Inheritance of waterlogging tolerance in cucumber (Cucumis sativus L.)

Flooding of vegetable crop fields along the Yangtze River basin in China has been an annual occurrence; therefore the cultivation of tolerant varieties has become one of the most promising control strategies. Our objective was to investigate the inheritance of waterlogging tolerance of cucumber at the early stage of growth with two cucumber parents consisting of PW0832 (tolerant) and PW0801 (susceptible). In 2006, 4-weeks-old potted plants of P-1, P-2, F-1, F-2, B-1 and B-2 generations were subjected to one week waterlogged stress, control plants were not flooded. The simple additive model explained the variations of tolerance score (TOL) adventitious root formation (ARF) and waterlogged root dry weight (RDW) while the additive-dominance model explained the control treatment of RDW. Non-allelic interactions were detected for waterlogged vine length (VLH) and root length (RLH). Complementary epistasis occurred in waterlogged VLH while additive x additive, additive x dominance and dominance x dominance epistastic effects were significant for waterlogged RLH. Transgressive segregation was also observed in most of the traits in the F-2 generation indicating some alleles are dispersed in the parents used in this study. The estimates of narrow-sense heritabilities for TOL and ARF were moderately high. Backcross of F-1 to both parents in ARF, waterlogged SDW and waterlogged RDW showed good convergence of genes in the B-2. These results suggest that it should be possible to develop varieties with high levels of tolerance by selecting transgressive segregants in this cross.