Odziv male vodne leče (Lemna minor L.) na različne oblike in koncentracije selena : magistrsko delo

Brudar, Nina (author), Germ, Mateja (mentor)

Selen je kemijski element v sledovih in esencialen mikroelement za ljudi, živali in mikroorganizme, medtem ko za rastline to še ni dokazano. Je široko razširjen v zemeljski skorji, pojavlja pa se tudi v tleh, morski ter sladki vodi, rudninah in sedimentih. Na prisotnost selena v okolju vplivajo klimatske razmere, geološka sestava tal in številni antropogeni dejavniki. Pojavlja se v štirih oksidacijskih stanjih. Selenit je najpomembnejša oblika selena v tleh. Ta se lahko zaradi mikrobiološke aktivnosti pretvori v selenat. Selenit in selenat sta najbolj topni anorganski obliki selena in sta zaradi tega za rastline najbolj dostopni. Učinek selena je odvisen predvsem od tega, v kateri obliki in v kakšni koncentraciji je selen prisoten v rastlini. Preučevali smo vpliv različnih koncentracij in oblik selena na biokemijske in morfološke lastnosti male vodne leče. Rastline smo izpostavljali različnim koncentracijam (1 mg/L, 2 mg/L in 5 mg/L) raztopin natrijevega selenita (Na2SeO3) ter različnim koncentracijam (1 mg/L, 2 mg/L in 5 mg/L) raztopin natrijevega selenata (Na2SeO4). Rastline smo izpostavljali tudi kombinaciji selenita in selenata, s koncentracijo 2 mg/L selenata in 2 mg/L selenita. Uporabili smo tudi kontrolno skupino, ki je rasla v rastnem gojišču brez dodanega Se. Med poskusom smo merili fotokemično učinkovitost fotosistema II (FS II) s fluorometrom PAM 2500, aktivnost elektronskega transportnega sistema (ETS), s prostim očesom pa smo opazovali morfološke spremembe (sprememba barve stebelnih členkov, štetje stebelnih členkov in propadanje korenin) ter pripravili vzorce za merjenje fotosinteznih barvil (klorofil a, klorofil b, karotenoidi) in antocianov. Na koncu poskusa smo stehtali svežo in suho maso vseh rastlin in opravili meritve fotosinteznih barvil. Ugotovili smo, da so rastline, ki so bile izpostavljene koncentracijam (1 mg/L, 2 mg/L in 5 mg/L) natrijevega selenata, (1 mg/L, 2 mg/L in 5 mg/L) natrijevega selenita ter kombinaciji natrijevega selenita in natrijevega selenata, slabše rasle ter so imele posledično nižjo fotokemično učinkovitost fotosistema II (FS II), nižjo aktivnost elektronskega transportnega sistema (ETS) in nižje koncentracije fotosinteznih barvil. Študija bo pripomogla k razumevanju vpliva različnih oblik in koncentracij selena na malo vodno lečo.

• Language: Slovenian
• Keywords: selenit, selenat, mala vodna leča, Lemna minor L.
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: PEF - Faculty of Education
• Publisher: [N. Brudar]
• Year: 2017
• Number of pages: X, 68 str.
• PID: 20.500.12556/RUL-96205
• UDC: 546.23:582.532.4(043.2)
• COBISS.SI-ID: 11734601
• Publication date in RUL: 28.09.2017

Secondary language

• Language: English
• Title: The response of duckweed (Lemna minor L.) to different concentrations and compounds of selenium

Abstract

Selenium is a trace element and an essential microelement for humans, animals and microorganisms, whereas this has not been established for plants yet. It is widespread in the earth's crust and occurs in soil, seawater and freshwater as well as minerals and sediments. Climatic conditions, geological composition of the soil and numerous anthropogenic factors affect the presence of selenium in the environment. It can exist in four oxidation states. Selenite is the most important form of selenium in soil. It can convert into selenate due to microbiological activity. Being the most soluble inorganic forms of selenium, selenite and selenate are the most accessible to plants. The effect of selenium depends mainly on its form and concentration in plants. We studied the influence of different concentrations and forms of selenium on biochemical and morphological characteristics of common duckweed. Plants were exposed to various concentrations (1 mg/L, 2 mg/L and 5 mg/L) of sodium selenite solutions (Na2SeO3), various concentrations (1 mg/L, 2 mg/L and 5 mg/L) of sodium selenate solutions (Na2SeO4) and to a combination of selenite and selenate with a 2 mg/L concentration. Furthermore, we used a control group cultured in growth medium with no Se added. During the experiment, we measured the photochemical effect of photosystem II (FS II) with the PAM 2500 fluorometer, the activity of the electron transport system (ETS) and observed with the naked eye the morphological changes (changes in frond colour, counting fronds and root degradation) as well as prepared the samples for the measurement of photosynthetic pigments (chlorophyll a and b, carotenoids) and anthocyanins. We have established that plants that have been exposed to concentrations (1 mg/L, 2 mg/L and 5 mg/L) of sodium selenate, (1 mg/L, 2 mg/L and 5 mg/L) of sodium selenite and the combination of selenite and selenate, grew and developed poorly under stress conditions. Consequently, their photochemical effect of photosystem II (FS II), activity of the electron transport system (ETS) and concentrations of photosynthetic pigments were lower. This study will improve the understanding of how different forms and concentrations of selenium affect the common duckweed.

• Keywords: chemistry, kemija