Cucumber (Cucumis sativus L.) is one of the more chilling sensitive crops. Chilling resistance could provide growers with protection against late spring frost. Significant differences for chilling resistance were observed among a set of 9 diverse cucumber cultigens when grown at 22 C to 1st true leaf stage, then given a chilling treatment of 4 C for 7 hours in full light (PPFD 500 μmol.m-2.s-1). Two populations, NCWBP and NCES1, were used to measure narrow-sense heritability (estimated as twice the parent-offspring regression coefficient) for chilling resistance. Sets (256/population) of parents and offspring were evaluated in separate tests for seedling resistance. Plants were rated for damage 0 (none) to 9 (dead) on the cotyledons and 1st true leaf, 3 and 5 days after chilling. Ratings were corrected for position in the Phytotron chamber, and log transformations used to normalize the data. Generally, correction reduced the heritability estimates and transformation improved them. Heritability was highest for cotyledon ratings made 5 days after chilling, ranging from 0.35 for NCWBP to 0.70 for NCES1. Ratings of the 1st true leaf were more difficult to make, and produced lower estimates of heritability. Breeders should be able to make good progress in selecting for chilling resistance using this seedling test.
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