Abstract
ABSTRACT The objective of this study was to evaluate the effect of combinations of nitrogen, phosphorous and potassium doses on the production components of custard-apple irrigated with saline waters. The experiment was conducted in a greenhouse, using a Neossolo Regolítico (Entisol) of clay loam texture in Campina Grande-PB, Brazil. The treatments were distributed in a randomized block design, in a 2 × 8 factorial scheme, with three replicates, corresponding to two levels of electrical conductivity of water - ECw (0.8 and 3.0 dS m-1) and eight combinations of fertilization with nitrogen, phosphorus and potassium (100-100-100; 100-100-125; 100-125-100; 100-125-125; 125-100-100; 125-100-125; 125-125-100 and 125-125-125% of the recommendation, for the third year of cultivation). The combination of 100-100-100% corresponded to 100, 60 and 60 g of N, P2O5, K2O per plant per year, respectively. High concentrations of salts in the irrigation water reduced the number of fruits, fresh fruit mass, total number of seeds and mass of seeds of custard-apple. Plants achieved the best development when grown under 125-100-100, 125-125-125 and 100-100-100% combinations of N-P-K recommendation. Irrigation with ECw of 3.0 dS m-1 associated with the 100-125-125% combination of fertilization increased the average mass and height of the custard-apple fruits.
Highlights
Custard-apple (Annona squamosa L.) is a fruit crop belonging to the Annonaceae family, which has stood out due to its economic importance for the Northeast region, especially in the states of Bahia, Pernambuco and Ceará, which have the highest levels of productions of this fruit in the country (ANDRADE et al, 2018)
Despite the good adaptation of custard-apple to the Brazilian Northeast, in this region its productive potential is limited by the water quality, especially in its semi-arid region, due to the spatial and temporal irregularity of rainfall, which increases the concentration of salts in water, especially sodium contents, which have negative effects on plants, resulting in lower growth and production of crops (SILVA et al, 2018; DIAS et al, 2019)
Studies have been carried out using saline water in custard-apple cultivation in the Northeast region, such as that of Fernandes et al (2021), who observed reductions of growth when plants were irrigated with water of 4.0 dS m-1
Summary
Despite the good adaptation of custard-apple to the Brazilian Northeast, in this region its productive potential is limited by the water quality, especially in its semi-arid region, due to the spatial and temporal irregularity of rainfall, which increases the concentration of salts in water, especially sodium contents, which have negative effects on plants, resulting in lower growth and production of crops (SILVA et al, 2018; DIAS et al, 2019). Phosphorus and potassium are the nutrients most exported by custard-apple and have been reported to have a pronounced effect on fruit quality (SÃO JOSÉ et al, 2014), which may enable fertilization management and irrigation with high salt content in semi-arid areas of Northeastern Brazil. Studies have been carried out using saline water in custard-apple cultivation in the Northeast region, such as that of Fernandes et al (2021), who observed reductions of growth when plants were irrigated with water of 4.0 dS m-1. There are few studies contemplating the use of saline waters up to the reproductive stage of the crop
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