Abstract
Increasing heavy metals in agricultural soils has deleterious effects on germination and growth of many crops. The present study investigated whether priming with phytomormones could alters the physiological responses of soybean seeds germinated under water and lead (Pb) stress. Seeds were soaked for solutions containing 10 or 100 mu M of indolebutyric acid (IBA), gibberellin (GA3), cytokinin (CK), ethylene (ET), abscisic acid (ABA) and distilled water (hydro-priming). Non-priming seeds (NP) were taken as control. Daily germinated seeds (Gd%), final germination (fG%), germination speed index (GSI), average germination time (AGT) and the time taken to reach 50% germination (T-50%) as affected by the phytohormone treatments were studied. Data showed that germination of Pb-stressed seeds improved with hormone treatments. High levels of the hormones gave higher Gd values than low levels. Moreover, the highest Gf values were recorded with Ck treatments of 10 mu m and 100 mu m at which Gf increased by about 77.5% and 73.8%, respectively. Treatments significantly affected the activity of antioxidant enzymes Catalase (CAT) and Peroxidase (POX). Water stress (NP) and ABA caused a significant increase in CAT and POX activities. Phytohormones can be used as an efficient priming method to enhance soybean seed germination under Pb stress.