plant morphology, photosynthetic and physiological responses as FLUORA lamps. Seedlings of common dandelion (<em>Taraxacum</em> <em>officinale</em>) and purple coneflower (<em>Echinacea</em> <em>purpurea</em>), species of high interest for their nutraceutical properties, were grown in controlled-environment chambers for 50 days under LED and FLUORA light sources as sole-source lighting systems, and the effects of artificial light supplies on plant photosynthetic performance and chlorophyll content (SPAD) were evaluated. The results were compared to plants grown under natural sunlight. In both species, total chlorophyll content (SPAD) values decreased for plants under sunlight, and for those grown under FLUORA lighting throughout the experimental period, while the values measured for plants grown under LEDs maintained a relatively constant value. At the end of the experiment, plant dry matter in both species was significantly lower under LEDs and FLUORA lighting, than the plants exposed to solar light. The two species showed different gas exchange dynamics under LEDs and FLUORA lighting, and photosynthetic performance decreasing after 10 days of light treatment compared to plants under sunlight. The results demonstrated that for common dandelion and purple coneflower photosynthetic processes are often modified when the species are cultivated under these artificial lighting and in controlled- environment chambers, because lamps do not able to generate the same spectrum and energy of sunlight.

Changes in Leaf Thickness, Chlorophyll Content, and Gas Exchange of a Landscape Tree, Xanthostemon chrysanthus, Treated with Paclobutrazol and Potassium Nitrate

2021 ◽  
Vol 47 (2) ◽  
pp. 53-63
Author(s):  
Ahmad Nazarudin Mohd Roseli ◽  
Tsan Fui Ying ◽  
Normaniza Osman
Keyword(s):  
Gas Exchange ◽  
Stress Tolerance ◽  
Chlorophyll Content ◽  
Tree Height ◽  
Potassium Nitrate ◽  
Leaf Thickness ◽  
Leaf Physiology ◽  
Urban Conditions ◽  
Leaf Greenness ◽  
Relative Chlorophyll Content

Paclobutrazol (PBZ)(0 g L-1, 0.125 g L-1, and 0.25 g L-1) and potassium nitrate (KNO3)(0 g tree-1, 100 g tree-1, and 200 g tree-1) were tested on a landscape tree, Xanthostemon chrysanthus (F. Muell.) Benth., in an attempt to enhance its stress tolerance under harsh urban conditions. Significant effects on tree height, diameter at breast height, canopy diameter, leaf area, and anatomy of tree leaves and stems in response to PBZ and KNO3 have been previously reported; in addition to these, the influences on leaf thickness and leaf physiology, including chlorophyll content and gas exchange, are discussed in this study. Relative chlorophyll content was significantly increased with PBZ and/or KNO3, enhancing leaf greenness. Increased leaf thickness of up to 13.37% at 6 months after treatment with a combination of PBZ and KNO3 was observed. The presence of PBZ significantly reduced the photosynthetic and transpiration rates and stomatal conductance. Reduced leaf physiological traits combined with thicker leaves would be beneficial for trees to tolerate harsh urban settings. Therefore, a combination of PBZ and KNO3 is recommended for stress tolerance enhancement of X. chrysanthus grown as a landscape tree.

A novel spectral index for estimation of relative chlorophyll content of sugar beet

2021 ◽  
Vol 184 ◽  
pp. 106088
Author(s):  
Jing Zhang ◽  
Haiqing Tian ◽  
Di Wang ◽  
Haijun Li ◽  
Abdul Mounem Mouazen
Keyword(s):  
Sugar Beet ◽  
Chlorophyll Content ◽  
Spectral Index ◽  
Relative Chlorophyll Content

scholarly journals The Preferences of Different Cultivars of Lettuce Seedlings (Lactuca sativa L.) for the Spectral Composition of Light

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1211
Author(s):  
Barbara Frąszczak ◽  
Monika Kula-Maximenko
Keyword(s):  
Chlorophyll Content ◽  
Blue Light ◽  
White Light ◽  
Leaf Shape ◽  
Red Light ◽  
Spectral Composition ◽  
Fresh Weight ◽  
Light Spectrum ◽  
Dark Green ◽  
Relative Chlorophyll Content

The spectrum of light significantly influences the growth of plants cultivated in closed systems. Five lettuce cultivars with different leaf colours were grown under white light (W, 170 μmol m−2 s−1) and under white light with the addition of red (W + R) or blue light (W + B) (230 μmol m−2 s−1). The plants were grown until they reached the seedling phase (30 days). Each cultivar reacted differently to the light spectrum applied. The red-leaved cultivar exhibited the strongest plasticity in response to the spectrum. The blue light stimulated the growth of the leaf surface in all the plants. The red light negatively influenced the length of leaves in the cultivars, but it positively affected their number in red and dark-green lettuce. It also increased the relative chlorophyll content and fresh weight gain in the cultivars containing anthocyanins. When the cultivars were grown under white light, they had longer leaves and higher value of the leaf shape index. The light-green cultivars had a greater fresh weight. Both the addition of blue and red light significantly increased the relative chlorophyll content in the dark-green cultivar. The spectrum enhanced with blue light had positive influence on most of the parameters under analysis in butter lettuce cultivars. These cultivars were also characterised by the highest absorbance of blue light.

Effect of short-term exposure to high ambient temperatures on gas exchange and heat production in boars of different breeds

1998 ◽  
Vol 66 (2) ◽  
pp. 431-440 ◽  
Author(s):  
A.-H. Tauson ◽  
A. Chwalibog ◽  
J. Ludvigsen ◽  
K. Jakobsen ◽  
G. Thorbek
Keyword(s):  
Heat Stress ◽  
Gas Exchange ◽  
Heat Production ◽  
Live Weight ◽  
Mean Value ◽  
Short Term ◽  
Ambient Temperatures ◽  
Cooling Period ◽  
Basal Period ◽  
Short Term Exposure

AbstractThe effects of short-term exposure to high ambient temperatures on gas exchange, heat production (HE), respiration rate (RR) and rectal temperature were evaluated individually with boars of approximately 100 kg live weight. The boars were of different breeds with four of Yorkshire (YS), eight of Danish Landrace (DL), out of which three were found stress susceptible by the halothane test (DLH+), eight of Duroc (DR) and eight of Hampshire (HS) breeds. After 1 h rest in the respiration chamber at 17·0°C the gas exchange measurements started with al-h basal period at 17 °C, followed by 2h of heating during which temperature increased to 35·0 °C (period I) and then further to 39·7X1 (period II). Then cooling of the chamber started, and after 1 h (period III) temperature had decreased to 21·8°C, and after the 2nd h of cooling (period IV) temperature was 18·2 °C. The gas exchange was measured for each hour from 09.00 h (basal period) until 14.00 h (period IV). RR was recorded every 15 min. Rectal temperatures were measured when the animals were removed from the chamber. The gas exchange and HE increased slowly during period I but rapidly in period II, followed by decreasing values in the cooling periods. HS and DLH+ had considerably higher gas exchange and HE than other breeds in these two periods and the values remained high during period III. In period IV all breeds had gas exchange rates and HE below those of the basal period. RR increased slightly in period I and then a sharp increase followed during period II. Maximum RR was recorded in period III with an average of 183 breaths per min for all breeds. RR increased earlier and more steeply in HS and reached the highest mean value of 236 breaths per min. Four HS boars salivated heavily during heat stress and rectal temperatures of these animals were 39·7 °C when removed from the chamber compared with close to 39·0 °C for all other breeds. It was concluded that there were considerable breed differences in response to heat stress and that DLH+ and HS were more severely stressed than boars ofYS, DL and DR.

scholarly journals Chronicvs.Short-Term Acute O3Exposure Effects on Nocturnal Transpiration in Two Californian Oaks

2007 ◽  
Vol 7 ◽  
pp. 134-140 ◽  
Author(s):  
N. E. Grulke ◽  
E. Paoletti ◽  
R. L. Heath
Keyword(s):  
Gas Exchange ◽  
Water Loss ◽  
Exchange System ◽  
Short Term ◽  
Blue Oak ◽  
Unexposed Control ◽  
Nocturnal Transpiration ◽  
Gas Exchange System ◽  
Black Oak ◽  
Oak Seedlings

We tested the effect of daytime chronic moderate ozone (O3) exposure, short-term acute exposure, and both chronic and acute O3exposure combined on nocturnal transpiration in California black oak and blue oak seedlings. Chronic O3exposure (70 ppb for 8 h/day) was implemented in open-top chambers for either 1 month (California black oak) or 2 months (blue oak). Acute O3exposure (~1 h in duration during the day, 120–220 ppb) was implemented in a novel gas exchange system that supplied and maintained known O3concentrations to a leaf cuvette. When exposed to chronic daytime O3exposure, both oaks exhibited increased nocturnal transpiration (without concurrent O3exposure) relative to unexposed control leaves (1.8× and 1.6×, black and blue oak, respectively). Short-term acute and chronic O3exposure did not further increase nocturnal transpiration in either species. In blue oak previously unexposed to O3, short-term acute O3exposure significantly enhanced nocturnal transpiration (2.0×) relative to leaves unexposed to O3. California black oak was unresponsive to (only) short-term acute O3exposure. Daytime chronic and/or acute O3exposures can increase foliar water loss at night in deciduous oak seedlings.

scholarly journals Phytotoxic potential of essential oil of Melaleuca leucadendra against some agricultural weeds

2017 ◽  
Vol 6 (11) ◽  
pp. 1799
Author(s):  
Gunjan Goyal
Keyword(s):  
Essential Oil ◽  
Chlorophyll Content ◽  
Volatile Oil ◽  
Cyperus Rotundus ◽  
Maximum Effect ◽  
Dependent Manner ◽  
Weed Species ◽  
Concentration Dependent Manner ◽  
Root And Shoot Length ◽  
Melaleuca Leucadendra

The work was undertaken to investigate the phytotoxic potential of essential oil from Melaleuca leucadendra against three weed species, viz., Echinochloa crus-galli, Cyperus rotundus and Leptochloa chinensis. It was observed that volatile oil (0.25-1.5 mg ml-1) of Melaleuca retarded the germination and growth of all the test weeds in a dose-response bioassay conducted under laboratory conditions. Generally, both root and shoot length showed an inhibitory effect in a concentration dependent manner and the maximum effect was observed in C. rotundus, followed by E. crus-galli and L. chinensis. The Melaleuca oil not only affected the germination and seedling growth of the test weeds, but also inhibited the chlorophyll content and dry weight. At the highest dose of Melaleuca oil treatment (1.5 mg ml-1), the chlorophyll content declined by nearly 50% in E. crus-galli and 90% in L. chinensis over the control. Thus, it is concluded that volatile oil possesses phytotoxic potential towards other plants and could be further explored for weed management.

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