Morphophysiology of passion-fruit seedlings in different substrates under different strategies of irrigation with brackish water

Abstract

The presence of salts in the irrigation waters of the semiarid region negatively affects the production of seedlings. Thus, substrates based on carbonized rice husk are an alternative for production in saline environments, associated with irrigation management strategies with brackish water. This study evaluated the physiological responses of yellow passion-fruit seedlings as a function of irrigation strategies with brackish water in different substrates. The study was developed at the Universidade da Integração Internacional da Lusofonia Afro-Brasileira, Redenção, Ceará. The design was entirely randomized, in a 2 × 5 factorial scheme with two substrate compositions (S1 - soil; S2 – sandy soil, sand and carbonized rice husk - 1:1:1 – volume basis) and five irrigation strategies with brackish water (IS1 - low salinity water during the entire cycle 1-65 days after sowing (DAS); and salt stress initiation at: IS2 - 11 DAS; IS3 - 16 DAS; IS4 - 21 DAS; IS5- 26 DAS), with five repetitions. Soil as a substrate was efficient for photosynthesis and chlorophyll. It also provided better results for transpiration, stomatal conductance and leaf area regardless of the strategy. Internal carbon concentration and water use efficiency were higher in soil associated with saline stress at 11, 16 and 21 DAS. Under the same substrate, the stem diameter of the seedlings was greater when irrigated with lower salinity during the phase. The substrate composed of carbonized rice is associated with greater seedling height and increased leaf temperature.
 Keywords: plant physiology, Passiflora edulis, salinity, substrate.