الفهرس 
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Abstract
Two pot experiments were performed at the Experimental Station Farm , Faculty of Agriculture Mansoura university during two successive summer seasons of 2007 and 2008. This work was conducted to study the role of some antioxidant materials in alleviation the harmful effect of different salinity stress levels on sweet pepper cv. California wonder. Four levels of artificial sea water used. 1- Tap water (320 mg/l).2- 2000 mg/l.3- 4000 mg/l.4- 6000 mg/l. Applied antioxidants were:1- Tap water. 2- Humic acid (1000 mg/L).3- salicylic acid (250 mg/L).4- Ascorbic acid (250 mg/L).5- α- Tocopherol (250 mg/L).6- Reduced glutathione (250 mg/L).7- Citric Acid (250 mg/L).8- Putrescince (1 mg/L).9- Seaweed extract (1000 mg/L). The obtained main results of our investigations are : High salinity stress levels decreased all growth parameters of pepper plant such as plant height, number of branches, number of leaves, leaf area, shoot fresh weight and dry weight. Throughout the growth period stage during the two growing seasons (2007/2008). 6000 mg/l salinity stress level was the most effective in this respect. On the other hand, it could be show that any of each applied antioxidants could be partially counteracted the harmful effect of high salinity levels (4000 and 6000 mg/l) which enhanced all growth parameters under high salinity levels. This increasing effect of antioxidant on growth parameters comparing with the effect of salinity stress levels only without applied antioxidants but this increase nearly but less control. Salinity stress levels decreased total fruit yield of pepper plant. This decreasing effect was increased with increasing salinity level. On the other hand, all applied antioxidants (presoaking and for foliar spray) increased total pepper fruit yield during the two growing seasons. It could be recorded that applied antioxidants as (presoaking + foliar spray) could completely counteract the harmful effect of salinity stress levels (2000 and 4000 mg/l) and partially contract this harmful effect under the highest salinity stress level (6000 mg/l). The data show that salinity stress show that salinity stress levels decreased fresh and dry weight of pepper fruits. It could be say that the applied antioxidants completely counteracted the harmful effect of low and moderate salinity levels (2000 and 4000 mg/l) and partially counteracted stress level (6000 mg/l). Ascorbic and SWE were most effective in this respect.The data show that all salinity levels and each of applied antioxidants as well as their interactions slightly increase the contents of different non-enzymatic antioxidants (phenols, Ascorbic and Glutathione) in both shoot and fruits of pepper plant during the two growth seasons. Moreover SWE combined with highest salinity level treatment was the most effective in this respect. The data show that each of salinity stress levels (2000, 4000 or 6000 mg/l) increased Super oxide dismutase (SOD) and Ascorbic peroxidase ( APX) activity in both shoot and fruits of pepper plants. In addition The data show that any of applied antioxidants (HA, SA, ASA, Tochopherol, GSH, Citric , Put., SWE ) alone or combined with different salinity stress levels also increased the activity of SOD, APX on enzymes in both shoot and fruits of pepper plant, during the two growth seasons. Salinity stress levels (2000, 4000 or 6000 mg/l) decreased N, P, K and Ca while increased Na content in the shoot of pepper plant during the two growth seasons. the highest salinity levels (6000 mg/l) was the most effective in this respect. Moreover applied antioxidants enhanced N, P, K, Ca contents under the highest salinity levels (6000 mg/l) but the values still less control.