Assessment of fruit quality and volatile profiles in watermelons grafted onto various rootstocks

Abstract

Grafting is a common technique used to enhance watermelon yield under biotic and abiotic stress conditions; however, it may influence fruit development and quality. This study evaluated the impact of grafting on the fruit quality attributes and volatile profiles of 'Ningnongke huadai' watermelon using 11 commercial rootstocks, encompassing wild watermelons, bottle gourds, and pumpkins. Significant variations were observed in fruit weight, length, rind thickness, firmness of rind and flesh, and central soluble solids content. Notably, wild watermelon grafting increased central soluble solids, while pumpkin-grafted fruits exhibited higher fruit weight but lower central soluble solids. The analysis identified 122 volatile compounds in watermelon samples, primarily ketones, aldehydes, and alcohols. Regarding volatile composition, bottle gourd and wild watermelon grafts did not significantly differ from non-grafted watermelons, whereas pumpkin-grafted fruits showed distinctive volatile profiles characterized by higher aldehyde content and lower levels of alcohols and aromatic hydrocarbons. In conclusion, wild watermelon rootstocks increased soluble solids and had minimal impact on the volatile profiles of grafted fruits, making them potentially suitable for commercial production of 'Ningnongke huadai' watermelon. The evident variability in volatile profiles among grafting combinations underscores the need for watermelon rootstock breeding programs to account for the influence of rootstocks on fruit aroma.