Effect of saline water and shading on dragon fruit (?pitaya?) seedling growth1

: ?Pitaya? (Hylocereus undatus) is a fruit-bearing, climbing cactus with great food potential for the semiarid region. This study aimed to evaluate the production of ?pitaya? seedlings irrigated with low and high salinity water and grown in different light intensities. The experiment was conducted in a completely randomized design, in a 2 ? 2 factorial arrangement, with two electrical conductivities of irrigation water: S1 - 0.3 dS m-1 (low salinity) and S2 - 5.0 dS m-1 (moderate salinity) in two environments: A1 - black net with 50% shading, and A2 - full sun, with ten replicates. The variables evaluated were plant height, main cladode diameter, above-ground biomass, root biomass, total plant biomass, number of secondary cladodes, root length, and length of secondary cladodes. The 50% shading (black net) promoted higher plant height, number of secondary shoots, and root length of the ?pitaya? plants. The irrigation with moderate saline water (5.0 dS m-1) reduced the number of secondary cladodes, length of root, and length of secondary cladodes. The ?pitaya? seedlings grown under 50% shading (black net) showed greater root dry biomass when irrigated with low-salinity water. Greater values of diameter of the primary cladode, above-ground dry biomass, and total dry biomass were observed under full sunlight and elevated saline stress.