Genetic Diversity and Relationship Analysis of Different Local and International Cultivars and some Strawberry Clones (Fragaria× ananassa Duch)

Extended Abstract Background: Strawberry (Fragaria × ananassa) is a perennial shrub of the Rosaceae family that has become one of the most significant fruits globally due to its unique characteristics, ease of care, and delicious flavor. This plant thrives particularly well in temperate regions, although it can also be cultivated as an annual. These traits have made strawberries popular not only in home gardens but also in commercial agriculture. It has emerged as an important economic crop in many countries because of its tasty and nutritious fruits. Given the economic and nutritional significance of strawberries, it is crucial to assess their genetic diversity and identify various genotypes. Genetic diversity in this plant enables researchers to develop newer, higher-quality varieties that are more resistant to pests and diseases while yielding greater outputs. Therefore, the use of morphological markers is highly beneficial in distinguishing and identifying different strawberry cultivars and populations. Consequently, this study was conducted to investigate genetic diversity and identify relationships between domestic and imported strawberry genotypes and clones. Methods: The present study was carried out in Mazandaran Province, Sari City, from November 2020 to June 2021. Transplants of imported cultivars were sourced from the Kurdistan Agricultural and Natural Resources Research Center. This selection was made due to the high diversity of cultivars and their specific characteristics, allowing for an accurate assessment of their yields and quality. The plants were grown in pots filled with a substrate of cocopeat and perlite in a 70:30 ratio. Due to its favorable physical and chemical properties, this substrate promotes better root growth and enhances the absorption of water and nutrients, thereby providing optimal conditions for plant growth. The comparison stage of cultivars was conducted through detailed studies at the Sari University of Agricultural Sciences and Natural Resources, aiming to investigate genotypic and phenotypic diversity. The experiment utilized a completely randomized design with 23 treatments, including mother cultivars in three replications and daughter cultivars in four replications, all within a hydroponic medium. Measurements were taken on fertile plants, and various data points, including growth habit, leaf density, and growth vigor based on international descriptors, as well as traits such as leaf length and width, leaf area, the number of individual flowers, the number of inflorescences, and total flower count, were analyzed quantitatively. Results: The examined genotypes exhibited significant differences in reproductive and vegetative traits. The highest genetic diversity coefficient was associated with the number of fruits per plant, the number of flowers per plant, and plant yield, all of which showed variations exceeding 50%. In contrast, a narrower range of variation was noted in traits related to vegetative growth, likely due to environmental influences and cultivation conditions. The correlation analysis of the growth habit trait revealed that a more erect plant positively impacted the growth of leaf components, which in turn enhanced fruit length and width. This is a crucial discovery as it can aid in the selection and breeding of superior cultivars. Factor analysis successfully identified several main factors representing qualitative and quantitative traits, facilitating a better understanding of the relationships among these traits. The Camarosa cultivar, the predominant cultivar in Mazandaran Province, along with the cultivars Merck, Tan Beauty, Missionary, and Queen Eliza, demonstrated positive vegetative growth but negative reproductive growth. However, the selected clone from Ghaemshahr excelled in both vegetative and reproductive growth, placing it in the fourth quadrant and positive section. The evaluated values for strawberry traits indicated that phenotypic variance surpassed genotypic variance, highlighting the environmental impact on the studied traits. The maximum phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) were attributed to plant yield (67.25 and 65.67), followed by leaf area (38.92 and 39.47), respectively. Furthermore, high heritability was observed in the traits of leaf area (97.3%), plant yield (95.35%), and the number of flowers per inflorescence (90.59%). Conclusion: The results of the correlation of morphological traits indicate that the plant's growth habit has a positive and significant correlation with various traits, including leaf length, leaf width, leaf area, petiole length, and fruit length and width. The correlation results for the descriptive trait of growth habit in three forms (erect, semi-erect, and creeping) demonstrate that a more erect plant positively influences the growth of leaf components, leading to improvements in both fruit length and width. Additionally, the correlation findings suggest that an increase in shoot density and leaf number can negatively and significantly impact the plant's growth habit. Therefore, shoot density may decrease as the plant grows, resulting in a more open structure with fewer leaves. Finally, considering the genetic distance among the cultivars, it appears that crossing these genotypes could yield greater heterosis, which can be leveraged to produce new cultivars and enhance orchard yields. Utilizing genetic and phenotypic diversity and incorporating these traits into breeding programs can significantly improve the quality and yields of strawberries in Iran.