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Suša utječe na klijanje sjemena i formiranje klijanaca, što rezultira smanjenim rastom, razvojem i prinosom zrna pšenice. Zbog klimatskih promjena sve su češće godine s duljim razdobljima nedostatka vode, što ugrožava proizvodnju pšenice na svjetskoj razini. Kao odgovor na osmotski stres, biljke su razvile različite mehanizme tolerantnosti na sušu, uključujući i ekspresiju različitih gena osjetljivih na stres. Cilj ovog istraživanja bio je odrediti utjecaj osmotskog stresa na ekspresiju gena osjetljivih na sušu u šest hrvatskih genotipova ozime pšenice u fazi klijanaca. Analizirana je ekspresija gena koji kodira pirolin-5-karboksilat sintazu (P5CS), ključnog enzima u biosintezi prolina, te gena koji kodiraju dehidrine (DHN5 i WZY2). Uslijed osmotskog stresa klijanci pšenice akumulirali su prolin, koji je bio u korelaciji s ekspresijom gena P5CS. Ekspresija gena P5CS i WZY2, te posebno DHN5 bila je vrlo visoka i značajno povećana u svih genotipova uslijed većeg osmotskog stresa, dok je u kontrolnim uvjetima bila izrazito niska. Ekspresija gena osjetljivih na sušu doprinijela je tolerantnosti pšenice na sušu, pri čemu je veća ekspresija gena bila prisutna u tolerantnih genotipova. Analiza ekspresije navedenih gena važna je za razumijevanje molekularnih mehanizama tolerantnosti pšenice na osmotski stres, te može doprinijeti selekciji genotipova korisnih za razvoj novih sorti otpornih na sušu. Istraživanje je sufinancirano sredstvima Europske unije iz Europskog fonda za regionalni razvoj (KK.01.1.1.04.0067).

Wheat is one of the main cereal crops for ensuring food security for the 21st century. Thus, increase of grain yield is a major target for breeders, where insights into wheat productivity can be achieved by studying the activity of components of the photosynthetic apparatus, such as chlorophyll fluorescence kinetics. The present study was conducted in a set of three winter wheat varieties (Triticum aestivum L.) (Tika Taka, El Nino, and Vulkan) at two experimental sites in the vegetation season 2019/2020. Chlorophyll fluorescence measurements were used to evaluate the onset and rate of the flag leaf and head senescence every few days, beginning at the heading stage (0 day after heading, DAH) until mid-senescence stage (26 DAH) on field-grown varieties with similar grain yield capacity and maturation time. The objectives of this study were to evaluate the agronomical performance of wheat varieties and to test photosynthetic efficiency across different environments. Consequently, this research was focused on how Alternaria and Fusarium infections affected chlorophyll a parameters along with grain yield. The analysis of variance demonstrated significant effects of locations on the grain yield and its components. Tika Taka exhibited the highest yield reduction (27.1%) at Tovarnik, compared to Osijek, followed by El Nino (20.5%) and Vulkan (18.7%). Beside, significant differences for locations, 1000 kernel weight showed significant differences for varieties. Although there were not any significant differences in the grain yield between varieties, higher reductions over locations could be due to earlier senescence and contracted grain fill duration at location Tovarnik due to prolonged wet conditions which provoked natural infection by Fusarium or Alternaria species at the grain filling stage. This is supported by the evidence that at Tovarnik there were increased amounts of tentoxin, deoxynivalenol (DON), don-3-glucoside (D3G), 3-acetyldeoxynivalenol (3-ADON), zearelenone (ZEN), culmorin and 15-hydroxyculmorin and therefore the energy fluxes ratios ABS/RC, TR0/RC, ET0/RC, DI0/RC increased in effect of dual-stress. Opposite to that, at location Osijek, ‘staygreen’ traits positively affected grain size, and thus overall grain yield, through maintenance of grain fill.

Nettle (Urtica dioica L.) is a traditional medicinal plant in Croatia. It is considered as an important source of natural antioxidants that have a positive effect on the human health by fighting various diseases and slowing down aging. Nettle grows in different habitats and can easily adapt to changes in environmental conditions. However, prolonged exposure to a certain environmental factor, such as low temperature, can negatively affect the growth and development of plants causing increased formation of reactive oxygen species and the occurrence of oxidative stress. In such conditions, plants activate a highly effective antioxidant system. The aim of this research was to determine the influence of low temperature on nettle’s antioxidant activity. The nettles were grown under controlled conditions (temperature 22±1 °C, photoperiod 16h/8h, light intensity ~ 100 umol m-2s-1). When they reached adult stage, they were exposed to low temperature (10 °C) for various time periods: 12h, 24h and 48h. Untreated plants were considered as a control group. In order to describe the antioxidant activity, the iron reduction antioxidant capacity (FRAP), the content of total soluble polyphenols (PHE) and the content of ascorbic acid (AA) were determined. Exposure to low temperature after only 12h led to a decrease in AA compared to the control group, while the content of PHE did not change during exposure to low temperature. On the other hand, only long-term exposure to low temperature (48h) led to an increase in the antioxidant capacity of the nettle plants. The results indicate that prolonged exposure of nettles to low temperatures promotes the activation of the antioxidant system, while even short exposure to these conditions affects the reduction of secondary metabolites.

Predviđanje ishoda bioloških procesa jedan je od glavnih ciljeva modernih biljnih znanosti, a podrazumijeva uporabu modela. Strojno učenje (machine learning (ML)) predstavlja novi paradigmatski okvir s ciljem inkorporiranja velike količine podataka u svrhu predviđanja ishoda složenih bioloških procesa, doduše s ograničenom interpretabilnošću modela. Na temelju prethodnih istraživanja, pokušali smo predvidjeti dvije skupine signalnih puteva pomoću očitanja infracrvene spektroskopije s Fourierovom transformacijom (FTIR) iz sjemenki inbred linija kukuruza. Dvije skupine fenotipova klijanaca su bile otkrivene u prethodnom radu prema odgovoru na stres sušom: prva skupina s promjenom u produktima lipidne peroksidacije (TBARS) koja nadilazi promjenu slobodnog vodikovog peroksida (H2 O2 ) i druga skupina sa suprotnim rezultatom. Prva skupina (TBARS>H2 O2 ) je pokazala veću akumulaciju osmolita. Pretpostavili smo kako je ovaj rezultat uzrokovan kvalitativnim razlikama u sjemenu različitih inbred linija. Analizirani su uzorci sjemena 109 inbred linija samljevenih u fi ni prah i podvrgnuti FTIR spektroskopiji. Rezultati mjerenja su uvršteni u ML algoritam „metoda potpornih vektora“ i pripadnost skupini TBARS>H2 O2, odnosno TBARS

Industrial hemp (Cannabis sativa L. subsp. sativa) is one of the oldest cultivated plants used for many purposes throughout centuries. It has been valued for its nutritional and medicinal properties. Industrial hemp is primary a short-day plant but it can endure great changes in daylight intensity and length which can promote oxidative damage. Therefore, plants must modify their antioxidative responses to combat this stress. In this study, the antioxidative response of two hemp cultivars (USO and Finola) grown under violet light (250 mol m-2 s- 1) and different light/dark intervals (18/6, 20/4 and 24/0) was investigated. To determine antioxidative potential, ferric reducing antioxidant power (FRAP) and scavenging effect on the 1, 1-diphenyl-2-picrylhydrazyl free radical (DPPH) assays were employed. The content of total polyphenols was determined spectrophotometrically using Folin-Ciocalteu reagent. Highest FRAP values were observed at 20/4 in both cultivars. DPPH assay showed similar results as FRAP, except that no statistical difference was observed between 16/8 and 20/4 values for the Finola cultivar. The total phenolic content in both cultivars showed the highest values at 20/4 as well, correlating with other two methods and suggesting that phenolic compounds are likely to contribute to radical scavenging activity. All results indicate that 20/4 light interval causes the most stress in plants possibly inducing free radical formation and consequent increase in overall nonenzymatic antioxidant response in order to preserve important bioactive components.

Cannabis sativa L. subsp. sativa, or industrial hemp, has been cultivated for centuries for its nutritional and medicinal benefits. Recently, it has been introduced as functional food with indefinite health benefits and bioactive properties. Indoor cultivation implies control of plant life cycle, the optimum light quality, quantity and photoperiod which leads to a dynamic growth of Cannabis biomass as well as the production of desirable cannabinoid profile. Cannabis is a primary short–day plant and manipulations in photoperiod can favor vegetative growth or flower initiation. The aim of this study was to determine the influence of different photoperiods (16/8, 20/4 and 24/0 ; 250umol m-2s-1) on the photosynthetic efficiency in two cultivars of Cannabis (Finola and USO) by measuring fast chlorophyll a fluorescence. Both cultivars revealed lowest total performance index (PItotal) at 20/4 compared to 16/8 suggesting this was the least favorable light/dark ratio. By calculating total driving forces for photosynthesis (DFtotal), significant negative values were observed at 20/4 in both cultivars. Estimation of partial driving forces revealed that reductions in DFtotal were the result of more negative rate constants for electron transport between two photosystems (yE0) as well as of the events that involve PSI (dR0). Such results suggested that exposure to 20/4 photoperiod decreased the contribution of dark reactions to the overall potential of energy conversion in both Cannabis cultivars.

High temperature stress is one of the major abiotic stresses that causes different physiological and molecular responses in crops. Class III peroxidase reduce the levels of reactive oxygen species (ROS) in the cells and therefore, represent effective part of the antioxidant system. We investigated physiological and biochemical response of two barley varieties, modern Zlatko and old autochthonous variety Mursa, to short-term heat stress. Plants were grown under controlled conditions with a daytime temperature of 23 ℃ (16 hours) and a night temperature of 18 ℃ (8 hours). After 14 days of cultivation, barley seedlings were exposed to heat stress during 24 hours at 35 ℃ (day) and 23 ℃ (night). Oxidative stress parameters, hydrogen peroxide and lipid peroxidation, didn’t increased. However, significantly increased guaiacol peroxidase activity was observed in both genotypes. Measurements of photosynthetic efficiency indicated that shortterm heat stress decreased values of photosynthetic efficiency index (PIABS) and the maximum quantum yield (Fv/Fm) in both varieties. In conclusion, old variety Mursa showed increased total chlorophyll, carotenoid and protein concentrations in comparison to modern variety Zlatko indicating better activation of protective mechanisms. The antioxidative defense triggered efficient and fast activation of peroxidase directed to diminish deleterious action of ROS generated by short-term heat stress in both barley varieties.

Industrijska konoplja (Cannabis sativa L. subsp. sativa) je biljka kratkog dana no podnosi velike promjene u duljini i intenzitetu dnevnog svjetla što dovodi do promjena u antioksidacijskom odgovoru na oksidacijski stres. Antioksidacijska aktivnost je čest predmet istraživanja zbog važnosti u obrani organizma od različitih bolesti te usporavanju njegova starenja. Cilj ovog istraživanja bio je istražiti utjecaj različitih svjetlosnih intervala (18/6, 20/4 i 24/0 (svjetlost/tama)) na antioksidacijski odgovor dviju sorti industrijske konoplje (Finola i USO) uzgajanih na ljubičastom osvjetljenju (~250 mol m-2 s-1). U tu svrhu određena je koncentracija produkata lipidne peroksidacije (TBARS) i aktivnosti gvajakol-peroksidaze (GPOD). Uzgoj na najduljem svjetlosnom intervalu (24/0) doveo je kod obje sorte do stvaranja najviše razine TBARS. S druge strane, sorta USO pokazala je najvišu aktivnost GPOD pri istim uvjetima uzgoja. Svjetlosni interval 16/8 djelovao je najmanje stresno na obje sorte. Povećane vrijednosti produkata lipidne peroksidacije i aktivnost GPOD ukazuju da su biljke pri uzgoju na svjetlosnom intervalu 24/0 u stanju najvećeg stresa. Pri tome je vjerojatno došlo do nastanka slobodnih radikala koji uzrokuju povećanje antioksidacijskog odgovora kako bi se spriječila oštećenja važnih bioloških molekula.

Fusarium head blight (FHB) is a serious disease of wheat (Triticum aestivum L.) which can reduce yield and quality of the grain. In order to investigate effect of FHB on photosynthesis of winter wheat varieties with different susceptibility, artificial inoculation with Fusarium graminearum and F. culmorum (1:1) was performed in the field at the Agricultural Institute Osijek in 2019/2020. Analysis of fast chlorophyll a fluorescence transients of flag leaf and ear revealed that more significant changes in photosynthetic efficiency due to FHB occurred in ears, in comparison to leaves. Decrease of performance index (PIABS) and maximum quantum yield of PS II (TR0/ABS) in the inoculated ears, in comparison to control (natural infection) of variety Golubica was detected three days post inoculation, indicating that changes in photosynthetic apparatus of this susceptible variety occurred before visual symptoms of the infection. Upon symptom development, inoculated ears of Golubica showed increase of PIABS and TR0/ABS, while progression of the disease resulted in reduced photosynthetic performance, in comparison to control. Impact of FHB on ear photosynthetic efficiency of resistant variety (Galloper) was also evident, especially in the later stages of the infection, but it was less severe than for variety Golubica. Overall, this study indicated that Fusarium sp. infection may induce changes in photosynthetic performance and functioning of PSII in ears of wheat.

Microgreens have recently become very popular food product. They are considered as “functional food” containing high content of bioactive components and antioxidants that can benefit human health. Although they are easy to grow, the artificial lighting could significantly influence the antioxidant capacity and the content of phytochemical components. The aim was to determine the effect of two different artificial light sources on antioxidant properties of radish microgreens. The study was performed on three cultivars of radish (Raphanus sativus L.): China rose (CHR), Sango and Daikon. Radishes were grown in a growth chamber with artificial purple and white LED lighting (45 umol m2s-1, 24°C, photoperiod 16h/8h). Physiological status of 7-day old microgreens were determined by measuring total antioxidant capacity (DPPH and FRAP), amount of total soluble phenols (PHE), sugar and proteins, as well as the concentrations of ascorbic acid (AA), carotenoids, total chlorophylls and anthocyanins. Our results showed that white light provoked higher PHE ant ANTH in Sango. However, purple light induced higher antioxidant capacity, PHE and AA in CHR and Daikon as well as higher AA and PROT in all three cultivars. Therefore, purple LED lighting had more beneficial influence on antioxidant properties of radish microgreens compared to white LED lighting.

The use of Viscum album as a remedy has ancient tradition in treating various diseases. The cytotoxic and immunomodulatory properties of different Viscum album preparations have been intensively studied in the last years. Besides antitumoral and quality of life–promoting activities Viscum album applications reduce side effects of conventional anticancer therapies. Chemical properties of Viscum album could be influenced by factors like type of host, geographical locations, mistletoe harvesting season, freshenes of plant (fresh mistletoe/comercial tea pruducts/ dried fresh mistletoe, etc.). Information regarding the functional group presence in different mistletoe comercial products like teas and fresh leaves from the continental and coastal part of Croatia is lacking. We hypotheise that data obtained by FTIR spectroscopy will show a high correlation with the elemental composition of mistletoe samples. The FTIR spectra of the eight samples showed distinct features that enabled their discrimination through Principal Componenent Analysis (PCA) models with high accuracy. Regardless of the type of the sample, PCA showed that the location of a sample has substantial influence on the obtained FTIR results, so it is possible to distinguish the FTIR spectra of continental from coastal samples, as well as samples from eastern part of Croatia from those from central Croatia.

Microgreens are tender, immature green vegetables with fully developed cotyledons or partially developed first true leaves. They often contain higher concentrations of active compounds compared to mature vegetables or seeds. Microgreens are highly valued for their rapid cultivation and high concentrations of active compounds and are also considered a ‘functional food’ that contains healthpromoting properties and prevents the development of certain diseases. The biggest disadvantage of microgreens is their short shelf life. Microgreens are difficult to store due to their high surface-to-volume ratio, high respiration to transpiration rates, and accelerated senescence. The study was performed on three cultivars of radish (Raphanus sativus L.): China rose (CHR), Sango (S) and Daikon (D). Radishes were grown in a growth chamber with artificial purple (3 red: 1 blue) LED lighting (45 umol m2s-1, 24°C, photoperiod 16h/8h). The aim of this study was to determine the effect of storage (7 days, +4C°) on the physiological status of microgreens compared to fresh ones by measuring total antioxidant activity (DPPH and FRAP). The amount of total soluble phenols (PHE), sugar (TSS) and protein (PROT), as well as the concentrations of ascorbic acid (AA), carotenoids (CAR) and anthocyanins (ANTH) were also determined. Three investigated cultivars revealed similar response to 7-day storage. Generally, all three cultivars showed increase of CAR and decrease of AA while PROT and ANTH levels remained unchanged. Unlike S and D cultivars, CHR displayed significant decrease of antioxidant capacity what lead to simultaneous decrease of PHE and AA. On the other hand, D showed significant decrease of PHE, while TSS content increased compared to fresh ones. Our results suggested that seven-day storage in refrigerator does not induce inhibition of most secondary metabolites. However, CHR cultivar was shown to be the most sensitive to low temperature storage.

Dnevni unos selena (Se) kroz prehranu najčešće je odraz njegove prisutnosti u tlu određenog područja. Zbog velike zastupljenosti područja siromašnih Se, sve je veći broj oboljelih od malnutricije, koja se može spriječiti biofortifikacijom usjeva i različitim dodacima prehrani. Danas su na tržištu dostupni različiti preparati klijanaca pšenice koji se zbog svoje velike nutritivne vrijednosti koriste kao dodatak svakodnevnoj prehrani. Zbog velike važnosti Se za zdravlje čovjeka i biljaka kao glavnog izvora ovog esencijalnog mikronutrijenta, cilj je ovog istraživanja bio uzgojiti klijance pšenice (Triticum aestivum L., sorta Kraljica) obogaćene Se. Kako asimilacija Se može utjecati na različite metaboličke puteve, cilj je također bio odrediti utjecaj različitih kemijskih oblika Se (selenata i selenita) u rastućim koncentracijama na nutritivnu vrijednost klijanaca pšenice (7 dana starih). Kao pokazatelji nutritivne vrijednosti mjereni su koncentracija vitamina C, koncentracije klorofila i karotenoida, sadržaj topljivih fenola, sadržaj proteina, ukupnih šećera i količina celuloze (vlakana), te ukupna antioksidacijska aktivnost. Tretmani selenatom i selenitom značajno su povećali količinu Se u izdancima pšenice ovisno o primijenjenoj koncentraciji, s tim da su količine Se bile znatno veće pri tretmanu selenatom. Selenat kao i selenit neznatno su ili uopće nisu utjecali na većinu mjerenih parametara nutritivne vrijednosti, osim u slučaju antioksidacijske aktivnosti gdje su oba tretmana uzrokovala njeno povećanje. Stoga, klijanci pšenice obogaćeni Se zbog svoje velike nutritivne vrijednosti obećavajući su dodatak prehrani te bi mogli pridonijeti rješenju problema malnutricije.

The agriculture is economically very significant for Croatia, so this sector should be more productive and sustainable. However, crop production is relatively low in Croatia and the yields of basic crops are below European levels. One of the key problems is climate change, which results in significant damage to crop production, and can reduce crop yields up to 20-70%, depending on intensity and duration of unfavourable conditions. Consequently, farmers have reduced their agricultural activity or even abandoned it due to higher production costs and lower yields. Along with investigation of wheat response to drought, we will investigate the resistance of wheat to the most dangerous diseases, such as rusts and Fusarium Head Blight (FHB).Those diseases can spread and cause disease epidemics which can result in reduced yield and quality of the wheat. Through the project, the effect of abiotic (drought) and biotic (FHB and rusts) stresses on wheat are investigated by different assessments in the field, accompanied by laboratory analysis including expression of the genes and proteins and analysis of physiological status of the plants. Thus, dehydrins (DHNs) will be investigated which are believed to play an important protective role in plant cell during dehydration. In addition, abscisic acid (ABA) will be determined because expression of many DHNs increases by this phytohormone. Furthermore, different pathogen resistance (PR) genes could be induced or suppressed independently in response to diseases which will be determined in the post inoculation time. Overall, this study may help to develop precise phenotyping tools to identify physiological traits such as ear and leaf photosynthesis that could contribute towards increasing grain yield. The ear photosynthesis is thought to play an important role in terms of the source of photo- assimilates during grain filling, not only under different stresses, but also under optimal agronomical conditions. The social benefit of the project will be manifested in the creation of healthier wheat varieties with more resistance to Fusarium spp. and therefore with decreased concentration of mycotoxins, in order increase food safety and protect the human health. In addition to health risks, mycotoxins have a detrimental effect on the quality and the processing performance of wheat. Furthermore, multi‐mycotoxin contamination from FHB is of great concern and it will be investigated, as co‐ contaminated samples might exert adverse health effects due to synergistic effect during co- occurrence of several mycotoxins.

Diffuse agricultural pollutants, such as agricultural residues, fertilisers, pesticides and excessive salt release in the environment have potentially devastating effects on the plants. Common dandelion (Taraxacum officinale Weber) is herbaceous perennial with wide geographic distribution that often grows in extremely polluted habitats. It is considered as good biological indicator of contamination since it can tolerate wide range of environmental conditions. The aim of this study was to assess the physiological state of dandelion in rural environment by measuring iron (III) reducing antioxidant capacity (iRAC) and ferric reducing antioxidant power (FRAP) that describes antioxidative activity. Total phenolic content (PHE), ascorbic acid content (AA) and total protein concentration (PROT) were determined as well. Dandelion leaves were collected at 30 different agricultural areas near Osijek that had differential exposure to pollution (polluted and non-polluted). Significant increase of antioxidative capacity and PROT concentration in dandelions in polluted areas was accompanied with decrease of PHE and AA content. Our results suggested that dandelions in polluted agricultural areas show inhibition of secondary metabolites production despite good physiological performance due to high antioxidant capacity

In urban areas plants are most often exposed to various abiotic stress factors. Dandelion (Taraxacum officinal Weber) is a very abundant species which can grow in urban areas. In this study we collected samples from 30 locations in city of Osijek which included traffic zones and parks (polluted and less polluted locations). Analyses included total chlorophylls, carotenoid, polyphenols and ascorbic acid content as well as antioxidant capacity measured by FRAP (Ferric Reducing Antioxidant Power) and iRAC (Iron (III) Reducing Antioxidant Capacity) assays. Results showed decrease in all measured biochemical parameters and antioxidant capacity in dandelion plants growing on/near traffic locations in comparison to less polluted locations such as parks and meadows. Observed results suggest suppression of metabolic processes and higher sensitivity to ecological stress in dandelion plants exposed to traffic zones. Results of this work will contribute to the understanding of physiological and biochemical responses of dandelion to environmental stress and its role as a bioindicator of environmental pollution in urban areas.

Biljke su tijekom rasta i razvoja često izložene različitim stresnim čimbenicima. Budući da je ječam jedna od glavnih žitarica koja se koristi u ljudskoj i životinjskoj ishrani nužno je razumjeti strategije prilagodbe na stres i kreirati tolerantne kultivare. Cilj ovog istraživanja bio je odrediti sadržaj ukupnih topljivih šećera (TSS) u listovima dvadeset kultivara ozimog ječma tijekom razvoja u varijabilnim vremenskim uvjetima. Kultivari su rasli na eksperimentalnim poljimaPoljoprivrednog instituta Osijek. Uzorkovanja su izvršena tijekom tri fenološke faze. Prosječne vrijednosti TSS izmjerene tijekom vlatanja, cvatnje i nalijevanja zrna su iznosile 37, 18, 43, 44 i 46, 17 mg g-1 suhe tvari. Porast količine izmjerenih šećera može se povezati sa blagom sušom koja je zabilježena tijekom cvatnje i nalijevanja zrna. U istraživanim kultivarima zabilježena je različita akumulacija šećera. U pet kultivara ('Zlatko’, ‘Casanova’, ‘Maxim’, Osk.5.87/1-13 i ‘Lord’) sadržaj šećera nije se mijenjao tijekom razvoja. U dva kultivara ('Barun' i 'Bravo') akumulacija ukupnih šećera započela je u fazi nalijevanja zrna, dok je u ostalima akumulacija šećera zabilježena već tijekom cvatnje. Rezultati ovog istraživanja ukazuju na prisutnost različitih mehanizama prilagodbe na blagu sušu. Brojna dosadašnja istraživanja također su pokazala osjetljivost TSS na stres izazvan sušom. Nadalje, razlike u sadržaju ukupnih topljivih šećera mogle bi se koristiti tijekom selekcije kultivara tolerantnih na sušu.

Climate changes and their negative impacts on environment are in the focus of scientific community for the last decades. Big interest is pointed towards plant stress physiology as plant’s growth and development are highly affected upon presence of stressors. Salinity and drought are considered the major abiotic stresses resulting in decreased crop’s yields and quality. Knowledge about survival and sustained growth of agronomical important crops during severe environmental conditions presents valuable tool to cope with these issues. Within this purpose, three important Brassica cultivars (Chinese cabbage, white cabbage and kale) were selected and exposed to drought and salinity treatments. Using the interdisciplinary approach, we wanted to underline the response of selected cultivars by observation of salt ions uptake, osmotic adjustment, oxidative stress defense mechanisms and impairment of photosynthesis and biomass production. Furthermore, the fluctuations in phytohormones levels and hormonal cross-talk were the focus of the research due their role in environment sensing and mediating physiological processes. Response mediated by abscisic acid (ABA), salicylic acid (SA) and jasmonates (JAs) together with the altered levels of growth promoting hormones: indole-3- acetic acid (IAA), cytokinins (CKs) and brassinosteroids (BRs) revealed differences in tolerance of Brassicas to drought and salinity. Research conducted on different response levels enabled us to characterize selected crops from the most tolerant to the most sensitive in following order: kale, white cabbage, Chinese cabbage and conclude that drought and salinity tolerance is mostly determined by changes in endogenous levels of phytohormones. However, as the hormonal cross-talk and defense mechanism are very complex, additional research at the molecular level is necessary to shed light on the hormonal players and the interactions responsible for drought and salinity tolerance in Brassicaceae.

Fruktani u biljkama predstavljaju rezervne ugljikohidrate koji se skladište u stabljici, lukovici i korijenu, a imaju važnu ulogu u zaštiti biljke u stresnim uvjetima. U žitaricama, kao što je ječam (Hordeum vulgare L.), fruktani se tijekom razvoja pohranjuju u stabljici i poslije cvatnje se mobiliziraju u zrno te mogu značajno utjecati na prinos u normalnim, a posebno u stresnim uvjetima. Cilj ovog istraživanja bio je istražiti sadržaj fruktana u stabljici 15 odabranih kultivara ozimog ječma iz oplemenjivačkog programa Poljoprivrednog instituta Osijek. Uzorci su prikupljeni u tri razvojne faze: vlatanje, cvatnja i nalijevanje zrna. Uočene su značajne varijacije sadržaja fruktana u pojedinom kultivaru. Budući da nakupljane fruktana počinje u fazi cvatnje, tako je i ovdje zamijećen značajni porast kod 14 kultivara, u odnosu na fazu vlatanja, osim kod kultivara Osk.4.37/14-14. Značajni porast sadržaja fruktana, u odnosu na cvatnju, uočen je kod sedam kultivara u fazi nalijevanja zrna, a najveći porast je kod kultivara Osk.5.36/25-15 (187 µg g-1 suhe tvari, s.t.), 'Panonac' (121 µg g-1 s.t.), 'Titan' (177 µg g-1 s.t.) te 'Osvit' (138 µg g-1 s.t.) u odnosu na cvatnju gdje je zabilježena prosječna vrijednost sadržaja fruktana ova četiri kultivara od 53 µg g-1 s.t. Budući da je došlo do pojave blage suše u fazi cvatnje koja se zadržala i u fazi nalijevanja zrna, ovakav značajni porast sadržaja fruktana ukazuje na potencijalnu osjetljivost pojedinih kultivara na stresne uvjete.

Sadržaj lignina i celuloze ovisi o brojnim čimbenicima uključujući genotip, razvojnu fazu te čimbenike u okolišu. U ovom radu istraživane su promjene sadržaja lignina i celuloze u deset kultivara ozimog ječma (Hordeum vulgare L.) oplemenjivačkog programa Poljoprivrednog instituta Osijek tijekom jedne razvojne sezone. Biljni materijal, koji je uključivao stabljiku, uzorkovan je u tri razvojne faze: vlatanje, cvatnja i nalijevanje zrna. U fazi vlatanja najmanji sadržaj lignina izmjeren je u kultivaru 'Osk5.36/25-15' i iznosio je 36 mg g-1, a najveći sadržaj, 150 mg g-1 suhe tvari (s.t), izmjeren je u kultivaru 'Osk.4.36/9-14'. Sadržaj celuloze kretao se od najmanje 41 % u kultivaru 'Osk.4.37/14-14', do 59 % s.t. u kultivaru 'Panonac'. U fazi cvatnje sadržaj ukupnog lignina i celuloze varirao je među kultivarima u odnosu na vlatanje. U pojedinim kultivarima došlo je do smanjenja sadržaja lignina i celuloze. U fazi nalijevanja zrna sadržaj lignina i celuloze porastao je u odnosu na cvatnju. Najveći sadržaj lignina iznosio je 157 mg g-1 kod kultivara 'Osk.4.37/14-14', a najmanji 133 mg g-1 s.t. kod kultivara 'Osk.5.36/25-15', dok je sadržaj celuloze varirao od najmanje 36 % do najviše 52 % s.t. kod svih kultivara. Smanjenje ukupnog sadržaja lignina u cvatnji može se pripisati pojavi blage suše. Porast lignina u fazi nalijevanja zrna posljedica je razvojnih procesa vezanih za lignifkaciju stabljike, ali može također predstavljati i mehanizam adaptacije pojedinih kultivara na uvjete blagog stresa.

Global warming and climate changes have enormous negative impact on crop production in affected areas. Increased soil salinity and drought are abiotic stresses particularly pronounced in Mediterranean, semi-arid, and arid climates. The abiotic stress tolerance of Brassica crops correlated with certain changes in plant hormones such as salicylic acid (SA), abscisic acid (ABA), auxins (IAA), cytokinins (CS) and brassinosteroids (BR). The effect of salinity stress and drought was evaluated on selected Brassica crops: Chinese cabbage (Brassica rapa ssp. pekinensis), white cabbage (B. oleracea var. capitata forma alba) and kale (B. oleracea var. acephala) with particular focus on the role of plant hormones in abiotic stress tolerance. Based on the physiological and biochemical markers the Chinese cabbage exhibited the lowest tolerance, followed by the white cabbage, while the kale appeared to be the most tolerant to drought and salinity stress in aplied experimental conditions.

Remote sensing by acquirement of Normalized Difference Vegetation Index (NDVI) is widely used nowadays for assessing crop biomass, yield and other traits. This study aimed to determine the variation of NDVI and its relationship with the most significant agronomic properties of 20 elite winter barley genotypes. NDVI measurements were conducted at several vegetation stages while grain yield, hectoliter and lodging were the observed traits. Results from this study showed that the influence of genotype varied significantly for grain yield and hectoliter, especially when measured biomass displayed a successive rise of genotypic variability after the onset of booting towards anthesis which was confirmed by correlation. Therefore, significant genotypic variation of NDVI values could be efficiently used for indirect identification of productive winter barley genotypes.

Aleppo pine (Pinus halepensis L.) is widely spread Mediterranean woody species. Its natural and cultivated populations can be frequently found in the coastal area of the Adriatic Sea. Usually, needles fall down after the second year, what can be the reason for substantial crown defoliation under extreme environmental stress. The aim of this investigation was to compare the chlorophylls content and photosynthetic performance in current- year (CY) and previousyear (PY) A. pine needles. Chlorophylls concentrations were determined spectrophotometrically and the photosynthetic performance was determined by measuring the increase in chlorophyll a fluorescence (JIP test). Results revealed that concentrations of chlorophylls a and b were almost two folded in PY needles compared to CY ones, what was statistically significant. Chlorophylls a to b ratio and values of the maximum quantum yield of the photosystem II (Fv/Fm) showed no statistical significance between CY and PY needles. However, performance index (PIABS) was significantly higher in CY needles compared to PY ones. Based on the presented results it can be concluded that despite of considerably lower chlorophylls content, CY needles reveled enhanced photosynthetic performance than older needles. The analysis of JIP test parameters showed that the main reason for this was better utilization of absorbed light energy in CY needles due to their more competent photosynthetic electron transport, in comparison to PY needles.

Prijašnja istraživanja pokazala su da manjak vode i teški metali, poput kadmija (Cd), imaju snažan učinak na biosintezu lignina u korijenu kukuruza. U ovom radu istraživan je utjecaj manjka vode i kadmija na sadržaj lignina u korijenu dvije roditeljske linije (B73, Mo17) i njihovog hibrida (B73xMo17). Biljke su bile izložene manjku vode, kadmiju (otprilike do 5 mg Cd/ kg tla) i kombiniranom tretmanu kadmija i manjka vode. U dobro navodnjavanim biljkama (kontrola), B73, Mo17 i B73xMo17, ukupni sadržaj lignina iznosio je 131, 96, 103, 19 i 212, 56 mg/g suhe tvari. U linijama B73 i Mo17 nije zamijećeno značajno smanjenje sadržaja ukupnog lignina u odnosu na kontrolu bez obzira na tretman. Međutim, u hibridu (B73xMo17) sadržaj lignina značajno se smanjio nakon tretmana kadmijem (182.26 mg/g suhe tvari) u usporedbi s kontrolom. Najmanji sadržaj lignina izmjeren je u hibridu izloženom manjku vode (154, 34 mg/g suhe tvari), a također i u biljkama podvrgnutim kombiniranom tretmanu manjka vode i kadmija (162, 98 mg/g suhe tvari). Dobiveni rezultati pokazuju da korijen hibrida kukuruza (B73xMo17) ima generalno niži sadržaj lignina bez obzira na tretman u usporedbi s dobro navodnjavanim biljkama (kontrolom). Objašnjenje za ovo smanjenje ukupnog sadržaja lignina moglo bi se pripisati adaptivnom odgovoru hibrida budući da je sličan efekt zabilježen u listovima kukuruza izloženih suši.

Cadmium exposure and water deficit are among the most powerful abiotic stress factors affecting crop growth and productivity. Present study was conducted to evaluate the oxidative damage and the antioxidative response management in the leaves of two maize inbred lines (A: B84, B: Os6-2) and their hybrid (AxB: B84xOs6-2) subjected to excess Cd and or no water limitation in the greenhouse experiment during flowering phase. In well- watered conditions, the increase of lipid peroxidation level (LP) in A and AxB affected by Cd indicates its toxicity, while in B higher amount of accumulated proline could be the reason of maintained LP. In A increased activities of guaiacol peroxidase (POD), ascorbate peroxidase (APX) and catalase (CAT) were shown while in B POD and APX were increased. Water limitation caused decrease in RWC in A, B and AxB. Higher decrease of RWC was observed in combination of stress factors in A and B but not in AxB. The increase of LP and proline content as well as higher activity of POD and APX was observed in A. In B only POD and APX were increased. Increased APX and higher proline accumulation in AxB might be the reason of decreased LP and unchanged POD. Inhibition of CAT activity was observed in A, B and AxB. Obtained results showed different strategies of antioxidative mechanisms in maize inbred lines and their hybrid subjected to investigated stress factors. It seems that hybrid is more tolerant than its parental lines probably due to heterosis and dilution effect.

Indigobush (Amorpha fruticosa L.) is widely distributed invasive species native to North America. It was deliberately introduced to Europe primarily to prevent soil erosion, but recently it is often planted for decoration, honey production and biomass energy production. Uncontrolled expansion of Indigobush represents a significant threat to native species due to its rapid growth and reproduction as well as its allelopathic activity that negatively affects nearby vegetation. The aim of this study was to analyze and compare changes in photosynthetic performance of Indigobush and accompanying woody species (Quercus robur L. and Alnus glutinosa (L.) Gaertn.). Therefore, photosynthetic performance was analyzed by measuring direct chlorophyll fluorescence twice during the vegetation season, in May and July. Indigobush seedlings grow in the Pokupsko basin forest complex near Karlovac (Croatia) in stands of varying size and age. For this investigation, three locations were chosen that were about the same size and age. Our results showed that performance index (PIabs) in Indigobush increased significantly in July at all three locations compared to both accompanying species. Moreover, more enhanced electron transport per reaction center (ET0/RC), the efficiency that an electron moves further than primary electron acceptor QA− (ET0/ TR0), maximum quantum yield of primary photochemistry (TR0/ABS) as well as quantum yield of electron transport (ET0/ABS) followed by an increase in structure-function index (SFIabs) in Indigobush was observed in July. Our results suggested that Indigobush was able to utilize absorbedlight energy more efficiently than accompanying native species.

In order to investigate early photosynthetic responses of Chinese cabbage (B. rapa ssp. pekinensis) and kale (B. oleracea var. acephala) to the increased salinity, photosynthetic performance, chlorophylls concentration and relative accumulation levels of the photosynthetic proteins (Rubisco LSU, Cyt f, LHC b II and D1) were analyzed. Plants were grown hydroponically, treated with NaCl in a range of conc. 0-200 mM for a short-term (24 hours). Results showed that investigated species had different tolerance to the salt stress what was based on their different photosynthetic adjustment strategies. Kale, as a more salt tolerant species, revealed considerably better photosynthetic performance under increased salinity conditions due to more competent electron transport, in comparison to the moderately sensitive Chinese cabbage. On the other hand, Chinese cabbage plants decreased considerably their photosynthetic performance under the salt stress conditions. This was due to the less competent electron transport as well as increased light harvesting and trapping properties of PSII. This led to the increase in dissipation flux and the modification of a certain number of RC from active to dissipative ones. The observed differences in the photosynthetic performance of two investigated species corresponded to the differential accumulation of chlorophylls and photosynthetic proteins that regulate electron transport and light harvesting.

Soil salinity is one of the world wide problems affecting crop productivity. In order to evaluate early plant response to high salinity and characterise tolerance markers, three important Brassica crops: Chinese cabbage, white cabbage and kale were exposed to short term salt stress (24 h) in the range of NaCl concentrations (50, 100 and 200 mM). Physiological markers including Na+/K+ ratio and photosynthesis efficiency followed by biochemical stress markers such as proline, antioxidant enzymes and lipid peroxidation (MDA) as well as phytohormones (ABA, SA, JA, JA-Ile, brassinosteroids and IAA) were measured. Significant increase in proline and MDA contents, which are usually reported as strong biomarkers of abiotic stress, were obtained in roots and leaves tissue of Brassica crops, although photosynthetic efficiency was reduced only in Chinese cabbage. In parallel, osmoregulation through increased levels of ABA was shown to be one of the most dominant markers of salinity response among Brassicas. Contrary, levels of jasmonates (JA and JA-Ile) were significantly lower upon high salt in roots and leaves of cultivars. Salinity affected accumulation of growth promoting hormones brassinosteroids and IAA. Levels of brasinolide where significantly increased in roots and leaves of Chinese cabbage compared to other two Brassica crops and similar pattern was observed for active IAA. Salinity induced successive increase in IAA precursors (TRP, IPyA, IAM and IAN) in roots and leaves of three Brassicas but levels of active IAA were significantly higher only in leaves of Chinese cabbage followed by increased level of catabolic oxIAA. Performed PCA analysis revealed correlations among observed phytohormones, biochemical and physiological markers, and revealed Chinese cabbage as the most sensitive cultivar.

Cadmium (Cd) toxicity in soil and water deficit are causing serious problems in natural and agricultural ecosystems. The aim of this study was to investigate the influence of Cd and/or drought on photosynthetic performance of maize. Two maize lines (B84 and Os6-2) as well as their hybrid (B84xOs6-2) were subjected to Cd- induced stress (Cd), drought (D) and combined stress (Cd+D). To evaluate photosynthetic performance, chlorophyll a fluorescence was measured. Total performance index (PItot) is the most sensitive parameter of JIP-test that includes functional activity of photosystem II (PSII), photosystem I and intersystem electron transport chain. The line Os6-2 showed significant decline of PItot subjected to D and Cd+D treatments. In addition, both treatments showed positive L and Kbands, indicating lower PSII stability and destabilization of oxygen evolving center of PSII, respectively. The PItot in the line B84 declined only at D treatment with parallel increase in L-band and positive inflection of K-band. The hybrid showed decrease of PItot at Cd+D treatment with corresponding positive L and K- bands. Decline of the PItot parameter indicated that drought is the main reason for photoinhibition in Os6-2 and B84 lines. Photoinhibition due to the combination of Cd and drought occurred in hybrid and also in line B84. Our results suggested that both investigated maize lines and their hybrid have different strategies to cope with Cd-induced stress and/or drought.

The current cereal production is challenged by the abiotic stress induced by climate changes. Selection and breeding processes aim to select barley cultivars with better adaptation to stress. Drought stress presents one of the environmental stresses with significant impact on agricultural production worldwide. The main objective of this study was to screen and evaluate twenty winter barley cultivars for their photosynthetic performance by using fast chlorophyll a fluorescence parameter during growth season in the experimental fields where plants were exposed to stressful conditions due to drought treatments. Measurements were taken at three growth stages: booting, flowering and grain filling. Total performance index (PITOTAL), which describes potential of energy conservation within photosynthetic apparatus from exciton to the reduction of end acceptors of photosystem I, showed that barely cultivars differed in their response to drought stress. PITOTAL increased from booting to grain filling stage in most of the cultivars except for nine cultivars were decline was observed. In order to estimate the contribution of the different components (density of reaction centers, trapping to dissipation ratio and efficiency of excitation energy conversion to electron transport and performance index) to PITOTAL value, we transformed data to logarithmic values to obtain the parameter of partial driving forces. Stress conditions during growth season induced decrease of total driving force (DFTOT) in six cultivars at flowering stage. Dissipation and density of reaction centers mainly contributed to the lower value while efficiency of excitation energy conversion to electron transport and performance index mainly contributed to higher PITOTAL value in all other cultivars. At grain filling stage all cultivars, except one, revealed positive total driving forces. In conclusion, obtained results suggested that at flowering stage of growing, barley cultivars were more sensitive to stressful conditions comparing to grain filling stage during which plants exhibited more stability in processes within photosynthetic apparatus indicating an adaptation to stress conditions.

Amorpha fruticosa is invasive alien species deliberately introduced to Europe from North America, primarily to prevent soil erosion. It is often planted for decoration and for honey production. Due to its rapid growth and reproduction as well as its allelopatic activity that negatively affect nearby vegetation, uncontrolled expansion represents significant threat to native species. The aim of this study was to examine the influence of seasonal changes of environmental factors, such as temperature, light intensity or water availability on photosynthetic efficiency of A. fruticosa and accompanying woody species (Populus alba or Cornus sanguinea). Therefore, photosynthetic performance was analysed by measuring direct chlorophyll fluorescence twice during vegetation season, in May and July. A. fruticosa seedlings grows in the wide area of the city Županja (Croatia) in stands of varying size and age. For this investigation, three locations (sites) were chosen that were about same size and age. All results were compared to ones measured in May. Our results showed that overall photosynthetic performance (PItotal) of A. fruticosa increased in July while both, P. alba and C. sanguinea revealed decline of the same parameter. The PItotal parameter indicate the integral functional activity of photosystem II (PSII), photosystem I (PSI), and intersystem electron transport chain. In addition, the quantum yields (QY), namely maximum QY of primary photochemistry (TR0/ABS), QY of electron transport (ET0/ABS) and QY for reduction of end electron acceptors at the PSI acceptor side (RE0/ABS) as well as efficiency that an electron moves further than primary electron acceptor QA− (ET0/TR0) increased in A. fruticosa in July at all three sites. At the same time, both accompanying species did not follow increase of those parameters. Therefore, our results suggested that invasive species A. fruticosa follows seasonal variation of environmental factors better than native species.

Promjene u okolišu imaju presudnu ulogu u fotosintetskim procesima što utječe na rast, razvoj i prinos. Budući da se metoda mjerenja fluorescencije klorofila a kontinuirano razvija, analizom podataka koje nam daje ova metoda dobivamo nove informacije o funkcioniranju cjelokupnog fotosintetskog aparata te nam daju trenutnu informaciju o fiziološkom stanju i vitalnosti biljke. Razumijevanje mehanizama odgovora i prilagodbe biljaka na stresne uvjete u okolišu (suša, visoki intenzitet svjetlosti, povišeni salinitet i drugi) od velike je važnosti u uzgoju poljoprivrednih kultura u svrhu odabira otpornijih kultura. Solni stres utječe na smanjenje fotosintetske učinkovitosti, a intenzitet ovisi o duljini stresa te o koncentraciji soli. Dio istraživanja u sklopu projekta PhytoBraCro je upravo utjecaj solnog stresa na fotosintetsku učinkovitost odabranih kultura iz porodica kupusnjača: kineski kupus (Brassica rapa L. ssp. pekinensis), bijeli kupus (Brassica oleracea var. capitata cv. 'Varaždinski') i raštiku (Brassica oleracea var. acephala). Pokazalo se da je kineski kupus najosjetljiviji na promjene u koncentraciji soli, dok je kod bijelog kupusa i raštike tek najviša koncentracija soli značajno utjecala na fotosintetsku učinkovitost. Osim istraživanja utjecaja abiotičkog stresa u kontroliranim uvjetima, dio istraživanja obuhvaća i sezonska istraživanja fotosintetske učinkovitosti invazivne vrste čvitnjače (Amorpha fruticosa L.) te njezin utjecaj na okolnu floru. Invazivne vrste obično karakterizira brzi rast uslijed učinkovitijeg iskorištavanja limitirajućih resursa u odnosu na nativne vrste te su sposobne brzo prilagoditi fiziološke procese promjenama u okolišu. Upravo ta sposobnost brze prilagodbe te manja osjetljivost na promjene u okolišu glavni su razlozi brzog širenja na nova staništa. Naši rezultati su pokazali da čvitnjača ima sposobnost održavanja visoke fotosintetske učinkovitosti sve do stadija stvaranja sjemena, dok okolne vrste ne pokazuju takav trend. To ukazuje da čvitnjača zaista bolje prati sezonske varijacije okolišnih čimbenika u odnosu na nativne vrste.

Ginko biloba and Liriodendron tulipifera can be found in urban environments as a street trees and park trees. Solitary street trees in city centers, compared to trees from city parks, which grow in community with other species, can have different response to stress conditions. The aim of this work was to investigate and compare photosynthetic performance of two species subjected to heat stress. After dark adaptation of plants for 24 h, leaf disc were exposed to varying temperatures (25°C, 30°C, 40°C and 50°C) in a water bath for 10 minutes. Results showed that overall vitality index (PIabs) decreased with higher temperature in both plant species, with Ginko biloba being more tolerant in comparison to Liriodendron tulipifera. Ginko plants growing in streets, as opposed to park, exhibited higher tolerance to increased temperature while Liriodendron showed the opposite pattern. Changes of ratio of trapping excitons and dissipation (TR0/DI0), and of electron transport beyond primary acceptor QA- (ET0/(TR0-ET0)) were shown to be the main reason for the observed differences in PIabs between two species. The selection and use of suitable tree species present important elements in a successful urban landscaping. City’s visual appearance depends on the choice of plant species that could be adapted to urban environmental conditions.