Surface sterilization is the most important step in preparation of explants for micropropagation, because controlling fungal and bacterial contamination of woody plant from field sources is very difficult. Six sterilizing agents: sodium hypochlorite (NaOCl), calcium hypochlorite [Ca(ClO) 2 ], sodium dichloroisocyanurate (DICA), mercuric (II) chloride (HgCl 2), silver nitrate (AgNO 3) and hydrogen peroxide (H 2 O 2) were tested for sterilization of 'Oblačinska' sour cherry buds, by varying their concentration and time of exposure. The aim of this study was to establish best surface sterilization for in vitro propagation of 'Oblačinska' sour cherry. Aseptic cultures of 'Oblačinska' sour cherry were established from axillary buds which were placed in nutrient medium, supplemented with plants hormones 6-benzylaminopurine (BA), 1naphthaleneacetic acid (NAA) and gibberellic acid (GA 3). The results indicated that among these sterilizing agents silver nitrate (AgNO 3) at concentration of 1% for 20 minutes was the best for controlling the infection, whereas sterilization with sodium dichloroisocyanurate (DICA) at concentration of 1% for 10 minutes was not satisfactory.

Fruit skin colour plays a major role in quality assessment of food, significantly determining consumer`s choice. Colour of sour cherries depends on anthocyanins which are phenolic compounds (flavonoids) present in high amounts in fruits. The aim of this study was to determine a possible relation between polyphenols (total phenolics and anthocyanins) and colour parameters of fruit skin of sour cherries. The plant material used in this study was twenty two sour cherry genotypes from an orchard of Agricultural Institute Osijek. Total phenolics and anthocyanins contents as well as colour parameters (L*, a*, b*, h and C) of fruit skin were determined. Variability between sour cherry genotypes in total phenolics and anthocyanins as well as in colour parameters was revealed. Total polyphenols content varied from 462.7 to 1049.0 mg GAE/100 g of fresh weight, while total anthocyanins ranged from 160.1 to 495.6 mg CGE/100 g of fresh weight. A significant positive correlation was found between polyphenols and anthocyanins content. Total phenolics content had a significant negative correlation with colour parameters b* and h, while anthocyanins content negatively correlated with colour parameters L*, b* and h. According to the obtained results, genotypes Maraska, Heimanns Konservenweichsel and Rexelle are the richest genotypes in polyphenols and anthocyanins content

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-Drought is a limiting factor in fruit production today. Identification of sour cherry genotypes tolerant to drought will enable the sustainability of fruit production. The aim of our study was to select sour cherry genotypes according to their genetic background as well as drought tolerance and investigate possible mechanisms of drought tolerance through the changes in photosynthetic apparatus (i.e. photosynthetic pigment content) and photosynthesis process assessed through the chlorophyll fluorescence transient. All of them together with molecular markers (SSRs and AFLPs), relative water content (RWC) as indicator of plant water status distinguish two genotypes (Kelleris 16 and OS), which are the opposite in regards to drought tolerance. Down-regulation of photosynthesis in drought-treated Kelleris 16 plants was seen as changes in antenna complexes of PSII (decreased total chlorophylls content (a+b) and chlorophylls ratio (a/b)). Despite unchanged maximum quantum yield of PSII in drought-treated leaves of genotype OS, overall photosynthetic performance expressed as PI ABS was down-regulated in both investigated genotypes. However, decrement of PI ABS was much pronounced in genotype Kelleris 16, mainly because of changes in a certain fraction of RCs, which become dissipative centres, seen as increase in ABS/RC and DI 0 /RC, in order to avoid photooxidative damage of photosynthetic apparatus. Also, electron transport, seen as decrease in ET 0 /(TR 0 -ET 0 ) and ET 0 /RC, was impaired which lead to impaired CO 2 fixation and photosynthesis. The described changes in the functioning of photosynthetic apparatus in drought-treated plants of Kelleris 16 constitute the main distinction between the two investigated genotypes regarding drought adaptation mechanisms.

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SUMMARYAsparagus is an interesting vegetable as a part of a healthy diet and has been widely studied due to the high nutritional value and potential positive effects on human health. Wild asparagus (Asparagus acutifolius L.) grows along the Adriatic coast and islands, while the cultivated asparagus (A. officinalis L.) is mostly grown in the eastern region of Croatia. The aim of this study was to determine total polyphenol content (measured spectrophotometrically) and antioxidant activity (DPPH) in wild and cultivated asparagus. No significant differences in total polyphenol content were found between wild and cultivated asparagus. The highest content of polyphenols in wild asparagus was 6. [mg GAE/g fresh weight] and 49.60 [mg GAE/g dry weight], and in cultivated asparagus it was 4.52 [mg GAE/g fresh weight] and 50.93 [mg GAE/g dry weight]. Antioxidant activity measured using DPPH (2,2-diphenyl-1-picrylhydrazyl) method showed statistically significant difference. Higher antioxidant activity was measured in cultivated than in wild asparagus. The results also indicate that increased polyphenol content leads to higher antioxidant activity, but more so in the cultivated asparagus. Based on the results, the cultivated asparagus is an excellent alternative to wild asparagus that should be protected from over-harvesting, thus preventing devastation of plant diversity of islands and coast.

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