The Pear Tree Response to Phosphorus and Potassium Fertilization

Abstract

-The aim of this study was to evaluate the response to phosphorus (P) and potassium (K) fertilization and to establish the critical levels of P and K in the soil and in the plant tissue in pear trees. Two experiments were conducted in São Joaquim (SC), Brazil. In experiment 1, the plants received annually the application of increasing rates of phosphate fertilizer (0, 40, 80, 120 and 160 kg P 2 O 5 ha -1 ), while in experiment 2, increasing rates of potassium fertilizer (0, 40, 80, 120 and 160 kg K 2 O ha -1 ) were applied annually. In the two experiments, soil was collected annually from the 0-10, 10-20 and 0-20 cm layers, and the available P (experiment 1) and exchangeable K (experiment 2) content was analyzed. Whole leaves were collected annually, which were subjected to analysis of total P (experiment 1) and total K (experiment 2) content. The number and weight of the fruits per plant and fruit yield were evaluated. Application of P on the soil planted with pear trees increased the nutrient content in the soil and, in most crop seasons, in the whole leaf, but it did not affect the yield components and fruit yield. The application of K on the soil with pear trees increased the nutrient content in the soil and, in most of the crop seasons, in the whole leaf, but the potassium content in the whole leaf decreased in the crop season with greater fruit yield. The yield components and fruit yield were not affected by K fertilization. Index terms: Pyrus communis L., sufficiency level, phosphate fertilization, potassium fertilization, yield. RESPOSTA DA PEREIRA À APLICAÇÃO DE FÓSFORO E POTÁSSIORESUMO -O trabalho objetivou avaliar a resposta à adubação com fósforo (P) e potássio (K) e estabelecer o nível crítico no solo e no tecido de P e K em pereira. Dois experimentos foram conduzidos em São Joaquim (SC). No experimento 1 as plantas receberam anualmente a aplicação de doses crescentes de fertilizante fosfatado (0; 40; 80; 120 e 160 kg de P 2 O 5 ha -1 ), enquanto no experimento 2 foram aplicadas anualmente doses crescentes de fertilizante potássico (0; 40; 80; 120 e 160 kg de K 2 O ha -1 ). Nos dois experimentos foi coletado anualmente solo nas camadas de 0-10; 10-20 e 0-20 cm, onde foi analisado o teor de P disponível (experimento 1) e K trocável (experimento 2). Anualmente foram coletadas folhas completas que foram submetidas à análise do teor total de P (experimento 1) e K (experimento 2). Avaliaram-se o número e a massa dos frutos por planta e a produção de frutos. A aplicação de P no solo cultivado com pereira incrementou o teor do nutriente no solo e, na maioria das safras, na folha completa. Porém, o incremento do teor de P disponível no solo e na folha não foi acompanhado de aumentos nos componentes de produção e na produção de frutos, impossibilitando o estabelecimento do nível crítico de P no solo e no tecido. A aplicação de K no solo aumentou o teor do nutriente no solo e, na maioria das safras, na folha completa da pereira, mas o teor de K na folha completa diminuiu na safra com maior produção d...

‘Fuji’ Apple Tree Response to Phosphorus Fertilization

“…In the 10-20 cm layer, there was no increase in the available P, even after five years of successive applications of P fertilization ( Table 2), indicating that P is strongly retained in most superficial layer of the soil. The P forms an inner-sphere complex with functional groups of reactive soil particles, which decreases its mobility in soil solution and encourages its buildup in more superficial layers (BRUNETTO et al, 2015). In addition, the accumulation of available P in the 0-10 cm layer could have occurred because P fertilization was applied on the soil surface and without incorporation, in addition to the cycling of P promoted by the species of ground cover plants that lived together in the orchard or by the apple trees.…”

“…Fruit trees, in general, show a little response to maintenance P fertilization conducted along the productive period of the plants (LONGLINERS et al, 2004;BRUNETTO et al, 2015). This low response can be attributed to the perennial feature, which allows a longer period of nutrient absorption from the soil (ERNANI et al, 2000), also the distribution of roots at greater depths in the soil profile, which enables nutrient absorption not only from the soil surface layer (AMARANTE et al, 2015).…”

“…According to Brunetto et al (2015), in a pear tree orchard submitted to the addition of P in the soil, in the same soil type and region as that in this study, it was not possible to establish the critical level of P in the soil and leaves, which was partly explained because the soil samples were collected only within the canopy projection range where P was applied and because the roots can also absorb P not supplied by the fertilizer from the areas located between the plant rows. …”

“…The P applied on the soil surface during maintenance fertilization can be adsorbed with high binding energy with the mineral fraction surface of the soil (SCHMITT et al, 2013;BRUNETTO et al, 2015). However, successive applications of P onto the soil surface may cause the occupation of adsorption surfaces, decreasing their adsorption energy, which can enhance desorption and therefore migration in the soil profile, increasing the P amount in deeper layers.…”

“…However, successive applications of P onto the soil surface may cause the occupation of adsorption surfaces, decreasing their adsorption energy, which can enhance desorption and therefore migration in the soil profile, increasing the P amount in deeper layers. With the increase of available P content in the soil, it is expected that part of the nutrient can move closer to the outer surface of the roots and be absorbed, increasing its levels in the plant (BRUNETTO et al, 2015). This can increase the production components, such as the number and mass of fruits, which can affect the productivity (DAR et al, 2015).…”