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Špargelj (Asparagus officinalis L.) je trajnica iz družine beluševk (Asparagaceae). Je gospodarsko pomembna vrtnina, pri kateri nabiramo mlade poganjke. V špargljiščih ga pridelujemo predvsem v poznem spomladanskem času, ki je glavni čas pobiranja špargljev. Zaradi povpraševanja po tej vrtnini v drugih delih leta, so razvili različne tehnike gojenja izvensezonskih špargljev, s katerimi bi zadovoljili potrebe kupcev. Po svetu uporabljajo različne tehnike, ki se razlikujejo predvsem glede na klimatske razmere. Poznani so klasični preprosti postopki, kot so uporaba zavarovanih prostorov, prekrivanje tal in nizki tuneli, s katerimi lahko spodbudimo zgodnejši pridelek. Na nekaterih toplejših območjih se je za uspešno metodo izkazala uporaba benzil adenina, za kasnejši prehod v stanje dormance, ali pa sistem »matičnih stebel«, ki omogoča celoletno pridelavo, vendar take rastline dosežejo krajšo življenjsko dobo. Zelo uspešne, vendar investicijsko nekoliko dražje tehnike za izvensezonsko pridelavo, uporabljajo ogrevanje tal pod grebeni špargljev, iz različnih toplotnih virov (geotermalna energija, uporaba biomase). Vsi ti načini pridelave in kombinacije le teh, so zaradi višje cene samega prodajnega produkta izven glavne sezone, uspešni in ekonomsko upravičeni. Asparagus (Asparagus officinalis L.) is a perennial plant of the asparagus family (Asparagaceae). It is an economically quite important vegetable, from which we select young shoots. The main harvesting season in the asparagus fields is in late spring. Due to the demand for this vegetable at other times of the year, various techniques have been developed for growing asparagus out of season to meet the needs of customers. Different techniques are used all over the world, depending mainly on climatic conditions. There are well-known classic, simple techniques such as the use of protected areas, ground cover and low tunnels that can be used to encourage earlier harvesting. In some warmer areas, the technique of using benzyladenine for a later transition to dormancy or the "mother shoot" system is used, which allows year-round production. However, with this technique, the plants have a shorter life span. Very successful, but more expensive techniques for off-season cultivation are heating the soil under the asparagus shoots by various heat sources (geothermal, use of biomass). All these methods of cultivation and their combinations are successful and economically justified, because the product itself out of the main season, obtains a higher price.

Priljubljenost špargljev v zadnjih letih narašča, predvsem zaradi njihovega ugodnega vpliva na zdravje človeka. V okviru diplomske naloge smo želeli podati pregled literature s področja bioaktivnih snovi, ki se nahajajo v navadnem šparglju (Asparagus officinalis L.). Naloga zajema seznam in opis bioaktivnih spojin ter njihovih antioksidativnih in fizioloških učinkov. Poglobi se v delovanje različnih sekundarnih metabolitov kot so fenolne spojine, predvsem flavonoidi, fenolne kisline in antociani ter saponini in ostali antioksidanti. Podrobneje obravnava najbolj zastopane spojine, kot sta rutin in protodioscin, vključuje pa tudi v manjših koncentracijah prisotne bioaktivne komponente, kot so glutation, žveplo-vsebujoče spojine, karotenoidi, klorofili, vitamini in minerali. Opisana je tudi primerjava prisotnosti teh spojin med različnimi deli rastline. Naloga predstavi, kako različni načini pridelave in predelave vplivajo na njihovo vsebnost. Opiše vpliv organske in konvencionalne pridelave ter svetlobe in temperature na stabilnost bioaktivnih spojin. Raziskali smo tudi vpliv različnih načinov skladiščenja, kot je modificirana atmosfera, zamrzovanje in hlajenje na vsebnost omenjenih fitokemikalij. Podani so tudi rezultati določanja antoksidativnega potenciala špargljev. The popularity of asparagus has been rising in the recent years due to its positive effect on human health. In this graduation thesis we wanted to put forward a comprehensive review of literature from the field of bioactive compounds, that are found in the asparagus plant (Asparagus officinalis L.). This thesis includes a list and descriptions of bioactive compounds and their antioxidant and physiological effects. It dives deeper into the function of different secondary metabolites like phenolic compounds, most importantly flavonoids, phenolic acids and anthocyanidins but also includes saponins and other antioxidants. It elaborates on the most abundant compounds such as rutin and protodioscin in addition to those less represented, such as glutation, sulphur-containing compounds, carotenoids, chlorophylls, vitamins and minerals. Furthermore, it compares the content of these compounds in different parts of the plant. This thesis presents how different cultivation systems and processing methods affect bioactive compound concentrations. It focuses on the effects of organic and conventional cultivation along with light and temperature on their stability. We researched how different storage methods like modified atmosphere, freezing and chilling affect phytochemical concentrations. Results of antioxidant potential assays done on asparagus are presented as well.

Namen poskusa je bil preučiti dva ukrepa za pospešitev rasti pri pridelavi zelenega šparglja ter na osnovi zbranih podatkov podati informacijo o uporabnosti ukrepov za pospeševanje rasti in njihov vpliv na zgodnost pridelka. V poskus smo vključili dve obravnavanji: neposredno prekrivanje tal s polipropilensko prekrivko in postavitvijo nizkih tunelov nad vrsticami špargljišča ter nepokrita tla. Poskus smo izvedli v 4 ponovitvah, po 10 rastlin na ponovitev. Tla so bila neposredno prekrita s polipropilensko prekrivko od začetka marca do vznika prvih poganjkov nato smo prekrivko odstranili. Od začetka marca 2017 so bili postavljeni nizki tuneli, prekriti s polietilensko prekrivko, visoki 0,5 m in dolgi 5 m. 3. aprila 2017 smo postavili merilce relativne vlage in temperature. V poskus je bila vključena sorta šparglja 'Dariana'. Meritve na rastlinah smo izvajali med 8. in 18. aprilom 2017. Merili smo hitrost rasti poganjkov ter ob pobiranju dolžino, premer in maso tržnega poganjka. Na podlagi rezultatov, ki smo jih pridobili s poljskim poskusom, smo ugotovili, da neposredno prekrivanje tal s polipropilensko prekrivko in prekrivanje z nizkimi tuneli vplivata na dvig talne temperature, v povprečju za 6,1 °C. Prekrivanje z nizkimi tuneli vpliva na mikroklimo, ustvarja višjo relativno zračno vlago (v povprečju za 3,4 %) in višjo temperaturo zraka (v povprečju za 11,9 °C). Vpliva tudi na hitrejšo rast poganjkov, kar se na koncu odrazi v večjem pridelku (na pokritih tleh 244,5 g/m2, na nepokritih 37,9 g/m2). Na pokritih delih nasada se pobiranje poganjkov začne 6 dni prej kot na nepokritih delih in zato se lahko posledično podaljša sezona pobiranja pridelka. Ugodnejša mikroklima pod nizkimi tuneli je omogočila razvoj večjega števila poganjkov, ki so bili večji, debelejši in težji v primerjavi z nepokritimi gredicami. In our research, two measures to stimulate growth in green asparagus production were studied in order to provide information on the usefulness of growth promotion measures and their impact on crop yield. Two treatments were included in the experiment: covering of soil with polypropylene cover and the placement of low tunnels covered with polyethylene above the rows of asparagus and the uncovered rows. The soil was directly covered with polypropylene from the beginning of March until the first shoots emerged. Then, the cover was removed and the low tunnels, 0.5 m high and 5 m long covered with polyethylene were installed (from the beginning of March 2017). A variety of 'Dariana' asparagus was included in the study. The experiment was designed in 4 replicates and 10 plants in one replication. Measurements on plants were performed between April 8 and 18, 2017. During this period, the growth rate of shoots was measured and at harvest, the length, diameter, and mass of individual shoot were measured. Results showed that low tunnels have an effect of increasing the soil temperature by an average of 6.1 °C. Bed covering with low tunnel affected the microclimate creating higher relative air humidity (on average for 3.4%) and higher air temperature (on average for 11.9 °C) and also affects faster shoot growth which resulted in higher yield (on the covered soils 244.5 g/m² and on the uncovered 37.9 g/m²). On the covered parts of the plantation, the harvest of the shoots starts 6 days earlier than on the uncovered parts and as a consequence, the harvesting season can be prolonged. The more favorable microclimate under the low tunnels resulted in a larger number of harvested shoots that were larger, thicker, and heavier in comparison to the uncovered plots.