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In pot experiments on cucumber cv. Śremski F1, the effect of short-term chilling on plants earlier treated with triacontanol (TRIA) and Asahi SL was investigated. These plants were grown in a phytotron at an air temperature of 27/22ºC (day/night), using fluorescent light with far flux density of 220 μmol x m-2 x s-1, with a photoperiod 16/8. At the 4th true leaf stage, the respective experimental series were sprayed with: 1) H2O – control, 2) TRIA 0.01, 3) TRIA 0.1, 4) TRIA 1.0 mg x dm-3, 5) Asahi SL 0.2, 6) Asahi SL 0.3%. After 24 hours one half of the plants from each experimental series was treated for a period of 3 days at a temperature of 12/6ºC, with all the other growth conditions unchanged. The obtained results have shown that short-term chilling stress caused a significant increase in electrolyte leakage, free proline content and in the activity of guaiacol peroxidase in leaves, but a decrease in chlorophyll a+b content, stomatal conductance, transpiration, photosynthesis, leaf area and in the activity of catalase in leaves. The application of TRIA or ASAHI SL on leaves in the pre-stress period reduced the values of the traits which had been increased as a result of chilling and increased those which had reduced. Generally, TRIA was most effective at a concentration of 0.1 mg x dm-3, and Asahi SL at a concentration of 0.3%.
In pot experiments conducted on cucumber cv. Śremski F1, the effect was studied of short-term chilling stress on plants which had grown from seeds germinating in the solution of Asahi SL or treated with this biostimulator during the early growth period. The plants were grown in a phytotron at an air temperature of 27/22ºC (day/night), using fluorescent light with FAR flux density of 220 μmol x m-2 x s-1 and with a photoperiod of 16/8. The biostimulator was applied using the following methods: a) germination of seeds in 0.01% and 0.05% solution, b) watering of plants twice with 0.01% or 0.05% solution, c) spraying leaves with 0.3% or 0.5% solution. Plants sprayed with distilled water were the control. After 24 hours from foliar or root application of Asahi SL, one half of the plants from each experimental series was treated for a period of 3 days at a temperature of 12/6ºC, with all the other growth conditions unchanged. The obtained results show that short-term chilling stress caused a significant increase in electrolyte leakage, free proline content and in the activity of ascorbate peroxidase in leaves, but a decrease in the content of chlorophyll, its maximum fluorescence (Fm) and quantum yield (Fv/Fm), carotenoid content, stomatal conductance, transpiration, photosynthesis, leaf biomass and in the activity of catalase in leaves. Foliar or root application of Asahi SL in the pre-stress period decreased the values of the traits which increased as a result of chilling or increased those which decreased. Higher concentrations of the biostimulator solutions, applied using this method, were more effective. The application of the biostimulator during seed germination did not result in significant changes in the response of plants to chilling stress.
In experiments carried out in a phytotron using aqueous cultures, there was investigated the effect of root or foliar application of different types of iron salts on spinach plant productivity, leaf and root iron content as well as the rate of transport of iron from the roots to the leaves. Plants were grown in Hoagland’s solution with a single concentration at two fluorescent light intensities: 290 and 95 μmol × m-2 × s-1 PAR. To fertilize the plants, iron was supplied at a dose of 25 mg Fe in the nutrient solution or as foliar sprays using the following salts: 1 – Fe 0; 2 – FeCl2 × 4H2O; 3 – FeCl3 × 4H2O; 4 – FeSO4 × 7H2O; 5 – Fe2(SO4)3 × nH2O; 6 – Fe-Cit. The obtained results showed that the productivity of spinach plants treated with FeCl2 and FeSO4 using foliar sprays and of those fed with Fe-citrate (Fe-Cit) through the roots was significantly higher than in the case of the other salts used. Root application of the salts used had a significant effect on root iron content, whereas their foliar application significantly affected leaf iron content. In this respect, ferrous salts were generally the most beneficial, while ferric salts were the least beneficial. The rate of transport of iron to the leaves, irrespective of the method of its application, was clearly higher for ferrous salts and Fe-Cit than for ferric salts. The free proline content in the leaves of plants not fertilized with Fe was 2–4 times lower than in plants supplied with this nutrient. An irradiance of 290 μmol × m-2 × s-1 had a positive effect on plant productivity and root Fe content.
In pot experiments carried out in 2005 and 2006, tolerance to sodium chloride salinity of 4 cultivars of perennial ryegrass (Lolium perenne) (‘Nira’, ‘Stadion’, ‘Ronija’, ‘Darius’) was studied. Three concentrations of NaCl in medium (earth + sand): 0.0 mM (control); 50 mM; 100 mM, were used in the investigations. In three successive crops of grass, fresh weight yield of leaves, stomatal conductance, photosynthesis intensity, content of chlorophyll and PS II maximum quantum yield (Fv/Fm) were determined. The obtained results showed that perennial ryegrass is a species tolerant to NaCl salinity. Among the studied cultivars, cv. ‘Ronija’ showed the highest tolerance, whereas cv. ‘Nira’ showed the lowest. The growth of perennial ryegrass plants under salinity conditions was limited by low stomatal conductance of leaves and photosynthesis, but not by the photosynthetic activity of chlorophyll and its contents.
W dwu oddzielnych doświadczeniach (wazonowym i polowym) badano wpływ dodatku do gleby Ekosorbu potasowego w dawce 0; 1 i 3 g·dm⁻³ na stosunki wodne w roślinach, wymianą gazową, kwitnienie oraz produkcją biomasy w warunkach zasolenia NaCl. W obu doświadczeniach zastosowano 3 koncentracje soli: 0, 1500 i 3000 mg·dm⁻³ . Wyniki uzyskane w doświadczeniu wazonowym wykazały, że dodatek hydrożelu w dawce 1 i 3 g·dm⁻³ zwiększał potencjał wody w roślinach, liczbą wytworzonych kwiatów i świeżą masę, a zmniejszał deficyt wody. Dodatek Ekosorbu w dawce 1 g·dm⁻³ zwiększał fotosyntezę roślin i wartość WUE, zaś nie wpływał na transpirację. Wyższa dawka hydrożelu (3 g·dm⁻³) obniżała tempo fotosyntezy i transpiracji roślin. Zasolenie gleby w doświadczeniu wazonowym zwiększało wartość deficytu wody w roślinach, natomiast obniżało wartość pozostałych analizowanych cech roślin. Wpływ NaCl na rośliny kontrolne (bez Ekosorbu) był znacznie większy niż na rośliny rosnące w glebie z hydrożelem. Zastosowanie Ekosorbu i zasolenie gleby w doświadczeniu polowym nie wykazały istotnego wpływu na stosunki wodne, wymianę gazową (dane niepublikowane), a także kwitnienie i produkcję biomasy u roślin rudbekii (Rudbeckia hirta L.).
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