Estimativa da área do cladódio em palma forrageira orelha de elefante mexicana(Opuntia stricta Haw)

Abstract

The semi-arid region is characterized by climatic instability, which ends up limiting the performance and development of some agricultural and livestock activities in the Brazilian Northeast. The forage cactus (Opuntia stricta Haw) has been studied and used in agriculture in arid and semi-arid regions worldwide, mainly due to its adaptation to poor soils and adverse climatic conditions, representing an efficient and non-destructive food option during dry periods. The evaluation of cladode area is essential to understand the plant’s performance, but there are direct and indirect methods to obtain leaf area, with the use of linear mathematical models being more common.Therefore, this study aimed to determine cladode area using a mathematical formula with correction factor compared to different existing methods. Thus, two direct methods (Planimetric – APL and Paper Weight – APP) and one indirect method (Biometric Measures – AMB) were used for comparison in determining cladode area (CA). Regression analyzes of cladode dimensions showed significant differences at 1% compared to other methods, mainly for the evaluated cladode area. Simple linear regression models demonstrate that all tested independent variables (Aplan, Aqua, Aret, Acirc, FORM) are significant predictors of APP. The correlation ranged from 0.9243 to 0.9673, indicating that these variables have high efficacy in determining cladode area. Considering the high correlation values, it was observed that the methods with the highest precision were the circle method (R² = 0.9673) and the formula method (R² = 0.9673), indicating even precision than other methods.