Effect of steel slag on growth and physiology of corn (Zea mays L.)

Abstract

Bazična troska koja se koristi u ovom istraživanju je nusproizvod pri proizvodnji čelika u elektrolučnoj peći. Obzirom da je sadržaj P, Fe, Ca, Mg i Mn u tako dobivenoj troski visok, a sadržaj Cd, Pb, Hg i ostalih toksičnih teških metala vrlo nizak, usitnjena troska je potencijalni izvor mineralnih tvari za rast i razvoj biljaka, posebice na tlima siromašnim željezom. Cilj istraživanja bio je procijeniti učinkovitost troske kao izvora određenih hranjivih elemenata na rast i fiziološke procese kukuruza te utvrditi da li troska u biljci dovodi do oksidacijskog stresa kao posljedica primanja povećanih količina Fe i Cu. Kao supstrati za sadnju biljaka korištene su mješavine zemlje i pijeska u različitim omjerima. Sjemenke kukuruza su zasijane u posudice i napunjene samo supstratom (kontrola) ili supstratom uz dodatak fino mljevene troske. Nakon dva tjedna, dijelu kontrolnih biljaka kao i onih uzgojenih uz dodatak troske dodan je NH4NO3 kao izvor N. Dijelu kontrolnih biljaka koje služe kao pozitivna kontrola dodano je tekuće gnojivo – NPK i Fe. Osim parametara rasta, izmjerena je fluorescencija klorofila i prinos suhe tvari biljaka, sadržaj mineralnih tvari u supstratu i listovima biljaka, sadržaj klorofila i karotenoida, lipidna peroksidacija te aktivnosti antioksidacijskih enzima. Rezultati su pokazali da je troska vrlo dobar i jeftin izvor mikroelemenata poglavito Fe, Mn i Mg potrebnih biljci te da se njezinom upotrebom znatno smanjuje kloroza listova u biljaka koje rastu na tlima siromašnim željezom.Basic slag used in this study is a byproduct in the production of steel in electric arc furnaces. Given that the content of P, Fe, Ca, Mg and Mn in the slag is high and those of Cd, Pb, Hg and some other toxic heavy metals is very small, finely ground slag is a potential source of minerals necessary for plant growth and development, especially on iron-poor soils. The aim of this study was to evaluate the effects of steel slag, as a source of specific nutrient elements, on growth and physiological processes of corn and to determine whether steel slag can induce oxidative stress in plant cells. A mixture of earth and sand in different proportions was used as a substrate for planting. Corn seeds were sown in containers and filled with either pure substrate (control) or substrate mixed with finely ground slag. After two weeks, control plants and those grown with the addition of slag were supplemented with NH4NO3 as a source of N. A part of control plants that served as a positive control was supplemented with liquid fertilizers - NPK and Fe. Beside growth parameters, chlorophyll fluorescence, dry matter yield of plants, mineral content in the substrate and plant leaves, chlorophylls and carotenoids content, lipid peroxidation and antioxidant enzyme activities were measured after six weeks of cultivation. The results showed that steel slag is a very good and inexpensive source of microelements especially Fe, Mn and Mg essential to plants and that its usage significantly reduces leaf chlorosis in plants growing on iron-deficient soils