Características produtivas e estruturais de genótipos de palma forrageira irrigada em diferentes intervalos de corte.

The spineless cactus receiving additional water may constitute alternative food for the flocks of the Brazilian semiarid; however, the information about structural and productive responses of genotypes, as well as the range of the plant cuts are scarce. This research aimed to evaluate the productive and structural characteristics of genotype at different cutting intervals. The experimental design was a randomized block with split plot (genotypes in the plots and cutting intervals in the subplots), with four replicates per treatment, totaling 48 experimental units. The experiment was conducted from May 2014 to September 2015, with three genotypes of cactus, the Orelha de Elefante Mexicana (OEM) (Opuntia stricta (Haw.) Haw.) IPA 20 (Opuntia ficus indica (Mill.) and Miuda (Nopalea cochenillifera Salm. Dyck) and at a cutting interval of 4, 8, 12 and 16 months after planting. The OEM at 16 months presented higher forage mass (t dry matter/ha and green matter/ha) compared to the Miuda and IPA 20 at the different cut intervals, with a higher rate of forage accumulation rate and better water use efficiency. Miuda had more and lighter cladodes. The OEM together with Miuda presented higher cladode area index from eight months after planting compared to IPA 20. The genotypes as well as the cut interval affect the productive and structural characteristics of spineless cactus.