63ª Reunião Anual da SBPC

E. Ciências Agrárias - 1. Agronomia - 4. Fitotecnia

Nutrients in shoot of Phaseolus vulgaris under different phosphorus fertilizations

Igor Vinicius de Oliveira 1 Eldenira Barbosa Uchôa 1 Argemiro Pereira Martins Filho 1 Fabricio William de Ávila 2 Valdemar Faquin 2 Allan Klynger da Silva Lobato 1

1. Núcleo de Pesquisa Vegetal Básica e Aplicada, Universidade Federal Rural da Amazônia 2. Departamento de Ciência do Solo, Universidade Federal de Lavras

INTRODUÇÃO:

Limited phosphorus (P) availability in Ultisols and Oxisols has been identified as one of the major problems for plant growth in tropical and subtropical regions of the world. High rate P “fixation” and formation of insoluble complexes with aluminum and iron under acid conditions are recognized as an important factor contributing to the low P availability. Thus, application of P-containing fertilizers in these soils is a necessary practice for adequate crop yields in many instances. Objective of this study was to measure concentrations of N, K, Ca, Mg, S and micronutrients in common bean (Phaseolus vulgaris cv. Radiante) shoot under different phosphorus fertilization.

METODOLOGIA:

Study was implemented in Departamento de Ciência do Solo of the Universidade Federal de Lavras, Brazil. Plants remained in glasshouse environment under natural conditions day/night. Substrate used was composed by Oxisol placed in plastic pots with capacity of 6 L. For plant material was used common bean (Phaseolus vulgaris cv. Radiante) plants.Experiment was organized in factorial scheme completely randomized using 2 soil phosphate levels (Pi-starved and Pi-sufficient), combined with 3 nutrient sources supplied via foliar application (KH2PO3, KH2PO4, and KCl used as control), and 2 foliar application numbers (single and two applications). This study had 3 replicates, and each experimental unit consisted of one pot containing two plants, and all variables measured were expressed as mean of two plants.Concentrations of N, K, Ca, Mg, S and micronutrients in common bean shoot were determined after nitric-perchloric digestion as follows: S by turbidimetry; K by flame photometry; Ca, Mg, Cu, Mn, Fe, and Zn by flame atomic absorption spectroscopy. Total N was determined using the Kjeldahl method after sulphuric digestion, and B by colorimetry using the Azomethine-H method after dry digestion, with ash content obtained in muffle furnace by 1 h at 550 ºC. Results were submitted to variance analysis and applied to Tukey test at 5% level, as well as the standard errors were calculated in all evaluated points.

RESULTADOS:

Concentrations of N, K, Ca, Mg, S and micronutrients in plant shoot tissues were not significant affected (p > 0.05) by foliar application numbers. Apart from the K, common bean grown under limiting phosphate availability exhibited higher concentrations of nutrients in shoot, regardless of the foliar-applied treatments. Foliar application of potassium phosphite increased concentrations of N, K, Mg, B, Cu, Mn and Fe in shoot tissues of phosphate-starved plants. However, this increased concentration of nutrients coincides with the decreased shoot dry mass production (data not shown), which may suggest that it is involved with the “concentration effect”. When biomass production decreases, the “concentration effect” for some nutrients may occur, which is the elevation of their concentration in the tissues without having there being an alteration in the quantity of nutrient taken up. Indeed, the applied treatments did not increase accumulation of nutrients in shoot (data not shown), supporting the suggestion above.

CONCLUSÃO:

This study reveals that foliar application of potassium phosphite increased concentrations of N, K, Mg, B, Cu, Mn and Fe in shoot tissues of phosphate-starved plants.

Palavras-chave: common bean, phosphorus, nutrients.