Combining Ability And Genetic Analysis For Characters Of Cucumber Seedlings Under Low Light

Six cucumber inbred lines provided by horticulturedepartment of He Nan Agricultural university were used as materials in the experiment. The combining ability and genetic analysis of some characters of cucumber seedlings, including photosynthetic indexes , night respiration, physiological indexes and morphologic indexes ,were conducted by using complete diallel crossing Griffing Ⅱ.The six inbred lines were classified according to their tolerance to low light. 1.This paper studies the combining ability and genetic law of cucumber seedlings photosynthetic light compensation point, photosynthesis and night respiration We classified the six cucumber inbred lines according to their tolerance to weak light and found tow kinds of hybrid better than others. The results showed that the broad heritabilities of cucumber seedlings photosynthetic light compensation point and photosynthesis under 25℃ is separately 71.25% and 73.62%,the narrow heritabilities of which is separately 21.42% and 0.The broad heritabilities and narrow heritabilities of cucumber seedlings night respiration under 20℃ is separately 49.77% and 20.59%. 2.The combining ability and genetic analysis of several physiological indexes, including the activity of superoxide dismutase (SOD), the activity of peroxidase (POD)and polyphenal oxidase (PPO), the content of MDA and the ratio of chlorophyll a to chlorophyll b , were conducted by using complete diallel crossing Griffing Ⅱ . We found that three inbred lines and five kinds of hybrid better than others. The results showed that the narrow heritabilities of all the five indexes were very low under normal temperature (25℃/15℃) and weak light. 3. The genetic analysis were conducted for ten morphologic characters measured in cucumber seedlings under low light. The narrow heritabilities for eight morphologic characters were low, including stem thickness , cotyledon area ,true leaf area ,specific leaf area,fresh mass above ground , whole biomass , which were mainly dominant effect. The genetic model of stem length and specific stem length agreed with additive-dominant model.