Optimizing Growth, Seed Yield and Quality of Soybean (Glycine max L.) Plant Using Growth Substances

Abstract

Aims: It is become necessary to reduce the gap between the demand and supply of edible oil and protein. So, the aim of the present investigation is to study the effect of foliar application with humic acid, salicylic acid and paclobutrazol on some morphological, anatomical and seed yield characteristics, as well as on some biochemical constituents of soybean (Glycine max L.) seed for maximizing its growth, yield and nutritional value. Methodology: A 2 year field trial was carried out during 2015 and 2016 at the Faculty of Agriculture Experiment Station, Benha University, Egypt . Soybean (Glycine max L.) cv. Giza 111 seeds were sown into plots (each plot unit about 3.5 m long and 3.0 m wide) in clay loam soil. A total of six treatments of humic acid, salyclic acid, and paclobutrazol were foliarly applied: humic acid at 2.5 and 5.0 gl-1, salicylic acid at 50 and 100 mgl-1, paclobutrazol at 10 and 20 mgl-1 and Control in a 3 randomized complete blocks. Results: All rates of humic acid, salicylic acid and paclobutrazol had a significant effect on soybean morphological characters during the 2 years. The treatment set of 10 mgl-1 paclobutrazol, 5 gl-1 humic acid, and 100 mgl-1 salicylic acid resulted in relatively higher means for most vegetative growth characters compared to both the other 3 and the Control treatments. Despite variations among the 6 rates effects, all enhanced chlorophyll and carotenoids contents. This positive response extended to include the contents of soybean shoot endogenous phytohormones.  Soybean yield components and yield were significantly improved due to applying these 3 growth substances using these current rates, this in addition to their positive effect on N P K content, crude protein, total carbohydrates and percentage total lipids in soybean seed yield.  Under the conditions of this trial, either of 10 mgl-1 paclobutrazol, 5 gl-1 humic acid, or 100 mgl-1 salicylic acid proved useful to improve soybean growth and yield, yet more further research deem necessary to include more expanded set of rates to be assessed under other perspectives.