Studies On Heterosis And Genetics Of Different Ecotype Of Cucumber Parents

The experiment was conducted in Huazhong Agriculture University from 2003 to 2006. Seven inbred lines of cucumber were used. The combining ability and genetic parameters of twelve agronomic characters and genetic laws of two physiology characters and three qualitative characters were studied with a design of Griffing complete diallel cross method two. Heterosis of quantitative characters including three nutritional quality characters and twelve agronomic characters were also analysed. According to results of the combining ability and heterosis analysis, seven inbred lines and part of their execellent F₁ hybrids were estimated. The main results are showed below:The spire types were dominant over the types without spire; The fruit end types were dominant over the types without fruit end; The long fruit end types were dominant over the short fruit end types.The average heterosis of yield per plant at early stage, yield per plant, solid content and V_C content were highly positive conspicuous. The average heterosis of first pistillate flower bearing node and weight per fruit were lowly negtively conspicuous. Inbred line 3 can be used as an parent of high yield. Inbed 1 can be used as an early-maturing parent. Inbred 2 can be used as an parent of big fruit. Inbred line 1 can be used as an parent to increase the pistillate flowers of F₁. According to the result of F₁ agronomic characters in field and combining ability analysis, two F₁ hybrids with characters of big fruit and high yield were acquired, they were 3×6 and 6×7.The additive effects of first pistillate flower bearing node, number of pistillate flower below the 20th node of main vine, fruit length, weight per fruit, index of fruit shape, length of fruit end, yield per plant and node length were more important than the dominant effect, so they can be used for combining breeding. The dominant effects of leaf area at early stage, yield per plant at early stage, stem thickness and plant length were more important than the additive effect, they can be used for dominant breeding. The sequence of H_b² from high to low was yield per plant at early stage, plant length, leaf area at early stage, yield per plant, stem thickness, weight per fruit, node length. The sequence of h²_n from high to low was yield per plant, weight per fruit, node length, yield per plant at early stage, stem thickness, plant length, leaf area at early stage.The analysis of correlation and path showed that the factors which had great effect on yield per plant were first of pistillate flower bearing node, number of pistillate flower below 20th node of main vine, node length and yield per plant at early stage.