Grafting increases tolerance to aluminum in dwarf cashew seedlings

ABSTRACT Using grafted and aluminum (Al) tolerant seedlings can be a strategy to enable the cultivation of dwarf cashew (Anacardium occidentale L.) in regions with predominance of soils with acidic reaction and high concentrations of exchangeable Al. In this context, the objective was to evaluate the influence of grafting on dwarf cashew genotypes cultivated in the presence of Al. For this, the experimental design was completely randomized in a 3 × 2 × 2 factorial scheme, with seedlings of three dwarf cashew genotypes (‘CCP 06’, ‘CCP 09’, and ‘CCP 76’) and two types of seedlings (ungrafted and self-grafted), cultivated in the absence and presence of Al (30 mg L-1), with six replicates. One hundred and ten days after the beginning of Al application, the seedlings were evaluated for growth, dry matter and accumulation of nutrients and Al (in shoots and roots). Al caused reductions in the height (25.8%), stem diameter (6.7%), number of leaves (43.3%), leaf area (46.3%), stem dry matter (29.8%), and shoot dry matter (37.0%) of dwarf cashew. Application of 30 mg L-1 of Al increased the accumulation of Al in the roots and, as a consequence, reduced the accumulation of N, P, K, Ca, Mg, S, Cu, Fe and Zn in the shoots and roots. Dwarf cashew accumulates greater amount of Mn in the leaves and smaller amount in the roots, contrary to what occurs with Al. Al limits growth and nutrient accumulation in the clones ‘CCP 06’, ‘CCP 09’, and ‘CCP 76’; however, the use of grafted seedlings increases the tolerance of the plants to this element.