Screening of rootstocks with resistance to chilling and continuous cropping but without compromising fruit quality for protected watermelon production

Abstract

Chilling stress and continuous cropping obstacles limit sustainable production of watermelons under controlled environments. Grafting of watermelon scions onto resistant rootstocks is an effective strategy currently used to overcome these environment limitations. However, currently used commercial rootstocks adversely affect watermelon fruit quality. The chilling tolerance and Fusarium oxysporum f. sp. niveum race 1 (FON1) resistance of seven Cucurbit germplasms, including four watermelon germplasms (M08, TC, YL, and MY), two muskmelon cultivars (JT1 and JSM), and one commercial Cucurbita rootstock (QZ1) of watermelon, were explored in the current study. The effects of the rootstocks of these germplasms on watermelon resistance to chilling stress and continuous cropping obstacles were evaluated. TC rootstock showed the highest chilling tolerance and increased chilling tolerance of watermelon scion. All Cucurbit germplasms showed higher resistance to FON1 than watermelon cultivar N5 (control). Watermelons grafted onto QZ1 showed the lowest wilt incidence and highest fruit yield but had the worst fruit quality after planting on soils continuously cropped for 11 years. Watermelons grafted onto TC showed higher resistance and yield and the best fruit quality. These findings indicate that TC has a large potential for use in grafting watermelon planted in continuously cropped soils (< 10 years). TC can also be used as breeding rootstocks to improve watermelon resistance against continuous cropping obstacles without compromising fruit quality.