High temperatures have significant impacts on fruit tree production. Foliar spraying application of promoting agents can be a sustainable approach to managing high-temperature stress in orchards. The mechanism of certain improving agents on photosynthesis is not yet well understood, particularly in fruit trees. Photosynthesis, as a vital and very sensitive process in plants, is a pivotal component in fruit production. Therefore, in this study, we explored the potential of two different promoting agents, salicylic acid (SA) and ascorbic acid (AsA), to alleviate oxidative stress caused by high temperature in controlled conditions (37°C for 1 h) at the photosynthetic level. For studying photosynthetic responses, we used chlorophyll fluorescence measurements. According to our findings, foliar application of promoting agents effectively increased the high-temperature tolerance of apple leaves, when compared to sole heat stress treatment. Both promoting agents significantly increased photosynthetic efficiency under stress, while the maximum was observed with AsA. In general, AsA and SA applications had a positive effect on the photosynthesis of apple leaves at high temperatures.

• Klíčová slova
• chlorophyll a fluorescence, chlorophyll content, electron transport chain, high temperature, photosystem II,
• Publikační typ
• časopisecké články MeSH

A manipulative experiment with two different water regimes was established to identify the variability of physiological responses to environmental changes in 5-year-old Norway spruce provenances in the Western Carpathians. While variations in the growth responses were detected only between treatments, photosynthetic and biochemical parameters were also differently influenced among provenances. Following drought treatment, an obvious shrinkage of tree stems was observed. In most provenances, drought had a negative effect on leaf gas-exchange parameters and kinetics of chlorophyll a fluorescence. Secondary metabolism was not affected so much with notable differences in concentration of sabinene, o-cimene, and (-)-alpha-terpineol monoterpenes. The most suitable indicators of drought stress were abscisic acid and fluorescence parameters. Seedlings from the highest altitude (1,500 m a.s.l.) responded better to stress conditions than the other populations. Such provenance trials may be a valuable tool in assessing the adaptive potential of spruce populations under changing climate.

• Klíčová slova
• Norway spruce, abscisic acid, drought, monoterpenes, photosynthesis, provenance,
• Publikační typ
• časopisecké články MeSH

Quinoa has been identified as a climate-resilient crop that can overcome unfavorable conditions. This study explores the photochemical efficiency of quinoa compared to maize subjected to drought stress. The JIP-test was used to assess the photochemical efficiency of both crops. Proline content, leaf water potential, and membrane leakage were also determined. The maximum photochemical efficiency (Fv/Fm) did not change for quinoa and maize under moderate stress. However, severe drought conditions resulted in a decline in Fv/Fm in maize but not quinoa. Furthermore, the PSII performance index (PIABS,total) declined steadily in maize soon after the onset of drought stress. The decline in the PIABS,total values for quinoa was only observed after a period of severe drought stress. Membrane leakage was also more prevalent in the maize plants, while quinoa had higher proline contents. This study concluded that both quinoa and maize maintained PSII structure and function under moderate drought conditions. However, only quinoa maintained PSII structure and function under severe drought conditions.

• Klíčová slova
• drought, leaf water potential, membrane leakage, performance index, photosynthesis, quantum yield,
• Publikační typ
• časopisecké články MeSH

Drought and heat stress are two major abiotic stresses that challenge the sustainability of agriculture to a larger extend. The changing and unpredictable climate further aggravates the efforts made by researchers as well as farmers. The stresses during the terminal stage of cool-season food legumes may affect numerous physiological and biochemical reactions that may result in poor yield. The plants possess a good number of adaptative and avoiding mechanisms to sustain the adverse situation. The various agronomic and breeding approaches may help in stress-induced alteration. The physiological and biochemical response of crops to any adverse situation is very important to understand to develop mechanisms and approaches for tolerance in plants. Agronomic approaches like altering the planting time, seed priming, foliar application of various macro and micro nutrients, and the application of rhizobacteria may help in mitigating the adverse effect of heat and drought stress to some extent. Breeding approaches like trait-based selection, inheritance studies of marker-based selection, genetic approaches using the transcriptome and metabolome may further pave the way to select and develop crops with better heat and drought stress adaptation and mitigation.

• Klíčová slova
• adaptation, drought stress, heat stress, legumes, mitigation strategies,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

We assessed the photosynthetic responses of eight wheat varieties in conditions of a simulated heat wave in a transparent plastic tunnel for one week. We found that high temperatures (up to 38 °C at midday and above 20 °C at night) had a negative effect on the photosynthetic functions of the plants and provided differentiation of genotypes through sensitivity to heat. Measurements of gas exchange showed that the simulated heat wave led to a 40% decrease in photosynthetic activity on average in comparison to the control, with an unequal recovery of individual genotypes after a release from stress. Our results indicate that the ability to recover after heat stress was associated with an efficient regulation of linear electron transport and the prevention of over-reduction in the acceptor side of photosystem I.

• Klíčová slova
• heat stress, high temperatures, photoinhibition, photoprotection, photosynthesis, photosystem I, wheat,
• Publikační typ
• časopisecké články MeSH