Iron doses on growth and gas exchange of dwarf cashew seedlings

Abstract

Cashew plants have shown, a few days after planting in the field, interveinal chlorosis in young leaves and, as the symptoms become worse, the leaves are completely chlorotic, a nutritional disorder that is related to iron (Fe) deficiency. Thus, the objective was to evaluate the growth and physiological responses of grafted seedlings of dwarf cashew as a function of Fe doses. The experiment was conducted in a greenhouse, in a completely randomized design, with four replicates. Treatments consisted of five doses of Fe (0; 2.5; 5; 7.5 and 10 mg L−1), using iron sulfate (20% Fe) as source. The following parameters were evaluated: growth variables – height, number of leaves, leaf area, stem diameter and dry matter (roots, shoots and total); and physiological variables – photosynthesis (A), stomatal conductance (gs), transpiration (E), water use efficiency (WUE), instantaneous carboxylation efficiency (A/Ci), photosynthetic pigments and relative chlorophyll index. Fe deficiency affected the photosynthetic process, causing significant reductions in the evaluated characteristics, indicating the need for its adequate supply for the growth of dwarf cashew plants.