Leaf area of snap bean (Phaseolus vulgaris L.) according to leaf dimensions

Abstract

The aim of this work was to compare the methods of leaf discs and digital photos used to determine the leaf area of snap bean (Phaseolus vulgaris L.), with indeterminate growth habit, and model complete leaf area (three leaflets) according the length, or width and or the product of length width, for different sizes of leaves. An experiment was conducted in a greenhouse at University Federal of Santa Maria, in Rio Grande do Sul State, Brazil. For this, in 191 leaves, collected 55 days after sowing, it was measured the maximum length and maximum width of central leaflet, and calculated the product of length width. After was determined leaf area of complete leaves (left, central and right leaflets), by the methods of digital photos and leaf discs. Linear regression analysis and correlation were used to compare the methods. The quadratic, potency and linear models of the leaf area as a function of the length, or width, or product of length width were adjusted, and validated by different indicators. In snap beans, the leaf disks and digital photos methods are discordant. The method digital photos adequately represent the leaf limb, regardless of different mass per area exist, and is appropriate for the determination of leaf area. Quadratic model (? = –4.8376 + 1.8908 x + 2.2027 x2, R2 = 0.9901) and potency model (? = 2.5806 x1.9565, R2 = 0.9883) based on the width of central leaflet (x) are adequate to estimate complete leaf area (three leaflets), determined by digital photos.