Mineral nutrition of bean lines under iron chlorosis

Abstract

Iron deficiency exists in almost every crop in the world and the ability to absorb iron varies widely between plant species. There are groups of plants that are characterized by their ability to grow in soils with low iron availability, called Fe-efficient. In this experiment, bean plants were grown in a greenhouse, in a nutrient solution with suboptimal and optimal concentrations of Fe. The objective was to evaluate the mechanisms of tolerance, concentration and distribution of Fe in bean lines. Six bean lines (three tolerant and three susceptible to iron deficiency) were established. The nutritional concentration and SPAD units were evaluated in young leaves and roots, root volume and dry matter. The results obtained determined a high nutritional imbalance index (NII), transfer coefficient, the ratios P/Fe and K/Ca, concentration of K, Ca, Mg, Mn, Zn, Cu and B in young bean leaves in leaves with iron chlorosis. In the absence of Fe, line 496 showed less chlorosis, the P/Mg ratio and the concentration of P and K increased. When Fe was present in the nutrient solution, lines 496 and 33 had low nutritional indices and higher dry matter production. Line T2 was susceptible to iron chlorosis, but with a concentration of 1 mg L-1 of Fe in the nutrient solution, it had greater production of dry matter, root volume and did not manifest iron chlorosis. Line 33 was susceptible and in the absence of Fe in the solution, the ratios N/P, B/P, Ca/P increased, and the concentration of P, K and B decreased. The addition of 1 mg L-1 of Fe in the nutrient solution increased the concentration of N, P, K and Fe, while in the absence, the concentration of Mn, Zn and Cu in root increased. The differences found in iron bean chlorosis in tolerant and susceptible plants are not due to the concentration of Fe but to internal mechanisms, related to other mineral elements that affect their metabolism.