Bulldog - Citrullus lanatus var. citroides line, a potential rootstock for watermelon grafting

R.L. Hassell, W. Pat, A. Levi
USVL246-FR2 and USVL252-FR2 are Citrullus lanatus var. citroides watermelon developed and released in our laboratory, both with high levels of tolerance to Fusarium oxysporum f. sp. niveum (Fon) race 1 and race 2. Both lines are currently at the S9 filial generation, but exhibit 5-10% segregation away from the tolerant phenotype, thus the lines are not 100% “fixed”. These two lines were crossed by hand pollination. Hybrids of these two lines appear to be fixed for this phenotype in only 5 generations (F5), leading us to hypothesize that tolerance genes between the two lines may be different. These lines are currently being called 'Bulldog'. The earlier generations of these hybrid lines have been tested in field trials with excellent results in terms of Fon race 2 tolerance. In 2014, 2015 and 2016, this line was tested for grafting ability, plant vigor and yielding ability in the field as a potential rootstock, with the scion material being 'Fascination'. This line was tested against interspecific hybrid squash rootstock ('Carnivor'), and Lagenaria hybrid rootstock ('Macis'). Grafting results demonstrated a very vigorous rootstock that resulted in a 90% survival rate, equal to that of both 'Carnivor' and 'Macis'. Fruit yields exceeded rootstock 'Carnivor' but were not significantly different in both fruit number and marketable fruit size. Rootstock 'Bulldog' was significantly higher than both 'Macis' and 'Fascination' (non-grafted). However the fruit quality was not equal to the other two rootstocks. Fruits were not as firm and the holding ability of the fruit in the field was reduced.
Hassell, R.L., Pat, W. and Levi, A. (2018). Bulldog - Citrullus lanatus var. citroides line, a potential rootstock for watermelon grafting. Acta Hortic. 1204, 219-222
DOI: 10.17660/ActaHortic.2018.1204.28
vegetable breeding, rootstocks, grafting

Acta Horticulturae