scholarly journals Effect of the Presence/Absence of Sugar in the Medium and Natural/Forced Ventilation on the Net Photosynthetic Rates of Potato Expants in vitro.

1991 ◽  
Vol 8 (2) ◽  
pp. 105-109 ◽  
Author(s):  
M. NAKAYAMA ◽  
T. KOZAI ◽  
K. WATANABE
Keyword(s):  
Forced Ventilation ◽  
Photosynthetic Rates

LEAF CO2 EXCHANGE RATES IN WINTER RYE GROWN AT COLD-HARDENING AND NONHARDENING TEMPERATURES

1986 ◽  
Vol 66 (3) ◽  
pp. 443-452 ◽  
Author(s):  
N. P. A. HUNER ◽  
W. MIGUS ◽  
M. TOLLENAAR
Keyword(s):  
Photosynthetic Electron Transport ◽  
Co2 Exchange ◽  
Cold Hardening ◽  
Photosynthetic Acclimation ◽  
Winter Rye ◽  
Photosynthetic Rates ◽  
Secale Cereale L ◽  
Stimulation Of

CO2 gas exchange measurements were performed on cold-hardened and unhardened Puma rye (Secale cereale L.) leaves at 10 and 20 °C in the presence of 2 and 21% O2 and as a function of irradiance and CO2 concentration. A decrease in O2 concentration from 21 to 2% appeared to result in a differential stimulation of photosynthetic rates in cold-hardened and unhardened rye leaves. Under light saturating conditions the former exhibited photosynthetic rates that tended to be 1.4- to 1.5-fold higher in the presence of 2% O2 than 21% O2 when measured at either 10 or 20 °C. In contrast, unhardened rye leaves exhibited photosynthetic rates that tended to be about 1.3-fold higher in the presence of 2% O2 than 21% O2 when measured at 10 °C but about 1.8-fold higher when measured at 20 °C. Similarly, at high CO2 concentrations, leaves of unhardened plants exhibited a greater temperature-dependent stimulation of photosynthetic rates by low O2 than leaves of hardened plants. An increased capacity for CO2 utilization in cold-hardened rye could be observed when photosynthetic rates were monitored at 2% O2. Differences in transpiration rates were insufficient to account for these results. The increased capacity for CO2 utilization observed in vivo is discussed with respect to a recent report which described an increased capacity for photosynthetic electron transport in vitro in cold-hardened rye thylakoid membranes. However, photosynthetic acclimation to the contrasting growth temperatures could only be observed when CO2 exchange was measured at 2% O2. We conclude that photosynthetic acclimation in vivo may be severely limited due to the restrictions imposed by photorespiration.Key words: Cold-hardening, winter rye, CO2 exchange, photosynthesis

scholarly journals Limitations to leaf photosynthesis in field-grown grapevine under drought — metabolic and modelling approaches

2002 ◽  
Vol 29 (4) ◽  
pp. 451 ◽  
Author(s):  
João P. Maroco ◽  
M. Lucília Rodrigues ◽  
Carlos Lopes ◽  
M. Manuela Chaves
Keyword(s):  
Gas Exchange ◽  
Stomatal Closure ◽  
Net Photosynthesis ◽  
Co2 Assimilation ◽  
Quantum Yields ◽  
Vitis Vinifera L ◽  
Lower Efficiency ◽  
Photosynthetic Rates ◽  
Fructose 1,6 Bisphosphate

The effects of a slowly-imposed drought stress on gas-exchange, chlorophyll a fluorescence, biochemical and physiological parameters of Vitis vinifera L. leaves (cv. Aragonez, syn. Tempranillo) growing in a commercial vineyard (South Portugal) were evaluated. Relative to well-watered plants (predawn water potential, ΨPD = –0.13 ± 0.01 MPa), drought-stressed plants (ΨPD = –0.97 ± 0.01 MPa) had lower photosynthetic rates (ca 70%), stomatal conductance, and PSII activity (associated with a higher reduction of the quinone A pool and lower efficiency of PSII open centres). Stomatal limitation to photosynthesis was increased in drought-stressed plants relative to well-watered plants by ca 44%. Modelled responses of net photosynthesis to internal CO2 indicated that drought-stressed plants had significant reductions in maximum Rubisco carboxylation activity (ca 32%), ribulose-1,5-bisphosphate regeneration (ca 27%), and triose phosphate (triose-P) utilization rates (ca 37%) relative to well-watered plants. There was good agreement between the effects of drought on modelled biochemical parameters, and in vitro activities of key enzymes of carbon metabolism, namely Rubisco, glyceraldehyde-3-phosphate dehydrogenase, ribulose-5-phosphate kinase and fructose-1,6-bisphosphate phosphatase. Quantum yields measured under both ambient (35 Pa) and saturating CO2 (100 Pa) for drought-stressed plants were decreased relative to well-watered plants, as well as maximum photosynthetic rates measured at light and CO2 saturating conditions (three times ambient CO2 levels). Although stomatal closure was a strong limitation to CO2 assimilation under drought, comparable reductions in electron transport, CO2 carboxylation, and utilization of triose-P capacities were also adaptations of the photosynthetic machinery to dehydration that slowly developed under field conditions. Results presented in this study confirm that modelling photosynthetic responses based on gas-exchange data can be successfully used to predict metabolic limitations to photosynthesis.

Effects of forced ventilation at different relative humidities on growth, photosynthesis and transpiration of geranium plantlets in vitro

1993 ◽  
Vol 73 (1) ◽  
pp. 249-256 ◽  
Author(s):  
De Yue ◽  
André Gosselin ◽  
Yves Desjardins
Keyword(s):  
Key Words ◽  
Transpiration Rate ◽  
Photosynthetic Capacity ◽  
Dry Weight ◽  
Forced Ventilation

Shoots of geranium (Pelargonium × hortorum Bailey ’Hollywood Red’) were cultured under forced ventilation with air of different relative humidities (RH). In comparison with those grown under conventional in vitro conditions, plantlets grown under forced ventilation had greater dry weight of both shoots and roots. Grey pigment zonation, which appears on leaves grown in either the greenhouse or the field, was not observed on leaves cultured under conventional in vitro conditions but was found on leaves cultured under forced ventilation. Forced ventilation at 100% RH, or at 100% RH before rooting and 46% after rooting, did not have a significant effect on the photosynthetic capacity of leaves. However, leaves grown at 46% RH after rooting showed a much lower transpiration rate than leaves grown under conventional in vitro conditions or in vessels ventilated with air of 100% RH. Key words: Pelargonium × hortorum, micropropagation, forced ventilation, growth, photosynthesis, transpiration

scholarly journals An in vitro Propagation of Aspilia africana (Pers.) C. D. Adams, and Evaluation of Its Anatomy and Physiology of Acclimatized Plants

2021 ◽  
Vol 12 ◽  
Author(s):  
Denis Okello ◽  
Sungyu Yang ◽  
Richard Komakech ◽  
Endang Rahmat ◽  
Yuseong Chung ◽  
...  
Keyword(s):  
Medicinal Plant ◽  
Large Scale ◽  
Near Infrared ◽  
Culture Media ◽  
Nodal Segments ◽  
Naphthaleneacetic Acid ◽  
African Countries ◽  
Photosynthetic Rates ◽  
Chlorophyll Contents

Aspilia africana (Pers.) C. D. Adams is an important medicinal plant, that has been used as traditional medicine in many African countries for the treatment of various health problems, including inflammatory conditions, osteoporosis, tuberculosis, cough, measles, diabetes, diarrhea, malaria, and wounds. We developed an efficient and reproducible protocol for in vitro regeneration of A. africana from nodes. We assessed the effects of plant tissue culture media on A. africana growth, cytokinins for in vitro shoot regeneration and proliferation, and auxins for the rooting of regenerated shoots. Furthermore, chlorophyll content, photosynthetic rates, anatomy (leaves, stems, and roots), and Fourier transform near-infrared (FT-NIR) spectra (leaves, stems, and roots) of the in vitro regenerated and maternal A. africana plants were compared. Murashige and Skoog media, containing vitamins fortified with benzylaminopurine (BA, 1.0 mg/l), regenerated the highest number of shoots (13.0 ± 0.424) from A. africana nodal segments. 1-naphthaleneacetic acid (NAA, 0.1 mg/l) produced up to 13.10 ± 0.873 roots, 136.35 ± 4.316 mm length, and was the most efficient for rooting. During acclimatization, the in vitro regenerated A. africana plants had a survival rate of 95.7%, displaying normal morphology and growth features. In vitro regenerated and mother A. africana plants had similar chlorophyll contents, photosynthetic rates, stem and root anatomies, and FT-NIR spectra of the leaf, stem, and roots. The established regeneration protocol could be used for large-scale multiplication of the plant within a short time, thus substantially contributing to its rapid propagation and germplasm preservation, in addition to providing a basis for the domestication of this useful, high-value medicinal plant.

scholarly journals MICROPROPAGATION OF PISTACIA LENTISCUS L. - OPTIMIZATION OF THE SURFACE STERILIZATION PROTOCOL AND FORCED VENTILATION IN TEMPORARY IMMERSION CULTURE

2020 ◽  
Vol 36 ◽  
pp. 75-82
Author(s):  
Mohammad Javad Mahmoudi Meimand ◽  
Barbara Ruffoni ◽  
Carlo Mascarello ◽  
Mohammad Hossein Shamshiri ◽  
Khalil Malekzadeh
Keyword(s):  
Ventilation System ◽  
Initial Growth ◽  
Pistacia Lentiscus ◽  
Forced Ventilation ◽  
Temporary Immersion System ◽  
Temporary Immersion ◽  
Surface Sterilization ◽  
Micro Propagation ◽  
Shoot Weight

Pistacia lentiscus L., belonging to Anacardiaceae family, is a typical species of the Mediterranean maquis and it is widely grown in Greece and Italy mainly for its aromatic resin extraction or as ornamental plant and also as Pistacia vera L. rootstock. Its propagation is difficult either by seed or by cuttings. The current study was carried out to optimize the micro propagation of Pistacia lentiscus L. starting from seedlings and woody explants. For the surface sterilization two different protocols were evaluated for woody explant and 6 treatments with combinations of different sterilizing agent types and concentrations were used for mature seeds. For woody explants, no significant differences could be evidenced on contamination percentage and plant survival but the initial growth in vitro of the explant was better in case of the first treatment (1.5% NaOCl for 30 min and 70% Ethanol for 1 min) than opposite combination. The highest seed contamination percentage occurred in case of treatment with 1% NaOCl for 30 min. The treatment with Ethanol (70%) for 30 second followed by three times washing with distilled water then use of NaOCl (1%) for 30 min permitted to obtain 100% of sterility. The highest seed germination (100% after 3 days) was obtained in seeds treated with Ethanol (70%) for 30 second then NaOCl (1%) for 30 min. In order to study the proliferation two different procedures were compared in liquid and agar-based media. Our results proved that proliferation rate increased 6.5 % by forced ventilation system. Longer shoots (10.5 cm) were obtained in temporary immersion system using RITA boxes. This culture system induced also the highest shoot weight which is the increasing of the 29.56% respect common vessels and agar-based medium

scholarly journals Re-examination of the Photosynthetic Capacity of In Vitro-cultured Strawberry Plantlets

1993 ◽  
Vol 118 (3) ◽  
pp. 419-424 ◽  
Author(s):  
De Yue ◽  
André Gosselin ◽  
Yves Desjardins
Keyword(s):  
In Vitro Culture ◽  
Photosynthetic Rate ◽  
Photosynthetic Capacity ◽  
Dark Respiration ◽  
Ex Vitro ◽  
Photosynthetic Rates ◽  
Respiration Rates ◽  
Rooting Medium

Photosynthesis and growth of in vitro-cultured strawberry plantlets (Fragaria × ananassa Duch. cv Kent) were investigated during a 4-week in vitro culture in a rooting medium and a 4-week ex vitro period. The leaves formed in vitro on a medium containing sucrose developed a positive photosynthetic capacity. At transplanting to the ex vitro environment, their photosynthetic rate was 12.76 μmol CO2/m2 per second, which was as high as that of leaves generated and grown in the greenhouse. During the ex vitro period, photosynthetic rates of in vitro-generated leaves decreased and dark respiration rates increased. However, in vitro leaves were photosynthetically active throughout the 4 weeks ex vitro. In the first 2 weeks of the ex vitro period, in vitro-generated leaves had an important contribution to the overall plantlets' photosynthetic capacity.

Ultrastructural Investigations of the Contractile Filaments of Amoebae

1974 ◽  
Vol 32 ◽  
pp. 188-189
Author(s):  
P.L. Moore
Keyword(s):  
Cytoplasmic Streaming ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Amoeboid Movement ◽  
Different Types ◽  
Chemical Conditions ◽  
Complete Interpretation

Previous freeze fracture results on the intact giant, amoeba Chaos carolinensis indicated the presence of a fibrillar arrangement of filaments within the cytoplasm. A complete interpretation of the three dimensional ultrastructure of these structures, and their possible role in amoeboid movement was not possible, since comparable results could not be obtained with conventional fixation of intact amoebae. Progress in interpreting the freeze fracture images of amoebae required a more thorough understanding of the different types of filaments present in amoebae, and of the ways in which they could be organized while remaining functional.The recent development of a calcium sensitive, demembranated, amoeboid model of Chaos carolinensis has made it possible to achieve a better understanding of such functional arrangements of amoeboid filaments. In these models the motility of demembranated cytoplasm can be controlled in vitro, and the chemical conditions necessary for contractility, and cytoplasmic streaming can be investigated. It is clear from these studies that “fibrils” exist in amoeboid models, and that they are capable of contracting along their length under conditions similar to those which cause contraction in vertebrate muscles.

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