In many regions of the world, the production of vegetable crops is limited by a deepening water crisis. Drought stress affects productivity and the chemical composition of crops. The variability of drought tolerance between species and cultivars of economically important crops, such as pepper (Capsicum species), requires specific investigations to understand the physiological and biochemical responses to the aftermath of drought. The fruits and leaves of four chilli pepper cultivars were investigated to elucidate the fruits' pungency (Scoville Heat Units, SHU), ascorbic acid content, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, polyphenol content, membrane lipid peroxidation and key protective antioxidant enzyme activity under drought stress (18-28% volumetric water content) as compared to the control (35-60%). Drought increased the chilli pepper fruits' pungency expressed in Scoville Heat Units (SHU) as well as ascorbic acid content, but this relationship was also dependent on genotype and stress duration. 'Jolokia' was marked as most sensitive to drought by increasing content of capsaicinoids and DPPH • scavenging activity under stress conditions. Capsaicinoids and Ascorbic acid (AsA) greatly influenced the antioxidant activity of highly pungent chilli pepper fruits, although total phenols played a significant role in the mildly pungent genotypes. Generally, the activities of antioxidant enzymes increased under drought in chilli pepper leaves and fruits, although the intensity of the reaction varied among the cultivars used in the current research. All the investigated biochemical parameters were involved in the drought response of chilli pepper plants, but their significance and effectiveness were highly cultivar-dependent.Plants 2020, 9, 364 2 of 17 substrates, fertigated, and bell pepper canopy training is a common practice. The chilli pepper is cultivated without training. The container growing cost is higher, but it decreases the risk of adjacent plant contamination with root-borne diseases [2,3].Chilli pepper is added to dishes in small amounts, but the intake of chilli even as a spice enriches the diet with polyphenols and other bioactive compounds, especially ascorbic acid and other vitamins, carotenoids (α-and β-carotene), capsaicinoids and mineral salts [4]. The most characteristic phytochemicals of all members of the genus Capsicum are capsaicinoids, compounds providing the pungent taste but also of exhibiting antioxidant activity [5]. There is a growing interest in the enhancement of compounds in food having health-promoting attributes such as antioxidants, and which were previously regarded as non-nutritive, including phenolic compounds (simple phenols, flavonoids, anthocyanins, lignans and lignins, stilbenes and tannins). Phenols are antioxidants in nature, often associated with plant defence against biotic and abiotic stress factors. Additionally, phenols modify fruit colour, taste, aroma and flavour, and also provide health-beneficial effects for humans [6,7].Variability in ...

Reduced and soil-protective tillage technologies may represent certain negatives for cultivated crops associated with the biomass of mulch from intermediate crops and post-harvest residues. Sown crops, as well as field weeds, are exposed to impaired soil conditions. Soil conditions were assessed using biological tests. Eight plant species were chosen for the tests. Germination of tested plant species took place in controlled conditions in climaboxes. Seeds on Petri dishes were watered with soil leachates from three variants of tillage (Conventional, Minimum tillage, Direct sowing). Soil samples were collected from a 15-year field experiment. The soil leachates inhibited the germination rate of the chosen plant species. In the first term, all species exhibited a lower germination capacity in variants watered with the soil leachate. The reduced tillage technologies can apparently significantly slow down the germination rate in field crops and vegetables. Simple biological tests have the potential to assess the condition of arable soils.

The study focusses on alternative substrates with the potential to replace common substrates, such as mineral wool and perlite, as the influence of these on ecosystems and resources is being debated. To this aim, wood fibre, sheep wool and coco peat substrates were selected for testing. Leaf lettuce (Lactuca sativa L. ‘Lisboa’) is taken as the model crop for the evaluation of alternative substrates. The closed hydroponic system ebb and flow with growing in pots was used for the experiment. The parameters of the nutrient solution were EC 1.5–2 mS and pH 6–7. Biological parameters, content of nitrates, plant stress indicators, antioxidant activity (AA) as % scavenging of DPPH (AA), glutathione (GSH), ascorbate peroxidase (APX), total phenol content (TPC) and the content of chosen elements in the drain from substrates were evaluated. According to the biomass production of lettuce, the substrates can be ranked from the lowest as follows: sheep wool < wood fibre < mineral wool < perlite < coco peat. The levels of GSH and APX did not affect AA. The TPC showed the greatest effect on AA and the stress response in general. The nitrate content ranged between 426 and 686 mg · kg–1 of fresh mass. Instead of mineral wool and perlite, coco fibre could be a promising alternative organic substrate for lettuce production in the ebb and flow hydroponics system. Wood fibre and sheep wool still have unresolved circumstances regarding their physical and chemical parameters.

Symbiotic interaction between plants and microorganisms in the rhizosphere is an important factor affecting plant growth and fitness. Arbuscular mycorrhiza fungi symbiosis increases resistance of the plants to stress factors, including pathogens. Tomato brown rugose fruit virus (ToBRFV) is an important destructive virus damaging tomatoes and peppers with losses that can reach 100%. It is listed on the list of current quarantine organisms in the Czech Republic. The aim of this study was to evaluate influence of root colonization with Funneliformis mosseae or/and Azospirillum brasilense on ToBRFV symptoms and viral titre reduction. Plants treated with arbuscular mycorhizal fungi (AMF) had lower symptom emergence after 14 dpi, however there was no difference in symptoms emergence after 21 dpi within all treatments. The highest colonization intensity by Funneliformis mosseae was detected in ToBRFV negative plants treated with both AMF and Azospirillum (AZO) and the lowest in ToBRFV positive plants with the same treatment (AMF + AZO). Colonization intensity of Azospirillum brasilense in all treated variants went from 20% to 41%. Results suggest that the combination of those two beneficial microorganisms in ToBRFV-infected plants negatively affected AMF colonization.