Resumo O adequado manejo nutricional de qualquer espécie vegetal requer quantificar os nutrientes acumulados na planta e conhecer sua alocação nos diferentes órgãos. O trabalho teve como objetivo avaliar a partição, o conteúdo, a exportação de macronutrientes e a eficiência nutricional de plantas de bananeira-Prata fertirrigadas. Realizou-se um levantamento histórico de produtividade anual de frutos em 66 talhões de bananeira-Prata, selecionando-se quatro que atendessem às classes de produtividade anual (< 30,0; 30,0 = 37,5; 37,5 = 45,0 e > 45,0 t ha-1). Utilizando-se da massa de matéria seca dos diferentes órgãos da planta-mãe e da planta-filha, bem como dos respectivos teores de macronutrientes, estimaramu-se o conteúdo, a partição, a exportação, a sequência de acúmulo dos macronutrientes e a eficiência nutricional por meio do coeficiente de utilização biológica (CUB). A partição do conteúdo de macronutrientes variou com a classe de produtividade e o órgão da planta. A distribuição média de nutrientes na planta-mãe e na planta-filha apresentou amplitudes de 67,5 a 82,8 % e de 17,2 a 32,5 %, respectivamente. As exportações de macronutrientes por tonelada de cacho foram 4,334; 1,660; 0,361; 0,224; 0,148 e 0,119 kg t-1 para K, N, P, Mg, S e Ca, respectivamente. A bananeira possui padrão de partição de nutrientes para diferentes rendimentos, ou seja, o trabalho traz evidências de que existe uma “compartimentalização ideal” que promove maiores produtividades; entretanto, há necessidade de mais pesquisas para suportar essa afirmação. Os nutrientes mais exportados por tonelada de cacho foram K e N. A ordem decrescente de acúmulo foi: K > N > Ca Mg > P > S. Observou-se que os CUBs de N e P foram menos sensíveis às variações de produtividade, enquanto Ca e Mg foram os mais sensíveis.
Abstract Adequate nutritional management of any plant species requires quantifying the nutrients accumulated in the plant and knowing their allocation in the different organs. The objective of this study was to evaluate the partitioning, accumulation, export of macronutrients and the nutritional efficiency of fertigated Prata banana plants. A historical survey of annual fruit productivity was conducted in 66 plots of Prata banana, selecting four that met the annual productivity classes (< 30.0; 30.0 = 37.5; 37.5 = 45.0 and > 45.0 t ha-1). The dry matter weights of the different organs of parent plant and follower, as well as the respective contents of macronutrients, were used to estimate the accumulation, partitioning, export, sequence of accumulation of macronutrients and nutritional efficiency using the coefficient of biological utilization (CBU). The partitioning of macronutrient accumulation varied with productivity class and plant organ. The average distribution of nutrients in the parent plant and in the follower ranged from 67.5 to 82.8 % and from 17.2 to 32.5 %, respectively. Macronutrient exports per ton of bunch were 4.334, 1.660, 0.361, 0.224, 0.148 and 0.119 kg t-1 for K, N, P, Mg, S and Ca, respectively. Banana mats have a nutrient partitioning pattern for different yields, that is, this work provides evidence that there is an “ideal compartmentalization” that promotes higher productivity; however, more research is needed to support this statement. The most exported nutrients per ton of bunch were K and N. The descending order of accumulation was: K > N > Ca > Mg > P > S. It was observed that the CBUs of N and P were less sensitive to productivity variations, while those of Ca and Mg were the most sensitive.
ABSTRACT: In banana cultivation, fertilization recommendations are almost exclusively based on soil chemical analysis, without considering leaf analysis and expected yield, which can help in the adjustment of fertilization programs. The aim of this study was to develop a method to recommend macronutrient fertilization rates which integrates data on leaf analysis, soil chemical analysis, and yield. Yield, soil chemical analysis, and leaf analysis data of fertigated plantations of ‘Prata’ banana were obtained for the first and second halves of the years from 2010 to 2015. Yield was correlated with soil organic matter (SOM) and soil contents of macronutrients (P, K, Ca, and Mg) to obtain the critical level (CLNui). Then, leaf nutrient contents were plotted on a dispersion graph as a function of soil contents using the method of Quadrant Diagram of the Plant-Soil Relationship (QDpsR). Based on leaf analysis, recommended rates were simulated for four plots and compared with rates recommended by other methods. The values of CLNui obtained were 13.2 g dm−3for SOM; 97.5 and 91.5 mg dm−3for P and K; and 2.71 and 0.61 cmolc dm−3for Ca2+and Mg2+. The rates recommended based on leaf analysis diverged from the recommendations of Ferticalc®-Bananeira and the Recommendation Table for Banana Fertilization; in plots for which recommendations were made, there were higher rates of P2O5 and Ca and lower rates of K2O. However, in most cases, applications were not recommended, either because contents in leaves and soil were adequate or because yield was being limited by non-nutritional factors or, if nutritional, related to other nutrient(s). Leaf analysis satisfactorily adjusts the recommended rates of nutrients and has advantages if incorporated in nutritional balance models.