ABSTRACT Plant biostimulants are commercial products based on different chemical substances used to enhance plant growth and productivity. The effects of biostimulants, Megafol and Viva, with different dominant compositions (amino acids and humic acids) on two tomato cultivars (cv. Gravitet F1 and cv. Minaret F1) exposed to conventional and low-input macronutrient nutrition were investigated. Application of both biostimulants positively affected yield at conventional nutrition. In low-input nutrition variant, biostimulant application prevented yield loss only in cv. Minaret F1. Inter-cultivar differences were noticed in fruit characteristics (total phenol content, total flavonoids content and total antioxidative capacity) where application of biostimulants leads to opposite results in the examined cultivars. We considered the possibility of biostimulant usage as an effective nutritional addition for overcoming the problem of excessive fertilisation.

Summary The apple (Malus domestica Borkh.) possesses a number of health-promoting properties. The main beneficial effects of apple fruits on human health are associated with the antioxidant properties of components synthesising in apple fruits during their growth and development. Phenolic compounds and flavonoids are such components that contribute significantly to the antioxidant capacity of fruits, thus enhancing their health properties. The purpose of this study is to compare the antioxidant properties (namely antioxidant capacity, ascorbic acid, total phenolic and flavonoid contents) of the ‘Idared’ and ‘Braeburn’ apple cultivars, grown under optimal growing conditions in the Goražde area. Ascorbic acid contents were estimated using the 2.6-dichlorophenolindophenol titration method, whereas total phenolics were determined using the Folin-Ciocalteu method. Furthermore, total flavonoids were determined using the aluminium chloride colorimetric assay, whereas the ferric reducing/antioxidant power assay was used to determine the total antioxidant capacity of the apple fruits examined. The average values of the ascorbic acid, the total phenolic and flavonoids contents, and the total antioxidant capacity of the ‘Idared’ apples under consideration were 8.09 mg 100 g−1, 34.56 mg gallic acid equivalents 100 g−1, 12.62 mg catechin equivalents 100 g−1 and 323.28 μmol Fe2+ 100 g−1of fresh weight, respectively. The average values of the total phenolic and flavonoids contents, as well as the antioxidant capacity of the ‘Braeburn’ apples examined were as follows: 8.89 mg 100 g−1, 33.4 mg gallic acid equivalents 100 g−1, 13.56 mg catechin equivalents 100 g−1 and 367.01 μmol Fe2+ 100 g−1 of fresh weight, respectively. The analyses performed indicate that the differences recorded in the parameter values between the apple cultivars ‘Idared’ and ‘Braeburn’ were statistically non-significant. A correlation data analysis confirmed that phenolic compounds are the carriers of the antioxidant activity of apples.

Two commercial tomato cultivars were used to determine whether grafting could prevent decrease of Ca2+ concentration under salt stress conditions. The cultivars Buran F1 and Berberana F1 were grafted onto rootstock "Maxifort" and grown under three levels of the elevated soil salinity (S1 EC 3.80 dS m-1, S2 6.95 dS m-1 and S3 9.12 dS m-1). Ca2+ concentration of non-grafted plants of both examined hybrids was lower at all salinity levels in comparison to the control. In the fruits of grafted plants salt stress significantly decreased Ca2+ concentration only at the third salinity level (EC 9.12 dS m-1). The possibility of grafting tomato plants to improve influx of Ca2+ under salt stress conditions is discussed.

Salinity is one of the most important ecological problems that affect irrigated agriculture in the world. Increased soil salinity inhibits plant growth through osmotic and ionic stress, but can also decrease availability of certain micronutrients. Copper is an essential metal for normal plant growth and development that participates in numerous biochemical and physiological processes and it is an essential cofactor for many metalloproteins. Copper concentration in two commercial tomato cultivars (grafted and non-grafted) was investigated under different levels of elevated soil salinity. Soil with EC 9.1 dS m-1 led to the highest copper deficiency, approximately by 37% in the non-grafted and 25% in the grafted tomato plants. The effect of a grafting technique is considered as an environmentally friendly tool for overcoming soil salinity problem.

Three commercial apple cultivars ('Jonagold', 'Granny Smith' and 'Idared') and the local apple cultivar ('Prijedorska Zelenika') from Bosnia and Herzegovina were analysed by HPLC-MS for the content of phenolic compounds in peel and pulp as well content of individual sugars and organic acids. Catechin, (-)-epicatechin, chlorogenic acid, caffeic acid, quercetin 3-O-xyloside, quercetin 3-O-arabinoside, quercetin 3-O-rhamnoside, quercetin 3-O-rutinoside, quercetin 3-O-galactoside and quercetin 3-O-glucoside were identified in apple peel and (-)-epicatechin, chlorogenic acid and caffeic acid in apple pulp at all observed cultivars. The total sugars content of analysed apple cultivars ranged between 91.61 and 105.45 g kg-1 FM, while the total organic acids content was from 5.70 to 15.05 g kg-1 FM. The levels of total organic acids and sugars, glucoce/fructose ratio and sugar/acid ratio were affected by cultivars. The mean content of total phenolic compounds was between 427.92 and 1457.95 mg kg-1 FM in peel and from 113.58 to 439.83 mg kg-1 FM in pulp and depending upon the cultivars. The presented data clearly demonstrated that traditional apple cultivar ('Prijedorska Zelenika') had significantly higher individual phenolic compounds in pulp in comparison to the commercial cultivars, i.e., 'Idared', 'Jonagold' and 'Granny Smith' and with respect of that 'Prijedorska Zelenika' is recommended as raw material for cloudy juice processing.

The aim of this study was to evaluate the dynamics of Mn in ‘soil - raspberry’ system on the area around the manganese ore deposits Radostovo in Bužim municipality. Atomic absorption spectroscopy was used to determine the concentration of Mn in soil and plant samples. Fe, Zn and Cu concentration in soil and raspberry plants was also subject of analysis, since these elements have antagonistic relationship with Mn in soils. The concentration of available Mn in soils was low, although the total Mn in the same soils exceeded the Mn toxic values noted in the scientific literature. The chemical and physical properties of the examined soils characterized by a relatively high pH value and good ability to store root-zone air certainly contributed to the decreasing release of available Mn2+ from manganese oxides in soils as well as Mn2+ oxidation to insoluble Mn3+ or Mn4+ ions, resulting in low uptake of Mn by plant roots. The results of study also showed that the absorbed Mn mostly accumulates in leaves and roots of raspberry, and much less in the stem and fruits. That rule in Mn distribution within raspberry plant is in fact identical to all food crops.

The main purpose of this study was to evaluate the effect of calcium fertilizer treatments on fruit quality and distribution of calcium in apple fruit (Malus domestica Borkh. cv. Idared). Four treatments were tested: application of calcium nitrate through the fertigation system, foliar application of calcium nitrate, application of calcium oxide through soil, and control treatment (without calcium fertilizer). In the experiment, freshly picked apples harvested in Gorazde region (eastern Bosnia) in September 2018 were analyzed. The highest impact to increase calcium content in apple had a treatment where calcium nitrate was added through the fertigation system. It was the result of the balance between calcium and nitrogen in the applied solution as well as the fertigation capacity to timely deliver nutrition to the main rooting zone. Calcium distribution was not uniform within the fruit: the highest content was found in the apple core, decreasing in the apple flesh, and rising again in the apple skin, regardless of fertilizer treatment. There was no difference among calcium fertilizer treatments in total soluble solids and titratable acidity of apple, indicating that these treatments were insufficient in order to improve the examined parameters of fruit quality.