الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Two field experiments were carried out at Tag-El- Ezz Research Station in Dakahlia Governorate, Agric–Res-Center, Ministry of Agric during 2007 and 2008 seasons to investigate the role of selected antioxidants on mitigation or alleviate the harmful effect of drought stress condition on maize and soybean plants. Five irrigaton intervals were applied for experimental units of each of soybean and maize plants as follow: Irrigation every 12 days (control) , 14, 16, 18 and 20 days. Soybean or maize plants were sprayed with some antioxidants at 30 , 45 , and 60 days from sowing. Antioxidant materials used were: Tap water., Citric acid (300 mg/l)., Ascorbic acid ( ASA,300 mg/l).,Sea weed extract(SWE,1000 mg/l). The obtained main results of our investigations are :- Growth, photosynthetic pigments, N, P and K contents : -Increasing irrigation intervals (every 14, 16, 18, 20 days ), decreased growth parameters (stem diameter, stem fresh and dry weight, leaves fresh and dry weight, leaf area, leaves number, leaf area ratio and leaf area index) and (photosynthetic chlorophyll a, b, carotenoids in the leaves & N, P and K concentrations in leaves and stems) of maize and soybean plants throughout the whole experimental periods during the two growing seasons ( 2007& 2008 ). -Applied antioxidants Citric, ASA or SWE increased all growth parameters & photosynthetic pigments & N, P and K concentrations of maize and soybean plants throughout the experimental periods during the two growing seasons. Applied antioxidants could partially counteract the harmful effect of drought stress (irrigation every 16, 18, 20 days ) on growth of maize and soybean plant . Antioxidants SWE was the most effective in this respect. Endogenous non-enzymatic Antioxidants content: -The data show that irrigation intervals treatments and applied antioxidants as well as their interactions slightly increased all endogenous non-enzymatic antioxidants contents such as total phenol, praline, ascorbic and glutathione in the shoot of both maize and soybean plants during the two growing seasons. It could be show that applied antioxidants (Citric, ASA, SWE ) promoted the synthesis and accumulation of endogenous non-enzymatic antioxidants under drought stress levels treatments ( irrigation every 16, 18, 20 days ). SWE and irrigation every 20 days were most effective in this respect. Yield and its components: 1-Drought stress levels decreased the yield and its component of both maize and soybean plants during the two growing seasons. 2-The highest drought stress level ( irrigation every 20 days) was the most effective in decreasing the yield of both plants. 3-Applied antioxidants (Citric, ASA, SWE ) increased yield and its components of both maize and soybean plants during the two growing seasons. SWE was the most effective in this respect. 4-As for the interactions treatments, the data show that each of applied antioxidants enhanced the yield and its components of both plants compared with the drought stress treatments but the values were nearly or still less control of plants. SWE combined with irrigation every 14 days was the most effective treatment in this respect. 5- It Could be showed that applied antioxidants could counteract the harmful effect of drought stress levels on the yield of both maize and soybean during the two growing seasons. Moreover, SWE was the most effective antioxidant in this respect.