Jaroslava Martinková

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.

Growth and photosynthesis of Upland and Pima cotton: response to drought and heat stress

The effects of drought and heat stress on physiology of two common cotton species, Gossypium hirsutum L. (Upland) and G. barbadense L. (Pima) were investigated in this study. Four consecutive 28-day pot experiments were carried out in a fully controlled growth chamber under four temperatures (25, 30, 35 and 40°C), while two water treatments (well-watered and drought) were imposed for 10 days to both cotton species. Growth according to dry matter accumulation of G. barbadense was more limited by sole drought conditions (50%), whereas heat stress was more remarkable on growth of G. hirsutum (64%). Chlorophyll (Chl) a and b content were more temperature-sensitive in G. hirsutum than G. barbadense under well-watered conditions. The most noticeable decrease in droughtinduced rates of photosynthesis rate (P n ), transpiration rate (E) and stomatal conductance (g s ) were recorded under 35°C, although genotypic variation was found under 25°C. Higher water use efficiency was associated with higher temperature. Relative decrease in Chl a content, g s and maximal quantum efficiency of PSII exhibited by both spe cies were distinctive physiological traits for heat and drought tolerance.

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.

Physiological responses as influenced by night freeze stress at the beginning of vegetative growth of sunflower

Physiological changes on leaves of young sunflower plants (genotypes C120, C124, C148 and PAC2) were evaluated in a growth chamber after exposure to night frost of -3 and -5°C for a period of 12 h. Net CO2 assimilation rate (PN), potential photochemical efficiency of electron transport PS2 (FV/FM), relative electrolyte leakage (REL%) and osmotic potential (ψπ) were monitored in the plants. Stressed plants were evaluated immediately (2 h) after the effect of the freezing temperature (var. S1), after 2-day recovery (var. S2) and after 6-day recovery (var. S3). The PN was determined as the most sensitive of the evaluated parameters of the sunflower. In genotypes C120, C148 and PAC2, a statistically evident decrease of PN in all variants S1-S3 was found during a temperature of -3°C. To the contrary, the results have proved minor sensitivity or, more precisely, a high stability of FV/FM, ψπ a REL% at the freezing temperature of -3°C. The results showed that physiological parameters were more sensitive to a freeze temperature at −5°C. It was also possible to determine the differences between genotypes. Statistically evident changes were found there in comparison to control plants: decrease of PN in genotypes C120 and C148 in all variants S1-S3, in genotype C124 in variant S1 and in genotype PAC2 in variant S3. There was also the decrease of FV/FM in genotypes C120, C124 and C148 in variant S1; increased REL% in genotype C120 in variants S1 and S3 and in genotypes C124 and C148 in variant S1; decreased ψπ in genotype C124 in variants S1-S3 and in genotypes C120 and C148 in variant S2. As apparent from the above, the PAC2 genotype may be considered relatively resistant to freeze stress, while genotypes C120, C124 and C148 rather sensitive to freeze stress.

Isoflavones Production and Possible Mechanism of Their Exudation in Genista tinctoria L. Suspension Culture after Treatment with Vanadium Compounds

The family Fabaceae traditionally serves as a food and herbal remedies source. Certain plants serve for treatment of menopausal symptoms based on a presence of typical secondary metabolites, isoflavones. Beside soybean and clovers, other plants or cultures in vitro can produce these molecules. A cultivation in vitro can be enhanced by elicitation that stimulates metabolites biosynthesis via stress reaction. Vanadium compounds have been already described as potential elicitors, and the aim of this study was to determine the impact of NH4VO3 and VOSO4 solutions on isoflavones production in Genista tinctoria L. cell cultures. The significant increase of isoflavones content, such as genistin, genistein, or formononetin, was measured in a nutrient medium or dry mass after NH4VO3 treatment for 24 or 48 h. The possible transport mechanism of isoflavones release as a result of elicitation was further evaluated. An incubation with different transport inhibitors prior to elicitation took effect on isoflavones content in the medium. However, there was a non-ended result for particular metabolites such as genistein and daidzein, where ATP-binding cassette (ABC) or, alternatively, multidrug and toxin extrusion (MATE) proteins can participate. Possible elicitation by some inhibitors was discussed as a result of their pleiotropic effect. Despite this outcome, the determination of the transport mechanism is an important step for identification of the specific transporter.