63ª Reunião Anual da SBPC

E. Ciências Agrárias - 1. Agronomia - 1. Ciência do Solo

Accumulation of Phosphorus in common bean exposed to different phosphorus forms

Josiane Santos da Silva 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:

In the year 1990, it was reported foliar application of potassium phosphite improved set fruit and yield of avocado, and restored normal growth of phosphate-starved citrus. Similarly, positive effects of phosphite on plant P nutrition or crop yields also were demonstrated in other works. On the other hand, recent studies have indicated phosphite anion may not be used by plants as a P nutrient, even though it is well absorbed by leaves and roots. Aim of this study was to investigate action produced by soil phosphate levels and foliar-applied phosphorus forms on concentration and accumulation of P in shoot and root in common bean (Phaseolus vulgaris cv. Radiante) plants.

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 applied via foliar (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. Shoot and root dry mass were ground and analyzed for total P content colorimetrically (Murphy and Riley, 1962) after nitric-perchloric digestion of the plant material (Johnson and Ulrich, 1959). Data from shoot and root dry wt and total P concentration were used to calculate the P accumulation. 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:

Common bean plants grown under limiting phosphate availability (Pi-starved) showed decreased concentrations and accumulations of P in shoot and root. Foliar-applied potassium phosphite did not affect P nutrition of phosphate-sufficient plants, but increased concentration of P in shoot of phosphate-starved plants. However, accumulation of P was not significant varied among foliar application treatments (p > 0.05), showing that this increased concentration of P was not due directly to the P from the foliar-applied phosphite, but likely to “concentration effect”, which is confirmed by the lower shoot biomass yield (data not shown). When biomass yield 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. In addition, foliar-applied potassium phosphate did not significantly affect (p > 0.05) concentrations and accumulations of P in common bean, when compared with the control. This shows that either one or two foliar applications of phosphate were not sufficient to affect the plant P status.

CONCLUSÃO:

Results obtained reveal that plants grown under limiting phosphate availability presented decreased in concentrations and accumulations of P in shoot and root. And foliar-applied potassium phosphite did not affect P nutrition of phosphate-sufficient plants.

Palavras-chave: Phaseolus vulgaris, phosphorus, phosphite.