assessment of phenotypic diversity among mulberry (morus spp.) genotypes in south khorasan province

Mulberry (morus spp.) is an economically important plant in iran. this research was conducted to identify and collect mulberry germplasm to preserve genetic resources over 3 years in south khorasan province. accordingly, during different growth stages, visits were made to mulberry cultivation areas to record important characteristics of the genotypes based on the provided descriptors.  in total, 31 different mulberry genotypes from 3 species (m. alba, m. nigra, m. macroura) from seven regions were identified, and morphological traits were recorded in accordance with the guidelines of upov. in quantitative traits, the strongest positive correlations were obtained in shoot number, shoot length, lateral shoot number, leaf blade width, leaf blade length, peduncle length, petiole length, mature fruit length, fruit weight, mature fruit length/width, and sweetness (brix). in qualitative traits, the strongest positive correlations were obtained in leaf blade texture, leaf blade thickness, leaf blade glossiness of the upper side, and the shape of the apex leaf blade, and the strongest negative correlations were obtained in mature fruit color, shape of the apex leaf blade, and leaf blade shape. the lowest fruit sweetness (brix) value (15.3) was recorded in genotype m22, whereas the highest value (36.5) was observed in genotype m5. the mean fruit sweetness(brix) across all genotypes was 24.05. furthermore, the highest fruit weight (4.26 g) was obtained from genotype m16, while the lowest (1.08 g) was recorded in genotype m2. the average fruit weight among the genotypes was 2.69 g. cluster analysis using the ward method for farm data classified the studied genotypes into five groups. apparently, cluster analysis was unable to fully differentiate among the three species. only the genotypes belonging to m. nigra were partially grouped into a single cluster, likely due to the overlap of some of their phenotypic traits. this study revealed high morphological diversity in the mulberry genotypes dispersed in south khorasan province. 31 distinct selected genotypes were transferred to the collection for the preservation of genetic resources and their use in breeding programs. this study had certain limitations, including potential environmental interference and the lack of molecular validation.