الفهرس 
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Abstract
Two pot experiments were conducted during the two successive seasons
of 2013/2014 and 2014/2015 at the Experimental Farm of the Faculty of
Agriculture, Fayoum University, Fayoum, Egypt. The aim of this study was to
evaluate the beneficial effects of grain soaking or foliar spray using spermine
(Spm; 0.25 mM), spermidine (Spd; 0.5 mM) or putrescine (Put; 1 mM) on
heavy metal-tolerance in wheat plants (Triticum aestivum L., cv. Sakha 94)
irrigated with water contaminated by cadmium (CdCl2; 2 mM) or lead (PbCl2;
2 mM). The effects on growth and yield characteristics, concentrations of
osmoprotectants, endogenous Cd2+ and Pb2+, mineral nutrients and nucleic
acids, and antioxidative defense system activity and tissue health in wheat
plants were assessed. Under each of the three applied polyamines (PAs)
applications, the efficiency of wheat plants to tolerate Cd2+ or Pb2+ stress in
terms of growth and yield characteristics was noticed to varying degrees. The
enhancements in osmoprotectant concentrations and plant health [in terms of
relative water content (RWC) and membrane stability index (MSI)], and
reductions in electrolyte leakage (EL) and endogenous Cd2+ and Pb2+
concentrations were correlated with the reasonable growth of Cd2+ or Pb2+-
stressed plants and their grain yield and its quality. Results pointed out also
that, better growth and yield characteristics, MSI%, RWC%, leaf
photosynthetic pigments concentrations, activities of antioxidant enzymes,
osmoprotectant (i.e., proline, total soluble sugars) and nucleic acids
concentrations, nutrient contents and tolerance index were obtained with seed
soaking in each of the three PAs than those generated with seed soaking in
water under 2.0 mM Cd2+ or Pb2+ stress. In contrast, EL%, concentrations of
endogenous Cd2+ or Pb2+ and hydrogen peroxide, injury index, 1, 1- diphenyl-
2-picrylhydrazyl (DPPH) and reducing power were significantly reduced.
However, the Cd2+ or Pb2+-free control plants was exceeded the all stressed
treatments and the economic grain yield was negatively correlated with Cd or
Pb stress. These results are important as the potential of Spd or Put used for
seed soaking to alleviate the harmful effects of Cd2+ or Pb2+ stress offer an
opportunity to increase the resistance of wheat plants to growth under Cd or Pb
stress conditions.