| Summary: | 碩士 === 國立嘉義大學 === 園藝學系研究所 === 98 === Correlation among growth, yield and quality attributes in cucumber (Cucumis sativus L.) was estimated through a field study with a randomized complete block design (RCBD). Thirty-four varieties of cucumber were evaluated and eighteen growth and morphological traits including plant height, leaf length, leaf width, number, branch number, stem width, plant height, number of node, stem width, number of branch, leaf length, leaf width, days of 1st female opening, node of 1st female opening, days of 1st male opening, node of 1st male opening, total flower number, total fruit number, total number of marketable fruit, fruit length, fruit width, fruit weight, marketable yield and total fruit yield were investigated at Chi-nan Branch Station, Kaohsiung District Agricultural Research and Extension Station (KDARES) Kaohsiung, Taiwan, between Decembers 2008 to April 2009.Genetic variability is needed for selection in breeding program and generally selection is aimed at improving some morphological characters. They may contribute significantly to plant final yield and should be considered as indicators, just as reproductive characteristics, for selection to improve yield in breeding program. With correlation, path coefficient analysis and factor analysis the results suggested that characters including leaf length, leaf width, total fruit number, fruit length, fruit width and fruit weight are effective indicators to final yield and breeders could pay attention to these characters in breeding projects. Further according to the extent of the survey related traits, will be 34 varieties of cluster analysis results to genetic distant 40% of diversity criteria, all varieties can be divided into four groups, were strongly associated with leaf length, leaf width, fruit length, fruits weight, and there were close similarity in their general topology compared with the principal component analysis of all traits to be divided into three principal components (factors), the first principal component plot cumulative contribution tribute to 34.02%, can be summarized as yield-related traits; cumulative contribution of the second principal component was 57.23%, can be summarized as the number of flower and fruit related traits; cumulative contribution of the third principal component was 66.50%, can be summarized as plant height related traits. The results of this clustering and principal component analysis scatter plot of clustering results are consistent. The multivariate analysis clearly showed that there was wide variation among tested thirty-four varieties in these important characteristics.
From thirty-four cucumber varieties four from different group were selected for further study on the antioxidant enzyme activity under high temperature, four cucumber varieties are ‘Merry Swallow’, ‘FIVOS’, ‘Drawer ground frost’ and ‘Treasure’. Three antioxidant enzyme activities, guaiacol peroxidase (G-POD), ascorbate peroxidase (A-POD) and catalase (CAT) were further determined at vegetative and reproductive stage under heat stress. The results showed that ‘Treasure’ had the highest fruit production than others grown in net-house in Kaohsiung, Taiwan. We grouped ‘Treasure’ into heat-tolerant line, the other three cultivars into heat-sensitive lines. Besides, we found the G-POD, A-POD, and CAT activities increased significantly after exposure to high temperature especially at reproductive stage in ‘Treasure’. This phenomenon can not show in heat-sensitive varieties. It suggested that antioxidant enzyme activities would be closely related to heat stress tolerance. They are probably reliable indicators for heat tolerance to be useful in cucumber breeding.
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