Estimation of combining ability of hull-less-pumpkin (Cucurbita pepo L. var. styriaca ) lines for yield component

Document Type : Full Paper

Authors

• Maria Yousefi ¹
• Jamal-Ali Olfati ²
• Hedayat Zakizadeh ²
• Sima Davoodi ²
• ََAmir Sahraroo ²

¹ Department of Horticultural Sciences, Faculty of Agricultural Sciences University of Guilan, Guilan, Iran.

² Department of Horticultural Sciences, Faculty of Agricultural Sciences, University of Guilan, Guilan, Iran

Abstract

Keywords

• Diallel
• Hybrid seed
• General combining ability) GCA)
• Specific combining ability )SCA)
• Heterosis

Main Subjects

• Medicinal plant science

Extended Abstract

Introduction

    Pumpkin is a monoecious, and herbaceous plant with an indeterminate growth habit. The fruit of this plant is not edible for human consumption. Oil and its products are used in the treatment of diseases such as stomach problems, arteriosclerosis, and irregular heart contractions. Considering the high economic value of the seeds of this plant, this research was conducted with the aim of evaluating the general and specific combining ability of six breeding lines of hull-less pumpkin and its direct hybrids for yield-related traits.

Materials and Methods

   The plant materials of this research included six lines of hull-less pumpkin seeds, which were obtained from Negin Bazar Guilan company. The lines were crossed and 21 direct hybrids were obtained from them, which were used along with the parental lines in this research. In order to evaluate the genotypes, after preparing the soil and installing the irrigation and mulching system, transplanting of the studied genotypes was done with distances 100 and 50 cm between and within the rows respectively to reach a plant density of 20,000 plants per ha. In the physiological stage, fruit and seed characteristics were collected and recorded. The process of extracting oil from seeds was carried out by a semi-industrial oil extraction machine of Oeltek brand OPM550+, during which the percentage and yield of oil and meal were calculated. Variance analysis was performed by SAS software version 9.4. Comparison between means was taken on Tukey's test. Genetic analysis was done with the help of the Diallel program, version 1.1. General and specific combining ability, heterosis, dominance, and additive variance and dominance degree for different traits were calculated.

Results and Discussion

    According to the results of the analysis of variance, the effect of genotype was significant for all traits. The highest fruit yield and seed length was related to the hybrid 14×16, the highest number of seeds was related to the hybrid 16×23, the highest percentage of oil was related to the hybrid 11×14, the highest number of final lateral branches was related to the hybrid 8×16, the highest yield of oil was related to 11×23. Considering the high value of combining ability and the heterosis compared to the average of the parent and high parent, it is possible to increase the oil yield and the seed yield by using the 11×23 hybrid. The 16×23 hybrid proposes to increase the number of seeds. Considering the significance of general mean-squares versus specific mean-squares, observing both additive and non-additive effects is important for controlling these traits. The effect of general combining ability is positive and significant for the traits showing the high potential of the lines to be used in the breeding programs of this plant. The high specific combining ability for the studied traits showed that the crosses that show heterosis can be used in future breeding programs.

Conclusion  

   The results of this research showed that the role of non-additive variance in the control of traits is greater than the additive variance, which is recommended for the selected hybrids.