ABSTRACT Little is understood about the nutritional status of manganese (Mn) in oil palm (Elaeis guineensis Jacq.), further research is needed to provide technological support for greater productivity, especially on the dynamics of accumulation, recycling, immobilization and export. Thus, the objective of this work was to evaluate the dynamics of accumulation, immobilization, recycling, exportation and the efficiency of Mn use in oil palm plants at different ages. The experiment was carried out in a completely randomized design, with seven treatments (plant age: 2, 3, 4, 5, 6, 7, and 8 years of planting) and four replicates. The leaflets and male inflorescence were, the vegetative and reproductive organs with the highest Mn concentration, respectively. The accumulation of this nutrient in the tree crown predominated in the stipe through all years. The bunch exported the highest amount of Mn, especially in older plants. The oil palm immobilizes and recycles, more than exports, a large amount of Mn. The Mn use efficiency is increased as a function of the age of the crops in all the oil palm organs. In conclusion, the nutritional demand of oil palm is altered as a function of age, altering the dynamics of immobilization, recycling and exportation of Mn.

ABSTRACT Cultivation and commercialization of Capsicum pepper have great importance in Brazil. This work assessed the influence of omission of macro and micronutrients on the growth and mineral nutrition of sweet pepper plants (Capsicum chinense Jacquin). The research was carried out in a greenhouse with washed sand as substrate. The experimental design was completely randomized with five replications and eight treatments: complete (control), omission of N, P, K, Ca, Mg, S, and micronutrients (B, Cu, Fe, Mn and Zn). The plants were submitted to the treatments when they reached an average height of 20 cm and the nutrient solution was supplied by percolation in plastic pots and renewed every 15 days. Nutrients omission affected negatively plant growth as a whole. The omission of N, Ca, and micronutrients greatly reduced sweet pepper yield. The C. chinense plants presented the sequence by dry matter production of shoots and roots in descending order: COMP > OP > OS > OK > Omg > ON > Oca > OMicro.

ABSTRACT Oil palm production is strategic in the Amazon with high productive potential, but information on its fertilization is still relatively scarce for the region. The objective of this work was to evaluate the effects of phosphorus, potassium and magnesium fertilizations on oil palm production in different years in the state of Pará, Brazil. The study was conducted in Tailândia, Northeastern of Pará, Eastern Amazon, Brazil. A randomized block design was used in a 4 x 2 x 3 x 2 factorial scheme, with four levels of phosphorus, two sources of phosphorus, three levels of potassium and two levels of magnesium. Oil palm production responded positively to the increase in phosphorus levels, and until the eighth year of age of the plants, there was greater production when triple superphosphate was applied. From the ninth year onwards, fertilization with phosphine provided a production equal to the supply of phosphorus with triple superphosphate. The application of potassium chloride increased the number, weight and production of the bunches from the sixth year. The supply of magnesium sulfate increased the average weight of the bunches. Thus, phosphorus, potassium and magnesium fertilizations become essential to increase oil palm production in the Northeast of Pará.

Resumo O açaizeiro é a principal palmeira cultivada na Amazônia brasileira, e a diagnose nutricional torna-se uma ferramenta essencial ao manejo da cultura. O objetivo deste trabalho foi determinar a folha padrão para a diagnose nutricional do açaizeiro por meio da avaliação dos teores foliares e da utilização de dois métodos de análises estatísticas, tradicional (univariada) e multivariada. O estudo foi conduzido no munícipio de Belém - PA, com oito tratamentos: posições filotáxicas das folhas (folhas 2 a 9), em delineamento inteiramente casualizado. A concentração foliar dos nutrientes (N, P, K, Ca, Mg, S, B, Cu, Fe, Mn e Zn) foi determinada para a realização das análises descritivas, de variância, correlação e análise de componentes principais. As folhas novas apresentaram maiores concentrações de N, P, K, Mg, S, Cu e Zn, ao passo que, nas folhas mais velhas, houve maiores concentrações de Ca, B, Fe e Mn. As folhas que apresentaram menor variação nas concentrações dos nutrientes foram de 2 a 5. A análise de PCA indicou interação de cargas positivas de N-P e Cu-Mg e interação de cargas negativas de Ca-Mn. O índice de distribuição dos nutrientes indicou a folha 5 com o menor valor de carga fatorial. Nesse sentido, a folha número 5 é a mais indicada para a diagnose nutricional de plantas de açaizeiro por meio de amostragem de 25 plantas.

Abstract Assai palm is the main palm tree grown in the Brazilian Amazon. Nutritional diagnosis has become an essential tool in management of the crop. The aim of this study was to determine the standard leaf for nutritional diagnosis of the assai palm tree through evaluation of leaf nutrient content and use of two methods of statistical analyses: traditional (univariate) and multivariate. The study was conducted in the municipality of Belém, with eight treatments: the phyllotaxic positions of the leaves (number 2 to 9), in a completely randomized design. The leaf concentration of nutrients (N, P, K, Ca, Mg, S, B, Cu, Fe, Mn and Zn) was determined for performing descriptive analyses, analyses of variance, correlation analysis, and principal component analysis (PCA). Young leaves had greater concentrations of N, P, K, Mg, S, Cu, and Zn, whereas in the older leaves, there were greater concentrations of Ca, B, Fe, and Mn. The leaves that exhibited less variation in nutrient concentrations were from 2 to 5. PCA analysis indicated interaction of positive loads of N-P and Cu-Mg and interaction of negative loads of Ca-Mn. The index of nutrient distribution indicated leaf number 5 as having the lowest factor loading value. Thus, leaf number 5 is most recommended for nutritional diagnosis of assai palm plants through sampling of 25 plants.

ABSTRACT In the northeastern of Pará, cowpea is one of the main protein sources of the population. This study aimed to evaluate the effects of liming, the P and K mineral fertilization, and the combination of seed inoculation with Rhizobium associated with mineral N supplementation in the growth and production of cowpea cultivars. Two experiments were carried out in two consecutive years at the Federal Rural University of Amazonia (Capitão Poço-PA). A randomized block experimental design with subdivided plots was used with four replications, two cowpea cultivars (BRS Tapaihum and BRS Marataoã) and six fertilization and liming treatments: i) without fertilization and without liming; ii) P and K mineral fertilization, liming and seed inoculation with Rhizobium; iii) P and K mineral fertilization and seed inoculation with Rhizobium; iv) N, P and K mineral fertilization and liming; v) P and K mineral fertilization and liming; and vi) N, P and K mineral fertilization, liming and seed inoculation with Rhizobium. Cowpea responded to liming and P and K mineral fertilization, but not N fertilization. There was no difference between the supply of N through seed inoculation or mineral fertilization. Thus, it is suggested to inoculate seeds with Rhizobium in order to maintain the soil N reserve.