Non-destructive models for estimating leaf area of guava cultivars

Leaf area is a commonly used measurement in many agronomic studies, but its assessment is generally destructive, and then simple, accurate and non-destructive methods are really appreciated. The objective of this study was to develop a non-destructive model that could be used to estimate the leaf area of four guava (Psidium guajava L.) cultivars by using leaf linear dimensions. Leaves from guava cultivars ‘Paluma’, ‘Sassaoka’, ‘Século 21’, and ‘Tailandesa’ were sampled randomly from an experimental orchard. Leaf length and maximum leaf width were measured with a ruler in 120 leaves from each cultivar. Leaf areas were also measured with a leaf area meter. Linear and power models relating leaf area to length, width, and length × width were fitted to the data. The most precise models were regressed again with a new data set to validate the proposed models. The power model (y = 0.61 x1.06) using the length × width was more precise and accurate to estimate the leaf area of all four cultivars evaluated herein, grown in field or greenhouse conditions. When only one leaf dimension was used, the power model (y = 1.81 x1.93) using the width was the best-performing model. Although models with only one leaf dimension (length or width) have shown good performance for estimating the guava leaf area, models based on the leaf length × width were more precise.