Potassium Phosphite and Water Deficit: Physiological Response of Eucalyptus Using Multivariate Analysis

This study aimed to evaluate the physiological response of Eucalyptus citriodora Hook seedlings subjected to foliar application of potassium phosphite and water deficit with the aid of multivariate statistical analysis, using MANOVA and canonical discriminant analysis. The experiment was conducted in a completely randomized design with five treatments (0.0 L c.p. ha-1 of potassium phosphite with irrigation; 0.0; 1.25; 2.50 and 5.00 L c.p. ha-1 of potassium phosphite without irrigation) and six replicates, in a greenhouse located in the municipality of Cruz das Almas, Bahia, Brazil. Treatments with potassium phosphite were applied by foliar spray, using the commercial product Reforce from Agrichem® (25.0% K2O + 35.0% P2O5 p/v). Irrigation was suspended seven days after application of the product. The correlation (0.6603) between the evaluated variables indicated that the use of multivariate analysis techniques was adequate to analyze this data set. Eucalyptus plants of the control treatment without irrigation responded to the water deficit conditions with inhibition of photosynthetic activity and increase of free proline content in the leaves. On the other hand, plants which received foliar application of potassium phosphite at highest concentrations (2.50 and 5.00 L c.p. ha-1), even under water deficit conditions, preserved the photosynthetic activity and proline content in the leaves with values equal to those observed in the irrigated control treatment. From this result it is possible to infer about the role of potassium phosphite as an attenuating effect of the water deficit in Eucalyptus citriodora Hook.