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Boja pokožice, pomološka i interna kvaliteta ploda predstavljaju jedan od ključnih i pokazatelja kvalitete u intenzivnoj proizvodnji jabuke. Istraživanje sa ciljem utvrđivanja utjecaja reflektivnog mulcha na poboljšanje i očuvanje interne kvalitete jabuke cv. FUJI Raku Raku u pre- i post-harvest periodu provedeno je 2020. godine u pokusnom nasadu jabuka (Istočna Hrvatska). Sorta je cijepljenja na podlogu M. N.9 NAKB T 339, uzgojnog oblika vitko vreteno s gustoćom sklopa 0.9 x 3.2 m. Pokus je postavljen po split-plot metodi (4 repeticije po 6 stabala). Tretmani su uključivali stabla ispod kojih je postavljena reflektirajuća folija i kontrolni tretman. Tretman folijom je postavljen 20 dana prije očekivane tehnološke berbe plodova s obije stane reda (istok i zapad). Pri berbi plodovi su odvajani po strani reda s kojeg su ubrani (istok i zapad) te su obavljena pomološka mjerenja (promjer, visina, masa, tvrdoća, Brixi i JŠI), intenzitet obojenosti plodova chromametrom po CIE L*a*b* sustavu te mjerenja internih pokazatelja kvalitete plodova (antocijani, fenoli i vitamin C). Navedeni interni pokazatelji kvalitete plodova mjereni su neposredno nakon berbe te su ponovljeni nakon 3 mjeseca skladištenja (hladnjača s kontroliranom atmosferom). Na razini cijelog pokusa između plodova ubranih s istočne i zapadne strane reda nije bilo značajne razlike u intenzitetu obojenosti plodova te internoj kvaliteti dok je koncentracija šećera i JŠI bila značajno veća na plodovima sa zapadne strane. Plodovi ubrani na istočnoj strani reda bili su jedino značajno veće mase. Vitamin C bio je značajno veći u plodovima analiziranim neposredno nakon berbe dok su fenoli bili značajno veći u plodovima analiziranim nakon skladištenja. Plodovi na tretmanu pod folijom rezultirali su značajno većim promjerom, visinom i masom te sadržajem antocijana i fenola. Također plodovi pod reflektirajućom folijom bili su tamniji i s više crvene, odnosno manje žute boje prema CIE L*a*b* sustavu (saturiraniji bojom) ; značajno niži L* i b*. u odnosu na plodove bez folije. Dobiveni rezultati istraživanja upućuju na veliki potencijal reflektirajuće folije u dostizanju, odnosno povećanju dopunske boje i interne kvalitete plodova. Standardiziranje ove dopunske pomotehničke mjere nameće se kao kvalitativno rješenje u prevladavanju nepovoljnih klimatskih prilika u periodu dozrijevanja.

Kompostiranje ili vermikompostiranje organskih ostataka poljoprivrednih, prehrambenih, šumarskih i komunalnih djelatnosti mogu rezulitrati proizvodima s različitim stupnjevima zrelosti i fitotoksičnosti. Fitotoksičnost uslijed prisutnosti organskih kiselina, amonijskog oblika N, fenola, soli ili teških metala može biti posljedica svojstava sirovina ili načina kompostiranja, a najčešće se evaluira testom klijavosti. Cilj ovog istraživanja bio je utvrditi stupanj fitotoksičnosti 11 različitih svježih i kompostiranih poljoprivrednih, šumarskih i komunalnih nusproizvoda i njihovih smjesa (vinogradarski trop, konjski stajski gnoj, kamena vuna, piljevina, lišće, drvena sječka) prije i nakon 14 dana vermikompostiranja pomoću gujavica (Eisenia andrei). Test klijavosti kres salate (Lepidium sativum L.) proveden je u Petrijevim zdjelicama s po 20 sjemenki tretiranih ekstraktima 11 različitih smjesa prije i nakon vermikompostiranja (ukupno 22 ekstrakta). Utvrđena je visoka fitotoksičnost (indeks klijavosti GI 1, 0) utvrđen je za vermikompostirane smjese vinogradarskog tropa, konjskog stajskog gnoja i kamene vune (1, 68) te vinogradarskog topa, kamene vune i piljevine (1, 76). Nešto manji fitostimulativni učinka utvrđen je i za vermikompostirane smjese konjskog stajskog gnoja i kamene vune (1, 54) te konjskog stajskog gnoja i vinogradarskog tropa (1, 31). Testom je utvrđena najveća fitotoksičnost vinogradarskog tropa, zatim konjskog stajskog gnoja i kamene vune, ali se fitotoksičnost smanjuje u njihovim smjesama. Piljevina učinkovito smanjuje fitotoksičnost vinogradarskog tropa i bez vermikompostiranja. Dvotjedno vermikompostiranje prosječno je povećalo GI na 11 ispitivanih smjesa za 68, 13 % (s 0, 71 na 1, 19) i neutraliziralo sve fitotoksičnosti u potpunosti (djelomično samo za vinogradarski trop). Najveći učinak gujavica utvrđen je na smjesi vinogdarskog tropa i kamene vune sa ili bez konjskog stajskog gnoja gdje je umjerena fitotoksičnost (0, 70-0, 77) transformirana do izrazito fitostimualtivnog učinka (1, 54-1, 68), što potvrđuje veliki potencijal vermikompostiranja u proizvodnji supstrata i organskih gnojiva.

Young shoots of wheat (Triticum aestivum L.), called wheat grass, are most often consumed in human and animal nutrition as juice, powder or tablets. It contains numerous phytochemicals that are essential to human such as fatty acids, enzymes and antioxidants. Furthermore, it is a rich source of chlorophyll, vitamins (A, B, B17, C, E, F, and K), minerals (iron, potassium, calcium and magnesium), and unlike wheat grain it doesn't contain gluten. Due to its nutritional value, wheat grass juice has become popular food supplement all over the world. The aim of this study was to determine the differences in the content of total chlorophyll, carotenoids, phenols and vitamin C in the juice and plant residue. Ten varieties of wheat grass (Pipi, Osječka crvenka, Ružica, Eurofit, Divana, Katarina, Janica, Ludwig, SW Maxi and Felix), were sown into the substrate and grown in a fully controlled conditions in growth chamber. On twelfth day after sowing leaves were cut two centimeters above the ground and squeezed. The extracts of juice and plant residue were spectrophotometrically analyzed for the content of chloroplast pigments, ascorbic acid and total phenols. In average for all parameters examined, the plant residue was found to contain more total chlorophyll, carotenoids and vitamin C, while juice was significantly richer in total phenols content. Also, a significant difference in total content of chlorophyll, carotenoids, phenols and vitamin C, was found between the examined varieties of wheat grass. According to the content of physiologically active compounds tested, the juice of variety Ružica and plant residue of variety Divana, showed the highest nutritional value. Oppositely, Felix and Ludwig were two varieties with the poorest nutritional value of both, juice and plant residue. It can be concluded that fresh, whole leaves of wheat grass would be the best to consume, because beside the beneficial phytochemicals, we also ingest plant fibers which are generally lacking in the human diet. In addition, home growers should take care to choose nutritionally high- quality variety for cultivation.

Nedostanta koncentracija mikroelemenata u hrani rezulira pothranjenošću koju je moguće riješiti agronomskom ili genetskom biofortifikacijom. Cilj istraživanja bio je utvrditi utjecaj folijarne aplikacije mikrooelemenata na akumulaciju cinka (Zn) u zrnu suncokreta (Helianthus annuus L.) i soje (Glycine max L.). Pokus suncokreta postavljen je na jednom lokalitetu (Tenja), dok je pokus soje postavljen na dva lokaliteta (Tenja i Rakitovica) u istočnoj Hrvatskoj. Agronomska biofortifikacija suncokreta i soje provedena je folijarnom aplikacijom otopine ZnSO4 (100gZn/l) u fenofazi cvatnje u količini od 3 kg/ha Zn i 6 kg/ha Zn. Folijarna aplikacija Zn nije utjecala na povećanje prinosa zrna suncokreta i soje, ali je povećala kocentraciju Zn u zrnu. Folijarna aplikacija Zn u količini od 3 kg/ha povećala je koncentraciju Zn u zrnu suncokreta za 63, 4 % i koncentraciju Zn u zrnu soje za prosječno 17, 5 %. Folijarna aplikacija Zn u većoj koncentraciji od 6 kg/ha Zn povećala je koncentraciju Zn u zrnu suncokreta za 61 % i koncentraciju Zn u zrnu soje za prosječno 17, 8 %. U kontrolnom tretmanu u suncokretu je utvrđena koncentracija 39, 47 mg/kg Zn, a nakon folijarne aplikacije s 3 kg/ha Zn 64, 50 mg/kg Zn i sa 6 kg/ha Zn 63, 56 mg/kg Zn. Kontrolni tretman u soji prosječno je imao koncentraciju 42, 51 mg/kg Zn, a nakon folijarne aplikacije s 3 kg/ha Zn 49, 95 mg/kg Zn i sa 6 kg/ha Zn 50, 08 mg/kg Zn. Pokus je pokazao učinkovitost folijarne aplikacije cinkovim sulfatom na obogaćivanje biljnog materijala cinkom i opravdao postupak agronomske biofortifikacije s 3 kg/ha Zn dok aplikacija 6 kg/ha Zn nije dodatno povećala koncentraciju Zn.

Organske karboksilne kiseline fitotoksičnim učinkom mogu inhibirati rast biljaka, posebice u najranijim fazama. Cilj provedenog istraživanja bio je testom klijavosti kres salate i krastavca utvrditi fitotoksičnost različitih koncentracija mliječne i maslačne kiseline. Testom klijavosti analizirano je 7 različitih koncentracija kiselina (0, 10 mM ; 0, 25 mM ; 0, 50 mM ; 1, 00 mM ; 2, 00 mM ; 4, 00 mM ; 8, 00 mM) uključujući i deioniziranu vodu kao kontrolni tretman (0, 00 mM). Maslačna i mliječna kiselina nisu smanjile klijavost krastavca dok su klijavost kres salate značajno smanjile samo 3 najveće koncentracije maslačne kiselina (2, 00 mM, 4, 00 mM i 8, 00 mM). Obje kiseline smanjile su duljinu korijena krastavca uz fitotoksični učinak mliječne kiseline u koncentracijama ≥ 0, 50 mM i maslačna kiseline u koncentracijama ≥ 4, 0 mM. Istovrsni fitotoksični učinak na korijen kres salate utvrđen je za mliječnu kiselinu samo u najvećoj koncentraciji (8 mM), a za maslačnu kiselinu već u koncentracijama ≥ 2, 0 mM. Međutim, za razliku od krastavca, na korijen kres salate utvrđen je i fitostimulativni učinak niskih koncentracija maslačne kiseline (0, 1 mM ; 0, 25 mM i 0, 50 mM) i gotovo svih istraživanih koncentracija (≤ 4, 0 mM) mliječne kiseline. Indeks klijavosti krastavca također je bio indikator fitotoksičnog učinka mliječne (koncentracije ≥ 0, 50 mM) i maslačne kiseline (koncentracije ≥ 1, 00 mM), dok je indeks klijavosti kres salate bio u rasponu od fitostimulativnog (mliječna ≤ 4, 0 mM i maslačna ≤ 0, 25 mM) do fitotoksičnog učinka (mliječna 8, 0 mM i maslačna ≥ 2, 0 mM). Provedena istraživanja ukazuju da je krastavac bolji indikator fitotoksičnosti mliječne i maslačne kiseline, a kres salata otpornija na fitotoksičnost uz fitostimulativnu reakciju na niže koncentracije kiselina

Selen kao važan mikronutrijent ima značajnu ulogu u fiziološkim procesima kod ljudi, životinja, biljaka i mikroorganizama. Biofortifikacijom biljaka selenom povećava se njegova koncentracija u biljci, a u generativnoj fazi veliki dio selena bude translociran u zrno. Biofortifikacija kukuruza i soje selenom obavljena je folijarnom aplikacijom na tri lokaliteta: lokalitet 1 - Tenja, lokalitet 2 - Tenja i lokalitet 3 - Rakitovica. Cilj istraživanja bio je istražiti utjecaj folijarne aplikacije otopine natrijevog selenata na koncentraciju selena u zrnu soje i kukuruza. Četiri tretmana folijarne aplikacije provedeni su u fenofazi cvatnje soje i kukuruza (Se0 – kontrola bez selena, Se1 - 10 g/ha Se, Se2 – 20 g/ha Se i Se3 - 30 g/ha Se). Na lokalitetu 2 koncentracije selena u zrnu soje u odnosu na kontrolu (50, 5 µg/kg Se) bile su 7, 21 i 37 puta veće na tretmanima Se1 (374, 8 µg/kg Se), Se2 (1073, 8 µg/kg Se) i Se3 (1879, 3 µg/kg Se), dok su na lokalitetu 3 koncentracije tretmana Se1 (1003, 1 µg/kg Se) i Se2 (1337, 8 µg/kg Se) bile 26 i 35 puta veće od kontrole (38, 7 µg/kg Se). Višestruko povećanje koncentracije selena utvrđeno je i u zrnu kukuruza na lokalitetima 2 i 3. Koncentracije selena u zrnu kuruza na tretmanima Se1 (108, 8 µg/kg Se), Se2 (223, 3 µg/kg Se) i Se3 (361, 8 µg/kg Se) na lokalitetu 3 bile su 25, 52 i 84 puta veće od kontrole (4, 32 µg/kg Se), a na lokalitetu 1 bile su 40 (Se1 199, 4 µg/kg Se), 50 (Se2 248, 7 µg/kg Se) i 63 (Se3 309, 1 µg/kg Se) puta veće od kontrole (4, 9 µg/kg Se). Porast koncentracije selena u zrnu soje bio je veći na lokalitetu 3 nego na lokalitetu 1, a u zrnu kukuruza na lokalitetu 1. Folijarna aplikacija rastućih doza selena u obliku natrijevog selenata pokazala se učinkovitom, nije utjecala na prinos zrna soje i kukuruza, ali je rezultirala razmjernim porastima koncentracija selena u zrnu.

Due to similar electrochemical properties, the plants often assimilate selenium and sulfur through the same membrane transporters. Selenium is a beneficial element for plants that is involved in sulfur assimilation pathways and can replace sulfur in organic compounds without the adverse effects on their physiological function. Also, both elements are known to be extremely important in plants’ response to abiotic and biotic stress. The aim of this study was to determine the effect of sodium hydrogen sulfide (NaHS) solution, sodium selenate (Na2SeO4) and their combinations on the content of chloroplast pigments, phenols, flavonoids, vitamin C, proline and the level of lipid peroxidation in three cultivars of wheat grass (Triticum aestivum L.), grown at 10, 20 and 30ºC. Significantly higher contents of phenols and flavonoids were found in wheatgrass plants grown at 10°C. Regarding the cultivar Katarina, the highest content of vitamin C and proline was determined in the variant of seed priming by the combination of Na2SeO4 and NaHS solutions. The highest level of lipid peroxidation was found in the hydro-priming variant. In the cultivar Osječka 20, the highest content of vitamin C was found in plants developed from hydro-primed seeds, and in the case of cultivar Super Žitarka this was seen in the NaHS- priming variant. The results of this research confirm the protective role of both tested elements at growing temperatures outside the optimum limits for wheatgrass, because they affect the synthesis of protective molecules and signaling components in plant metabolism. Also, it has been proven that there is a genetic specificity of wheat grass in response to seed priming variants at different growing temperatures.

Fitotoksičnost uzrokuje smanjenu klijavost, inhibira rast i razvoj biljke uz druge štetne učinke, a može biti uzrokovana solima, teškim metalima, fenolima, amonijskim oblikom dušika ili organskim kiselinama koje mogu nastati razgradnjom inkorporiranih svježih biljnih ostataka ili nezrelih organskih gnojiva. Cilj provedenog istraživanja bio je testom klijavosti utvrditi fitotoksičnost octene i limunske kiseline. Osnovna hipoteza istraživanja je da postoji razlika u fitotoksičnosti octene kiseline i limunske kiseline te da postoji razlika između kres salate i krastavca kao testnih vrsta. Za test klijavosti kres salate i krastavca korišteno je 20 sjemenki i 5 mL otopine rastućih koncentracija octene ili limunske kiseline (0, 10 mM ; 0, 25 mM ; 0, 50 mM ; 1, 00 mM ; 2, 00 mM ; 4, 00 mM ; 8, 00 mM) te Petrijeve zdjelice, a kao kontrolni tretman korištena je deionizirana voda. Rezultati ukazuju da je krastavac osjetljiviji na fitotoksični učinak kiselina, ali je kres salata imala intenzivniju reakciju na različite koncentracije kiselina. Octena kiselina je intenzivnije utjecala na korijen kres salate i krastavca nego limunska kiselina, a kres salata je pogodnija kao indikator vrsta za osjetljivost na organske kiseline. Octena i limunska kiselina imaju visoki fitotoksični učinak u koncentracijama ≥ 4, 0 mM. Fitostimulativni učinak nemaju na krastavac, a na kres salatu imaju u koncentracijama 0, 5 mM i 1, 0 mM, pri čemu je izraženiji fitostimulativni učinak octene nego limunske kiseline. Octena kiselina također ima veće raspone fitostimulativnog i fitotoksičnog učinka nego limunska kiselina, tj. krivulja utjecaja octene kiseline je strmija nego krivulja učinka limunske kiseline. Zaključno, octena kiselina je pri nižim koncentracijama fitostimulativnija, a pri višim koncentracijama fititoksičnija nego limunska kiselina

Hydrogen sulfide (H2S) as a component of cellular signal transduction is involved in a large number of physiological processes and responses to abiotic types of stress. It is known it increases photosynthesis by stimulating the carboxylation pathway of RuBISCO and increasing chlorophyll synthesis. The aim of the study was to determine the influence of sodium hydrogen sulfide (NaHS) and time of application on the physiological properties of etiolated wheatgrass plants. Wheatgrass was grown under controlled conditions for five days without light and then with a 12-hour photoperiod, watered for 3 days with 100, 200 and 500 mM of NaHS solutions. Plants were watered from 7th-9th, 10th-12th and 13th-15th day. The highest content of phenols (268.56 µgGA/100 mg FW), flavonoids (153.72 µgQC/100 mgFW) and hydrogen peroxide (9.617 nmol/gFW) was found in wheatgrass plants watered with 100 mM NaHS. The highest proline content and lipid peroxidation were found in plants at 500 mM NaHS. At 200 mM NaHS, the highest content of total chlorophyll (1.08 mg/gFW), vitamin C (0.897 mg/100gFW) and antioxidant activity (IC50% 13.837 mgFW) were determined. Watering period significantly influenced the examined physiological parameters, as well. The results show that H2S significantly affects the de-etiolation process in wheatgrass plants.

Hydrogen sulfide (H2S) is involved in many physiological processes and responses to the abiotic types of stress. The aim of the study was to determine the effect of sodium hydrogen sulfide (NaHS) and the time of application on the physiological properties of etiolated wheatgrass plants. Two genotypes of wheatgrass were grown under controlled conditions for five days without light and then with a 12-hour photoperiod, watered for three consecutive days with 100, 200, and 500 mM NaHS solutions. The plants were watered in three variants, 7-9, 10-12, and 13-15 days after sowing, respectively. The highest content of phenols, flavonoids, and hydrogen peroxide was found in wheatgrass plants watered with 100 mM of NaHS solution. The highest proline content and lipid peroxidation levels were found in the plants at 500 mM of NaHS solution. Also, the significant influence of the watering period on the examined physiological parameters was determined. The results show that H2S significantly affects the de-etiolation process and concentration of physiologically active compounds in wheatgrass plants., Sumporovodik (H2S) je uključen u velik broj fizioloških procesa i reakcija na abiotske tipove stresa. Cilj istraživanja bio je utvrditi utjecaj natrijevog hidrogensulfida (NaHS) i vremena primjene na fiziološka svojstva etioliranih biljaka pšenične trave. Dva su genotipa pšenične trave uzgajana u kontroliranim uvjetima pet dana bez svjetlosti te nakon toga uz dvanaestosatni fotoperiod, zalijevane tri dana zaredom otopinama NaHS koncentracija 100, 200 i 500 mM. Varijante tretmana zalijevanja uz osvjetljenje bile su sedmoga do devetoga, desetoga do dvanaestoga te trinaestoga do petnaestoga dana nakon sjetve. Najveći sadržaj fenola, flavonoida te vodikova peroksida utvrđen je kod biljaka pšenične trave zalijevanih otopinom 100 mM NaHS. Najviši sadržaj prolina i lipidna peroksidacija utvrđeni su kod biljaka pri 500 mM NaHS. Također, utvrđen je i značajan utjecaj perioda zalijevanja na ispitivane fiziološke parametre. Rezultati pokazuju da H2S značajno utječe na proces deetiolacije kod biljaka pšenične trave i sadržaj fiziološki aktivnih komponenata u pšeničnoj travi.

The maturity and quality of the substrate is most often evaluated by the cultivation of plants by direct sowing into the growing media. The limit of the toxic impact of plant nutrients, in addition to chemical form and concentration, depends on the physico-chemical properties of the growing medium. The aim of this study was to determine the effect of commercial substrate, compost and vermicompost, and their mixtures with commercial substrate in a 1:1 ratio, watered using solutions with 400 or 600 mg NH4+ L-1 on the content of chloroplast pigments, phenols, flavonoids and antioxidant activity. Four plant species were used in the bioassay: garden cress (Lepidium sativum L.), cucumber (Cucumis sativus L.), barley (Hordeum vulgare L.), and wheat (× Triticosecale Wittmack). The plants were grown under controlled conditions for four weeks during which they were watered with deionized water or NH4+ solutions. The growing medium, solutions and their interactions significantly influenced the content of chloroplast pigments. No significant effect of before mentioned treatments on carotenoid content was found in barley. Substrate significantly influenced the phenol content in barley and lettuce, and the interaction medium×solution significantly affect its content in barley and wheat. The content of flavonoids in barley was significantly influenced by the substrate, while their content in salad was significantly influenced by the NH4+ solution. Total antioxidant activity in wheat was significantly influenced by both treatments. The highest value of the antioxidant activity according to DPPH method, was found in wheat grown in commercial substrate (0.023) and lowest in mixtures of compost (0.012) and vermicompost (0.016) with commercial substrate. Higher antioxidant activity was found in wheat watered with deionized water (0.021) compared to watering solutions containing 400 mg NH4+ L-1 (0.016) and 600 mg NH4+ L-1 (0.015).

Biofortifikacija predstavlja oplemenjivačke i agronomske postupke obogaćivanja jestivih dijelova biljaka esencijalnim elementima poput selena i cinka. Nedostatak mikroelemenata u prehrani ljudi smatra se jednim od vodećih svjetskih problema koji se pokušava riješiti postupcima biofortifikacije povrtlarskih i ratarskih kultura koje su visoko zastupljene u ishrani ljudi. Obzirom da je kupus kultura široke proizvodnje i značajnih nutritivnih vrijednosti cilj ovog istraživanja je bio istražiti neke od fizioloških mehanizama kupusa kao odgovor na gnojidbu selenom i cinkom u svrhu biofortifikacije. Pokus je proveden na dva slavonska lokaliteta u istočnoj Hrvatskoj gdje su prije sadnje kupusa mikroelementi plitko uneseni na proizvodne površine u obliku vodenih otopina. Uzorci lista kupusa prikupljeni su tijekom dvije razvojne fenofaze kupusa tijekom svibnja i lipnja 2017. godine. Aplikacija selena rezultirala je statistički značajnim smanjenjem sadržaja vitamina C dok je aplikacija cinkom rezultirala statistički značajnim povećanjem sadržaja fenola u odnosu na kontrolu. Lokalitet i fenofaza uzorkovanja, u prosjeku za sve tretmane, značajno su utjecali na sadržaj vitamina C, vodikovog peroksida, prolina, fenola, karotenoida, klorofila A i B, intenzitet lipidne peroksidacije te na sadržaj vode u listu (RWC i WSD). Na oba lokaliteta utvrđene su statistički značajno veće koncentracije vitamina C, fenola, klorofila i karotenoida u uzorcima lista kupusa u svibnju u odnosu na lipanj. RWC i WSD značajno su se razlikovali između lokaliteta. Pokus je pokazao kako biofortifikacija selenom i cinkom nije nepovoljno utjecala na fiziološke mehanizme kupusa dok su ekološki činitelji (lokalitet i fenofaza) imali vrlo značajan utjecaj.

Young seedlings of wheat (Triticum aestivum L.) that can be used as a dietary supplement, are called wheat grass. Its juice is rich in chlorophylls, phenols and other antioxidant components, which is why it is considered a functional food. Chlorophyll is a rich source of bioavailable magnesium bounded to the porphyrin core in a similar way as iron is bounded to the hemium structure. Phenolic compounds are secondary metabolites of plants with high antioxidant activity. The aim of the research was to determine whether there are differences in the content of chloroplast pigments and phenols in wheat grass in five Croatian, five Hungarian and five Serbian cultivars, grown under controlled conditions. The highest ratio of chlorophyll a/b is found in Croatian and Hungarian cultivars in comparison to Serbian cultivars, and the highest average content of phenols was found in the group of Croatian cultivars. In all fifteen examined cultivars, the highest content of chlorophylls and carotenoids was found in the cultivar Žitarka, and the highest content of phenols in the cultivar Srpanjka. The highest content of chlorophylls and carotenoids in the group of Hungarian cultivars was found in the Chardas cultivar, and phenols in the cultivar MV Emese. In the group of Serbian cultivars, the Pesma cultivar was characterized by the highest content of chloroplastic pigments, while the highest content of phenols was found in the Sremica cultivar. The data obtained show that even in young seedlings of wheat, the specifity in chloroplastic pigments and phenols content is highlited and the correct selection of cultivar for domestic growing of this functional dietary supplement, is very important.

U mnogim područjima u svijetu koncentracija Se u tlu je mala, što utječe na razinu Se u krmi i hrani te, posljedično, na zdravlje životinja i ljudi. U prethodnim su istraživanjima različiti autori objavili da je prosječan dnevni unos Se u istočnoj Hrvatskoj vrlo nizak te da biofortifikacija može ublažiti pothranjenost selenom. Cilj je ovog istraživanja utvrditi uspješnost biofortifikacije matovilca (Valerianella locusta L.) uzgajanog u kontejnerima dodavanjem Se u različite medije za uzgoj. Pokus je proveden uzgojem matovilca u kontroliranim uvjetima u tri različita medija (komercijalni medij na bazi bijelog treseta, vermikompost i 1:1 smjesa komercijalnog medija i vermikomposta) u sjetvenim kontejnerima s volumenom 52 mL po sjetvenom mjestu. Biofortifikacija Se provedena je dodavanjem 15 mL 40 μM otopine Na2SeO4 u medij 40 dana nakon sjetve. Medij je značajno utjecao na prinos matovilca jer je najveći prinos ostvaren uzgojem na komercijalnom mediju i na 1:1 smjesi s vermikompostom, a značajno niži uzgojem na čistom vermikompostu. Biofortifikacija nije utjecaja na prinos. Utjecaj medija i biofortifikacije na koncentracije Se bio je suprotan, nije utvrđen utjecaj medija, a aplikacija Se rezultirala je 173 puta većom koncentracijom Se u matovilcu nego u kontrolnom tretmanu (1123, 6 prema 6, 5 μg Se kg-1 u svježoj tvari). Rezultati dokazuju veliki potencijal biofortifikacije jer je za preporučeni dnevni unos selena (55 μg) dovoljno konzumirati 48, 9 g svježeg biofortificiranog matovilca ili 8.461, 5 g matovilca bez biofortifikacije.

It is known that wheatgrass is a rich source of nutrients that have a positive impact on human health. Making the juice of it using juicer, the cellulose residue is most often thrown away. The aim of the study was to determine the content of photosynthetic pigments, phenols and vitamin C in the juice and the cellulose residue in ten varieties of wheatgrass and evaluate the amount of active components remaining in the cellulose residue. On average for all varieties, significantly higher amounts of these compounds were found in the cellulose residue as compared to the juice. There was also significant difference in the content of the before mentioned compounds between wheat varieties. The highest average content of chlorophyll a, carotenoids and phenols was found in Katarina variety, the highest content of chlorophyll b in the variety Eurofit and the highest content of vitamin C in the variety Pipi. The data obtained show that the variety significantly affects all of the examined parameters and that more than half of the biologically active compounds tested are lost by throwing the cellulose residue.

Nedostatak selena i cinka u prehrani značajno utječe na zdravlje ljudi. Negativni utjecaj nedostatka i pothranjenost se mogu otkloniti povećanjem koncentracija i bioraspoloživosti mineralnih elemenata (biofortifikacija) u biljnim prehrambenim proizvodima. Cilj ovog istraživanja bio je odrediti utjecaj gnojidbe selenom i cinkom na koncentraciju oba elementa u listovima i glavici kupusa. Pokus s biofortifkacijom proveden je na dva slavonska lokaliteta u istočnoj Hrvatskoj. Mikroelementi su prije sadnje kupusa plitko uneseni na proizvodne površine u obliku vodenih otopina natrij selenata (10 g Se ha-1 u obliku Na2SeO4) i cinkovog sulfata (2, 5 kg Zn ha-1 u obliku ZnSO4×H2O). Aplikacija selena rezultirala je statistički značajnim povećanjem koncentracije Se u listovima i glavi kupusa. Koncentracije selena u listovima bile su osam puta veće, a u glavici četiri puta veće nego u kontrolnim biljkama (642, 4 ; 383, 0 i 79, 5 μg Se kg-1). Suprotno tome, biofortifikacija cinkom imala je zanemariv utjecaj na koncentraciju cinka u ispitivanom biljnom materijalu. Niti jedan tretman nije imao značajan utjecaj na prinos. Pokus je pokazao učinkovitost aplikacije natrij selenata na obogaćivanje biljnog materijala selenom i opravdava praktične i ekonomske aspekte biofortifikacije.

The quality and quantity of light are important factors for the production of quality seedlings of vegetables. Effective portion of the spectrum for photosynthesis is in the red and blue light, however, in the production of seedlings additional LED lighting that emits light just in the range of those wavelengths are often used. The aim of this study was to determine the effect of red, blue and combinations of red and blue LED lights and fluorescent lights on morphological characteristics, SPAD index and the content of chlorophyll, carotenoids and phenol in the leaves of pepper (Capsicum annuum L.) in two terms of measurements during the growth. The highest content of chlorophyll, carotenoids, SPAD index and the largest leaf area was established in the treatment red + blue LED illumination. The lowest values of the width and length of the leaves were found in plants grown under red LED light while the lowest total plant height determined in plants grown under fluorescent lights. From these results we conclude that additional LED lighting using a combination of light from the blue and red parts of the spectrum can positively affect the growth and development of seedlings of pepper. Further research is needed to determine the most favourable ratio of before mentioned wavelengths of the spectrum through the stages of growth and development as well as for individual varieties, because numerous studies confirm different response of certain varieties in the same plant species.

The reflective mulch foil is used for increasing fruit quality of different fruit crops, including apple, especially in orchids where hail nets are installed. Fruit crops under hail nets can have enhanced vegetative growth, reduced photosynthesis and lower fruit quality. Reflective mulches especially influence coloration of apple fruits through effect on anthocyanins and flavonoids. This makes fruits more attractive to consumers, but also increases their nutrient value. In this study effect of reflective mulch foil on photosynthesis of apple leaves was investigated. The study was conducted in the apple orchard of Agricultural Centre Ltd. in Valpovo (Eastern Croatia) with hail nets. Two cultivars were used, Idared and Jonagold. Treatments included trees beneath which reflective foil was set, while control had regular inter- row cultivation. Photosynthetic efficiency was analysed by measuring polyphasic chlorophyll a fluorescence rise (OJIP). Measurement were performed on east and west side of the trees. Results did not indicate strong influence of reflective mulch foil on PSII functioning and photosynthetic performance of apple plants. In some cases overall photosynthetic performance index (PIABS) was increased in treated plants and slight differences in absorption of light energy, trapping, electron transport and dissipation of excitation energy were detected, but generally both treated and control plants showed high levels of photosynthetic efficiency. This might be due to favourable environmental conditions which enable use of maximal photosynthetic capacity even without reflective mulching. Additional experiments in less favourable environmental conditions could provide better inside into possible effects of reflective mulches on photosynthesis of apple plants.

Numerous studies so far confirmed the positive effects of low concentrations of hydrogensulfide (H2S) on the physiological response of plants, in the conditions of various types of abiotic stress. However, the effect of sodium hydrogensulfide (NaHS) as donor of H2S in plant organism is still not clarified enough. Here, the influence of NaHS solutions (0, 50, 100, 200 i 500 mM) applied into the supstrate, on the pepper plants (Capsicum annuum L.) grown in the presence of 150 mM NaCl was evaluated. On average, in both variants of NaCl stress, clorophyll content was unaffected by the applied NaHS treatments, whereas the highest NaHS concentration significantly reduced the carotenoid content. In salt stress conditions, the application of 50 as well as 100 mM NaHS significantly reduced lipid peroxidation rate in pepper leaves. Also, NaHS application lowered proline content regardless of salt stress. Leaf area of the plants treated with 50 and 100 mM NaHS was not significantly reduced in salt stress conditions. The obtained results suggest the positive effect of low H2S concentrations on pepper plants grown under salt stress conditions.

U standardnoj tehnologiji proizvodnje sadnog materijala in vitro kao i uporabom novih poboljšanih TIB sustava vrlo često dolazi do oksidativnog stresa i oštećenja staničnih struktura biljnog tkiva. Termalna destrukcija visoko koncentriranih otopina šećera u postupku autoklaviranja pod visokim pritiskom dovodi do ubrzane degradacije šećera (saharoze) hidrolizom pri čemu nastaje toksičan HMF (5- hydroxymethylfurfural). Također dolazi do ireverzibilnog snižavanja pH usljed sinteze organskih kiselina (mravlja, mliječna i levulinska) koji imaju vrlo izražen inhibitorni efekt na rast biljaka. Cilj istraživanja bio je utvrditi antioksidativni odgovor analizom tkiva malina pri čemu razina lipidne peroksidaze predstavlja jedan je od najčešće prihvaćenih biomarkera oksidacijskog stresa. 2017. godine na Poljoprivrednom fakultetu Osijek provedeno je ispitivanje mogućnosti stabilizacije tekućeg hranjivog medija bez autoklaviranja kod multiplikacije malina u sustavu submerznih bioreaktora (TIB). Modifikacija DKW tekućeg medija izvršena podešavanjem razine pH (6.2 i 7.2) uz dodavanje 0.03 % NaOCl. Kao kontrola analizirane su biljke malina multiplicirane standardnim postupkom u staklenim teglama na polučvrstom mediju (DKW, pH 6.2). Na kontrolnom tretmanu utvrđena razina lipidne peroksidaze je značajno viša u odnosu na tretmane iz TIB sustava. Međutim, nema značajne razlike u ukupnom sadržaju fenola i ukupnoj antioksidativnoj aktivnosti između kontrole i oba tretmana iz TIB sustava. Daljnja istraživanja potrebno je usmjeriti na uspostavljanje boljeg antioksidativnog statusa tretiranih biljaka i različitih antioksidacijskih parametara.

Metallopeptidases of the M49 family are proteolytic enzymes that contain highly conserved HEXXXH motif and whose catalytic activity depends on the zinc cation [1]. Dipeptidyl peptidase III (DPP III) is the best characterized member of this family with distribution detected in almost all forms of life. The physiological role of DPP III has not been precisely determined, however it is assumed that it is involved in intracellular protein catabolism, mammalian pain modulatory system, and in the defense against oxidative stress. Flavonoids belong to the group of polyphenolic compounds that are ubiquitous in plants. They are important component of human diet and seem to have various pharmacological actions [2]. In this study, we selected 15 dietary flavonoids belonging to four different structural subclasses to investigate their potential inhibitory activity (at the physiological concentration i.e., 100 μM) against human DPP III. Inhibition of DPP III activity was determined using the spectrophotometric method [3] with minor modifications. For that purpose, purified recombinant human DPP III was briefly preincubated with a flavonoid in buffered solution and the enzymatic reaction was started with a Arg-Arg β- naphthylamide as a substrate. After the incubation time the reaction was stopped and the absorbance at 530 nm was measured. The percentage of enzyme inhibition (% inh.) was calculated by comparing the enzymatic activity without (normal activity) and with a flavonoid (inhibited activity). The results, obtained by in vitro assay showed that all analyzed dietary flavonoids have inhibitory effect against human DPP III hydrolytic activity at given concentration. The strongest inhibition (% inh. > 90) has been obtained with galangin, genistein, fisetin, kaempferol, and luteolin. A slightly lower inhibition (% inh. 50-90) has been observed for 3, 6- dihydroxyflavone, 3, 7- dihydroxyflavone, 6- hydroxyflavone, apigenin, morin and quercetin, while 3-hydroxyflavone, chrysin, flavone and flavanone have shown an inhibition of less than 50%. These data indicate that the presence and exact distribution of different structural groups on dietary flavonoids are important for their inhibitory properties. [1] N. D. Rawlings, F. R. Morton, C. Y. Kok, J. Kong, and A. J. Barrett Nucleic Acids Res 36 (2008) D320– D325. [2] S. Kumar, A. K. Pandey, Sci. World J. (2013) 162750. [3] M. Abramić, M. Zubanović, Lj. Vitale, Biol. Chem. Hoppe-Seyler 369 (1988) 29–38.

During the 3-years study maize (Zea mays L.) production in the eastern Republic of Croatia suffered a great losses due to periods of flood (2010) and droughts (2011 and 2012). Excessive amount of water as well as lack of it caused variation of yield and efficiency of irrigation scheduling. Irrigation treatments included a rainfed treatment and irrigation up to soil water content 80-100% of field capacity. The nitrogen fertilization treatments were 0 (control) and 200 kg N/ha. The analyzed crop productivity parameters were 1000-grain mass and grain yield, in two hybrids. The irrigation significantly increased maize grain yield in dry years, while in extremely wet year 2010 yield in the irrigated plot was reduced doe to stress caused by excessive rainfall and over- irrigation. Both tested hybrids responded positively to the combination of nitrogen fertilizer and irrigation. Regardless of if expressed on fresh tissue or dry weight basis, proline content in maize leaf did not show clear effect of irrigation treatment, whereas nitrogen fertilization stimulated this amino acid accumulation. There was a close relationship established between proline in leaf dry matter in both growth stages and 1000- grain mass, as well as a weak relationship between this parameter at flowering and final grain yield.

Moderna rasadničarska praksa razvijenih članica Europske unije u proizvodnji sadnica specijaliziranih kultura (maline, kupine, borovnice, aronije i dr.), ali i strateških kultura kao što su masline, temelji se dijelom ili u potpunosti na uporabi suvremenih biotehnoloških metoda (mikropropagcija in vitro). U cilju još veće učinkovitosti i masovnosti posljednih godina veliku ekspanziju ima reprodukcija klonskog materijala u bioreaktorima nove generacije. TIB (eng. „Temporary Immersion Bioreactor“) sustavi, odnosno submerzni bioreaktori. To su visoko modularni biotehnološki sustavi koje karakterizira visoka učinkovitost i skraćeni ciklus proizvodnje usljed bržeg rasta biljnih kultura. Povećana je stopa multiplikacije, stopa preživljavanja u fazi aklimatizacije (ex vitro) te je utvrđena odlična adaptibilnost transplatiranih biljka in vivo. Dodatno prednosti su smanjenje troškova pripreme medija, ušteda električne energije, potrebne radne snage i laboratorijskog prostora. Zbog poboljšanih konstrukcijskih rješenja olakšana je manipulacija biljnim materijalom čime se lakše i jednostavnije postiže masovna proizvodnja. Visoka razina automatizacije te masovna proizvodnja velikim kompanijama omogućava superiorne uvjete na tržištu, a europskim proizvođačima voća osigurava repromaterijal deklarirane kvalitete po povoljnijim cijenama. Iako je naglašeno smanjenje troškova proizvodnje i povećana učinkovitost, navedeni sustavi zahtjevaju naročitu pozornost u poštovanju protokola i kontroli aseptičnih uvjeta pri manipulaciji biljnim materijalom. Kako je tehnologija nova i podložna brojnim modifikacijama, neprestano se radi na poboljšanju laboratorijskih protokola za komercijalni uzgoj sve većeg broja biljnih kultura.

Suvremena rasadničarska praksa u svijetu pri proizvodnji sadnica i podloga specijaliziranih kultura već 30-tak godina koristi tehnologiju kulture biljnog tkiva (mikropropagacija in vitro). Konvencionalana metoda temeljena na polučvrstom mediju (agar) je široko rasprostranjenna zbog jednostavnosti i niskih troškova, međutim veliki utrošak ljudskog rada definira njene limite. Submerzni bioreaktori nove generacije TIB (eng. „Temporary Immersion Bioreactor“) su visoko modularni biotehnološki sustavi koje karakterizira visoka učinkovitost i skraćeni ciklus reprodukcije klonskog materijala. Poboljšana multiplikacija, aklimatizacija (ex vitro) te odlična adaptibilnost transplatiranih biljka in vivo uz dodatno smanjene troškove pripreme medija, uštede električne energije, potrebne radne snage i laboratorijskog prostora, glavne su prednosti navedenih sustava. Visoka razina automatizacije te masovna proizvodnja velikim kompanijama osigurava superiorne uvjete na tržištu, a europskim proizvođačima voća repromaterijal deklarirane kvalitete po povoljnijim cijenama. TIB tehnologija je još „mlada“ i razvija se, a njena modularnost pogoduje brojnim modifikacijama u cilju neophodne standardizacije laboratorijskih protokola za komercijalni uzgoj sve većeg broja biljnih kultura

Otpornost na stres je znaĉajan preduvjet za uspješnu proizvodnju soje u sve zahtjevnijim agroekološkim uvjetima, a meĊu razliĉitim vrstama abiotskog stresa istiĉu se sušni, temperaturni i solni stres. Cilj ove disertacije je bio istražiti neke od fizioloških mehanizama reakcije soje na navedene vrste stresa. Istraživanja su provedena sa šest kultivara soje u fazi klijanje-nicanje te dva kultivara u fazi cvatnje. U prvom pokusu je sjeme soje naklijavano u papirnim ruĉnicima natopljenim vodom ili otopinom koja je imala odreĊeni osmotski potencijal. Primijenjene su po dvije razine sušnog (otopina PEG 5% i 10%), solnog (otopina NaCl 50 i 100 mM) i temperaturnog stresa (10°C i 30°C, voda) te kontrola (20°C, voda) tijekom 7 dana. Osim % klijavosti, mase klijanca i hipokotila, analiziran je sadržaj vodikovog peroksida, prolina, fenola, intenzitet lipidne peroksidacije te ukupna i specifiĉna aktivnost enzima askorbat-peroksidaze, katalaze, gvajakol-peroksidaze i glutation-reduktaze u hipokotilu. Najjaĉi stresni uĉinak imali su viša razina sušnog stresa (PEG 10%) te niska temperatura (10°C). Visoka temperatura je djelovala povoljno na razvoj klijanaca, a blagi sušni stres (PEG 5%) je imao „priming“ efekt i povećao klijavost. Odabrana dva kultivara su u drugom eksperimentu uzgojena u posudama s tlom na otvorenom do faze cvatnje (R2), nakon ĉega su izložene razliĉitoj temperaturi (30°C, 10°C i 20°C kao kontrola) tijekom tri dana u klima komori. U najrazvijenijoj troliski su analizirani sadržaji fotosintetskih pigmenata i pokazatelji uĉinkovitosti fotosinteze, te svi prethodno navedeni pokazatelji reakcije biljke na stres. Vrlo znaĉajan utjecaj tretmana u obje razvojne faze soje, potvrĊuje da su primijenjeni tretmani izazvali oksidacijski stres i obrambene reakcije soje na molekularnoj razini. U cjelini, ukupne aktivnosti ispitivanih enzima su bile veće u klijanju na 10°C, a u cvatnji na 30°C, što sugerira razliĉitost stresnog efekta ambijentalne temperature ovisno o fazi razvoja soje., Stress resistance is an important pre-condition of successful soybean production in demanding agroecological conditions. Among different types of abiotic stress, drought, temperature and salt stress are the most prominent. This PhD dissertation aimed to investigate some of the physiological mechanisms of soybean response to the above mentioned stresses. The research was performed with 6 cultivars in the germination - emergence stage and two cultivars in the flowering stage. In the first experiment, soybean seed was germinated in paper towels soaked with water or the solution with given osmotic pressure. Two levels of drought (5% and 10% PEG solutions), salt (50 and 100 mM NaCl solutions) and temperature stress (10°C and 30°C), as well as control treatment (20°C, water) were applied through a 7 days germination period. Beside the evaluation of the seed germinability (%) at the end of the treatment, seedling and hypocotyl masses, the content of hydrogen peroxide, proline, phenols, the lipid peroxidation rate were determined, as well as total and specific activity of ascorbate peroxidase, catalase, guaiacol peroxidase and glutathione reductase in hypocotyl tissue were analysed. The highest stress effect in the germination stage had a higher level of drought stress (10% PEG) and low temperature (10°C). High temperature (30°C) was favourable for seedling development and mild drought stress (5% PEG) have had a “priming” effect and increased germination rate. In the second experiment, selected two cultivars were grown in the pots, filled with soil and kept in the open until the flowering stage (R2), and afterwards exposed to different temperature conditions (30°C, 10°C and 20°C as control treatment) during 3 days in a climate chamber. The contents of photosynthetic pigments, photosynthesis efficiency parameters and all the aforementioned physiological indicators of plant response to stress were determined in the most developed trifoliate leaf. Highly significant treatment influence on the analysed parameters in the both growth stages, confirms that the applied treatments invoked the oxidative stress and defence reactions in soybean at molecular level. In general, the total activities of tested enzymes were higher at 10°C in germination stage, and at 30°C in flowering stage, which suggests a diversity of stress effects of ambient temperature depending on the growth stage in soybean.

Trends in intensive peach production point to a constant need to reduce production costs, which implies the need for finding quality solutions for thinning peaches. Thinning is in most cases carried out manually, which represents the most expensive technological operation. Chemical thinning was conducted in 2013 (Osijek, eastern Croatia) on cultivars ‘Redhaven’ and ‘Dixired’, age 14 years with planting distance 4 × 2 m (1250 trees/ha) on Prunus persica L. seedling rootstock. The individually treatments included different chemical concentrations of ATS (1, 5 and 3 %) and soybean oil (5 %). All treatments applied to the observed varieties had a positive impact in reducing the number of fruits as compared to the control. Reduction in the percentage of the fruit at ‘Dixired’ ranged from 53 % (5 % soybean oil) to 73 % (3 % ATS), or the 64 % at ‘Redhaven’ (ATS 1.5 %) to 85 % (3 % ATS). Treatment ATS (3 %) was significantly more effective as compared to other treatments for variety ‘Dixired’ or ATS (3 %) and soybean oil (5 %) in the variety ‘Redhaven’ were significantly more effective compared to the ATS (1.5 %). Based on pomological analyzes all treatments with ATS applied on the cultivar Dixired resulted in significantly higher fruit weight, while treatment with soybean oil resulted in a significantly greater fruit firmness in Redhaven. The results indicate the potential use of the ATS on the cultivar Redhaven and ‘Dixired’ in order to achieve a balanced control of tree crop load and fruit quality while, at the same time reducing the consumption of human labor. The ATS and soybean oil with regard to the composition and origin of the active substances exhibit the full potential use in ecological mode of stone fruit production.

The research of light and substrate role in leaf photosynthetic pigments, free proline content and flower quality indices in two gerbera cultivars (Vino and Ruby Red) showed that flower stems were longer in additional lighting treatment, coco’ s peat amended with rice chaff and cultivar Ruby Red. Chlorophyll b concentration was in negative relation to leaf proline content and correlated to longer flower stems. In general, the higher leaf total chlorophyll concentration was related to longer stems, and such flowers have had larger flower heads. Flower head diameter did not differ significantly between cultivars ; it was dependent on light regime, substrate and their interaction.

Besides already well known actions in animal organisms and described effects on stomata closing in plants, nitric oxide (NO) influences on seed dormancy, flower development, root gravitropism, gene expression, plant defence reactions in pathogen attack, photomorphogenesis, Zn excess tolerance, antioxidative protection from UV-B radiation etc. Similar issues are now being addressed with regards to hydrogen sulphide (H2S). A body of literature exists which shows that H2S can affect the growth of plants, but more recent work has been published that suggests that H2S is a more fundamental molecule which is produced by plants and used to control different plant functions. Known as a signalling molecule in both animal and human tissues, H2S participates in signalling crosstalk in plants during stress, helping them to overcome unfavourable growth conditions through an increase of stress enzymes activity, preventing membranes destruction and enhancing accumulation of osmoprotective metabolites such as proline. It is probably the interaction of H2S with metabolism of other reactive species which accounts for many of the effects seen. Furthermore, we showed that H2S mediates stomatal opening using A. thaliana L. and Capsicum annuum L. plants as a model systems. Using the specific NO fluorescence probe it was shown that H2S reduced NO accumulation to a large extent, which may account for the effects of H2S seen. Further research should reveal if the interactions of H2S and NO signalling pathways may regulate some other metabolic responses in plants, as well, with possible influence of H2S on plant productivity and quality.

Polietilen glikol (PEG) se dobiva polimerizacijom etilen oksida (EO) s vodom, monoetilen glikolom ili dietilen glikolom uz alkalnu katalizu. Produkt je molekula jednostavne kemijske strukture: HO [CH2 CH2 O]n H, gdje je (n) broj EO jedinica. Najznačajnije svojstvo svih PEG-a je topljivost u vodi, što ih čini prikladnim za bezbrojne različite aplikacije. PEG-i se često primjenjuju u istraživanjima odnosa biljaka prema vodi, osobito za simulaciju sušnih uvjeta (osmotski stres). Osmotski potencijal vodenih otopina PEG-a 6000 je u vezi s njegovom koncentracijom. U ovom radu su prikazani rezultati fiziološkog odgovora sjemena soje uvjetovan osmotskim stresom primjenom PEG-a u fazi klijanja. Uz vodu kao kontrolu, primijenjene su dvije razine osmotskog stresa – 5% (-0, 5 bara) i 10% (-1, 48 bara) otopina PEG 6000 kao medij za klijanje sjemena. Sadržaj slobodnog prolina, ukupnih fenola i intenzitet lipidne peroksidacije tkivu hipokotila klijanaca soje se povećao pri višoj koncentraciji otopine PEG 6000 (jači intenzitet osmotskog stresa). Budući da su se ispitivani kultivari soje razlikovali u pojedinim parametrima metaboličkog odgovora, PEG se može smatrati pogodnim sredstvom za simulaciju osmotskog stresa. Polyethylene glycols (PEG) are produced by polymerization of ethylene oxide (EO) with water, mono ethylene glycol or diethylene glycol under alkaline catalysis. The result is a very simple chemical structure: HO [CH2 CH2 O]n H, where (n) is the number of EO- units. The most important property of all PEGs is their solubility in water, which makes them ideally suitable for use in countless different applications. PEGs have been widely used in the study of the water relations of plants, especially for simulating drought (osmotic stress) conditions. Osmotic potential of aqueous solutions of PEG 6000 is related to its concentration. Here, we presented the results of physiological response of soybean seed to PEG-imposed osmotic stress in germination stage. Beside water (control), two levels of osmotic stress were applied - 5% (-0.5 bars) and 10% (-1.48 bars) PEG 6000 solution as a medium for seed germination. The level of free proline, total phenols and lipid peroxidation in hypocotyl tissue increased with PEG concentration (osmotic stress intensity). As the tested soybean cultivars differed in particular metabolic parameter response, PEG might be considered as a convenient tool for osmotic stress simulation.

High salinity in soil, substrate or nutrient solution reduces the availability of free water resulting in cell protoplasm dehydration, oxidative stress and overall disruption of plant physiological processes. A good water supply to leaf epidermal cells is crucial for proper stomata movements, thus an important physiological adaptation of plants to salt stress includes a modulation of guard cells function. As opposite to salt tolerant halophytes, most agricultural plants are glycophytes with an increased susceptibility to Na+ ions, which stimulate stomata opening and affect transpiration regulatory mechanisms. Here, leaves of a typical glycophyte i.e. pepper plant (Capsicum annuum L.) were treated with hydrogen sulfide (H2S) donors (NaSH, GYY4137), a nitric oxide (NO) donor (SNP) and their combinations in vitro, with the aim to establish the effects of H2S and NO on stomata movements during salt stress and a recovery period. As expected, in unstressed plants, both the H2S donors stimulated stomata opening, with a pronounced effect of NaSH. In combined treatments the effects of NO and H2S were mutually neutralized, and the apertures were similar to control (untreated epidermal peels). In plants exposed to 150 mM NaCl for three days, SNP closed the stomata while both H2S donors led to stomata opening, again with the pronounced effect of NaSH. Combinations of SNP and H2S donors had similar effects on stomata aperture as observed in unstressed plants. After a recovery period, treatment with SNP caused stomata closure and the effect of H2S donors alone was ablated. Although the effect of NO was more suppressed when in the combination with GYY4137. In general, salt stress stimulated pepper stomata to open, which continues even during a recovery phase. These results suggest that NO and H2S interact during and after salt stress in pepper, with different H2S donors efficacy seen in recovery stage. As water availability and other ecological conditions such as CO2 concentration, temperature and irradiation affect stomatal movements, H2S and NO donors could be used as potential regulators of plant transpiration rate, especially in salt sensitive plants. Further research should give an insight into how these two gasotransmitters interact in multiple stress conditions and other agricultural species.

Grain crops such as soybean are very sensitive to unfavourable climatic conditions at flowering stage. Drought and/or temperature deviations at this developmental stage result with low fertilization, diminished grain number per plant and consequently significant yield loss. In such stress conditions various antioxidative mechanisms at physiological levels can be detected. This research shows some of the responses to unfavourable temperature in flowering stage of two soybean cultivars, after three day exposure to heat (30oC) and chilling stress (10oC) in growth chamber. As the water supply was not restricted, leaf tissue analysis showed different responses to temperature treatments in particular cultivar. In general, lipid peroxidation intensity was higher at low temperature, however, hydrogen peroxide level, free proline and total phenols content were higher at 30oC. This temperature resulted with higher antioxidative enzymes activities (ascorbate peroxidase, catalase, guaiacol peroxidase) as compared to low temperature conditions. On the contrary, the highest glutathione reductase activity was established at low temperature but not statistically different from 20oC (control) and 30oC. Tested cultivars showed significant differences only at high temperature, with lower lipid peroxidation level in cultivar Zora, which had the higher ascorbate- and guaiacol peroxidase activity as well, in comparison with cultivar Tena. As a low temperature is rare during the soybean flowering stage in a continental climate, and above optimal temperatures are expected to occur more frequently due to global climate changes, it is obvious that high temperature stress tolerance is an important trait in soybean.

Heavy metal Cd is a cumulative poison and poses a threat to the environment due to its extreme toxicity, and is known to elicit an oxidative stress in plant cells. Almost 50% of Cd that enters the living organisms is introduced through food of plant origin (vegetables, fruits and grains). Besides other origins of soil contamination with Cd, it may be introduced into the soil solution by phosphorus fertilizers which may contain Cd as an impurity. Therefore, our aim was to assess the effect of Cd on growth of soybean plants and their potential to uptake and accumulate Cd from the nutrient solution. Seeds of four soybean cultivars (NS-OPTIMUS, NS-MAXIMUS, KORANA and TENA) were germinated in dark at 26°C in sterilized sand. After four days of germination, the seedlings were transferred to pots containing ½ strength Hoagland nutrient solution. Plants were grown in a greenhouse, under semi-controlled conditions. When the first trefoil developed, CdCl2 was added to the nutrient solution to attain 0 (control), 0.5, 5 or 50 µM final Cd concentrations. Twenty six days after treatment with Cd begun, plants were harvested. Cd content was analysed in dry matter of roots, stems, the youngest fully developed trefoil and the other leaves. Cd treatment reduced both fresh and dry mass of soybean plants. This reduction increased with Cd concentration in growth media. At 50 µM Cd in NS-OPTIMUS and NS-MAXIMUS root dry weight was only about 40% of the respective control whereas in Korana and Tena it was as much as 70%. Leaf dry weight, on the contrary, was much less reduced in NS-cultivars (80% and 93% of the control) whereas in Korana and Tena it was 45% and 57%, respectively. These two cultivars did not show plant dry weight decrease at 5 µM Cd. Percentage of dry matter increased in all cultivars and at all applied Cd concentrations, with the highest increase in leaves, implying tissue dehydration as an effect of Cd toxicity. Concentration of Cd in roots of all cultivars and at all Cd treatments was about 10 ppb. Surprisingly, concentration of Cd in stems and leaves was very similar to the one measured in roots. In general, higher differences were found in plant fresh and dry weight, as well as in dry matter percentage, depending on Cd treatment and cultivar, than in the concentrations of Cd in different tissues of tested soybean cultivars.

Hydrogen sulphide (H2S) is known to be produced by both animal and plant tissues suggesting that this compound may be involved in cell signal transduction. There is a growing body of evidence to suggest that the presence of this gasotransmitter may modulate oxidative stress metabolism in cells. In collaboration between English and Croatian Universities, it was found that pepper plants pre-treated with H2S donors, such as NaSH and GYY4137, and exposed to the salt stress, showed significant differences in lipid peroxidation levels, hydrogen peroxide and proline concentrations. Cucumber seeds pre- treated with H2S donors and germinated in NaCl solution, showed a significant influence of H2S treatments on the same parameters as in pepper. The results suggested that H2S may have a regulatory role in stressed plants and may affect the accumulation of protective metabolites such as proline. Crucial tools in this kind of research are H2S-releasing compounds with different chemical properties, such as cell permeability or H2S releasing rate, along with in vivo methods of detection of H2S using highly specific fluorescence probes. As well as for purely academic reasons these compounds may have practical applications in agriculture through the fostering of plant environmental stress tolerance.

Functional food such as fruits and vegetables, gained much interest due to beneficial impact on human’s health - reduced risk of chronic, degenerative and of oxidative stress mediated diseases, such as cancer, cardiovascular and neurodegenerative diseases. The strawberry (Fragaria x ananassa Duch.) fruit generally possesses a high level of antioxidant activity that can be related to total phenols content, to high vitamin C content or both. In this research the effects of biostimulators (Viva and Megafol) and reduced fertilization level on the productivity and fruit quality of soilless grown strawberry cultivar Elsanta have been investigated, during two fruitbearing seasons. The tested fruit quality parameters were the total antioxidant capacity (TAC), total ascorbic acid (AA), total anthocyanins (AC), total phenolics (PHE) and nitrates (NO3) content. Our results indicated a stimulating effect of a combination of biostimulators but only in the second year of fruitbearing (the spring experiment), where plants treated with both Viva and Megafol gained the highest yield. In the first year of fruitbearing (the fall experiment), at reduced rate of fertilization, total phenolics content in strawberry fruits was significantly higher while nitrates content was significantly lower which is of particular importance for its nutritional value.

In plants high concentrations of hydrogen sulphide (H2S) can inhibit enzymes such as cytochrome oxidase. Based on this, and its similar inhibitory effects, H2S has commonly been thought of as a phytotoxin. However, at lower concentrations, it may act in a more positive manner. Many plant species have been found to generate H2S suggesting that it may be an endogenous chemical and suitable to be considered as signalling molecule. There is a growing body of evidence to suggest that the presence of this gasotransmitter may impact on oxidative stress metabolism in plants. The treatment of plant cells with H2S affects both cysteine and glutathione metabolism but are there other plant physiological pathways which can be affected by H2S? The activity of stress- related enzymes and also the content of some specific metabolites are often used as physiological stress response parameters. In greenhouse growing, plants are often exposed to unfavorable growth conditions due the salt stress, while at the same time numerous H2S- based preparations are often used as fungicides. Thus, our study aimed to further explore the potential role of H2S in plant physiological pathways, with a particular focus on the possible protective role of H2S in salt stress conditions. Pepper plants grown in substrate under fully controlled conditions were pre-treated with H2S donors (NaHS, GYY4137) and exposed to the three different levels of salt stress. Significant differences between individual treatments and pre- treatments were observed. Total activity of catalase, glutathione reductase and guaiacol peroxidase were significantly increased at 100 and 200 mM NaCl. The applied salt stress treatments increased lipid peroxidation rates as well as free proline and hydrogen peroxide content. In general, both H2S donors decreased lipid peroxidation levels in leaves, while NaHS reduced free proline and hydrogen peroxide content. Salt stressed plants pretreated with GYY4137 showed significantly higher free proline content. The results suggest that H2S may have a protective role in the case of salt stress, through increasing enzymatic activity and the accumulation of stress protective metabolites such as proline. Lowered lipid peroxidation in plants pre-treated with H2S donors implies that this gasotransmiter can protect cell membranes constituents from chain destruction, whether through direct involvement in ROS neutralization, or through the synthesis of important antioxidants such as glutathione.

Krupna i srednja frakcija sjemena tri kultivara soje (Zora, Lucija i Korana) su testirani uobičajenim metodama analize kvalitete sjemena (masa 1000 zrna, sadržaj vlage, energija klijanja - EK, standardni test klijavosti - SK) te “cold” testom (CT). Zatim je proveden test konduktiviteta sjemena (EC) “bulk” metodom na tri konstantne temperature imbibicije (10, 20 i 30oC, 24 h), uz određivanje % usvojene vode sjemenom tijekom imbibicije. Ispitivani kultivari soje se nisu značajno razlikovali po EK, SK i CT. Srednja frakcija je imala vrlo značajno veću EK i SK u odnosu na krupnu frakciju. Prema postojećoj kategorizaciji EC sjemena za krupnozrne leguminoze i CT, obje frakcije sjemena pokazuju visok vigor. EC sjemena soje je varirao od 18, 0 μScm-1g-1 do 29, 5 μScm-1g-1, s vrlo značajno većim vrijednostima na 30oC. Najveći EC, uz najmanji CT, utvrđen je kod sjemena kultivara Korana. Frakcija sjemena nije značajno utjecala na EC. Značajna negativna korelacija između EC i CT kod sjemena srednje frakcije indicira da je EC na 20oC pogodan za brzu analizu vigora sjemena soje, ukoliko u uzorku prevladava srednja frakcija. Količina usvojene vode sjemenom nakon imbibicije u EC je iznosila od 114, 5 do 130, 4% u odnosu na početnu masu sjemena. Uz značajan utjecaj kultivara, frakcije i njihove interakcije, najveći intenzitet usvajanja vode utvrđen je pri najvišoj temperaturi imbibicije i kod srednje frakcije sjemena. Dobiveni rezultati upućuju na daljnja istraživanja procesa imbibicije sjemena u laboratorijskim i poljskim uvjetima, sa svrhom boljeg poznavanja genetskog potencijala soje za otpornost na imbibicijsko oštećenje i uspješno nicanje u nepovoljnim uvjetima.

Fotokemijski pokazatelji fotosustava II (Fo, Fm, Fv/Fm i Fv/Fo) su analizirani kako bi se ustanovio utjecaj različitih temperaturnih tretmana (10C, 20C i 30C) na osjetljivost fotosustava u listovima dva kultivara soje (Tena, Zora) u fazi cvatnje, u kontroliranim uvjetima. Temperatura od 30C kod ispitivanih genotipova je izazvala veći stres u odnosu na temperaturu od 10C. Masa listova po biljci je na 30C kod oba genotipa bila značajno manja kao i učinkovitost fotosustava II (Fv/Fm). Učinkovitost fotosintetskog transporta elektrona je kod Zore više varirala ovisno o temperaturi nego kod Tene. Obzirom da je kultivar Tena pokazao manju varijabilnost i kod morfoloških svojstava lista, može se zaključiti da je prema otpornosti na temperaturni stres u fazi cvatnje stabilniji genotip od Zore.