Influence of Leaf Water Content on the Prediction of Nutrient Stress in Strawberry Leaves using Chromameter
Chemical soil and plant tissue analyses require considerable amount of labor, time, and cost. Non-destructive prediction of nutrient stress from chromameters may save time and labor. Previous studies did not assess multiple nutrient stresses together with the effect of leaf water content (WC). The aim of this work was to investigate the effect of leaf WC on the prediction of leaf nutrient stress from leaf color. A commercial strawberry field with a significant amount of leaf color variability was selected in Hatay province of Turkey. Forty eight leaf samples with varying colors were collected. A hand-held chromameter was used for leaf color measurements in two color systems as L*a*b* and L*C*h°. Leaf WC was determined using oven drying method. Leaf nutrient contents of N, P, K, Ca, Mg, Mn, Fe, and Cu were obtained using chemical analysis. Correlation and Partial Least Square Regression (PLSR) methods were utilized for data analysis. Leaf WC ranged from 58.3 to 65.7%. High correlation existed between color parameters and N, Ca, and WC (|r|>0.66). Also, correlation was high between leaf WC and leaf N content (r=0.75), suggesting that the leaves with high WC had also high N content. Using color data, it was possible to predict leaf N content (R 2 =0.66), Ca content (R2 =0.70), and WC (R 2 =0.65). Using WC as a variable together with the color parameters slightly improved the model performance to predict strawberry leaf nutrient concentrations.