Evaluation of morphological diversity in thornless blackberry in Mazandaran

This research was performed to evaluate morphological diversity of 40 thornless blackberry genotypes to find their relation with thornless resources. The samples evaluated based on blackberry descriptor in SANRU blackberry collection. Results showed high diversity in empty seed, taste, weight and titrable acidity of fruit with 100, 59, 43 and 42%, respectively. Empty seeds showed positive correlation with number of shoot (0.325) and cross section of stem (0.365) and negative correlation with fruit TSS (-0.393) significantly. Morphological cluster separated two different class of thornless genotypes. The first class included Thornless Evergreen and Everthornless as first (chimera cultivar) and second (tissue cultured cultivar) resources of thornlessness in blackberry and separated based on flower lengths, TSS/TA, seed number and weight traits. The first class included most of evaluated thornless genotypes and it indicated genetic and recessive type of thornlessness (tissue cultured cultivar) which is the most popular cultivar in Mazandaran, Iran. Homonym genotypes identified, too. In second class, the vigorous thornless cultivars which could be related to poly ploiid cultivars belonged to Merton source of thornlessness, separated from others. Therefore, two early sources of thornlessness identified between Iranian genotypes inside of 'Merton thornless'. It seems that other distinct thornless genotypes related to evolution of thornlessness in diverse climate of north of Iran and will be valuable for future studies.