نوع مقاله : مقاله پژوهشی
عنوان مقاله English
نویسندگان English
To create inbred lines, expensive and time-consuming methods such as self-pollination are typically used. However, new efficient technologies like doubled haploids and inverse breeding offer effective and faster solutions for producing inbred lines. In this research, doubled haploid lines produced through parthenogenesis embryo induction following pollination with irradiated pollen were utilized. A top-cross test was conducted using 15 doubled haploid lines and the top-cross parent, Beit Alpha, to examine the general combining ability of the lines. Hybrids derived from line × tester (Beit Alpha) crosses were planted in the greenhouse. To evaluate the general combining ability of the lines, several traits were measured and analyzed, including days to flowering, fruit number, fruit weight, average yield per plant, placental diameter, fruit diameter, fruit length, and the length of 20 nodes of the main stem. Comparison of means using the Tukey test revealed that the doubled haploid lines DH34, DH102, DH4, DH36, and DH5, crossed with the common parent Beit Alpha, had the highest fruit yields, with averages of 854.3, 742.7, 617.7, 545.7, and 519.3 grams per plant, respectively. Among these, the top-cross progeny from DH34 × Beit Alpha and DH102 × Beit Alpha had the highest yields, averaging 854.3 and 742.7 grams per plant, respectively. The heritability of some evaluated traits was over 80%, with the number of days to flowering, fruit weight, and fruit length showing the highest heritability.
کلیدواژهها English
Extended Abstract
Introduction
Cucumber (Cucumis sativus L.) is a highly significant vegetable within the Cucurbitaceae family, cultivated globally. Iran ranks as the fourth-largest cucumber producer worldwide, with a cultivated area of 40,344 hectares yielding 1,205,679 tons. This places Iran behind Turkey, Russia, and China in production volume. Notably, Iran imports over $120 million worth of vegetable and summer crops annually. This figure represents only legal imports and excludes smuggled goods, with approximately 98% of the country’s vegetable and summer crop needs being imported. The production of F1 hybrid seeds presents the most efficient and appealing technology for seed production institutions, owing to substantial yield increases, premium pricing, and the potential to maintain breeder rights.
Materials and Methods
Doubled haploid lines of cucumber were developed by applying parthenogenesis embryo induction following pollination with irradiated pollen from the commercial hybrids Negeen, Isfahan, Datis, Emparator, and Hi Power. This process was conducted at the Department of Tissue and Cell Culture of the Agricultural Biotechnology Research Institute of Iran (ABRII). These doubled haploid lines, along with open-pollinated seeds of Beit Alpha, were cultivated. Upon reaching the flowering stage, the doubled haploid lines were crossed with Beit Alpha, serving as the common tester. The resulting seeds from these crosses were planted in a greenhouse for evaluation.
To assess and identify the best line × tester combinations, key traits were recorded from the plant’s early growth stages. These included days to flowering, fruit weight, placental diameter, single plant yield, fruit number, and other morphological characteristics such as fruit length, fruit diameter, and the length of 20 main stem nodes. The research was carried out in the greenhouse of ABRII using a completely randomized design with three replications. Statistical analysis, including analysis of variance and mean comparisons, was performed using Tukey’s test at a 5% probability level via SAS software. In this study, doubled haploid (DH) lines exhibiting high, low, or intermediate general combining ability for the desired traits were crossed with each other to examine the outcomes.
Results and Discussion
Out of the 15 selected lines, 12 proved capable of germination and crossbreeding. Variance analysis of the studied traits revealed significant differences among the progeny resulting from the crossing of the selected lines with the Beit Alpha tester across all traits. Mean comparisons using Tukey’s test indicated that the doubled haploid lines DH34, DH102, DH4, DH36, and DH5, when crossed with the common parent Beit Alpha, yielded the highest fruit production, with averages of 854.3, 742.7, 617.7, 545.7, and 519.3 grams per plant, respectively. The top-performing top-cross progeny were DH34 × Beit Alpha and DH102 × Beit Alpha, yielding approximately 854.3 and 742.7 grams per plant, respectively.
The heritability for some evaluated traits exceeded 80%, with days to flowering, fruit weight, and fruit length demonstrating the highest heritability. The heritability rate for fruit number was 53%, and for single plant yield, it was 57%. High broad-sense heritability values are associated with general combining ability, which was most pronounced in the DH34 and DH102 lines within this research.
Interestingly, crossing lines with high general combining ability, such as DH34 and DH102, did not result in hybrids exhibiting significant heterosis compared to the average of the parents for cucumber plant performance traits. Similarly, crosses involving lines with low or negative general combining ability, like DH25 and DH1, did not yield hybrids with high heterosis for those traits. Furthermore, progeny from crosses between lines with high general combining ability and those with negative or low general combining ability, such as DH102 and DH25, did not display substantial heterosis for cucumber plant yield traits relative to the average of the parents. It is important to note that since genetic variance incorporates a component of dominance variance, high general combining ability values do not automatically guarantee superior combinations through progeny selection. Additionally, the quality of progeny resulting from hybridization between such lines cannot be definitively predicted.
Author Contributions
All authors contributed equally to the development of this manuscript from the initial draft to the final submitted version, including all subsequent revisions.
Data Availability Statement
Data available on request from the authors.
Acknowledgements
This research was supported by grants from Agricultural Biotechnology Research Institute of Iran (ABRII) Project No.34-05-0533-014-020240.
Ethical considerations
The authors avoided data fabrication, falsification, plagiarism, and misconduct.
Conflict of interest
The author declares no conflict of interest.
