Effects of Biochar on Physicochemical and Sensory Quality of Watermelon (Citrullus lanatus Thunb.) Fruit from Grafted and Non-Grafted Plants

Biochar is increasingly used in agriculture as soil conditioner as well as to contribute to carbon sequestration and mitigate global warming. In a replicated field experiment, watermelon 'Sweet 16' (Citrullus lanatus) plants with or without grafting to squash 'Suprema' (Cucurbita maxima) rootstock were applied with 1.02.0 L of biochar (carbonized ricehull) per plant. Fruits were harvested at commercial maturity and subjected to physicochemical and sensory analysis. Fruit color and rind thickness, acidity, and sensory appearance, juiciness, crunchiness and mouth feel were not significantly affected by biochar application regardless of grafting treatment. Soluble solids content markedly increased in response to biochar application; this contributed to higher sweetness than that of fruit from biochar-free plants. Higher amount of biochar was needed to increase soluble solids content of fruit from non-grafted plants compared to that of grafted plants. Biochar application increased the potassium content of the plants.