Production and quality of watermelon fruits under salinity management strategies and nitrogen fertilization

The objective of this study was to evaluate the production and quality of ‘Sugar Baby’ watermelon fruits under different strategies of irrigation with saline water and nitrogen (N) fertilization in an experiment conducted in a protected environment in Campina Grande, Paraíba, Brazil. The experimental design adopted was in blocks with a 6 × 2 factorial scheme, corresponding to six strategies of irrigation with saline water applied at different phenological stages of the crop (SE irrigation with low-salinity water throughout the cycle; salt stress at the vegetative stage VE; vegetative and flowering VE/FL; flowering FL; fruiting FR; fruit maturation MAT) and two N doses (50 and 100% of the recommendation, equivalent to 50 and 100 mg of N kg-1 of soil) with five replicates. Two levels of irrigation water salinity were studied, one with low and the other with high electrical conductivity (ECw = 0.8 and 3.2 dS m-1). The salt stress applied at the vegetative and flowering stages reduced the contents of ascorbic acid and total soluble solids in ‘Sugar Baby’ watermelon fruits. The dose equivalent to 50% of the N recommendation promoted a greater fresh weight of watermelon fruits. Fertilization with 100% of N increased the hydrogen potential of watermelon fruits under salt stress at the vegetative and flowering stages. The anthocyanin content of watermelon fruits decreased under salt stress, regardless of the development stage; however, with 50% of recommendation of N, there was an increase in this variable.