Abstract
Fruit surface area is an important trait in studies of developmental physiology, as well as in entomological and phytopathological research, where damage caused by insects and/or microorganisms needs to be quantified. Nonetheless, direct measurement of this trait is difficult, not very precise and destructive. This study establishes allometric relationships to estimate the surface area of peach palm (Bactris gasipaes Kunth, Palmae) fruits. Five fruits were harvested, at different maturation stages, from each of 18 plants. Image digitalization and edition methodology was adapted and compared with the traditional gravimetric method. Regression analysis and curve fitting were used to compare the two methods and establish allometric relationships among fruit surface area and fruit weight and size. The method based on image digitalization was twice as fast as the gravimetric method. Curve fitting for all pairs of independent and dependent variables was better with the image method. For most relationships, the best model was the exponential function (Y = ax b), although, due to its simplicity, the linear model is also adequated. The best allometric estimates of fruit surface area (Y) were obtained using the product of fruit length by maximum width (x) were: Y = 2.077 x 1.189 (R² = 94.8%); and Y = - 6.261 + 3.961 x (R² = 94.5%). Traits needed to establish this relationship are easily measured and non-destructive in nature. Validation of the allometric equations is essential when applied to other populations or landraces.
Highlights
The determination of the surface area of fruits is necessary to quantify damage caused by insects and microorganisms (Meah, 1993; Yang et al, 1997; Padmanaban et al, 1997; Timmer et al, 1998)
The coefficient of variation (CV) for estimates obtained by image digitalization (20.38%) was lower than the one obtained by the gravimetric approach (21.34%), the former was used in the establishment of allometric relationships presented below
The exponential function of fruit maximum width is complex (Table 3), but deserves consideration in developmental physiology studies, because fruit surface area can be estimated with only one measurement, taken non-destructively, with a caliper
Summary
The determination of the surface area of fruits is necessary to quantify damage caused by insects and microorganisms (Meah, 1993; Yang et al, 1997; Padmanaban et al, 1997; Timmer et al, 1998). Surface area is important to establish the relations, in different maturity stages, between photosynthetic activity and fruit development (Banarar, et al, 1994; Lister et al, 1994; Marcelis & Hofmaneijer, 1995; Dias-Perez, 1998). The direct measurement of fruit surface area, is important in these studies, but difficult, not very precise and usually. 2002 destructive (Anadaraj & Bhagavan 1983; Clayton et al, 1995) Scientia Agricola, v.59, n.4, p.717-721, out./dez. 2002 destructive (Anadaraj & Bhagavan 1983; Clayton et al, 1995)
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