Effect of Water Irrigation pH Different Scales on Citrus Seedlings Growth under Several Fertilizer Levels.

Citrus is one of the most important fruit crops grown under tropical and subtropical conditions in many countries. At this moment, there is about 3.6 million fed. of citrus spp. cultivated at commercial scale in the world yielding nearly 40 million metric tons of oranges, lemons, limes,... etc. In Egypt, citrus has great attention due to its importance for local consumption and consider a popular fruit for it’s low acidity, juicy pulp and good flavor. All over, citrus fruits have an important role to prevent human cardiovascular diseases, and source for foreign currencies by exportation to the world markets. Recently, citrus cultivated area has increased rapidly with the reclamation of new desert lands reaching about486650 fed. And Valencia orange occupied 139851 fed. (28.74 % of total area) (Ministry of Agriculture and Land Reclamation, 2018). Fruit harvested through March to June period. In Egypt many Citriculture regions suffer from a low organic matter and high alkaline with limited phosphorus availability which causes, many problems are encountered that threatening some citrus growers and been among the difficulties hindering more extension. Generally, alkaline soil is a serious problem especially in arid or semi-arid regions. Irrigated water pH value is an important feature of water. Predecessors have reported the effects of different pH treatments on plant growth in Metroxylon sagu (Anugoolprasert et al., 2012), Camellia sinensis (Ruan et al., 2007), Chlamydomonas acidophila (Gerloff-Elias et al., 2005), Anabaenopsis elenkini (Santos et al., 2011) VALENCIA orange (Citrus sinensis) seedlings on Sour orange (Citrus aurantum ) “ SO” or Volkamer lemon (Citrus Volkamariana) “ VL” fertilized with three nutrient doses 50 ; 75 and 100 percentage of nursery recommendation and irrigated with water at four pH levels : the control ; pH5 ; pH7 and pH9. .Results showed that; Valencia orange seedlings on both SO or VL stocks gave the best stem: height and diameter; leaf area; root length and width; under 50% or 75 % nutrient doses of nursery recommendation when irrigated with water at pH7. SO stock fertilized with 50% nutrient dose and irrigated with water at pH7 gave the highest leaf Chl. a content , also, VL stock under 50% or 75% nutrient dose and irrigated with water at pH7 gave the same trend. Whereas, both stocks under 50% or 75% dose and irrigated with water at pH7 gave the highest leaf Chl. b content. SO or VL stocks fertilized with 50% or 75% of the control and irrigated with water pH7 significantly gave the highest leaf carbohydrates contents, both citrus stocks fertilized with 100% the control and irrigated with water pH9 was the lowest. SO or VL stocks fertilized with50% or 75% doses and irrigated with water pH7 significantly increased N , P & K percentage, but which fertilized with 100% dose and irrigated with water pH7 or pH9 was the lowest.