Growth Dynamic, Productivity, Evapotranspiration, and Water-Economic Indices of Forage Cactus under Different Irrigation Depths

Supplementary irrigation can be strategic for forage cactus, aiming to guarantee higher levels of productivity and economic return. Therefore, this study aimed to evaluate the growth dynamics, productivity, evapotranspiration, and water economy indices of three forage cactus clones under different water regimes. The study was carried out in the Brazilian semi-arid region during two cycles between 2020 and 2022. Clones of forage cactus Orelha de Elefante Mexicana—OEM (Opuntia stricta (Haw.) Haw.) were evaluated; IPA Sertânia—IPA and Miúda—MIU (both species Nopalea cochenillifera (L.) Salm-Dyck) were subjected to four water regimes: rainfed and three irrigation depths (4, 8 and 12 mm). Growth dynamics and evapotranspiration were evaluated throughout the cycles, and productivity and water economy indices were based on data from the harvest time. The OEM clone showed higher dry matter productivity (21.8 Mg ha−1). The MIU clone, when intended for seed sales, presented a higher economic return (USD 20,823.33). The use of irrigation brought forward the cutting time and reduced water saving rates. With this, it can be concluded that the increase in water availability in cactus increases water consumption and reduces economic-water indices but brings important productive returns.