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Antioxidants; ascorbic and /or citric acids in Bartamoda and sakkoty cv(s) increased F.Wt of the initial explant, its growth value and total phenols whereas decreased browning degree of the tissues and the adjacent medium as well as the concentrations of H2O2 and proline. AOs increased the concentrations of AsA and GSH in the developed explant of both date palm (Phoenix dactylifera L,) cv(s). AsA showed an additive effects to that of citric on increasing non-enzymatic and enzymatic antioxidants concentrations in both cv(s) .Bartamuda cv showed, in general, higher F.Wt as well as concentrations of total phenols, H2O2 and proline , than Sakkoty cv. However,concentrations of AsA and GSH as well as CAT, GPOD and SOD in Baramuda cv was found to be less than that of Sakkoty cv over all treatments. This indicated that Bartamuda cv has high ability to used AsA and GSH specially the latter, in the synthesis of thio containing molecules, particularly salfhydryl-containin amino acids.

A pot experiment was conducted during the growing seasons 2013/2014 and 2014/2015 at The Experimental Farm and laboratories of the Agricultural Botany Department, Faculty of Agriculture, Mansoura University to study the effects of yeast extract either at 0, 4 or 8 gL-1 on key primary and secondary metabolites of Catharanthusroseus, cultivars cv. rosea and cv. alba. Results indicated that total alkaloids, total soluble phenols and flavonoids were significantly higher in cvrosea compared with cvalba. Applicationof yeast extract (YE), generally, enhanced the accumulation of alkaloids, phenols and flavonoids. In addition, treatment with YE increased the concentration of kinetin, indole acetic acid, gibberellic acid and benzyladenine whereas decreased that of abscisic acid. Moreover, the concentration of the essential elements N, P, K, Ca and Mg were higher in YEtreated plants, and, the effect of the higher level was more effetine. It was concluded that YE could be utilized as an elicitor to enhance the accumulation of the medicinally-important secondary metabolites in C. roseus plants.

Heavy metals may be introduced in agricultural soil by many sources, one of which is sewage sludge application as a fertilizer. Heavy metals in polluted soil can negatively affect plant growth and productivity. Aiming at exploring means to alleviate heavy metals stress on soybean plant, the present study was performed with the objective to test the alleviating effect of ascorbic acid, salicylic acid, yeast extract, thyme oil as well as inoculation with arbuscular mycorrhizal fungi on soybean plants challenged with either cadmium, cobalt or sewage sludge. Results indicated that though all had beneficial effect manifested by maintaining yield and reducing its content from heavy metals as well as elevating stress-related metabolites, especially phenols, application of thyme oil or yeast extract and inoculation with arbuscular mycorrhizal fungi were the most effective and are recommended to be employed to mitigate heavy metals stress on soybean in heavy metals-affected soils. * Mechanical analysis followed the pipette method using sodium hydroxide as a dispersing agent (Piper, 1950). The contents of Cd, Cu and Pb were determined in DTPA (Diethylene triamine pentacetic acid) soil extract (1:2 w/v) by atomic absorption spectrophotometry. Other soil chemical analysis were carried out according to Jackson (1967).

To alleviate drought stress on moringa plant, the present study was performed aiming to test the alleviating effect of ascorbic acid, salicylic acid, humic acid ,seaweeds extract on moringa trees. Results indicated that treatments had beneficial effect manifested by maintaining yield and elevating stress-related metabolites, especially phenols , proline. Ascorbic acid , humic acid and seaweed extracts were the most effective and they are recommended to be employed to mitigate water stress on moringa trees which grow under drought stress conditions. * Mechanical analysis followed the pipette method using sodium hydroxide as a dispersing agent (Piper, 1950). Other soil chemical analysis were carried out according to Jackson (1973). RESULTS Chemical compositions 1. Photosynthetic pigments:Data in Table (2) and Fig.(1) show the effect of water stress levels, applied antioxidant, , ( ascorbic acid(AS), salicylic acid (SA) , humic acid (HA) ,seaweeds extract (SWE) )and their combination on total cholorophyll concentration of moringa leaves at vegetative growth stage .