Evaluation of rootstocks resistant to gummy stem blight and their effect on the fruit yield and quality traits of grafted watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai)

ABSTRACT Three gummy stem blight (GSB) resistant watermelon (Citrullus lanatus var. citroides) genotypes (IIHR-82, IIHR-617 and BIL-53), two resistant bottle gourd (Lagenaria siceraria) genotypes (BG-95, BG-77-6-1) and three hybrid combinations based on watermelon genotypes (IIHR-617 × Arka Manik, IIHR-82 × Arka Manik and IIHR-82 × IIHR-617) were evaluated as rootstocks for yield, quality and GSB incidence in a sick plot during spring 2019, spring 2020 and spring 2021 at Indian Institute of Horticultural Research, Bangalore. The commercial watermelon hybrid NS-295 was used as a scion for grafting onto these rootstocks. Significant differences were observed among the grafted entries and checks in terms of disease incidence (PDI). Among agronomic traits, grafting significantly affected plant growth, earliness and yield in a desirable direction. The grafted scion onto the hybrid rootstocks and BG-95 could maintain its oblong fruit shape compared to those onto IIHR-82 and BIL-53, whereas BG-77-6-1 produced spherical fruits. Quality traits showed an improvement in terms of total soluble solids (TSS), flesh colour, total carotenoids and lycopene content among the grafted entries as compared to non-grafted controls. Overall, the use of hybrid rootstocks i.e. IIHR-82 × IIHR-617 and IIHR-82 × Arka Manik was found to be advantageous in managing GSB apart from imparting desirable agronomic and fruit quality traits.