Water salinity and nitrogen fertilization in the production and quality of guava fruits

Abstract

Using nitrogen (N) to increase plant tolerance to salinity has been tested in many species. However, in addition to controversial results, most studies are conducted with annual species and/or in the initial growth stage and there are almost no studies with perennial fruit crops in the production stage. Thus, this study aimed to evaluate the production components and post-harvest quality of 'Paluma' guava irrigated with water of increasing salinity in soil fertilized with N. The experiment was carried out for two years in drainage lysimeters in an experimental area of the Federal University of Campina Grande (UFCG), Pombal, PB, Brazil. The experimental design was in randomized blocks, in 5 x 4 factorial scheme, with of five levels of water salinity-ECw (NaCl) (0.3, 1.1, 1.9, 2.7 and 3.5 dS m-1) and four N doses (ureia) (70, 100, 130 and 160% of the recommended dose-541.1 mg of N dm-3 of soil per year), with three replicates. Number of fruits, mean fruit weight, production per plant, polar and equatorial diameters of fruit and contents of soluble solids and ascorbic acid (vitamin C) decreased linearly with the increase in irrigation water salinity from 0.3 dS m-1. The interaction between water salinity and N doses and the isolated action of N did not interfere statistically with the studied variables.

West Indian cherry production under irrigation with saline water and potassium-phosphorus fertilization

“…Another factor that may have contributed was also the fertilizers used, because potassium chloride and MAP, sources of potassium and phosphorous, respectively, are salts that can potentiate the per unit increase in ECw, which is equivalent to a decrease of 34.26% in the number of fruits of plants irrigated with 3.8 dS m -1 water compared to those under ECw of 0.6 dS m -1 . In line with the results obtained in this study, Bezerra et al (2019) found a reduction of 28.13% in the number of guava fruits with the increase in ECw from 0.3 to 3.5 dS m -1 in the second production cycle. According to these authors, this is due to the intensification of osmotic effects and excessive accumulation of potentially toxic ions (Na + and/or Cl -) in plant tissues throughout the cultivation cycle.…”

“…In the second production cycle (Figure 3B), regardless of the potassium-phosphorus combination, the TWFr was lower than that obtained in the first cycle, confirming the premise that crop tolerance varies not only with stress intensity and plant variety but also with the time of exposure of crops to the stressful factor (Willadino & Camara, 2010;Bezerra et al, 2019).…”

Physicochemical Quality of Fruits of West Indian Cherry Under Saline Water Irrigation and Phosphate Fertilization1

“…The salinity × phosphate fertilization interaction, despite not interfering with pH and soluble solids content (ºBrix), which responded to the single action of water salinity, exerted significant effects on titratable acidity and ascorbic acid content in the pulp of West Indian cherry fruits (Table 3). Bezerra et al (2019), in a study evaluating the post-harvest quality of 'Paluma' guava cultivated with saline waters (ECw from 0.3 to 3.5 dS m -1 ) and nitrogen doses, also found that there was a significant single effect on soluble solids, titratable acidity and ascorbic acid. Table 3.…”

“…Evaluating the postharvest quality of West Indian cherry fruits, Sá (2018) found that under conditions of high water salinity (3.8 dS m -1 ), there was a reduction in fruit diameter as the salinity levels of irrigation water increased. In a study with guava, Bezerra et al (2019) evaluated the physicochemical composition of fruits of 'Paluma' guava irrigated with salinity waters (ECw from 0.3 to 3.5 dS m -1 ) and found reductions in fruit polar diameter of 7.08 and 7.43%, per unit increase of ECw, respectively, in the first and second years of cultivation. The fresh mass of West Indian cherry fruits decreased linearly with the increase in the levels of irrigation water salinity (Figure 2A), with loss of 11.07% per unit increment in ECw, resulting in a reduction of 37.96% (1354.81 g plant -1 ) in the FFM of plants irrigated with 3.8 dS m -1 water, compared to those subjected to salinity of 0.6 dS m -1 .…”

“…In addition, as West Indian cherry fruits are more intended for consumption in the form of pulp, the increase in titratable acidity reduces the need for adding acidifiers, ensuring food safety for consumers while maintaining organoleptic quality as found for yellow passion fruit (NASCIMENTO et al, 2015), reducing processing costs and increasing the shelf life of the juice (DIAS et al, 2011). In a study with 'Paluma' guava under irrigation with saline water (ECw from 0.3 to 3.5 dS m -1 ) and nitrogen fertilization, Bezerra et al (2019) obtained fruits with titratable acidity ranging from 4.1 to 4.59%, that is, values well lower than that of West Indian cherry.…”