Effects of urban sewage sludge on bean (Phaseolus vulgaris L.) seedling emergence rate and development

This study was carried out to determine the emergence rate and development of bean seedlings in response to the treatment with urban sludge in increasing doses (0%, 25%, 50%, 75%, 100%) applied to a dwarf (Efsane) and pole (Öz Ayşe) bean cultivar grown under climate chamber conditions. The following traits were investigated: first emergence and first leaf formation time, seedling length, root length, leaf color, leaf area, number of leaves, seedling age weight, seedling dry weight, root age weight and root dry weight of plant morphological properties and Na, Ca, K, Mg, Cu, Fe, Zn, Mn, Co, Ni, Cr, Cd concentrations. Morphological measurements show that 25 % and 50% sludge treatment doses have a positive effect on the seedling emergence and the first true leaf formation but sewage sludge is not effective at 75% and 100% doses. A significant increase in the content of heavy metals, such as Cu, K, Mg, Mn and Zn, could be expected under increasing doses of sludge, whereas in fact there was a decrease in Ni, Cd, Co, Cr, Fe, Na and Ca values. It was determined that the Ca content of plants was beneficial for the plant growth. Concentrations of the heavy metals Cu, Cd, Ni, Mn, Zn and Cr were high enough in some cases to cause toxic effects, which affected adversely the plant growth. In addition, it was determined that there is no plant emergence at the 100 % sludge treatment dose. It has been determined that the resistance of the dwarf variety Esfane to the application of sewage sludge in increasing doses is higher than that of the Öz Ayşe variety. The analyses showed that the dwarf variety contained more heavy metals than the pole type and in both types the content of heavy metals was above the toxic thresholds.