Cladode area of cactus forage clones: modeling, analysis and applicability

Abstract

The objective this work was to evaluate the use of the digital image technique and of mathematical models based on linear dimensions in the determination of the cladode area (CA) of cactus forage clones. These techniques were evaluated for nine clones of the genus Opuntia sp. e Nopalea sp. Linear, exponential and Gompertz models were fitted to estimate the area through biometric data. The Gompertz model was also applied in the analysis of the evolution of the cladodes. A relationship between the green mass yield and the cladode area index (CAI) was established. The CA models were used in analyze of the evolution of the CAI of three clones. With the results, it was observed that the digital image technique presented excellent performance in the determination of the cladode area (r = 0.9998; d = 0.9999; MBE = 4.90 cm2; RMSE = 5.83 cm2). The single linear model and the individual and unique Gompertz models are the most recommended in the estimate of the CA. It has been found that the evolution CA is associated to their length and width. The green mass yield of the cactus forage has tended to stabilize when the CAI values were above 1.5 m2 m-2, and the ‘Orelha de Elefante Mexicana’ obtained evolution of CAI greater to ‘IPA Sertânia’ and ‘Miúda’.