Effects of Different Nitrogen Fertilization Rates and Foliar Application of Humic Acid, Fulvic Acid and Tryptophan on Growth, Productivity and Chemical Composition of Common Bean Plants (Phaseolus vulgaris L.)

Abstract

Two field experiments were carried out during the two successive seasons of 2015 and 2016 in a newly reclaimed private farm at Abu El-Matamer region, El-Beheira Governorate. The objective of this investigation was to study the main effects of four N-fertilizer levels (0, 20, 40, 60 kg N fad-1) in the form of ammonium nitrate (33%) and three different stimulator treatments; humic acid (1 and 2 gmL-1) fulvic acid (2.5 and 5 gmL-1) and tryptophan (0.5 and 1 gmL-1 ), as well as their interactions on vegetative growth, leaf chlorophyll, N, P and K contents and yield and its components characters of common bean cv. Nebraska. The obtained results indicated that application of mineral N, significantly increased all the studied growth, minerals and yield characters. The highest N rates (60 kg N fad-1) was remarkable and associated with the highest mean values of the most studied characters. Moreover, the biostimulator treatments application exhibited higher mean values of all studied growth, minerals and yield parameters compared to control. Tryptophan treatment was more pronounced in this concern. It could conclude that fertilization of common bean plants with 60 kg N fad-1 combined with tryptophan at 1 gmL-1 was the best interaction treatment for all the studied parameters.