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The aim of this study was to investigate the effects of maleic acid (MA), salicylic acid (SA), and citric acid (CA) on alleviating the drought stress of a lettuce (Lactuca sativa L.) hydroponic culture. The effect of these organic acids was tested under stress conditions induced by polyethene glycol (PEG 6000) at 5% and 7.5% concentrations. Drought stress reduced the fresh and dry matter yields of plants. The acid treatment caused increasing tendencies in the fresh weight yield:control (SA, MA), PEG 7.5% (SA, MA, CA)) and dry weight yield (control (SA, MA), PEG 5% (MA), PEG 7.5% (SA, MA)). The acid treatment also enhanced the nutrient uptake of stressed plants: SA: N (PEG 7.5%), K (PEG 5 and 7.5%); MA: N, P, K, Ca (PEG 5 and 7.5%). This work found that chlorophyll a and b amounts did not change under applied experimental conditions. Most parameters of chlorophyll fluorescence did not depend on either the level of applied water stress (PEG level) or the type of spraying. Drought stress increased leaf superoxide anion (O2•−) and malondialdehyde (MDA) levels but decreased H2O2. Proline (Pro) and phenolic compounds (TFC), including flavonols (Fla), accumulated more in stressed plants. Drought stress also affected the chlorophyll fluorescence. Our results suggest that acids can improve plant tolerance to drought stress by boosting the antioxidant defence system and reducing the oxidative damage caused by reactive oxygen species. [ABSTRACT FROM AUTHOR]

Selenium (Se) and silicon (Si) are the beneficial elements that may significantly modify plants’ tolerance to various types of biotic and abiotic stress. They may be particularly important due to the current climate changes. The aim of model experiments was to assess how selenium and silicon could alleviate short-term drought stress in French marigold (Tagetes patula L. “Pascal”). Tagetes plant species are economically important annual plants and are also very popular decorative flowering species in city parks due to its beautiful colored flowers and resistance on drought stress. Silicon was applied in the form of silica sol and choline-stabilized orthosilicic acid (ch-OSA). Selenium was applied in the form of sodium selenate (Na2SeO4). They were tested at the following concentrations (mg dm−3 of NS): silica sol – level I (23.25), level II (31.0); ch-OSA – level I (0.21), level II (0.63); and Se – level I (0.4), level II (0.8). The experiment showed that silicon had stimulating effect on the biometric parameters of control plants cultivated under an optimal water regime. When the plants treated with selenium were exposed to stress, the values of their biometric parameters were generally higher than in the plants treated with silicon. Both silicon and selenium significantly modified the gas exchange parameters. During the growing season, the net photosynthesis activity (PN), stomatal conductance (gs), and transpiration rate (E) tended to decrease, but they increased significantly when selenium and silicon were applied. In general, the factors significantly modified the plants’ content of macro- and micronutrients as well as the proportions between them. Both selenium and silicon alleviated the short-term drought stress in French marigolds as a model plant, but when silicon was applied, the positive effect was modified by the source and its concentration.

The biofortification of plants seems to be a beneficial dietary strategy for alleviating iron deficiency around the world. The main aim of this study was to determine the content and bioaccessibility of minerals in biofortified lettuce in relation to plant morphological parameters. The experiment was conducted in a climate chamber under controlled conditions. Plants were grown in hydroponics with the application of nutrient solutions with varied iron levels (mg dm-3): 1.5, 3.0, and 4.5. The contents of Fe, Zn, Cu, Mn, Ni, Mg, Ca, Na, and K in the lettuce were assayed after the dry ashing of the samples. The enzymatic digestion in vitro was performed using fresh lettuce plants, and then the contents of released elements were assayed. The concentrations of elements in lettuce before and after digestion were determined by atomic absorption spectrometry. In the lettuce, the contents of total, soluble, and insoluble fiber were also measured. It was found that the highest Fe level significantly increased the yield of dry matter. The studied trends of chlorophyll fluorescence change indicated a positive effect of Fe biofortification on plants but, at the same time, an increase in the carotenoid content was observed along with an increase in Fe, which may indicate the plants’ initial defense response to increasing oxidative stress. Increasing Fe biofortification also caused an increase in the chlorophyll content in leaves. The higher content of Fe and of most other elements in the plant was determined in biofortified lettuces. Generally, biofortification of iron decreased Fe bioaccessibility and increased the bioaccessibility of other elements. In conclusion, the content of iron increases, but its bioaccessibility decreases in biofortified lettuce, and plant responses can be affected by biochemical reactions connected among others to carotenoids and the chlorophyll content. [ABSTRACT FROM AUTHOR]

In the years 1997-2008, 131 water samples were analysed. The concentration of N-NH4, N-NO3, P, K, Ca, Mg, Na, Cl, S-SO4, Fe, Mn, Zn, Cu, B, and HCO3 - was measured. In addition, the pH value and the electrolytic conductivity (EC) were determined and the sodium adsorption ratio (SAR) was calculated. The assessment of water was done on the basis of the classifications of water for the irrigation of greenhouse crops grown in soil or traditional media. According to guide values, water samples had to have high concentration of ions, especially HCO3, Mg, Na and K. The questioned quality in about one half of the water indicates that the limits proposed by different researchers are too restrictive. The criteria to be met by water admissible for irrigation and fertigation should take into consideration the regional differences in water characteristics. The adaptation of recommendations elaborated on the basis of analyses originating from other geographical and geological regions can lead to the elimination of waters possessing favourable quality parameters. For irrigation of field and greenhouse crops, the following concentrations of components in water might be recommended as safe ones: 30 mg N-NO3, 100 mg K, 150 mg Ca, 50 mg Mg, 100 mg Na, 100 mg Cl and 100 mg S-SO4 in 1 dm3. For soilless culture fertigation in an open system, the maximum ion concentrations in water cannot exceed the recommended ones in the nutrient solution for the given plant. Also, the EC value should be taken into consideration.

The experiment was carried out in the years 2002-2004. Its aim was the determination of the tendencies in the microelement nutritional status of the standard cultivars of Anthurium cultorum Birdsey (‘Baron’, ‘Choco’, ‘Midori’, ‘Pistache’, ‘President’, ‘Tropical’ from Anthura B.V.) in the autumn-winter and spring-summer vegetation periods. The plants were cultivated in expanded clay using a drop fertigation system with standard nutrition. A significant influence of the vegetation periods and the light conditions associated with them was found to be exerted on the microelement plant nutrition. In the autumn-winter period, characterized by light deficit, the plant age significantly modified the nutrition (increase or decrease of content with a plant’s aging) with regard to zinc (-23.7%), copper (-25.8%) and boron (+25%), while in the spring-summer period, iron (+12.9%) and copper (-21.7%) nutrition was modified. During the three years of the study, the autumnwinter period showed a significant increase of iron content (+9.8%) with a simultaneous decrease of copper content (-6.5%), in comparison with the springsummer period. The awareness of the cyclical nature of the changes in the nutritional status of plants, depending on the given vegetation season, supplies a valuable instrument in the interpretation of plant analyses for diagnostic purposes.

Chinese flowering cabbage (Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee) is an important leafy vegetable species, which originates from Guangdong province in southern China. There is a variety called purple Chinese flowering cabbage (Brassica campestris L. ssp. chinensis L. Makino var. purpurea Bailay), which is popular in the Yangtze River basin, e.g. in Wuhan and Sichuan provinces. This manuscript is a review of recent studies on the nutritional value, breeding methods and factors affecting the yield of Chinese flowering cabbage. This vegetable is rich in glucosinolates, polyphenols, amino acids, fatty acids, soluble sugar and vitamin C. It also exhibits some antioxidative activity, e.g. the TEAC value was 16.93 μmol Trolox g-1 and the FRAP value was 12.01 µmol Fe(II) g-1 in total. Controlling the Cd level in Chinese flowering cabbage is important due to the fact that it can easily accumulate Cd in its edible leaves and flowering stems. To reduce the effect given by Cd, foliar spray with trace elements had been studied. Moreover, nitrogen fertilizer, biofertilizer and several cultivation methods have been implemented to improve the yielding and nutritional value of Chinese flowering cabbage. Depending on the conditions, fertilisation increased the yield from 19.1% to 168%, whereas the fresh weight of a single plant varied from 0.835 kg to 1.683 kg and the average yielding in the field ranged from 7.857 t ha-1 to 19.1 t ha-1. In the last part of this paper, we reviewed the different breeding methods that have been used to develop new varieties of Chinese flowering cabbage meeting specific requirements, such as selecting a hybrid with kale to enrich the genotype, increase the resistance or discover a specific bolting gene. In brief, Chinese flowering cabbage has the potential for future research and commercial market. [ABSTRACT FROM AUTHOR]

There is a need to introduce to horticultural practice new methods of plant cultivation which will allow us to obtain optimal yields while reducing water and fertilizer consumption and avoiding environmental pollution. Four methods of growing greenhouse tomato cv. Tomimaru Muchoo F1 in a system with nutrient solution recirculation were compared, i.e. cultivation in new and re-used 1- or 2-year-old rockwool and polyurethane foam slabs, NFT and aeroponic culture. The highest marketable and total fruit yields were in the aeroponic culture. They were by 29.8 - 30.8% higher than in new rockwool slabs. Positive effects on tomato yield were obtained in the NFT (28.2% higher than in new rockwool slabs) and re-used 1-year-old (26.7 - 29.4% higher) or 2-year-old polyurethane foam slabs (23.5 - 25.4% higher). Tomato growing in re-used 1-year old rockwool slabs was demonstrated as a feasible solution. The marketable and total yields were by 10.0 - 7.5% higher (respectively) than from tomatoes grown in new rockwool. The marketable and total greenhouse tomato yields obtained in re-used 1- or 2-year-old polyurethane foam slabs were significant higher than in new polyurethane slabs. The increase was 14.7 - 15.9% for marketable and 14.2 - 19.7% for total yield. Greenhouse tomato yield in re-used 1- or 2-year-old polyurethane foam slabs was significantly higher than in new and re-used rockwool slabs. In re-used 1- or 2-year-old polyurethane foam slabs, the N-NO3, Ca, and Na content was significantly higher, which meant a higher EC of the nutrient solution. There was a significant decrease in the P content in re-used 1- or 2-year-old polyurethane slabs. A significant increase in the Ca content in re-used rockwool slabs was determined alongside a tendency towards higher Na, S-SO4 and EC in this substrate. The content of P, Zn and Cu in leaves of tomato plants grown in aeroponic culture was significantly lower, but Mg was higher than in leaves of tomatoes grown in rockwool, polyurethane and the NFT. A significantly lower content of K and Fe was determined in leaves of tomatoes grown in aeroponics than in rockwool and polyurethane substrates. [ABSTRACT FROM AUTHOR]

Changing climatic conditions in recent years, including droughts during the plant growing season, have become a serious problem in fruit production. In 2017 and 2018, the weather conditions varied considerably. The aim of study was to determine the effect of climatic conditions in consecutive plant growing seasons on the response of selected apple varieties as manifested by their growth and yielding. Significant uniformity in the tree growth was observed, expressed using trunk cross sectional area (TCSA) and leaf area. The best uniformity of yields was observed for the variety Beni Shogun (Fuji), while the varieties Gala Schniga and Ligol showed greater variation in fruiting. The tree growth and yielding were significantly dependent on the mineral content in leaves. At the same time, an apple variety was found to have a significant effect on the content of N, K, Ca, Mg, Mn and Cu in leaves, whereas no such effect was observed in the case of K, Fe, Zn and Na. Moreover, significant variation in the years of the study was recorded (for means of the cultivars) with respect to the N, P, Ca, Mg, Na, Fe, Mn, Zn and Cu content in fruit, at a lack of any such effect on the K content. An apple variety significantly modified the K content in fruit (the mean value for the two-year study), while no such effect was recorded for the content of N, P, Ca, Mg and Na, Fe, Mn, Zn and Cu. [ABSTRACT FROM AUTHOR]

Fertigation is a measure that combines irrigation and plant nutrition, thus producing a synergistic effect. The aim of this study was determine the applicability of fertigation in pot culture of selected taxa of ornamental shrubs: barberry (Berberis xottawensis var. Superba), juniper (Juniperus xpfitzeriana var. Mordigan Gold) and arborvitae (Thuja occidentalis var. Smaragd). Plants were grown in peat substrate and were fertigated with differentiated nutrient solution of the following chemical composition (mg dm-3) NS-I: N-NH4 <10; N-NO3 120; P 50; K 100; Ca 100; Mg 50; Fe 1.2; Mn 0.3; Zn 0.50; Cu 0.03; B 0.011; pH 5.50; EC 1.60 mS cm-1; NS-II: N-NH4 <10; N-NO3 160; P 60; K 130; Ca 110; Mg 60; Fe 1.5; Mn 0.4; Zn 0.50; Cu 0.04; B 0.011; pH 5.50; EC 2.00 mS cm-1. The control comprised plants grown using Controlled Release Fertilizer (CRF) Osmocote Exact Standard 5-6 M (2 g dm-3 substrate). Fertigation with NS-I had a significant effect on the growth parameters of barberry (height, width, length of lateral shoots) and arborvitae (height, plant spread, plant projected area) in relation to the control. In contrast, the effects of fertigation in the case of juniper were multidirectional. The nutrition level significantly modified the chemical composition of plants. Fertigation using NS-I resulted in a significant improvement (in comparison to the control) in P plant nutrition at a simultaneous reduction of Mn and Cu levels (in barberry), and an improved nutrition with N, P, K, Mg and Zn at a simultaneous decrease in Cu content (in arborvitae), an improved nutrition with P, K and Mg (in junipers). In view of biometric parameters, the application of NS-I could be recommended in fertigation of barberry and arborvitae. [ABSTRACT FROM AUTHOR]

Titanium (Ti) is classified as a beneficial element for plants. The aim of this study was to determine the effect of various Ti concentrations in nutrient solution on the alleviation of Mn-stress in hydroponically grown lettuce (Lactuca sativa L. cv. Zeralda). Plants were fertigated with nutrient solution of the following chemical composition (mg dm-3): N-NH4 < 10, N-NO3150, P-PO450, K 150, Ca 150, Mg 50, Fe 3.00, Mn 19.2, Zn 0.44, Cu 0.03, B 0.01, pH 5.50, EC 1.8 mS cm-1. The following Ti levels were tested (in mg Ti dm-3 of nutrient solution): 0 (control), 0.36; 0.72; 1.09 (denoted as Ti-I, Ti-II, Ti-III). The Ti source was Ti4+ ascorbate (Tytanit®). Ti had a positive effect on plant yielding: significantly the highest mean weight of a lettuce head and also the highest percentage of dry matter in leaves were found at Ti-II (+24.1% and 36.6%, respectively when compared with the control). Increasing Ti nutrition positively influenced the chlorophyll content (which was the highest at Ti-II and Ti-III), while it did not modify the Relative Water Content (RWC) in leaves. Despite the improved plant yielding, there were no differences in concentrations of macroelements (N, P, K, Ca, Mg) and some metallic microelements (Fe and Mn) in leaves. In turn, Ti nutrition significantly modified the nutrient uptake by aerial parts of plants, which increased up to Ti-II, while decreasing at Ti-III. The highest uptake of nutrients was recorded at Ti-II. Given the significant improvement in yield, Ti nutrition could be considered as an effective method to alleviate Mn-stress in lettuce. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the potential of cultivation of Pelargonium × hortorum cv. Survivor Dark Red in a substrate contaminated with sodium chloride. After applying 0.45, 0.96, 1.47, 1.98, 2.49, 2,99 g NaCl dm-3, the substrate contained 200, 400, 600, 800, 1000, 1200 mg Na+ and 287, 595, 903, 1211, 1519, 1827 mg Cl- dm³. Growing medium with natural sodium (22 mg Na+) and chloride (13 mg Cl-) content comprised the control. Electrical conductivity (EC) of the substrates was as follows: 0.11, 0.62, 1.28, 1.75, 2.42, 2.82, 3.72 mS cm-1. Water purified by reverse osmosis was used for watering the pelargonium plants. The effect of sodium chloride on the chemical composition of leaves was evaluated based on the analysis of leaf blades collected at the flowering stage. Sodium chloride negatively influenced all measured plant growth parameters. Increasing salinity also decreased the chlorophyll index values. Significant reduction in the number of inflorescences was recorded in plants grown at = 800 mg Na+ and = 1211 mg Cl- in 1 dm³ of peat substrate. However, the pelargonium plants grown in a substrate containing up to 600 mg Na and 903 mg Cl still retain high decorative value. The increasing sodium chloride content in peat substrate increased the concentrations of phosphorus and calcium in the leaves. Simultaneously, the concentrations of potassium and magnesium decreased, while the concentration of nitrogen was found to be stable. Despite increasing doses of sodium chloride, the content of N, P, K, Ca and Mg in pelargonium leaves fell within or slightly exceeded the established range of guideline values. [ABSTRACT FROM AUTHOR]