Studies On The Inheritance Of Chilling Tolerance And Characteristics Of Physiology-Biochemistry In Cucumber (Cucumis Sativus L.)

The low temperature becomes a major limited factor for cucumber production in protected land in winter or spring.In order to select inbred lines with high chilling tolerance, in this experiment,25 cucumber materials(9501,9502,…,9525) were used for identifying chilling tolerance,establishing identification system,discussing the characteristics of physiological-biochemical on chilling tolerance,and exploring the genetic models and relationships between characters..The details as follows:1.The preliminary identification of chilling tolerance was conducted through morphological characters such as germination rate,germination index,chilling tolerance index,the leaf number,and physiological characters including the soluble protein content and the proline content etc.25 materials were divided into 3 classes:The materials such as 9503,9504,9507,9513,9524,9525 are high tolerance to chijjing;The materials such as 9501,9502,9505,9508,9509,9511,9512,9514,9515,9516,9518,9520,9522,9523 are medium tolerance to chijjing;The materials such as 9506,9510,9517,9519,9521 are low tolerance to chijjing;The regression equation of chilling tolerance appraising on cucumber was obtained by correlation analysis and the gradually regression analysis,that is Y=0.04+0.002X₁-0.005X₂,+0.007X₃+0.023X₄In this equation Y is the chilling tolerance index;X₁,X₂,X₃,and X₄ are the relative percentages of 12℃relative germination percentages,the leaf area,the plant height,and the proline content respectively.2.The physiological-biochemical characters of the chilling tolerance of cucumbers were studied systematically by mensurating the components in seed,the mineral elements,the protective enzyme,the material metabolism,the pigment,the endogenous hormones,and so on.The result indicated that K content,the root activity,the pigment content decreasedand the soluble sugar content,the POD activity,the SOD activity,MDA content,the endogenous hormone content,the PA content increased after the low temperature treatment.Chilling tolerance character was significant positive correlation with the soluble protein content,Ca content,the soluble sugar content increase range and significant negative correlation with the chlorophyll a content.Ther was no difference between water content in seed and oleic acid content of different materials.There was no big influence for others characters.3.The inheritance of the closely related characters were studied and the result was that chilling tolerance index was a high correlation with the plant height,the number of nodes,the stem diameter,the plant dry weight,MDA content,the soluble protein content,Pro content,Pn,Ts,Gs,Ci ect..The heredity of above morphological characters and photosynthetic parameters conform to the additive - dominant model.The physiological character heredity did not conform to the additive - dominant model.Genetic correlation analysis indicated that chilling tolerance index was significant positive correlation with the plant height,the number of nodes,the stem diameter,the plant dry weight,the proline content,Pn;and significant negative correlation with the MDA content.Path analysis indicated that the plant dry weight,the proline content,the soluble protein content,P_n were the most important characters of chilling tolerance index of cucumber.There were more complex relations between the soluble protein content and C_i,so they would be studied further.There was small influence for others characters.BSH of the chilling tolerance index is very obvious,reached 82.133%,NSH of the chilling tolerance index,reached 73.170%,Dominant degree was 0.953,and they were controlled by 6 pairs of genes.Additive variance influence was strong.The combining ability analysis indicated that the GCA of 9507 and the SCA of 9506×9507 were highest.The BSH and NSH of p]ant dry weight were 41.073%,32.165%.The BSH and NSH of P_n were 87%,33.333%.4.The genetic rule of chilling tolerance index was analysed by utilizing major genemulti genes blending inheritance model method,the genetic parameter was further estimated. The result indicated that the chilling tolerance index inheritance cucumber was controlled by 2 pairs of additive major genes + additive - dominance multi genes and the average of chilling tolerance index was higher than midparent value in F₁.The major gene heredity rate was 62.871-79.310%,the multi genes heredity rate was 3.448-7.792%,and major gene + multi genes heredity rate was 74.026-82.759%.The ratio of environment variance accounts for phenotypic variance was 17.241-25.974%.