Regression plateau for plot size estimation with ‘Gigante’ forage cactus pear

Abstract

‘Gigante’ cactus pear (Opuntia ficus indica Mill. cv. Gigante) is a forage crop grown under semi-arid climates and because of its’ resilience to water-limiting conditions it can produce a high biomass yield. The objective of this study was to estimate the optimum experimental plot size for ‘Gigante’ using the linear Response Plateau Model. The study was carried out at Baiano Federal Institute, Guanambi Campus, state of Bahia, Brazil. A uniformity trial in which plants were subjected to the same cultural practices and spaced 2.0 m × 0.2 m apart was conducted. Each plant was considered as a basic unit. The Linear Response Plateau Method allowed fitting models with coefficients of determination ranging from 0.0772 to 0.881. Plot sizes ranged from 7.30 to 9.46 basic units for the evaluated characteristics. Using the Linear Response Plateau Regression model, a plot size of 10 basic units (4.0 m²) was estimated to be sufficient for field experiments with ‘Gigante’ forage cactus pear.