Growth and ionic homeostasis of custard apple seedlings irrigated with saline wastewater¹

Crescimento e homeostase iônica de mudas de pinha irrigadas com águas residuais salinas

ABSTRACT

Custard apple (Annona squamosa L.) is a sensitive fruit crop to salinity. One of the alternatives to minimize the deleterious effects of salt stress is adopting mineral fertilization management practices, promoting increased crop tolerance to salts. Therefore, the objective of the present study was to evaluate NPK doses to mitigate salt stress in custard apple seedlings irrigated with saline wastewater. The experiment was performed in a greenhouse, adopting a randomized block design in a 3 × 5 factorial scheme, corresponding to three irrigation waters (local-supply water of 0.53 dS m^-1 electrical conductivity (control); desalination reject of 3.5 dS m^-1; fish farming effluent of 3.5 dS m^-1) and five proportions of the NPK recommendation (25, 50, 75, 100, and 125% of the fertilization recommendation), with four replicates. The growth, biomass accumulation, and nutrients were evaluated. Irrigation with desalination reject, and fish farming effluent restricted the growth of custard apple seedlings, regardless of the NPK dose used. The ionic homeostasis of seedlings irrigated with desalination reject and fish farming effluent is optimized by fertilization with 50% of the NPK recommendation corresponding to 50, 150, and 75 mg of N, P₂O₅, and K₂O dm^-3, respectively. For the production of seedlings irrigated with local-supply water, the dose of 75% NPK, corresponding to 75, 225, and 112.5 mg of N, P₂O₅, and K₂O dm^-3, respectively, is recommended.

Key words:
Annona squamosa L.; irrigation; salt stress; fertilization; plant nutrition

HIGHLIGHTS:

Custard apple seedlings irrigated with saline wastewater achieve better ion homeostasis and save fertilizers.

Independent of the NPK amount applied, irrigation with saline wastewater limits the development of custard apple seedlings.

Under irrigation with local-supply water, custard apple seedlings require 75% of the NPK recommendation.