الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
Onion (Allium cepa L.), belonging to the family Alliaceae, it is a herbaceous annual for the edible bulb production and biennial for the seed production. Onion is one of the most important crop grown in Egypt and worldwide. Moreover, onion is the only vegetable in which Egypt figures prominently in the world for production and export. Egypt produces about 21.8% of Africa production, which produces about 11.2% of world production. (FAOSTAT, 2013). The total cultivated area of onion crop in 2013 reached about 117.000 feddan of which about 87.000 feddan in old lands which represents about 73.94% of the total cultivated onion crop area, and about 30.000 feddan in new lands represent about 26.06% of the total cultivated crop area. The total production of onions is around 1.754 million tons with average productivity 14.971 tons / fed. including 1.312 million tons of old lands with mean productivity 15.143 tons / fed. while in the new lands has reached about 442.000 tons with mean productivity 14.483 tons /fed. and the total production costs per feddan of the onion crop was estimated with 3767 pounds. The net return is about 9441 pounds.
Raw onion has an antiseptic value through the alimentary canal. It promotes bile production and reduces blood sugar. It is rich in minerals like phosphorus and calcium, vitamin C, protein and carbohydrates.
During the last two decades man realized the harmful effects using enormous amounts of chemicals as mineral fertilizers in agricultural production. Also, it is noticed that most of the used chemicals accumulate in this food chain causing disturbance in biological balance and contaminate under ground water. The increase in yield due to fertilization programs should be considered as a second priority after the reduction of possible health hazard due to the chemicals accumulated in plant fresh parts and fruits.
Crop production of onion is affected by several factors. Biofertilizers have recently gained with momentum for affecting the sustainable increase in crop yield under various agro climatic conditions. Biofertilizers are live carrier based microbial preparations used in agriculture as low in put resources to enhance the availability of plant nutrients or promote the growth by way of synthesizing growth factors (Subba Rao et al., 1982). They are low cost effective, in expensive and eco-friendly sources of nutrient. Role of biofertilizer on the crop growth and yield was documented by Yogita and Ram (2012). Azotobacter fixes atmospheric nitrogen in dependently near the root zone, thus, enhancing the available nitrogen to the soil, whereas phosphobacteria solublize the soil phosphorus and make them easily available for the plants.
Uses of bio-fertilizers in onion production, to at least partially supplement its nutrient demand and to improve soil fertility by way of the integration of different sources of plant nutrients is desired. Onion has a good response for biofertilizer inoculation due to real nature of their root morphology.
Anyhow organic manures alone are unable to give economic yield and it is vital to find appropriate combinations of inorganic and organic manure to obtain financially viable yield of crops. Keeping in view the above facts, present study was under taken to study the effect of different sources of bio-fertilizers and combinations of NPK fertilizer on growth, bulb yield and its components, blub quality under the environmental conditions of South Valley Egypt.