Autotoxic potential of cucurbit crops

Soil sickness is often observed in cucurbit crops such as Citrullus lanatus , Cucumis melo and Cucumis sativus, but not in cucurbit crops such as Cucur bita moschata, Lagenaria leucantha and Luffa cylindrica. Results showed tha t root aqueous extracts of Citrullus lanatus, Cucumis melo and Cucumis sati vus were autotoxic, but those of Cucurbita moschata, Momordica charantia an d Luffa cylindrica were less autotoxic to the radicle elongation of respect ive species. Plant growth of Citrullus lanatus, Cucumis melo and Cucumis sa tivus were greatly inhibited by autotoxic substances released from powered root tissue at a rate of 1 g per seedling. Root exudates of Citrullus lanat us, Cucumis melo and Cucumis sativus were autotoxic to radicle elongation a nd seedling growth of respective species. However, root exudates of Citrull us lanatus did not inhibit radicle elongation of Cucurbita ficifolia, which is commonly used as rootstock for the grafting of Citrullus lanatus, Cucum is melo and Cucumis sativus to decrease soil-borne diseases in commercial p roduction. It seems possible to overcome autotoxicity in cucurbit crops by grafting on Cucurbita ficifolia.