Yield and morphology of forage cactus cultivars under drip irrigation management based on soil water matric potential thresholds

The recent increase of irrigation practices in forage cactus crops makes appropriate irrigation management criteria necessary. In this study, the morphological and yield characteristics of forage cactus cultivars were evaluated for some soil-based irrigation management criteria. Five experiments were carried out simultaneously under semiarid conditions in a randomized block design, with forage cactus cultivars Orelha de Elefante (OE), IPA-Sertania (IPA), Doce (DC), Gigante (GG), and Orelha de Onca (OO). For each cultivar, irrigation management was performed using four upper thresholds of matric potential (-0.2, -0.33, -1, and -3 atm), as well as a nonirrigated (rainfed) treatment. Forage cactus crop yield was evaluated after 12 months and responded positively and similarly to irrigation management using any of the thresholds, with a significant increase in the cladode area and, overall, a positive effect on growth and yield parameters. Very high irrigation water productivity up to 75 kg m(-3) was obtained especially in the -3 atm threshold treatment, whereas an increase of the threshold potential caused a sharp reduction of water productivity. We conclude that irrigation management of forage cactus grown in semi-arid climates is highly beneficial and that unconventionally low matric potential thresholds may be used.