Submitted to: Journal of the American Society for Horticultural Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/20/2002
Publication Date: 12/15/2002
Citation: Lopez-Sese, A., Staub, J.E. 2002. Combining ability analysis of yield components in cucumber. Journal of the American Society for Horticultural Science. Interpretive Summary: Yields of U.S. pickling cucumber have increased dramatically since 1940 (~5% annual average increase). Improved cultural practices, the introduction of femaleness (increased number of female flowers), and the introduction of yield and disease resistance genes (groups of DNA on the chromosome) from exotic varieties (e.g., India, China, Japan) into U.S. commercial varieties has increased average yield three-fold from 4,076 (kg/ha) in 1920 to 12,550 (kg/ha) in 1980. Nevertheless, with the exception of perhaps some unique processing hybrids that are adapted to specific growing regions (e.g., specific areas in the southern U.S.), average yield has reached a plateau in the past 15 years (~13,400 kg/ha 1997). This plateau in yield is primarily due to the inability of the cucumber plant to produce more than one fruit once a fruit is produced. In order to produce another fruit on the same plant, fruit on the plant must first be harvested. A wild species of cucumber that freely mates with cucumber has been discovered in India. This cucumber species has the ability to produce many fruits per plant, and thus is genetically very different when compared to currently used U.S. commercial cucumber varieties. It would be useful to transfer the yield genes from this wild species into commercial cucumber. However, before great efforts are made to incorporate such yield genes, commercial cucumber varieties must be evaluated to determine which is the best choice for the initial transfer (mating) with the wild species. Therefore, an experiment was designed to determine which varieties are the best for such a transfer. Experimentation demonstrated that some varieties were better than others in this initial transfer. This information will be useful to public and private plant breeders interested in using this wild species for the improvement of commercial cucumber. The consumer will benefit directly from this research since high yielding varieties will be produced that result in lower product prices in the grocery store.
Technical Abstract: Three U.S. adapted Cucumis sativus var. sativus L. lines and one C. sativus var. hardwickii (R.) Alef. derived line were mated in a half-diallel design to determine their relative combining for several yield-related traits (yield components). The resulting six F1 progenies were evaluated in a randomized complete block design with eight replications in 1999 and 2000 at Hancock, Wisconsin for fruit number and length/diameter ratio (L:D), lateral branch number, number of female flowering nodes, and days to anthesis. Combining ability was significantly influenced (p < 0.05) by environment (year) for most of the characters examined. General combining ability (GCA) was significant for all characters in each year. Specific combining ability (SCA) was significant in magnitude and direction for the traits examined, except for L:D ratio, number of lateral branches, and number of female nodes per plant. Data indicate that the C. sativus var. hardwickii-derivated inbred line WI 5551 possessed SCA for yield component traits, and thus maybe useful for improving fruit yield in commercial cucumber.