Effect of rootstocks on fruit quality and aroma characteristics of watermelon (Citrullus lanatus)

In recent years, grafted watermelon seedling use has been rapidly increasing due to providing tolerance to stress conditions and positively affecting on yield potential. Fruit quality was varied depending on the rootstock used positively or negatively in grafted vegetables. The number of research is limited in this topic. The effect of the rootstocks on fruit quality has not been fully revealed in grafted watermelon production. In this study, the using of the inbred lines (one Cucurbita moschata and four Cucurbita maxima) and interspecific cross (five C. maxima × C. moschata) rootstocks were investigated for fruit quality and aroma characteristics on the watermelon. Non-grafted Crisby F1 watermelon cultivar, one bottle gourd (Argentario F1) and two interspecific rootstock cultivars (Obez F1, Shintosa F1) were used as control commercial cultivars. In all grafted watermelon, the fruit flesh firmness was higher than non-grafted watermelon (10.73 N). According to the rootstock x scion combinations, the fruit firmness was varied between 13.75 N (K6/C) and 22.53 N(M6/C). The rind thickness was changed between 16.05 (K9/C) - 18.24 mm (Argentario/C). In the most of the grafted combinations, the rind thickness increased. Rootstocks did not effect on fruit shape. Higher total soluble solids were determined in all graft combinations than non-grafted watermelon. The highest soluble solids contents were determined in the combination of M6/C (12.87%), M3/C (12.53%) and B1/C (12.50%). The vitamin C contents were significantly affected by rootstocks. These values in grafted watermelons increased by 30.30% (M3/C) and 17.09% (Argentario/C) reduction was observed compared to non-grafted watermelon. The lycopene content of eight combinations were found higher and four of them less than non-grafted watermelon. As a result of degustation panel tests, it was determined that M2/C (4.87), M3/C (4.53), B1/C (4.35) Argentario/C (29.4) and Obez/C (4.14) combinations scores were higher than non-grafted watermelon (4.08). However, they were determined that the majority of combinations (9) have slightly fibrous flesh structure. The use of grafted watermelon was found to be effective on the amount of volatile aroma compounds. M6 / C combination having high (Z,Z)-3,6-nonadien-1-ol (watermelon smell) compound and low (Z)-6-nonen-1-ol (squash smell) compound values was come into prominence. According to evaluated all fruit quality and aroma results; M6 and M2 genotypes were selected as the suitable local rootstock candidates for grafted watermelon production