Zlatko Čmelik

Genetic variation within the olive (Olea europaea L.) cultivar Oblica detected using amplified fragment length polymorphism (AFLP) markers.

The antioxidant properties and antimicrobial potential of three ethnomedicinal plants, (Momordica charanta, Senna alata and Nauclea lafifolia) extracted with acetone were investigated. Polyphenols from the medicinal plants were screened for their antioxidant and antimicrobial activities against pathogenic micro organisms (Staphylococcus aureus, Streptococcus pyogenes, Esherichia coli and Candida albicans). The medicinal plants displayed different polyphenols contents and antioxidant activities. In addition, varying antimicrobial susceptibility patterns were exhibited. The highest amount of total phenolic compounds was shown by S. alata and the lowest one was M. charanta. The extract of S. alata showed the highest antioxidant activity. Some micro organisms (S. aureus and C. albicans) were susceptible to the polyphenol extracts with minimum inhibitory concentration values between 1.25 to 5.00 mg/ml while other microorganisms (S. pyogenes and E. coli) appeared to be resistant to the extracts. The results suggested that these plants are not only potential sources of phenolic antioxidants but also potentially, good source of antimicrobial agents.

The change of fruit quality parameters in day-neutral strawberries cv. Diamante grown out of season

This research was conducted on the strawberry cultivar Diamante in continental parts of Croatia. The experiment was designed as four replicates with 100 plants for each harvest time. The quality of strawberries cv. Diamante grown out of season (fruit were picked in the early morning hours at three harvest times: 27 June, 7 September, 28 October) was determined. Total soluble solids (°Brix) ranged from 5.00% to 7.03%, total acidity ranged from 1.05% to 1.12%, total soluble solids/acidity ranged from 4.74 to 6.34, vitamin C ranged from 40.73 mg/100 g fresh weight to 46.68 mg/100 g fresh weight, pH ranged from 3.53 to 3.72, total phenols ranged from 276.48 to 326.76 mg/l, non-flavonoids ranged from 169.50 to 260.53 mg/l, and flavonoids ranged from 44.71 to 106.53 mg/l, respectively. In addition, total anthocyanins ranged from 15.95 to 21.70 mg/l. The lightness L values of fruits ranged from 30.24 to 41.05, chroma C values from 25.92 to 34.13, and Hue angle H values from 44.51 to 56.02. The data showed that cv. Diamante grown out of season is of satisfactory quality.

Intra-cultivar diversity in the Croatian olive cultivar, `Lastovka`

Summary The Croatian olive (Olea europaea L.) cultivar, ‘Lastovka’ is mainly used for oil production. While fruit yields are high and regular, the growing area is limited due to its sensitivity to low temperatures, with production concentrated on the South Dalmatian island of Korčula. Different morphological types have been observed during production. In order to determine the extent of intra-cultivar diversity, 47 individual ‘Lastovka’ trees were analysed for 11 morphological traits and assessed using AFLP markers, and compared to ten trees each of the cultivars ‘Oblica’ and ‘Drobnica’. Clear differentiation among cultivars was detected, and the results showed that both the morphological and molecular data were equally reliable for discriminating between cultivars. The existence of intra-cultivar diversity in ‘Lastovka’ was therefore confirmed at both the morphological and molecular levels, providing an opportunity for the selection of potentially superior clones.

Influence of four different dwarfing rootstocks on phenolic acids and anthocyanin composition of sweet cherry ( Prunus avium L) cvs 'Kordia' and 'Regina'

Influence of four different dwarfing rootstocks: ‘Gisela 5’, ‘Gisela 6’, ‘PHL-C’ and ‘PiKU1’ on the amount of polyphenols (total phenols, total and individual anthocyanins and individual hydroxycinnamic acids) of sweet cherry cultivars ‘Kordia’ and ‘Regina’ was researched as well as correlations between polyphenols and colorimetrically measured fruit skin colour. Total phenols (TP) and total anthocyanins (TA) were determined by spectroscopic methods, while individual anthocyanins and hydroxycinnamic were quantified and identified by high performance liquid chromatography (HPLC). ‘Gisela 6’ and ‘PiKU1’ had the strongest influence on the TP content of both cultivars. The main hydroxycinnamic acid identified was p -coumaric acid (p-CA) which content was influenced by cultivar, vegetation year and interaction of cultivar*rootstock*year. Content of p-CA varied the most on rootstock ‘Gisela 5’ for both cultivars, with its lowest amount obtained in 2013 and the highest in 2014 in comparison to other rootstocks.The largest difference in TA content in cultivar*rootstock interaction was identified in ‘Gisela 6’. Substantial difference in correlation pattern between cvs. ‘Kordia’ and ‘Regina’ lead to the conclusion that values L* and b* are better TA indicators rather than values a* and Hue.

The main Croatian olive cultivar "Oblica", shows high morphological but low molecular diversity

Summary The most important olive (Olea europaea L.) cultivar in Croatia is ‘Oblica’, which is cultivated in all growing regions and makes up ≤ 75% of all olive trees. A total of 36 typical ‘Oblica’ trees were sampled from five growing regions in Croatia. An analysis of 12 morphological traits revealed high variability among the samples. Geographical latitude had the greatest influence (r = 0.276) on morphological characteristics, followed by longitude (r = 0.223), and altitude (r = 0.127). The correlation between all 12 morphological characteristics and geographical coordinates was 25.7%, which indicates a strong environmental influence on morphology. Molecular identification of the 36 samples, based on AFLP markers, suggested that intra-cultivar genetic variability was limited (4.82%). These results suggest that a few closely-related clones constitute the genetic structure of ‘Oblica’, while the observed morphological diversity is due to environmental factors.