Two field experiments were carried out in Research and Experimental Center of the Faculty of Agriculture at Moshtohor during 1999 and 2000 seasons in order to study the effect of spraying aqueous solutions of iron (Fe) at 20mg L-1 and molybdenum (Mo) at 5mg L-1, and rock phosphate (RP) and phosphate dissolving bacteria (PDB) treatments on nodulation N2- ase activity, available-P, some macro and micro-nutrients content, growth characters, yield and yield components of soybean.
Results of this study showed that spraying with Fe or Mo solutions gave higher records of soybean nodulation, N2 -ase activity, ammonical and nitrate nitrogen, available phosphorus and CO2 evolution in rhizosphere. Moreover, macro- and micro- nutrients content in shoots of soybean plants were higher due to spraying with Fe or Mo solutions in both seasons. Also, application of Fe or Mo statistically increased leave area, dry weight of stem and leaves, number of pods/plant, weight of pods and seeds /plant, seed and protein yields / fed during the two growing seasons.
Combined inoculation of PDB and application of RP (RP + PDB) gave the highest nodulation, nitrogenase activity, ammonical and nitrate nitrogen, available phosphorus and CO2 evolution in rhizosphere as well as the macro and micro- nutrients content in shoots of soybean plants in the two seasons. All growth characters, yield and yield components as well as chemical composition of soybean seeds in both seasons were significantly increased by application of RP + PDB or inoculation with PDB alone except number of branches/plant and oil percentage in the second season only.
The interaction between micronutrients and RP combined with PDB had significant effect on seed yield / fed in both seasons and weight of seeds/plant and protein yield/fed in the first season only. The highest values were recorded when soybean plants were sprayed with Mo at 5mg L-1 or Fe at 20 mg L-1 and treated with RP + PDB.
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