The effect of freezing temperature on physiological traits in sunflower

This study was conducted to identify the physiological mechanisms associated with the resistance and tolerance of young sunflower plants to freezing temperatures. The effect of overnight temperature –3°C on the maximal quantum efficiency of PSII (Fv/Fm), the relative electrolyte leakage (REL) and the osmotic potential (Ψπ) was determined in five genotypes of sunflower: C33, C98, C124 and C148 were chosen from the population of recombinant inbred lines (RILs) based on contrasted responses to low temperature, and a wild genotype 2603 that was chosen for its ability to maintain activities in cold conditions. The night temperature –3°C over the course of 10 h caused an immediate significant decrease of Fv/Fm in C33, C98, C124 and C148. In the case of genotype C98, the effect of this freezing temperature was manifested by a significant increase of REL. Significant changes of Ψπ, as a reaction to the effect of freezing temperatures, were not found in any of the monitored genotypes. The measurements of the physiological traits after 5 days of regeneration indicated the renewal of integrity of cellular structures and an increase of PSII reaction centre efficiency in all monitored genotypes. From the point of view of tolerance or sensitivity, the wild genotype 2603 showed itself as tolerant towards the tested freezing temperature, displaying insignificant differences with control plants in all monitored traits. Genotype C98 appears to be the most sensitive from the monitored set, with evident changes in two traits signalling frost damage

The Physiology and Proteomics of Drought Tolerance in Maize: Early Stomatal Closure as a Cause of Lower Tolerance to Short-Term Dehydration?

Understanding the response of a crop to drought is the first step in the breeding of tolerant genotypes. In our study, two maize (Zea mays L.) genotypes with contrasting sensitivity to dehydration were subjected to moderate drought conditions. The subsequent analysis of their physiological parameters revealed a decreased stomatal conductance accompanied by a slighter decrease in the relative water content in the sensitive genotype. In contrast, the tolerant genotype maintained open stomata and active photosynthesis, even under dehydration conditions. Drought-induced changes in the leaf proteome were analyzed by two independent approaches, 2D gel electrophoresis and iTRAQ analysis, which provided compatible but only partially overlapping results. Drought caused the up-regulation of protective and stress-related proteins (mainly chaperones and dehydrins) in both genotypes. The differences in the levels of various detoxification proteins corresponded well with the observed changes in the activities of antioxidant enzymes. The number and levels of up-regulated protective proteins were generally lower in the sensitive genotype, implying a reduced level of proteosynthesis, which was also indicated by specific changes in the components of the translation machinery. Based on these results, we propose that the hypersensitive early stomatal closure in the sensitive genotype leads to the inhibition of photosynthesis and, subsequently, to a less efficient synthesis of the protective/detoxification proteins that are associated with drought tolerance

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Genetic and Environmental Factors Affecting Seed Germination

Plants have evolved various strategies allowing them to be successful in heterogeneous habitats, including the number and size of the seeds they produce, mechanisms for their dispersal, seed dormancy, seed vigor, seed germination, etc [...

Effect of long-term drought and waterlogging stress on photosynthetic pigments in potato

In potato tubers of four cultivars, the impact of drought and waterlogging stress on total carotenoid content (TCC) and individual carotenoids profile variance and total carotenoids, chlorophylls (a, b, a + b) content in leaves during period 71 days of stress in two-year pot greenhouse experiments were investigated. The different response between potato cultivars was observed after exposure to drought stress (an increase of TCC was in Marabel and Laura cultivars) and after waterlogging stress (in Milva and Marabel cultivars). On average, of all cultivars, both drought and waterlogging stresses caused total carotenoid content to increase with a higher impact of drought stress. In potato tubers, eight carotenoids were identified with the most represented violaxanthin, luteoxanthin, antheroxanthin and lutein. Significant differences in individual carotenoid amounts between cultivars have been determined. On average, drought and waterlogging stresses of all cultivars significantly increased contents of violaxanthin, 9'-(Z)-neoxanthin and luteoxanthin, while antheraxanthin, lutein and zeaxanthin levels decreased. In leaves, both abiotic stresses decreased chlorophyll contents (a, b, a + b) with a very destructive impact of drought stress. While carotenoids accumulated in tubers as a result of stress, the opposite trend was characteristic in leaves, where their content decreased depending on the duration of stress

Determining the saturation irradiance and photosynthetic capacity for new perspective varieties of hop ( Humulus lupulus L.)

For the hop varieties: Agnus, Harmonie, Premiant and Osvaldův klon 72, the values for the saturation radiance and photosynthetic capacity were determined. Photosynthetic capacity was determined gasometrically. For the varieties Premiant and Osvaldův klon 72 the saturation irradiance was 447 μmol.m −2 .s −1 and for the varieties Agnus and Harmonie 499 μmol.m −2 .s −1 . The lowest photosynthetic capacity was demonstrated by Osvaldův klon 72 (6.8 μmol CO 2 .m −2 .s −1 ) and the highest by Premiant (14.64 μmol CO 2 .m −2 .s −1 ). The results obtained supplemented the present knowledge from the area of hop physiology and will expand knowledge about the biological properties of the varieties in question

The effect of the aridisation of a habitat on the accumulation capability of sink in selected varieties of spring barley

One of the ways of reducing energy-intensive inputs to agricultural systems is to replace the less performing cultivars with more productive ones and to cultivate varieties with sufficient accumulation capabilities of sink even under worse environmental conditions, for example, in the event of aridisation of the environment. The cultivation process is managed in such a way so that the largest share of the total production of all the plant biomass is represented by the organs providing the actual economic yield. From the results there is a clear difference between the Czech variety Malz and the Dutch Jersey in the formation of spike under the effect of water stress. For the Malz variety the number of grains in the spike dropped by 17.5% compensated for by their increased weight. For the Jersey variety there was a 16.7% fall in the number of grains in the spike, but no compensation in the increased weight of the grains was observed

Effects of deficit irrigation and straw mulching on gas exchange of cucumber plants (Cucumis sativus L.)

Leaves gas exchange were studied in one cucumber (Cucumis sativus L.) cultivar Harriet F1 grown under control conditions (C), deficit irrigation (S) and straw mulch (M), as well as under control or deficit irrigation conditions and straw mulch in combination (CM or SM). Cucumber plants were grown in loose soil, foil tunnel. The photosynthesis rate (PN) and transpiration rate (E) were measured in the leaves in situ using the portable gas exchange system LCpro+. It follows from the results obtained that water deficit (PN was 11.88 μmol CO2.m−2.s−1 and E was 1.83 mmol H2O.m−2.s−1) provably decreases the gas exchange rate in cucumber plants in comparison with the irrigated control group (average value of PN - 15.03 μmol CO2.m−2.s−1 and E – 2.16 mmol H2O.m−2.s−1). The application of mulch in the control and stresses plants statistically insignificantly reduced the photosynthesis rates −14.91 μmol CO2.m−2.s−1 and 11.86 μmol CO2.m−2.s−1, respectively. However, after the application of the mulch to the plants growing in the variant of deficit irrigation and control conditions with mulch, the transpiration rate increased. The rate of transpiration (E) by plants from control and deficit irrigation with mulch was 2.28 mmol H2O.m−2.s−1 and 2.24 mmol H2O.m−2.s−1, respectively. Photosynthesis and transpiration rate is also influenced by stomatal conductance (gs). The obtained values ​of the coefficient of determination (r2) is evident no stomatal inhibition of gas exchange for variants C (r2 = 0.1404 – PN; 0.2352 – E) and CM (r2 = 0.2656 – PN; 0.2483 – E). No stomatal inhibition of photosynthesis was observed in SM variant (r2 = 0.2867), too. However, stomatal inhibition of photosynthesis and transpiration rate was based on the coefficient of determination found in plants with limited irrigation (PN – r2 = 0.5222 and E – r2 = 0.7191) and in SM variant (r2 = 0.8972)

The influence of drought and the application of 24-epibrassinolide on the formation of dry matter and yield in wheat

Winter wheat varieties: Ebi, Estica, Samanta were grown in three experimental variants (control, drought stress and high temperature, stress and the application of 24-epibrassinolide). The plants were monitored for the weight of the dry matter and the straw and grain yields. The stressors were found to have a negative effect on the amount of dry matter in the above-ground wheat biomass and the yield of grain and straw. Drought and high temperature lowered the amount of dry matter in the grain and straw in all varieties. For all monitored varieties the application of 24-epibrassinolide reduced the negative effect of the monitored stressors. The best reaction to the application of 24-epibrassinolide was seen in the variety Estica, the worst in the variety Samanta. Of the varieties monitored the variety Samanta exhibited the tolerance to drought and high temperatures. On the contrary Ebi is a sensitive variety