The contents of 15 different phenolic compounds in apple leaves and fruit skin from various orchards were determined by HPLC. High concentrations of flavan‐3‐ols were found in those orchards which were not infected by Venturia inaequalis. This observation corroborates earlier findings on different cultivars. The hypothesis that these compounds could be involved in the resistance of apple to scab was tested by inhibiting the key enzyme of the phenol biosynthesis, the phenylalanine‐ammonia‐lyase, in young shoots of the resistant genotype ‘Sir Prize'. After inoculation of the inhibitor‐treated leaves, severe symptoms of the disease occurred. The fungal infection was confirmed by histological studies. No flavonal‐accumulation could be observed at the infection site which was the case in the non‐inhibited but inoculated controls.

The study analysed the effect of silver nanoparticles (AgNPs) on seed germination, field emergence and the physiological parameters of seedlings of two bean cultivars, ‘Bali’ and ‘Delfina’, under normal and chill temperatures. AgNPs solutions (0.25, 1.25 and 2.5 mg dm−3) were applied together with the microbial preparation Nitragina (containing Rhizobium leguminosarum bv. phaseoli) on seeds as a short-term pre-sowing treatment. Low concentrations of AgNPs (0.25, 1.25 mg dm−3) had an immediate beneficial effect, resulting in fast and uniform germination in laboratory and field conditions, as well as a positive effect in the later stages of seedling development, manifested as an increase in the average seedling height, fresh and dry weight and net photosynthesis. Particularly, favourable effects were noted in suboptimal temperature conditions, suggesting that AgNPs activate plant mechanisms of tolerance to environmental stress. The highest concentration tested of AgNPs was not particularly effective for the plants but had a strong antimicrobial effect, which was beneficial in period of seed germination, but at the later stage of plant development was unfavourable probably due to disruption of symbiosis between the bean seedlings and rhizobia.

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A b s t r a c tIn a pot experiment conducted in a phytotron, the effectiveness of foliar nutrition of spinach (Spinacia oleracea L.) with different magnesium salts with and without the addition of 0.5% CO(NH 2 ) 2 was studied. Magnesium was applied 3 times in the form of solutions of MgSO 4 x 7H 2 O, Mg(NO 3 ) 2 x 6H 2 O, MgCl 2 x 6H 2 O, C 4 H 6 O 4 Mg x 4H 2 O, compared to water as the control treatment. The obtained results showed that foliar feeding of spinach with inorganic magnesium salts was an efficient method for supplementing the Mg level in plants during the growing period. But the application of a metalo-organic complex in the form of magnesium acetate (C 4 H 6 O 4 Mg x 4H 2 O) at a concentration of 1.7%, in spite of a similar effect on leaf Mg content, induced phytotoxic symptoms in the form of chlorotic and necrotic spots on the leaves. The application of the solutions of inorganic magnesium salts had a significant effect, resulting in more intensive leaf gas exchange (stomatal conductance, transpiration and photosynthesis) and an increase in leaf yield. Magnesium sulphate affected the abovementioned processes in the most effective way, while magnesium acetate had a negative impact. Foliar feeding of spinach with the magnesium salts resulted in an increased leaf content of protein, chlorophyll, carotenoids, nitrates and proline, but a decrease in vitamin C content. The addition of urea to the applied magnesium salt solutions increased the plant gas exchange rates and the leaf content of protein, chlorophyll, carotenoids, nitrates and proline, but it decreased the content of vitamin C, potassium and magnesium.

The aim of the study was to assess the impact of sulphur and molybdenum fertilization on the yield and chemical composition of common bean seeds. A field experiment was conducted in southeastern Poland in 2012–2014. The scheme of the study included the following treatments: O-control, Mo-molybdenum (100 g·ha−1), SBS-sulphur before sowing (50 kg·ha−1), SFA-sulphur foliar application (50 kg·ha−1), Mo + SBS-molybdenum (100 g·ha−1) and sulphur before sowing (50 kg·ha−1), and Mo + SFA-molybdenum (100 g·ha−1) and sulphur foliar application (50 kg·ha−1). After harvesting, the following determinations were made in bean seeds: content of nitrogen, sulphur, phosphorus, potassium, calcium, magnesium, methionine, and cysteine. Application of Mo increased seed yield and protein and methionine content, as well as the content and uptake of P, Mg, and Ca in common bean seeds. Sulphur application had a positive effect on seed yield (13.6% increase) and protein content. Moreover, sulphur improved the biological value of protein by increasing the content of methionine, cysteine, and some macroelements. The most beneficial effects were obtained when both molybdenum and sulphur were used in fertilization. Considering the yield-producing effect and the impact on the biological quality of protein, sulphur fertilization should be included in the crop management for the common bean.