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In this study, we determined the effectiveness of removal of nutrients (nitrates and orthophosphates) from greenhouse wastewaters (GW) using non-cross-linked chitosan (CHs) and chitosan cross-linked with epichlorohydrin (CHs-ECH) in the form of hydrogel beads. GW used in the study had the following parameters: N-NO3 621.1 mg/L, P-PO4 60.8 mg/L, SO42− 605.0 mg/L, Cl− 0.9 mg/L, Ca2+ 545.0 mg/L, Mg2+ 178.0 mg/L, K+ 482.0 mg/L, hardness 113° dH, and pH 6.2. The scope of the study included determination of the effect of pH on wastewater composition and effectiveness of nutrient sorption, analyses of nutrient sorption kinetics, and analyses of the effect of sorbent dose on percentage removal of nutrients from GW. CHs-ECH was able to sorb 79.4% of P-PO4 and 76.7% of N-NO3 from GW, whereas CHs to remove 92.8% of P-PO4 and 53.2% of N-NO3.Electronic supplementary materialThe online version of this article (10.1007/s11356-018-2078-z) contains supplementary material, which is available to authorized users.

Station owned by the University of Warmia and Mazury in Olsztyn. The experiment had a randomized block design with three replications. The first experimental factor was a number of common onion cultivars: 'Whitney Wing F1', 'Spirit F1' and 'Red Baron'. The second experimental factor was the effect of two plant growth biostimulants; Calleaf Aminovital and Maximus Amino Protect, on the yield and quality of the onions. In the control treatment, plots were sprayed with water. The total yield, marketable yield and the marketable yield as a percentage of the total yield, the weight, vertical diameter and horizontal diameter of each onion bulb, the content of dry matter, total sugars, reducing sugars, L-ascorbic acid and nitrates (V) in the onions were determined in the study. The evaluated cultivars differed significantly with regard to the weight and size of the onions. Onions of cv. 'Whitney Wing F1' were characterized by a greater yield, and the weight, vertical diameter and horizontal diameter of the bulbs were all higher than they were for the remaining cultivars. The concentrations of dry matter, total sugars, L-ascorbic acid and nitrates (V) were higher in cv. 'Red Baron'. The contents of L-ascorbic acid and nitrates (V) were significantly affected by the application of biostimulants, and the effects were more pronounced for onions treated with Maximus Amino Protect. The interaction between the experimental factors had a significant effect on the weight of individual onion bulbs, and on the concentrations of dry matter and L-ascorbic acid in the edible plant parts.

Shallots (Allium cepa L. Aggregatum group) are cultivated on small areas, mostly to harvest mature bulbs with dry scales. Due to their exceptional taste and nutritional value, and a short growing season, they can also be grown for early bunch harvest. New shallot cultivation strategies are being sought to meet consumers’ growing expectations regarding the quality of vegetables, and their increasing awareness of global food safety. Therefore, the aim of this study was to evaluate the effect of selected biostimulants on the biometric parameters, yield and nutritional value of shallot bulbs and leaves. The experimental factors were as follows: two biostimulant types—Effective Microorganisms (EM) and Goëmar Goteo (GG), two shallot cultivars—Bonilla F1 and Matador F1, grown for bunch harvest, and year of the study. Shallot leaves had a higher content of L-ascorbic acid, reducing sugars and nitrates than bulbs. Young bulbs had a higher content of DM and total sugars than leaves. The leaves and bulbs of shallot plants treated with EM accumulated the highest amounts of minerals. Macronutrient ratios were closer to optimal in shallot leaves than bulbs. The nitrate content of bulbs was inversely proportional to the nitrate content of leaves. Therefore, an increase in the nitrate content of leaves by around 330% led to an approximately 40% decrease in the nitrate content of bulbs. The correlations between the parameters of the chemical composition of shallots and shallot leaves show that the increase in the dry matter content of the bulbs (by approx. 60%) was accompanied by an increase in the L-ascorbic acid content in the leaves (by approx. 240%). The use of biostimulants in the cultivation of A. cepa L. Aggregatum group contributed to the reduction of L-ascorbic acid content in bulbs and had no positive effect on the leaves. Moreover, no positive effect of biostimulants on the reduction of nitrate content in shallot leaves and bulbs was observed, which is undesirable from the consumer’s point of view. After the use of biopreparations, the yield of shallots was lower than that of the control—by approx. 14% (EM) and approx. 4% (GG). Therefore, the measurable benefits of biostimulants in the cultivation of shallots grown for early bunch harvest do not balance the costs of their purchase and use.

Melons are highly demanding, thermophilous plants, which is why they are unpopular among fruit growers. Melon cultivation requires special treatment methods for the improvement of microclimatic conditions. Seven Polish melon cultivars are presently grown on the domestic market. They are well adapted to the local climate. The growth rate, vigor, fruit shape, fruit size, rind color and flesh thickness of those cultivars vary. The objective of this study was to determine the mineral content of edible parts of four field-grown melon cultivars in the Warmia region (NE Poland). This study discusses the mineral content of melon fruit subject to the investigated cultivar and cultivation method. In Poland, melon production is difficult and unreliable. The main problem is the selection of an appropriate cultivar and cultivation method. The analyzed material consisted of four Polish melon cultivars: Malaga F 1 , Melba, Oliwin, Seledyn F 1, grown in a field experiment without protective cover, under polyethylene (PE) sheet cover, under non-woven polypropylene (PP) cover, with soil mulching, as well as with soil mulching under PE sheet cover or nonwoven PP cover. The highest concentrations of total N, K, Ca and Cu were determined in melon fruit of cv. Oliwin. Significant variations in total nitrogen and phosphorus levels in the edible parts of melon plants were noted subject to the applied cultivation method. Cucumis melo L. grown in the control treatment without protective cover was marked by significantly higher levels of total nitrogen and phosphorus in the fruit, compared with fruit grown with the use of other cultivation methods. The results of this study indicate that the fruit of melon plants cv. Seledyn grown in mulched soil under non-woven PP cover was characterized by the most favorable Ca:Mg and Ca:P ratios in comparison with fruit from the remaining treatments.

A b s t r a c t. A field experiment was conducted in 2013-2014. The experiment had a randomised block design with three replicates. The first experimental factor was two carrot (Daucus carota L.) cultivars, 'Purple Haze F 1 ' and 'Deep Purple F 1 ', and the second experimental factor was the application of the biocontrol agent Bioczos BR. In the control treatment, plots were sprayed with water. The aim of the study was to determine the effect of Bioczos BR on selected morphological traits and the nutritional value of purple-coloured storage roots of carrots. The analysed carrot cultivars differed considerably in root weight and length. Carrots of cv. 'Deep Purple F 1 ' had higher average root weight. Consistent changes were observed in the nutrient content of carrot roots. Bioczos BR contributed to an increase in the content of dry matter (by 14%), total sugars (by 28%), reducing sugars (by 31%) and nitrates (V) (by 32%) in carrot roots, in comparison with the control treatment.K e y w o r d s: carrots, morphology, nutritional value, storage roots

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