Lead (Pb) is one of the most toxic heavy metals that entered extensively into environment through anthropogenic activities. The Pb became a source of negative impact on plant processes. It causes serious impairment to human health functions. Silicon (Si) can be used to overcome the adverse effects caused by Pb on crop plants. In present study, growth enhancement and the Pb noxiousness at the rate of 1000 and 2000 kg Pb ha^-1 in spinach (Spinacia oleracea) amended by Si at the rate of 400 and 800 kg Si ha^-1 soil was studied. The results exposed that Pb noxiousness at its higher applied level (2000 kg Pb ha^-1) reduced total chlorophyll content, relative water contents, membrane stability index, shoot length, shoot fresh and dry weights in 55 days old spinach seedling. The Si application increased growth and physiological parameters at both applied levels of Pb in soil. Under lower level of Pb contamination (1000 kg Pb ha^-1), use of Si (400 and 800 kg Si ha^-1) enhanced shoot length (6.8 and 17.1%), shoot fresh weight (6.2 and 11.6%), total chlorophyll contents (2.5 and 15.3%), relative water contents (2.4 and 7.7%) and membrane stability index (7.4 and 14.5%). Whereas by higher level of Pb (2000 kg Pb ha^-1), shoot length (12.5 and 17.9%), shoot fresh weight (30.1 and 47.7%), total chlorophyll contents (3.9 and 7.1%), relative water contents (9.7 and 13.3%) and membrane stability index (11.4 and 22.5%) increased by the Si application. The Si application reduced Pb uptake by 78 and 56% under lower level of Pb while Pb uptake reduced by 69 and 52% under higher level of Pb respectively. Thus, Si application can ameliorate Pb toxic effect in spinach under Pb stress. Silicon supplementation enhanced growth and physiological parameters and reduced Pb uptake by spinach grown in Pb poisoned soil.

Keywords - Silicon, Lead uptake, Spinach, Pb Contamination, Calcareous, Sandy Loam Soil