DRIS para cafeeiros podados
e Alexandre de Oliveira, pelo auxílio na realização das análises químicas e pela grande amizade; À CAPES. pela bolsa de estudo concedida durante o curso; Aos cafeicultores paranaenses e paulistas, senhores Orlando Orestes Patrial, Luiz Nick, pela grande amizade e abertura ao disponibilizar suas lavouras para a realização desta pesquisa; Ao Pesquisador científico M.S. Wagner Rodrigues dos Santos, pela troca de experiências sobre o método DRIS; Ao Pesquisador cientifico M.S. Júlio César Chaves,
... lio César Chaves, do Instituto Agronômico do Paraná, pela colaboração na definição da metodologia de lavagem das amostras foliares; Ao Professor Dr. Eduardo Meneghel Rando, da Fundação Faculdade de Agronomia "Luiz Meneghel", pela estrutura laboratorial que disponibilizou para a lavagem e secagem das amostras foliares; Ao amigo Mauricio Rizzato Coelho, pela grande amizade e coleguismo; À querida Denise, pelo apoio e carinho; Ao Sr. Johann Nick, pela inestimável contribuição técnica e apoio dedicados para a realização deste trabalho. SUM.~L-\RY Adviser: Prof. Df. ANTONIO ROQUE DECHEN Pruning techniques are essential to achieve and maintain high yields in coffee plantations. Among the several different pruning systems, the branch pruning system is actualy the best way for rejuvenating coffee plants while restablishing high yields in the short term ",ith low costs. Mineral nutrition in the early stages after pruning has a marked effect on yield one year Iater. There is, however, a gap in the norms for diagnosing nutritional disorders in these early stages. Therefore, this study was concerned with establishing Diagnosis and Recommendation Integrated System (DRIS) norms, for different cultivars at different stages after pruning. To determine the DRIS norms based on a number of coffee plantations in the states of Paraná and São Paulo, two limiting characteristics were noted. First, coffee plantations are quite variable with regards to planting density and canopy c1osure, which masks the nutritional effects on yield. Second, the DRIS method, which consists of several steps, presents many options for calculating variables in each step, which the best combination still has to be determined. In order to solve the first limiting characteristic, a study was performed to develop an alternative response variable, a vegetative variable, to be used in place of coffee yield. Branches and leaves from 117 coffee plantatíons, mainly from the cultivars Catuai Amarelo and Mundo Novo, were sampled at four periods (December/96; Februay, April and July/97). Leaf samples were analysed for determinig N, P, K, Ca, Mg, S, B, Cu, Fe, Mn and Zn concentraions. Number, weight and length of the internodes for the branches were IX detennined. and other variables derived from these basic ones, were calculated. Based on a study of cause and effect, the "new branch specific length" (in mm gol dry matter) was idenrified as the altemative response variable that best estimates the branch yie1d potential. In order to solve the second limiting characteristic, methods of three basic DRIS steps were evaluated. First, two methods for deciding the ratio order of a pair of nutrients.. either the F Value and the r Value, were compared. Second, three different methods for calculating ratio functions, either that of Beaufils, or Jones or Elwali & Gascho, were examined. Finally, two methods for summing the ratio functions, DRIS and modified DRIS CM-DRIS), were evaluated. The resuIts indicated: (i) DRIS norms determined by the r Value, which we created, were more precise than those determined by the F Value. since applied to ratio functions calculated by the Jones' method; (ii) the Jones' method resulted in a more precise DRIS or M-DRIS indeces than those calculated by the other nvo methods; and (iii) DRIS and M-DRIS resuIted in similar indices. Once defined. the best vegetative variable (new branch specific length) and the best combination of calculating methods (r Value, Jones, and optionally M-DRIS), specific DRIS norms for two cultivars and three periods were established. These improvements in the DRIS method and norms will help farmers better identifY and solve early nutritional disorders in their pruned coffee plantations.