Effect of nitrogen fertilization and biostimulative compounds on onion productivity

Two field experiments were carried out to investigate the optimum nitrogen rate (80, 100 and 120 kg N fed.-1; Fed = 0.38 ha) and stimulative compounds, i.e. foliar spraying with water, as control, Azotobacter spp. and Azospirillum spp., yeast, compost tea and humic acid on vegetative growth, yield, quality, as well as storability of bulb yield of onion (Allium cepa L.) under North Delta conditions. The results showed that the vegetative growth was positive influenced, also yield its components, quality and storability of onion were related to the medium rate of nitrogen (100 kg N fed.-1). Furthermore, foliar spraying with humic acid at the rate of 1 kg fed.-1 led to a significant increment in the most of vegetative growth characteristics, as well as total bulb yield and its components, bulb quality and storability of onion. Both of 100 kg N fed.-1 and spraying humic acid at the rate of 1 kg fed.-1 significantly increased most vegetative growth characteristics, total and marketable bulbs yield fed.-1, bulb quality and storability of onion. So, this study concluded that onion farmers at North Delta of Egypt should fertilize onions with nitrogen at the rate of 100 kg N fed.-1 with spraying humic acid at the rate of 1 kg fed.-1 to achieve the highest economic yield