PLANTLET RESISTANCE OF CUCURBIT CULTIVARS TO ROOT-ROT CAUSED BY PHYTOPHTHORA-CAPSICI

The aim of this work was to evaluate the resistance of cucurbit cultiv ars at seedling stage to root rot caused by Phytophthora capsici. Sixt y-three cucurbit cultivars, comprising Cucurbita moschata (17 cvs.), C . maxima (5 cvs.), C. pepo (10 cvs.), ''morango'' (Cucurbita spp., 3 c vs.), cucumber (Cucumis sativus, 13 cvs.), melon (Cucumis melo, 7 cvs. ) and watermelon (Citrullus lanatus, 8 cvs.) were evaluated. The exper iment was carried out in greenhouse, in a randomized block design with four replicates (8 plantlets/plot). Ten days after sowing, at the cot iledonar stage, the plantlets were inoculated by pouring 3 mL of inocu lum (10(4) zoospores/mL) at the plantlet base. Plants were rated for d isease symptoms three days after inoculation using a 0-7 scale (0=no v isible symptoms; 7=dead plant). By cluster analysis, cultivars with me an disease ratings 0.44 to 2.54 were considered as resistant (13 cvs.) ; 4.49 to 5.37 as intermediate; and 5.64 to 7.0 as susceptible. Twelve cucumber cultivars showed higher levels of resistance and were rated as resistant (0.44 to 0.54), and only one was considered as intermedia te (cv. Shibata, grade=4.56). Most of the cucurbit cultivars tested we re susceptible: watermelon (8 cultivars=7.0), melon (6 cvs., 5.97-7.0) . Imperial (2.05) was resistant; the others, ranging from 5.98 to 7.0, and the Cucurbita group, ranging from 4.49 to 7.0, were susceptible.