Yield Performance, Nutritional, and Sensory Qualities of Watermelon (Citrullus lunatus [Thunb.] Matsum and Nakai) Influenced by Humic Substances in Organic Production System
Field trials were conducted in the summer 2019-2021 to analyze yield response of Crimson Sweet and Sugar Baby watermelon to application of humic acid, fulvic acid and biochar. Fruit sensory attributes, phytochemical profile and food safety parameters was also determined. There were no significant differences in the number of fruits per plant between Crimson Sweet and Sugar Baby (P<0.05). Humic acid gave the highest number of fruit (6.4), followed by biochar (6.1). Fulvic acid had the least number of fruits (4.7), however, these values were not statistically different from the control (P<0.05). Humic acid and fulvic acid gave the highest fruit weight of 14.5 and 14.4 (lbs.), respectively. Variety contributed significantly to the phytochemical profile of watermelon. Treatments significantly increased percentage moisture content with humic acid and biochar giving the highest values of 94.2 and 93.9 for Crimson Sweet and 94.1 and 93.5 for Sugar Baby. Humic acid gave the highest a* (redness) value of 36.09 (for Crimson Sweet) and 35.63 (Sugar Baby) which were significantly higher than control (P<0.05). Crimson sweet grown conventionally also recorded a higher redness (a*) compared to organic. Farming system (organic vs conventional) influenced the type of volatile organic compounds of watermelon. The principal volatile organic compound in organic watermelon was 1-nonanol whereas, benzoic acid was the principal VOC in conventional watermelon. Mean values for texture analysis decreased from the rind towards the center of the fruit. There were no differences in texture between treatment and control. Brix value declined from the center of fruits towards the rind. Crimson Sweet had a higher mean brix value of 10.54, 9.54, and 6.54 for center, flesh, and rind, compared to Sugar Baby that had 8.8, 8.5, and 4.93 for center, flesh, and rind, respectively. Seventeen Enterobacteriaceae were isolated from organic and conventional watermelon field. Microbial count was significantly higher (P<0.05) on fruits that were in direct contact with the ground (9.49) compared to fruits on plastic mulch (9.29). Organic field had higher microbial count (9.5) compared to conventional (9.3)., Enterobacter sakazakii, Klebsiella pneumonia and Pseudomonas fluorescence were resistant to cephalothin.
"Yield Performance, Nutritional, and Sensory Qualities of Watermelon (Citrullus lunatus [Thunb.] Matsum and Nakai) Influenced by Humic Substances in Organic Production System"
ETD Collection for Tennessee State University.