African Journal of Biotechnology Vol. 10(36), pp. 7092-7098, 18 July, 2011 Available online at http://www.academicjournals.org/AJB DOI: 10.5897/AJB11.477 ISSN 1684–5315 © 2011 Academic Journals Full Length Research Paper Sunflower chlorophyll levels after magnetic nanoparticle supply Manuela Ursache-Oprisan*, Ecaterina Focanici, Dorina Creanga and Ovidiu Caltun University Alexandru Ioan Cuza-Iasi, Faculty of Physics, 11 Blvd. Carol I, 700506, Iasi, Romania. Accepted 19 May, 2011 This study reported the results of an experimental investigation regarding the chlorophyll contents in sunflower seedlings supplied with low concentrations of magnetic nanoparticles. Iron and iron-cobalt oxides were prepared in the form of colloidal nanoparticles for the administration in the culture medium of young plant seedlings during their very early ontogenetic stages - as possible basis of new biotechnological tool in plant growth controlling. The changes in the contents of chlorophyll A, chlorophyll B and carotene like pigments were evidenced by spectral measurements. Magnetite nanoparticles influenced negatively the photosynthetic pigment biosynthesis by diminishing chlorophyll content with up to 50% while slighter effect was evidenced in the case of cobalt ferrite nanoparticles that induced only up to 28% chlorophyll level decreasing. The influence upon photosynthetic system LHC II was revealed as consistent with the higher diminution of chlorophyll ratio in the case of cobalt ferrite supplied seedlings than for magnetite supplied ones sustaining the hypothesis of photosynthesis sensitivity to the presence of magnetic nanoparticles stress. Key words: Sunflower seedlings, photosynthetic pigments, nanosized metal oxides. INTRODUCTION Scientist interest in heavy metals impact on photo- synthesis processes may be considered one of the hallmarks of applied plant biochemistry as well as of plant environmental pollution research. Plant cultivation efficiency is more and more investigated with focus on the environment gradients effects – one of them being the result of nanometric metal oxides generated from both natural and artificial sources - that could be also used in controlled cultivation of agricultural plants. Granick (1957) was one of the firsts that evidenced the role of iron mixed oxide, the magnetite, in the redox processes from the chloroplast membrane –with possible implications in photosynthesis mechanisms clarification and even for its artificial modeling. In the frame of the studies dedicated to photosynthesis modeling, Jiao and Frei (2009) focused on cobalt oxides with nanometric size as inorganic catalysts able of water photooxidation and chlorophyll synthesis influence. *Corresponding author. E-mail: dorina.creanga@gmail.com. Abbreviations: SO, Sodium oleate; NP, nanoparticle; LHC, light harvesting complex. In recent decades, Sala was one of the firsts who evidenced the effects of magnetic nanoparticles in plants, that is the increase of chlorophyll levels and photosynthesis rate in seven days old beans seedlings following the addition of 0.1% magnetite based magnetic fluid in the culture medium (Sala, 1999). Considering the magnetic features of nanoparticulate matter composed by magnetic metal oxides, some considerations regarding the low magnetic field influence on plant growth need to be mentioned. For example, sugar beat plants exhibited slight increase of chlorophyll levels in their leaves after magnetic exposure to low flux density magnetic field (Rochalska, 2005); in vitro tissue cultures of soybean (Atak et al., 2003) as well as of Pawlovnia explants (Celik et al., 2008) presented increased chlorophyll levels for relatively short time exposure to low intensity magnetic field while for longer exposure time, the diminution of both chlorophyll types was observed; different responses of chlorophyll levels in maize (diminution) and sunflower (increasing) were evidenced after magnetic exposure to continuous static magnetic field (Temirci et al., 2007). In the next, we present comparatively the response of young sunflower plantlets to magnetite and cobalt ferrite nanoparticle suspensions added in the culture medium,