Effect of excess chelating agent on micronutrient concentrations in bush beans grown in solution culture

Bush bean plants (Phaseolus vulgaris L. cv. Improved Tendergreen) were grown for 18 days in 3700 ml nutrient solutions in a glasshouse in the presence of 2 X 10‐5 M NiSC4, at two different pH levels (4.3 and 7.5) and at 0, 10‐4, 5 x 10‐4 and 10‐3 M NaDTPA. The objective was to determine which micronutrients were changed in uptake by DTPA. Iron in leaves was increased slightly by 10‐4M DTPA (2 x 10‐5M FeEDDHA was applied in all treatments) but decreased slightly by the highest levels of DTPA. Nickel accumulation was absent in all plant parts as result of DTPA much unlike the effect observed in soil. The two highest levels of DTPA decreased plant yields which was probably the result of Cu deficiency at the low pH and Zn, Cu, and Mn deficiencies at the high pH (no Zn and Cu added to the solutions except as contaminants). The Mo in plant parts was decreased by DTPA at the low pH. In a similar experiment with EDTA and EDDHA (10‐4 and 5 x 10‐4M each) but with no Ni added and with plants grown for 17 days, and yields were decreased by the high level of EDTA with leaf decreases in Fe and Cu and also in Zn to a slight extent. The highest level of EDDHA had relatively little effect.