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1071. Effects of pH and chemicals affecting polypeptide conformation on inhibition of reducing and oxidizing sides of photosystem 2 by DCMU in pea chloroplasts

Creator:
Vasilev, I.R. and Venediktov, P.S.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Inhibition of photosystem 2 (PS2) reducing side in pea chloroplasts by 10-* M DCMU [3-(3,4-dichlorophenyl)-l,l-dimethylurea], resulting from its binding at the secondary quinone acceptor site is manifested by suppression of millisecond time range delayed fluorescence (DF). In concentrations hi^er than 10-^ M DCMU binds to another site in PS2 and inhibits the oxidizing side, thus leading to suppression of DF with ti/2 = 2 s. Based upon DF measurements, DCMU-affinity of the second site was increased upon chaotropic action of oleic acid, while addition of polyethylene glycol that stabilizes polypeptides lead to preferential decrease in aífinity of the main binding site. The afFmities of the two sites differred also in their dependence upon pH of the mediiun. Thus both binding sites can háve high or low aíiitities to DCMU depending on the statě of their microenvironment. A lower affmity to DCMU of the site responsible for inhibition of the oxidizing side is probably related to its more rigid conformation.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1072. Effects of pre-treatment temperature and cap closure on photosynthesis potentialities of potato cultivated in vitro

Creator:
Genoud-Gourichon, G., Veisseire, P., and Coudret, A.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Potato tubers, Solanum tuberosum L. cv. Bintje were stored at 4 or 20 °C. A segment of parenchyma with a bud was cultívated in vitro, in order to study the growth of plantlets according to the storage temperature and the atmosphere composition in vessels. The conservation temperature had no effect on the shoot length, the leaf area and the leaf number. On the other hand, the atmosphere composition in vessels modifíed the morphology. The plantlets cultívated in non-sealed vessels were more developed than the plantlets cultívated in hermetically dosed tubes. The photosynthetic potentíals were 4.7 times higher for the plantlets coming from the tubers stored at 20 °C than for the plantlets coming from the tubers stored at 4 °C. These potentíals were 1.7 times higher when the plantlets were cultívated in non- hermetícally dosed tubes than in hermetically dosed ones. So a conservation of tubers at 20 °C and a culture in non-enclosed vessels seemed to be the suitable conditions for the micropropagation of potatoes in viiro. Moreover, this culture type could improve the acdimatízatíon.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1073. Effects of shading and CO2 enrichment on photosynthesis and yield of winter grown tomatoes in subtropical regions

Creator:
Carmi, A.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
The effects of exposing winter-grown tomato {Lycopersicon esculentum L.) to various sunlight irradiances and CO2 concentrations, on dark respiration (Ro), night respiration (/?},}), net photosynthetic' rate (P^), dry matter production (DMP), yield earliness and yield amount were studied. Plants were grown in greenhouses under controlled temperatures and exposed to: fiill (FS) oř half (HS) sunlight irradiance in combination with atmospheric (A) oř enriched (E) concentrations of 300-330 or 1400-1500 g(C02) m'^, respectively. The of intact leaves at noontime reached 10.7, 15.2, 5.9 and 9.6 pmol(C02) m-2 s-i in treatments of FSA, FSE, HSA and HSE, respectively. The irradiances on the upper leaf surface during the measurements ranged between 160-190 and 450-550 pmol s'^ in the HS and FS treatments, respectively. of leaves which were kept in darkness following the measurement amved at efflux of 2.6, 2.5, 1.4 and 1.4 pmol(C02) m‘2 s'* while their Pn G^etween 20:00 and 24:00) reached values of 0.9, 1.3, 0.8 and 0.8 pmol(C02) treatments of FSA, FSE, HSA and HSE, respectively. Elevating the CO2 concentration from 300 to 1500 g m'^ increased P^ by 16, 28, 30 and 46 % under an irradiance of 160 pmol m‘2 s'*, and 19, 34, 59 and 44 % under irradiance of 320 pmol m-2 s'* in the FSA, FSE, HSA and HSE treatments, respectively. Increasing the measurement irradiance from 160 to 320 pmol m'2 s'* enhanced P^ by 69, 78, 23 and 49 % in an atmosphere of 300 g m-^ CO2, and by 73, 84, 49 and 47 % in an atmosphere of 1500 g m-^ CO2, in the FSA, FSE, HSA and HSE treatments, respectively. DMP was strongly influenced by the different environmental conditions and the total dry matter accumulation in the shoot per plant during 145 d reached 580, 347, 398 and 235 g in the FSA, FSE, HSA and HSE treatments, respectively. CO2 emichment promoted early yield under both full and partial sunlight irradiance. The HSE treatment led to earlier yield harvesting than the FSA and HSA treatments. The yield of the seven first trusses reached 6.8, 4.6, 5.7 and 3.2 kg per plant in the FSA, FSE, HSA and HSE treatments, respectively. Some increase in fruit fresh matter and diameter of fruits was detected in the C02-enrichéd treatments as compared to the non-enriched ones. Thus the combination of moderate shading and CO2 enrichment might provide a more productive option for winter- grown tomatoes in regions of subtropical climate, even in the winter, than the conventional management of aerated greenhouses without CO2 enrichment which are exposed to fiill sunlight.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1074. Effects of simulated orbital light/dark cycles on the photosynthesis of mungbean, soybean and millet

Creator:
Sacher, R. and Burian, K.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Crop plants in Closed Ecological Life Support Systems (CELSS), for future extended manned space missions, might use for photosynthesis natural sunlight rather than an artificial irradiation. In a low earth orbit (LEO: 300-600 km) space station CELSS, these plants would have to deal with very short light/dark cycles. As a result of the 90 min revolution period of the station around the earth, they would be subjected to approximately 60 min sunlight followed by 30 min darkness in the earth's shade. These orbital light/dark cycles were simulated in growth chambers, which was accompanied by control experiments under long-day conditions (16/8 h light/dark). In Phaseolus mungo L., Glycine max L. and Sorghum bicolor L. the net C02-uptake (PN) and stomatal conductance (gs), as well as 02-production and quantum yield (QY) were measured. P. mungo grown under orbital cycles was strongly affected by slow induction of photosynthesis and stomatal limitation, resulting in the photodestruction of pigment systems and leaf chlorosis. Stomata of G. max opened faster upon onset of irradiation, which resulted in a sufficient C02-supply to prevent photoinhibition. Stomata of S. bicolor opened very rapidly, and Pn resumed steady-state similar to that before the dark break, within the first minutes of the irradiation, thus utilizing the major part of the 60 min "day" for net carbon gain. These findings were supported by QY measurements of oxygen evolution. Strongly decreased QY in P. mungo compared to long-day grown plants indicated destruction in light-harvesting pigments and electron transport chains. No reduction in QY was observed in G. max and S. bicolor.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1075. Effects of Sr2+, Ca2+, and spermine on thylakoid protein and chlorophyll degradation during dark incubation of sugar beet leaf discs

Creator:
Kim, Wae Tan and Heinrich, G.
Format:
print
Type:
model:internalpart and TEXT
Subject:
Beta vulgaris L., polyamines, polyacrylamid gel electrophoresis, and cations
Language:
Multiple languages
Description:
The chlorophyll (Chl) and protein degradation during dark incubation of leaf discs was reduced by Sr2+, Ca^^, and spermine (Spm) treatments. Sr2+ inhibited most effectively the Chl degradation, which was remarkable 48 h after the treatment. The Chl degradation appeared in control discs within 24 h in the dark and Chl content decreased by about 50 % during 96 h. The proteins retained at least during 48 h of dark treatment in the presence of Sr2+, Ca2+, or Spm. The retardation effect of Sr2+, Ca2+ and Spm on the Chl loss and the disintegration of thylakoid membrane proteins may be due to a cationic protection of thylakoid membranes.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1076. Effects of temperature on energy-dependent fluorescence quenching in chloroplasts

Creator:
Krause, G. H.
Format:
print
Type:
model:internalpart and TEXT
Language:
Multiple languages
Description:
Energy-dependent quenching of chlorophyll fluorescence and its reversion in intact isolated spinách chloroplasts were recorded at temperatures between 0 and 20 ®C. A temperature-dependence of Ihe quenching formation (and of quenching relaxation) corresponding to Qio values between 2 and 3 was found. Long-term cold acclimation of the plants resulted in a decrease of die fluorescence dechne half-time. The finál steady-state extent of quenching (q^) was not influenced by temperature shifts or cold acclimation.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1077. Effects of the applícation of cement kiln exhausts on leaf biochemistry in certain legume crops

Creator:
Saralabai, V.C. and Vivekanandan, M.
Format:
print
Type:
model:internalpart and TEXT
Subject:
ascorbic acid, enzymes, growth characters, N-compounds, photosynthetic rate, photosystem 2, saccharides, stomatal resistance, superoxide dismutase, and transpiration rate
Language:
Multiple languages
Description:
Application of the electrostatic precipitator (ESP) dust to soil and leaves of Cajanus cajan, Vigna mungo, Vigna radiata, Vigna catjung and Glycina max increased biomass, chloroplast pigments, Chemical constituents and enzyme activities of leaves, besides crop productivity evidently indicating that the dust acted as a fertilizer. The net photosynthetic rate, photosystem 2 activity and rate of transpiration were not altered in špite of the dust forming a thin uniform coating ověř the leaf surface. The contents of intermediary N-compounds like allantoin, allantoic acid and total ureides of the leaves, which might serve as an indirect evidence of symbiotic N2-fixation, were higher in the treated plants. There were increments in free proline, soluble proteins, total nitrogen, nitrates, nitrites, soluble sugars and phenols in the treated plants. The concentrations of ffee amino acids, soluble starch, total sucrose and water soluble SH compounds of the leaves of the control and treated plants did not show any significant difference. The activity of superoxide dismutase was significantly higher which possibly indicated its role in alleviation of H2O2 and Oj toxicity. Enzymes like nitráte reductase, nitrite reductase, glutamine S3mthetase, acid and alkaline phosphatases, carbonic anhydrase, catalase, glutathione reductase and ascorbate peroxidase also functioned normally. In the treated plants, the concentration of ascorbic acid was significantly higher in the roots and nodules indicating the possible role of ascorbic acid in stress alleviation.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1078. Efficacy of a monensin-duokvin combination against Eimeria acervulina in chickens

Creator:
Varga, István and Sréter, Tamás
Format:
print
Type:
model:internalpart and TEXT
Subject:
potentiation of ionophores, anticoccidials, monensin, Eimeria acervulina, antioxidant, dihydroquinoline, duokvin, chicken, and coccidiosis
Language:
English
Description:
Anticoccidial efficacy of a drug combination containing monensin at 8 p.p.m. plus the new antioxidant duokvin at 120 p.p.m. in the feed was compared with that of monensin alone at the recommended level of 100 p.p.m. against a field isolate of the coccidium Eimeria acervulina Tyzzer, 1929 in a battery study. Both monensin and monensin duokvin combination were effective against E. acervulina when judged by weight gain, feed conversion and faecal scores. There was no significant difference in the chemoprophylactic activity of either treatments. Neither monensin at 100 p.p.m. nor the combination proved effective in terms of oocyst production. In accordance with the earlier findings with E. lenella, the combination seems appropriate for field trials.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public