ONION YIELD AS AFFECTED BY FOLIAR APPLICATION WITH AMINO AND HUMIC ACIDS UNDER NITROGEN FERTILIZER LEVELS

In order to investigate the effect of nutrient foliar spraying such as amino and humic acids under nitrogen fertilizer levels on growth, yield and keeping quality of onion bulbs cv. Giza 20. Two field experiments were conducted at Gemmeiza Agriculture Research Station Farm, Gharbeia Governorate, Agriculture Research Center, during 2010/2011 and 2011/2012 seasons. The obtained results showed that foliar spraying with humic acid resulted in highest growth characters, total and marketable yields, total culls and bulb weight as well as TSS %, dry matter and total weight loss percentages at storage period? compared with the control treatment. Increasing nitrogen fertilizer levels up to 214.2 kg N/ha significantly increased growth characters, total and marketable yields, total culls and bulb weight as well as total weight loss percentages at storage period. In addition, fertilization with 71.4 kg N/ha significantly increased TSS and dry matter percentages. It could be recommended that spraying with humic acid and adding 214.2 kg N/ha maximize onion bulb yield under the environmental conditions of Gharbeia Governorate. The interaction between nutrients spraying and nitrogen fertilizer levels significantly affected foliage fresh weight, total weight loss % after 1, 2, 3 and 5 months.