Calagem no desenvolvimento inicial do cajueiro e genótipos tolerantes ao alumínio

Abstract

Cashew tree (Anacardium occidentale L.) is widely cultivated in the northeastern region of Brazil, which accounts for 98% of the national production of cashew nut in natura. However, the productivity of orchards is low, and is explained by the low use of available technologies and the low fertility of soils in this region. In this sense, liming is one of the practices that can contribute to the increase of cashew yield, as well as the selection of genotypes with some tolerance to Al3+ in the soil. Thus, the objective of this work was to determine the base saturation adequate for the initial development of the cashew tree, as well as to select genotypes tolerant to aluminum in the soil. Two experiments were carried out, one on the effect of liming on the initial development of cashew tree, and another on the evaluation of cashew genotypes tolerant to Al for rootstock production. Both were conducted in a greenhouse at the Embrapa Agroindústria Tropical, in Fortaleza, Ceará State. The soils were incubated with increasing doses of dolomitic limestone, 91% PRNT, with CaO = 32% and MgO = 15%, in sufficient amounts to raise the saturation by bases (V2) to: PA (Ultisols Yellow) 45%, 55 %, 65%, 75% and 85%; PVA (Ultisols Red Yellow) 35%, 45%, 55%, 65%, 75% and 85%. Beyond the V% initial to the AP. Based on the results, was related to the biometric variables, five months after planting, with the base saturation, obtained by analysis after incubation. The experiment for the selection of cashew tree genotypes for the purpose of the formation of aluminum tolerant rootstocks was carried out in a greenhouse, in a split-plot design, in which the plots were five doses of Al in the form of AlCl3 .6H2O: 0, 10, 20, 30 and 40 mg L-1 and the subplots were eight genotypes of rootstocks: CCP 06, CCP 09, CCP 76, CCP 1001, Embrapa 51, BRS 189, BRS 265 and BRS 275, with ten replications, totaling 400 plants. Eighty days after the beginning of the application of aluminum doses (125 days after sowing), the plants were evaluated for biometrics. The practice of liming is fundamental in the implantation of orchards of cashew, emphasizing for its effect in the long term. The base saturation between 50% and 60% is the range in which the cashew plants obtained the best response to liming. The cashew tree presents a high variability to the effects caused by the aluminum, being genotypes BRS 265, Embrapa 51 and CCP 1001 are the most sensitive.