Use of some Bio-stimulants for Improving the Growth, Yield and Bulb Quality of Onion Plants (Allium cepa L.) under Sandy Soil Conditions

Increasing onion yield and improving bulb quality are essential aims for growers to fulfill the requirements of the market and the consumers. Two field experiments were carried out during two successive seasons; 2011/2012 and 2012/2013 at the experimental station of National Research Centre, Beheira Governorate (North of Egypt) to find out the influence of some bio-stimulants i.e., yeast extract, seaweed extract (Alga 600), garlic oil, licorice extracts, limonene oil, bee pollen extracts and potassium humate on plant growth, yield, yield components and bulb chemical contents of onion plants "Giza 20" cultivar. One month after planting, foliar applications of bio-stimulants were applied, and repeated 3 times at 15 days intervals throughout the growing season. The design of the experiment was a complete randomized blocks with three replicates. Results indicated that foliar application of yeast extract, seaweeds extract and licorice extract at the same time had the highest stimulation effect on onion plant growth characters i.e. (plant length and number of leaves as well as fresh and dry weight of leaves, nick and pulps), total bulb yield and its components as well as content of the percentage of bulb tissues of nitrogen, protein and dry matter compared to the control and other treatments.