The effect of lead on growth and development of pennycress (Noccaea praecox Wulf)

Ker je znano, da rani mošnjak (Noccaea praecox Wulf) v naravi hiperakumulira Cd in Zn v povečanih koncentracijah pa kopiči tudi Pb, je bil glavni namen diplomske naloge ugotoviti, kako svinec vpliva na rast in razvoj te rastline. Rastline ranega mošnjaka so štiri tedne rasle na osnovni hidroponski raztopini, kateri smo po enem tednu v ločene čaše dodali 1, 10 in 100 µM Pb, dve čaši pa sta bili kontrolni. Hidroponsko raztopino smo vsak teden zamenjali s svežo. Enkrat tedensko smo merili dejansko in potencialno fotokemično učinkovitost. Vsem rastlinam smo določili svežo in suho maso korenin in poganjkov ter iz teh podatkov izračunali še količino vode. Prisotnost Pb v vzorcih smo merili s prenosnim rentgenskim fluorescenčnim spektrometrom, sledila pa je analiza fotosinteznih pigmentov. Iz dobljenih podatkov smo izračunali povprečja in rezultate prikazali z grafi. Analize so potrdile, da različne koncentracije Pb različno vplivajo na rast in razvoj rastline in da se Pb večinoma akumulira v koreninah, povečane koncentracije Pb pa smo opazili tudi v poganjkih. Pri analizi fotosinteznih pigmentov smo povečano sintezo fotosinteznih pigmentov opazili pri rastlinah izpostavljenim 1 in 10 µM Pb. Pri fotokemični učinkovitosti fotosistema II (FS II) nismo opazili statistično značilnih razlik.It is well known that pennycress ( Noccaea praecox Wulf) hyperaccumulates Cd and Zn and also accumulates Pb under field conditions. The mai n purpose of the thesis was therefore to determine how lead affects the growth and developme nt of these plants. Plants of pennycress have been grown for four weeks in basic nutrient so lution in hydroponics and after one week 1, 10 and 100 μ M of lead was added into separated b eakers. Two beakers were left with basic nutrient solution. Hydroponic solution was replaced weekly. Once per week actual and potential photochemical efficiency was measured. We determined fresh and dry mass of roots and shoots, and from these data the water content w as calculated. The presence of lead in the samples was measured by a portable X-ray fluorescen ce spectrometer. After XRF analysis the concentrations of photosynthetic pigments were also determined. From the obtained data we calculated the average values and displayed results using graphs. Analyses have confirmed that various concentrations of lead differently aff ect the growth and development of plants and the lead mainly accumulated in roots, but also in the shoots. The analysis of photosynthetic pigments showed increased synthesis of photosynthetic pigments in plants exposed to 1 and 10 μ M lead. Photochemical efficien cy of photosystem II did not show statistically significant differences