Evaluation of Pomological and Morphological Traits of some Peach (Prunus persica L. BatSch) Cultivars and Genotypes under Khorasan Razavi Climatic Conditions

Introduction: Peach (Prunus persica L.) is one of the most essential fruit in Iran and the world. This fruit is suitable for both fresh markets and industrial producer and it is quite favorable by consumers. The efficiency of production is strongly influenced by the chosen peach cultivars. New cultivars are constantly in development by breeders. However, all characteristics are required to be examined include their ecological adaptation ability, productivity, fruit quality, and market value before orchard establishment. Studying the new cultivars is practically essential for exact determination of morphological and phenological features of genotype which is important. However, there is limited information on the global evaluation of fruit quality in breeding progenies and their relationships with pomological traits. Furthermore, the cultivated peach area under Khorasan Razavi province is 1850 ha and the production of fruit is 11283 tons. Therefore, the selection of suitable cultivars for cultivation in the region is very important due to the high economic lifespan of peaches (20-30 years), which in some commercial orchards this period is reduced to 12-15 years. Therefore, this study aims to evaluate the pomological and morphological traits of 14 peach genotypes and cultivars in Khorasan Razavi province climatic conditions to select cultivars or genotypes compatible with high quantitative and qualitative performance. Materials and Methods: This study was performed in two-years (2016-17 and 2017-18) experiments based on a complete randomized block design with three replications on 14 peach cultivars and genotypes in Golmakan Agricultural and Natural Resources Research Station on 4-years-old trees with density planting system at a spacing of 4 ×5 m. The type of applied irrigation was drip irrigation, with common fertilizer. Trees were trained to an open center system. The vegetative (tree height, trunk cross-section, the crown of the tree), phenological (first bloom, full bloom, end of flowering, flowering period, and harvest time) and reproductive (fruit weight, stone weight, fruit length, fruit width, fruit yield, total soluble solids, titratable acidity, flavor index, and pH) traits were evaluated. It is necessary to explain the soluble solids content by Refractometer (Model 7887, Osk Japan) in terms of percentage and acidity by titration with NaOH (0.1 N) based on predominant peach acid, malic acid. The ratio of soluble solids to acidity was obtained by dividing soluble solids by acidity. The pH of the fruit juice was measured with a portable pH meter at room temperature (23–18 °C). Data analysis was performed using SAS software (version 9.2) and means were compared using Duncan's multiple range test. Stepwise regression and cluster analysis (Ward method) was conducted by Minitab software (version 19). Simple correlation (Pearson) between traits from the mean of two-year data was performed using SAS statistical software (version 9.2), in which positive correlation with blue color and negative correlation with red color was determined, which increased the color intensity indicates an increase in the correlation coefficient. Results and Discussion: The results showed that year and genotype had significantly different effects on all studied traits. ‘Anjiri Maliki’ and ‘Shindabad Hastejoda’ were the earliest and the most late-flowering genotypes, respectively. Among the studied genotypes, ‘Shindabad-5’ and ‘Spring Time’ were the earliest fruiting genotypes, and ‘Meshkinshahr Paeeze’, ‘Kajil’, and ‘Anjiri Zafarani’ were the most late-fruiting genotypes. ‘Haj Kazem’ genotype had the highest tree height (236.18 cm), trunk cross-section (181.83 cm2), and tree crown volume (73.34 cm3), which compared to the control genotype (‘G.H. Hill’) showed  38.62%, 79.9%, and 55.7% increases, respectively. In the second year of the experiment, the characteristics of fruit weight, stone weight, fruit length, fruit width, and fruit yield increased by 41.72%, 43.45%, 16.61%, 16.40% and 81.99%, respectively, compared to the first year. The highest amount of single fruit weight (165.28 g) in ‘Fayette’ genotype, stone weight (7.04 g) and fruit length (65.05 mm) in ‘Shinabad Hastejoda’ genotype, fruit width (66.04 mm) in ‘Shandabad-5’, and fruit yield in ‘Fayette’ and ‘Paeeze Meshkinshahr’ genotypes (with an average of 21.78 and 21.33 kg, respectively) were obtained. ‘Anjiri Zafarani’ genotype had the highest content of soluble solids (16.95%), flavor index (48.38), and acidity (4.65), which compared to control genotype were increased 0.1%, 69.38% and 25.8%, respectively. Fruit yield had a positive and significant correlation with trunk cross-sectional traits, tree crown volume, fruit weight, stone weight, and fruit width. According to this study, the tree height, trunk cross-section, and fruit weight traits were entered into the regression model, respectively, and finally, the traits entered in the model justified 53.23% of the fruit yield changes. Conclusion: Generally, ‘Fayette’ and ‘Shindabad Hastejoda’ genotypes can be recommended as the best genotype for cultivation in the Khorasan Razavi region due to their high quantitative and qualitative yield.