عنوان مقاله [English]
Introduction: Cucumber (Cucumis sativus L.) breeding and seed production is highly important in Iran. Local varieties of cucumbers are desirable in terms of taste and resistance to diseases but in yield and some important traits such as number of female flowers are weak. There are three types of male, female and hermaphrodite flower in cucumber. Distribution of these three types of flowers leads to different sex types in cucumber. Generally, cucumber plants are monoecious. Monoecious plants produce male and female flowers on the same plant, while gynoecious plant produce only female flowers. Among the different types of sex in cucumber, gynoecious plant has a higher yield as they have only female plants in every node. Therefore, almost all cultivars used in commercial production are gynoecious. Increasing cucumber yield through gynocey was studied by several scientists. In previous researches superior lines of cucumber with general and specific combining ability were identified but these lines did not have enough gynoecious. In the current study, the possibility of crossing commercial Ailar cultivar with elite lines are studied and their progeny are evaluated.
Material and Methods: In previous research we obtained some breeding lines which showed suitable general combining abilities. Breeding lines are B10, A10 and B12. They are monoecious but they are different in growth habit so that the growth habit of B12 line is determinate with small fruits. Growth habit of B10 is semi-determinate with medium fruits and the A10 line has intermediate growth habit with large fruits. The commercial Ailar cultivar was used to transfer gynocious trait. The seeds of lines and commercial Ailar cultivar were planted in pot on January of 14, 2016. Pollination was done by hand before anthesis. A hand pollinated flower was covered with gelatin capsule to prevent insect pollination. After crossing between parent lines and commercial cultivar three fruits were kept in each line and their seeds were planted on September 30, 2016. We planted 60 shrubs in each crossing and 10 shrubs from parent. This experiment was conducted in complete randomized block design with three replications. Information such as the number of male flowers, the number of female flowers, the number of lateral branch, percentage of male flowers and female flowers were recorded. We investigated all three populations from the crossing and selected the plants with the maximum number of female flowers for the next step. At the end, data were analysis with SAS and compare means was done with Tukey’s test.
Results and Discussion: Investigation of the population of crosses in all three hybrids showed an increase in the average number and percentage of female flowers compared to the parent lines. The results showed that the progeny of commercial Ailar cultivar with B12 had the highest number and percentage of female flower. The maximum number of female flowers was found in the progeny of commercial Ailar cultivar with B12 and B10 lines, which showed a better result than the maximum number in commercial cultivars. Along with the increase in the number of female flowers, examination of male flowers in all three populations showed a decrease in the average percentage and the number of male flowers in all three populations compared to the parent lines. The highest percentage of male flowers was observed in the progeny of commercial Ailar cultivar with A10 lines. The number of lateral branches in each of three populations was approximately the same, but there was a large variation among the studied plants, so that some plants produced two and some ten lateral branches in the first ten nodes. The results showed no significant differences between lateral branches. The environment has a great influence on the expression of the number of lateral branches, and the low heritability of this trait confirms this (11). The t test was performed on parents and offspring of Ailar hybrid with all three lines at 1% level. The significance of the t test indicates progeny deviation relative to the parent's mean that can be a predominant factor for controlling genes in these traits. Comparison of means by Tukey test showed an increase in female flowers in the offspring compared to parental lines. According to these result it is possible to release recombinant inbred lines similar to elite lines with gynoecious in future.