Extracting potassium from mango leaves.
González-Acuña I. J., Llanos-Perales A., Hurtado-García B., Lang-Ovalle F. P.
Author Affiliation: INIFAP-C.E. Santiago Ixcuintla, Apdo. Postal #100, C.P. 63300, Mexico.
: 381-386
Abstract : Potassium is an essential nutrient in mango production. Tissue analysis is a useful tool for fertilization programs, and results affect orchard management and production costs. We evaluated four plant potassium extraction methods in 'Ataulfo' mango leaf samples: (1) distilled water, (2) 65-70% nitric acid (HNO3) and 69-72% perchloric acid (HclO4) wet digestion, (3) 1.0 N ammonium acetate (CH3COONH4) pH 7.0, and (4) 0.5 M barium chloride (BaCl2.2H2O). Protocols (1) and (2) are the most commonly used methods. Analytical quantification was achieved using atomic absorption spectrometry. Potassium content was expressed as a percentage. One hundred replications were used to evaluate each method. Statistical treatment included random variance analysis, mean comparison with Tukey (P=0.01), cluster analysis to determine canonical association between methods, and a technical aptitude test (Z-score). Each extraction method revealed a different capacity to dissolve mango leaf potassium: wet digestion extracted 0.9045%; distilled water 0.9707%; ammonium acetate 1.0 N, 1.0273%; and barium chloride 0.5 M, 1.2267%. The high activity of the 0.5 M barium chloride method allows for the exchange of potassium fixed in plant tissues, thus elevating levels of extraction. The Z-score revealed a significant Euclidian distance which separated it from traditional methods that often yield underestimates. Standardized field methods are currently under development.