الفهرس 
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Abstract
Two greenhouse experiments were undertaken in the present study. First experiment was conducted in pots of a sandy soil in a greenhouse of Agric. Bot. Department, Faculty of Agriculture, Ain Shams Univ., during the season of 2008 to evaluate the salt tolerance of different cucurbitaceous rootstocks; Shintosa supreme pumpkin (Cucurbita maxima x C. moschata), Bottle gourd (Lagenaria siceraria), Gourd black seed (Cucurbita maxima) and pumpkin (Cucurbita moschata)). Salinity was applied as 0, 2500, 3500, 4500 ppm NaCl to a base complete Hoagland nutrient solution. Second experiment was conducted in a greenhouse in El-Salehea Al-Gadeda, during the two successive seasons of 2008- 2009 and 2009-2010 to investigate the effect of grafting technique, bioregulators; salicylic acid (SA) at 0.5 & 1 mM, fulvic acid (FA) at 150 & 300 ppm and sea weed extract (SWE) at 2.5 & 5% in addition to compatible solute, glycine betaine (GB) at 2.5 & 5 mM in improving salt tolerant, growth and productivity of cucumber plants (Cucumis sativus L. cv. falcon, Hybrid F1) under saline conditions (1350 ppm for soil and 2500 ppm for irrigation water).
Obtained results from the previous study could be summarized as follow:
1. First experiment
• Increasing levels of NaCl significantly decreased shoot and root dry weights, plant height, leaf area and the root length of the different cucurbitaceous rootstocks cultivars.
• Shintosa supreme pumpkin (Cucurbita maxima x C. moschata) recorded the highest values of plant height, leaf area, shoot and root fresh and dry weights and root length at 3500 ppm NaCl.
• Shintosa Supreme pumpkin showed the highest salt tolerance (at 4500 ppm NaCl) comparing to other cultivars.
• Relative salt tolerance could be arranged in descending order as follow Shintoza < Bottle gourd < Pumpkin < Gourd black seed.
• The membrane permeability and salt injury index of Shintosa supreme pumpkin was significantly lower than those of other cucurbitaceous cultivars.
• Increasing concentration of NaCl significantly increased concentrations of Na+ in the root, stem and leaves of Shintosa supreme pumpkin. However, this increment was more obviously in the root than in the stem and leaves, whereas, K+ showed an opposite trend, resulting in a significant increase in the K/Na ratio in shoot.
2. Second experiment
• Grafting of cucumber on salt tolerance rootstock (Shintosa supreme pumpkin) significantly gave better growth, as indicated by fresh and dry weights, plant height and leaf area comparing with ungrafted plants in the both seasons under salt stress condition.
• Grafting cucumber on salt tolerance rootstock (Shintosa supreme pumpkin) increased fruit yield by 300% compared to ungrafted cucumber under salt stress condition.
• Foliar application with bioregulators (SWE, SA, and FA) as well osmolytes (GB) significantly improved growth parameters of grafted cucumber plants under salt stress condition.
• Application of SWE at 5% recorded the highest significant increase in growth parameters followed by the lower one (2.5%), then FA and GB at 300 ppm and 5 mM, respectively compared to other treatments and untreated plants (grafted and ungrafted) in both seasons under salt stress condition.
• Leaf relative water content (LRWC) was improved in grafted plants comparing with ungrafted plants under salt stress condition. However, all treatments significantly increased LRWC. FA at the higher concentration (300 ppm) showed the highest value followed by SWE at 5% then GB at 5 mM in both seasons under salt stress conditions.
• Plasma membrane permeability (MP) and malondialdehyde (MDA) concentration were significantly decreased in grafted plants compared with ungrafted plants under saline conditions. However, all treatments significantly reduced the negative effect of salinity on cellular membranes of grafted plants in both seasons. GB at 5 mM gave the highest significant reduction of MP and MDA in both seasons.
• Grafted cucumber plants had higher chlorophyll, carotenoid, total soluble protein and proline concentrations than ungrafted plants under salt stress condition. As well as, the application with bioregulators (SWE, SA, and FA) as well osmolytes (GB) significantly improved these measurements comparing with untreated grafted plants under salt stress conditions in both seasons.
• Grafting of cucumber on salt tolerance rootstock (Shintosa supreme pumpkin) significantly increased PAL, POD, CAT, SOD, PPO and APX activities comparison to ungrafted plants under saline conditions.
• Foliar application with bioregulators (SWE, SA, and FA) as well osmolytes (GB) significantly improved PAL, POD, CAT, SOD, PPO and APX activities compared to untreated grafted plants at the two dates under saline condition. The highest significant improvement was recorded by GB at 5 mM compared to other treatments and control plants at two dates.
• Grafted cucumber plants significantly increased the features of fruits quality, as indicated by reduced titratable acidity (TA %), total soluble solids (TSS %), electrical conductivity (EC) and increased Vit.C concentration in fruit juice comparing with ungrafted plants under salt stress conditions.
• Application with bioregulators (SWE, SA, and FA) as well osmolytes (GB) increased the features of fruits quality comparing with untreated grafted plants.
• Foliar application of SWE at 5 % on grafted cucumber increased fruit yield per plant by 46 % comparing to untreated grafted cucumber under salt stress condition.
It was concluded in this study that the use of salt-tolerant rootstock (Shintosa supreme pumpkin) could provide a useful tool to improve plant growth, fruit yield and quality of cucumber under salt stress. As well as, application of bioregulators (SWE, FA and SA) and osmolytes (GB) improved physiological modulation in the plants to enhance salt tolerance of grafted plants. from a human healthy and commercially points of view, SWA at 5% application is recommended on grafted cucumber plants under salinity stress condition.