Quality of seedless watermelon cultivated under different doses and phosphorus application forms

Abstract

Effects of doses and phosphorus application forms were studied on the postharvest quality in seedless watermelon hybrid 'Style'. For this, an experiment was conducted in Upanema/RN, Brazil, during the period of September to December 2013, in a randomized block at factorial scheme 5×2 constituting of five phosphorus doses applied in foundation (0, 76, 168, 275 and 397 kg ha -1 of P 2 O 5 ) and foundation + fertigation (0+50, 26+50, 118+50, 225+50, 347+50 kg ha -1 of P 2 O 5 ) with four replications. Fruit harvested at commercial maturity (78 days after sowing) were evaluated by average fruit weight (AFW), pulp firmness (PF), chroma index, hue angle, soluble solids content (SS), titratable acidity (TA), maturation index (MI), total phenols content (TP), vitamin C (VC), total sugars content (TS), reducing sugars content (RS) and pH. Among the quality parameters evaluated phosphorus application forms did not affect physical characteristics of fruit, but combination of application via foundation + fertigation increased VC, TS and MI. There was interactive effect of dose and phosphorus application form for the SS, TA, pH and TP. The dose of 50 kg P 2 O 5 ha -1 applied only in fertigation significantly increased values of SS, TA and TP. It is concluded that low doses of P in cultivation and its application via foundation and fertigation improved the main quality characteristics of 'Style' watermelon.

Prospection of the quality and bioactive potential of the seedless watermelon

“…The average soluble solids were about 10 ºBrix over all those studied hybrids, ranging by 9 to 11.6 ºBrix, for 'Extasy' and 'Valentino', respectively. These results are in line with related studies for commercial watermelon hybrids [26,29], which highlight that those hybrids are within the standards found in the market. The soluble solids content is a measurement of the concentration of reducing and non-reducing sugars, so that, the relative concentration of these sugars is influenced by cultivation and stage of maturity [9].…”

“…Average Hue angle in all those studied hybrids, except 'Extasy', fit close to 29°, which can be considered as mature fruits, in accordance with the findings in 'Style' watermelon hybrid in which the average °Hue fit 28.17° [29]. In the hybrid 'Extasy', °Hue fit close to 37°.…”

“…'Valentino' could show the best sweet taste among the hybrids, since soluble sugars are the low molecular weight carbohydrates, components of soluble solids, responsible for the sweet taste of fruits [4]. Our results are in line with Araújo et al (2016) [29] which observed average levels of 8.23% of total soluble sugars in watermelon fruits.…”

“…The average reducing sugars was about 3,02% over all those studied hybrids, ranging from 2.40 to 4.48% 'Ashira' and 'Extasy', respectively, in line with Araújo et al (2016) [29] (5.52%). It is noteworthy that the main sugars present in cucurbits are, in general, glucose, fructose, and sucrose.…”

“…Recent findings have reported that the variation in fruit firmness correlates with variation in cell composition, density and size, addition to polyuronide fractions, and possibly with the regulation of osmotic cell pressure by osmolytes such as citrulline [11,28]. Araújo et al (2016) [29], reported for 'Style' hybrids, average pulp firmness around 6.48 N and highlighted loses in the resistant.…”