Modelos matemáticos para a estimativa da área foliar de variedades de videira à campo (Vitis vinifera L.)

the leaf area determination is an important measure for the growth evaluation, conduction system comparison and phytosanitary damage valuation. direct and non destructive methods are used for ecophysiology and phytosanitary studies. however, it？s needed to establish a precise mathematic model for each variety. this work had the purpose of establishing equations to estimate the leaf area of the vine diversities cabernet sauvignon, merlot and sauvignon blanc. it was taken the main, the lateral (right and left) nervure length (cm) evaluating 70 leafs of each diversity, using a pachymeter and the leaf area measured with a portable analyzer (adc - am 300). the leafs were taken in different sizes and randomly chosen from several plants. the equations between the nervures and leaf area length for each variety were established from those measures, through the software statistica 6.0. the central nervure length for merlot specie, showed a high relation with the leaf area, while the length sum of the lateral nervures l1 and l2 for the cabernet sauvignon and sauvignon blanc were more representative of this measure. the leaf area, for specie merlot, was better defined by model polynomial 0,001x2 + 1,462x - 13,551 (r2 = 0,97). the exponential model was better suitable for the cabernet sauvignon and sauvignon blank, from equations y = 0,3039x2,1267 (r2 = 0,98) e y = 0,1732x2,3616 (r2 = 0,95), respectively. the equation to calculate the leaf area determination showed accuracy, being easy and fast to accomplish.