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.
Keywords:
Annona squamosa L; Salt stress; Mineral nutrition
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C1 = 100-100-100; C2 = 100-100-125; C3 = 100-125-100; C4 = 100-125-125; C5 = 125-100-100; C6 = 125-100-125; C7 = 125-125-100 and C8 = 125-125-125% of the recommended dose of N-P-K; Means followed by the same letter do not indicate significant differences for irrigation water salinity (A) and different combinations of fertilization with N-P-K (B), respectively, by Tukey and Scott-Knott test at 0.05 probability level.
C1 = 100-100-100; C2 = 100-100-125; C3 = 100-125-100; C4 = 100-125-125; C5 = 125-100-100; C6 = 125-100-125; C7 = 125-125-100 and C8 = 125-125-125% of the recommended dose of N-P-K; Means followed by the same letter do not indicate significant differences for irrigation water salinity (A) and different combinations of fertilization with N-P-K (B), respectively, by Tukey and Scott-Knott test at 0.05 probability.
C1 = 100-100-100; C2 = 100-100-125; C3 = 100-125-100; C4 = 100-125-125; C5 = 125-100-100; C6 = 125-100-125; C7 = 125-125-100 and C8 = 125-125-125% of the recommended dose of N-P-K; Means with same uppercase letters indicate that there are no significant differences between the combinations of N-P-K fertilization by the Scott-Knott test at 0.05 probability level, and same lowercase letters for the same fertilization combination indicate that there is no significant difference between salinity levels (Tukey test, p <0.05).
C1 = 100-100-100; C2 = 100-100-125; C3 = 100-125-100; C4 = 100-125-125; C5 = 125-100-100; C6 = 125-100-125; C7 = 125-125-100 and C8 = 125-125-125% of the recommended dose of N-P-K; Means followed by the same letter do not indicate significant differences for salinity of irrigation water (A) and different combinations of fertilization with N-P-K (B), respectively, by the Tukey and Scott-Knott test at 0.05 probability level.
C1 = 100-100-100; C2 = 100-100-125; C3 = 100-125-100; C4 = 100-125-125; C5 = 125-100-100; C6 = 125-100-125; C7 = 125-125-100 and C8 = 125-125-125% of the recommended dose of N-P-K; Means followed by the same letter do not indicate significant differences for irrigation water salinity (Figures A and B) and different combinations of fertilization with N-P-K (Figures C and D), respectively, by the Tukey and Scott-Knott test, respectively at 0.05 probability level.
C1 = 100-100-100; C2 = 100-100-125; C3 = 100-125-100; C4 = 100-125-125; C5 = 125-100-100; C6 = 125-100-125; C7 = 125-125-100 and C8 = 125-125-125% of the recommended dose of N-P-K; Means with same uppercase letters indicate that there are no significant differences between the combinations of fertilization with N-P-K by the Scott-Knott test at 0.05 probability level, and same lowercase letters for the same fertilization combination indicate that there is no significant difference between salinity levels (Tukey test, p <0.05).