الفهرس 
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Abstract
This investigation was carried out during the two successive seasons (2011-012) and (2012-013) on Valencia orange trees, grown in a private orchard in El Salhia region - Sharkia governorate. The trees were grown in sandy-clay loamy soil and subjected to normal cultural practices. This experiment included 16 treatments, which were three levels of Magnetite (250, 500 and 1000g) and three rates of K-humate(25, 50 and 100g) and their combinations beside control treatment.The experimental design was complete randomized blocks with replicates.Analysis of variance was made in order to test the significance of differences among the means of studied treatments.The objective of this study was to add more information about the effect of different magnetite and K-humate treatments on vegetative growth, leaf mineral content, yield and fruit quality of the Valencia orange trees.The obtained results could be summarized as follows:Vegetative growth:The combination of M3+H2 had significantly increased the shoot length, number of leaves per branch and canopy volume as compared with other treatments treatment, while, control treatment recorded the lowest values in both seasons The combination of M3+H2 treatment had significantly increased the shoot length, number of leaves per branch and canopy volume as compared with other Magnetite and K-humate treatments and control treatment which was the lowest values in both seasons.Application of M3+H3 treatment was significantly increased leaf area in compared to control treatment during both seasons.Blooming behavior and fruit set:M3+H3 treatment was significantly increased Leafy inflorescences percentage during both seasons in compared to M3H1treatment in the 1st season and the control treatment in the 2nd season respectively, of this study.M3H3 treatment was significantly reduced the woody inflorescences percentage when compared to M1H3 treatment in the in the 1st season and the control treatment in the 2nd season respect.M2H3 treatment was the highest initial fruit set percentage in the 1st season and M3+H2 treatment in the 2nd season in this respect.Generally, Valencia orange trees, final fruit set percentage were positively response to Magnetite and K-humate applications .Whereas,M3H2 treatment was the highest values in the 1st season and M3H3 treatment in the 2nd season respect, with this respect, when compared to the control treatment during both seasons.Leaf chlorophyll content:M3H3 application significantly enhanced leaf chl. a content, which was the highest values in both seasons.H3 treatment was the highest values of leaf chl. b content during both seasons; whereas, the control treatment was the lowest values of Chls. a and b in both seasons.In the contrary, the control and M3H3 treatments were the highest values of leaf total carotenoids content in both seasons.Total Carbohydrate and Proline leaf contents:M3H3 treatment was the highest values of leaf carbohydrate content in compared to control treatment which was the lowest values in this concern, in both seasons.The control treatment was the highest values of leaf proline content in compared to Magnetite and K-humate treatments which reduced proline leaf content. Also, M3H2 treatment was the lowest values in both seasons.Leaf Water relations:The highest values of relative water content were recorded with M2H3 treatment in the 1st season and M1H3 treatment in the 2nd season.Application of M1H2 positively affected and was the highest values of specific leaf weight in both seasons.The control treatment significantly recorded the highest values of saturated leaf weight in compared to all Magnetite and K-humate treatments .Whereas, M3H3 treatment was the lowest values during both seasons.Leaf mineral content:a) Macro elements:M3H2 and M3H3 treatments were significantly increased leaf N content; in compared to the control treatment which was the lowest values in this concern, in both seasons.M3H1 was the highest values of leaf P content were recorded in compared to the control treatment during both seasons.M3H2 treatment was significantly increased leaf K content in compared to the control treatment which the lowest values in this concern in both seasons.M3H2 was significantly increased leaf Ca content in compared to the control treatment which was the lowest values in both seasons.M3H2 treatment was the highest values of leaf Mg content in the 1st season and M3H3 in the 2nd one. The lowest Mg values were recorded with control treatment during both seasons.b) Micro elements:Magnetite application alone or with K-humate combination was significantly increased leaf Fe content. Whereas, M3H3 application was the highest values of leaf Fe content in compared to control treatments in both seasons.M1H3 treatment was the highest leaf Zn content in the 1st season and M3H3 in the 2nd season in compared to the control treatment.M3H3 was the highest values of leaf Mn content in the 1st season and M3H2 in the 2nd one. Whereas, the control treatment was the lowest in Magnetite and K-humate treatments reduced leaf B content.Whereas, M2H3 treatment was significantly the lowest value in the 1st season and M3H3 in the 2nd one, in compared to the control treatment which was the highest leaf B content in both seasons.M3H2 treatment was significantly reduced leaf Na content in compared to the control treatment which was significantly the highest values in both seasons.Also, control treatment was significantly increased leaf Cl content and recorded the highest values in compared with other Magnetite and Khumate treatments in both seasons.Magnetite and K-humate treatments were significantly improved the total yield of Valencia orange trees. M3H3 treatment was the highest values (kg/tree) in compared to the control treatment in both seasons.Whereas, M1H3 treatment was significantly increased yield efficiency (kg/m3 canopy volume) in both seasons in compared to M2H2 treatment in the 1st season and the control treatment in the 2ndseason .Fruit quality:The highest values of fruit weight, fruit volume, Juice weight,juice volume and total sugars of Valencia orange fruits were obtained with M1H3 treatment when compared to the control treatment in both
seasons.M3H2 treatment was significantly increased Valencia orange fruit (number/tree) in compared with the control treatment during both seasons.M1H2 was the highest peel thickness of Valencia orange fruit in the 1st season and M3H3 treatment in 2nd one. Whereas, the control
treatment was significantly the lowest values in both seasons.M1H2 treatment was the highest values of fruit juice (w/w) ratio of Valencia orange fruit in the 1st season and M3H1 treatment in the 2nd season in compared to the control treatment in booth seasons.The control treatment was the highest values of TSS% and acidity; M1H3 treatment was the lowest values of juice acidity and M3H3 treatment was the highest values of TSS in both seasons M1H3 treatment was significantly increased TSS/ acid Ratio in Valencia orange fruit juice in compared to the control treatment in both seasons.Application of M3H2 increased Valencia orange fruit juice Vit. content in compared to the control treatment during both seasons.Fruit Juice Total and reducing sugars:Magnetite and K-humate treatments were significantly increased juice total sugars. Whereas, M1H3 treatment recorded the maximum total sugars values in booth seasons in compared to the control treatment.H1 treatment increased Valencia orange fruit juice reducing sugars content in the 1st season, while, the control treatment was significantly the highest value in the 2nd season in compared to the M3H2 treatment in both seasons.Generally; Magnetite and k-humate have been utilized to reduce the effect of soil and water salinity on plant growth and enhancement different growth parameters, also, reduced negative effects of B, Na and Cl elements on trees performance.