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Title: Resistant Citrullus lanatus var. citroides Rootstocks for Managing Root-knot Nematodes in Grafted Watermelon

item Thies, Judy
item Buckner, Sharon
item HASSELL, RICHARD - Clemson University
item Ariss, Jennifer
item Levi, Amnon

Submitted to: Cucurbitaceae Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 10/27/2014
Publication Date: 10/27/2014
Citation: Thies, J.A., Buckner, S.A., Hassell, R.L., Ariss, J., Levi, A. 2014. Resistant Citrullus lanatus var. citroides Rootstocks for Managing Root-knot Nematodes in Grafted Watermelon. Cucurbitaceae Proceedings. 20:A22.

Interpretive Summary: N/A

Technical Abstract: Southern root-knot nematode (RKN), Meloidogyne incognita, is an important re-emerging pest of watermelon. Several factors have contributed to re-emergence of RKN including: 1) ban of methyl bromide for soil fumigation; 2) reduced land area for crop rotation; and 3) continuous cropping of cucurbits under protected culture. Grafting watermelon on disease resistant cucurbit rootstocks is widely used in many countries for managing soil-borne diseases such as Fusarium wilt. Unfortunately, commonly used hybrid squash and bottle gourd rootstocks are highly susceptible to RKN. Although, all cultivated watermelons are susceptible to RKN, we have identified resistance in the wild watermelon, Citrullus lanatus var. citroides. Our program has developed several resistant wild watermelon breeding lines (designated Root-Knot Vegetable Laboratory (RKVL)); many RKVL lines are useful rootstocks for grafted watermelon. In a 2-year study, ‘Tri-X 313’ seedless watermelon scions were grafted on F1 hybrid rootstocks derived from RKVL lines and grown in RKN-infested fields. Overall, resistance of F1 hybrid rootstocks was equal to or greater than their parental RKVL lines. In Year 1, three of four parental lines and all four of their F1 hybrids grafted with ‘Tri-X 313’ scions produced heavier (P<0.05) fruit yields than ‘Tri-X 313’ grafted on its own roots or on squash hybrid and bottle gourd rootstocks. In Year 2, three F1 hybrid rootstocks produced higher yields of grafted watermelon than their RKVL parental lines. These F1 hybrids proved to be vigorous rootstocks for grafted watermelon and should provide useful genetic sources for further development of RKN-resistant rootstock lines.