Effect of Black Soldier Fly Larvae Frass as Organic Fertilizer on Postharvest Quality and Shelf Life of Open-field-grown Tomato (Solanum lycopersicon L.)

Open-field-grown tomatoes in Saudi Arabia are stressed by poor soil fertility because of the low organic matter content, low nutrient availability, and high pH. Thus, high chemical fertilizer inputs are crucial for commercial production; however, they cause economic loss as well as negatively affect environmental sustainability. The use of efficient organic fertilizers would be useful for developing more cost-effective, environmentally friendly, and sustainable agriculture. The current study evaluated the impact of Black soldier fly (Hermetia illucens L.) frass (BSFF) fertilizer applications as organic fertilizer on postharvest fruit quality and shelf life of open-field-grown F1 hybrid ‘Sinag Tala’ tomatoes compared with those grown under control treatment (received recommended doses of chemical fertilizers for tomato production under open field conditions). The experiment was conducted using a randomized complete block design with four replicates. The results showed that the application of BSFF fertilizer, especially at the higher rate (5 ton/ha; BSFF3), improved the overall quality of tomato fruit. The BSFF fertilizer treatments reduced weight loss, maintained higher firmness, antioxidants [vitamin C, total phenol content (TPC) and total flavinoid (TFC)], total soluble solids (TSS), and titratable acidity (TA) contents, and lowered the TSS/TA ratio of fruits during shelf life compared with those of the control. The decay incidence was only detected after 9 days of shelf life and was significantly lower in all the BSFF fertilizer treatments (range, 8.40%-12.05%) than in the control (15.9%). In addition, BSFF fertilizer treatments reduced both disease incidence and severity of gray mold following pathogen inoculation during shelf life compared with those of the control. These results might be attributable to the higher antioxidants content (vitamin C, TPC, and TFC) and higher polyphenol oxidase activity in BSFF-fertilized tomatoes. In conclusion, BSFF fertilizer could be used as a potential eco-friendly alternative to chemical fertilizers to improve tomato fruit quality during shelf life.