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- Author or Editor: Samuel F. Jenkins Jr. x
The rate of natural outcrossing in cucumber (Cucumis sativus L.) was measured at 3 locations in North Carolina, using the dominant allele for scab resistance as the marker gene. Outcrossing was measured within and between 1.5 m plots in isolation blocks. Between-row outcrossing averaged 36% over the 3 locations, and within-row outcrossing averaged 17%. Self-pollination accounted for 47% of the pollinations. Results suggest that populations should be intercrossed either as single plants, or in family rows treated with growth regulators to control pollen flow and prevent sib- and self-pollination.
Seedlings of 35 cucumber (Cucumis sativus L.) lines were evaluated for resistance to damping-off caused by Rhizoctonia solani Kuhn. Five variables were measured, with the corrected disease rating (a rating for disease severity including a correction for seed vigor) being the most useful. Differences in resistance occurred among the lines, with ratings varying from 1.5 to 5.9 on a 0 (no disease) to 9 (plant dead) scale. The ratings for damping-off resistance were compared with ratings collected previously for rhizoctonia fruit rot resistance. The correlations were low and nonsignificant (r = −0.19 to −0.10). Thus, the damping-off test would not be a good substitute for the fruit rot test.
A wide-base pickling cucumber (Cucumis sativus L.) population was formed by intercrossing all available cucumber lines (1063) and selecting for short fruit length. After intercrossing twice, 112 S0 plants and their half-sib progeny were evaluated for Rhizoctonia fruit rot resistance using a detached-fruit test. Parent-offspring regression indicated a narrow-sense heritability of 0.24, considered low to moderate. Gain from selection was calculated for 2 recurrent selection systems. Based on the heritability estimate, selection using replicated progeny rows was recommended for improving resistance to this trait.