Indirect estimation of leaf area in genotypes of 'Conilon' coffee (Coffea canephora Pierre ex A. Froehner).

Leaf area is an important parameter in agronomic and physiological studies; thereby, the techniques used for its determination should be simple, fast and accurate. The objective of this study was to evaluate the efficiency of an equation for the indirect determination of leaf area in 'Conilon' (Coffea canephora) genotypes cultivated in the Western Amazon. The experiment was carried out in Porto Velho, Rondônia, in August and September 2011. It was arranged in a completely randomized 2 × 15 factorial design combining two methods of determining leaf area (estimated and actual) and fifteen 'Conilon' coffee genotypes, with 64 replicates. The estimated leaf area was determined by the equation LA = 0.3064 × Age-0.0556× LMR-2.0133(R2=0.98), developed by Partelli et al. (2006), while the actual leaf area was obtained from images of leaves scanned into digital format using an image scanner. The genotypes belong to the Coffee Breeding Program at Embrapa Rondônia. The efficiency of the equation for determining leaf area of 'Conilon' coffee varies according to the genotype evaluated; therefore, the equation must not be used without prior calibration. As the species is a perennial crop and the number of commercial genotypes widely accepted by farmers is restricted, the validation of the equation or the development of new equations capable of estimating the leaf area of the cultivated genotypes can help in the management of coffee plantationsn