[Selection of Some Apple Rootstocks Produced by Seeds]

This investigation was achieved in the general commission for scientific agriculture research- agricultural scientific research center in Sweida, by using 5 apple seedlings genotypes (A, B, C, D and E), and 3 local apple cultivars (S1, S2 and SK), in addition to H (hybrid between MM106 rootstock and the local apple cultivar Skarji), to establish genetic platform to select the most adaptable and tolerant genotypes to environmental stresses and pest resistance, beside detecting an important and desired traits by using biotechnology, then, to accredit the better genotypes as mother plants for seedling rootstocks. Primary evaluation was achieved for the nine genotypes by studying the characters of parents genotypes, and their progenies. The genotypes S1, Sk, E and D were excluded out of the breeding program due to the high percentage of bent plants, plants have a lot of spines, and the low number of seeds per fruit in S1 and Sk. On the other hand the genotypes A, B, C, H and S2 proved their ability to use as genetic platform in apple rootstocks breeding program, and as mother plants. However, each genotype characterized by special architectural characters and growth dynamic (growth rate average and the peak of growth) during the season. Likewise, the ratio between primary root length and plant length was highest one in genotype A among selected genotypes. On the other hand, the genotypes S2, H and B had the highest stem diameter at grafting point. Moreover, the percentage of success grafting was between 77% and 90% in the two genotypes A and S2 respectively. In addition, the studied genotypes proved their tolerance to deficit water in early stage, through the reduction of shoot length, and increase the depth of primary root, in addition to the decrease of fresh and dry weight in stem and shoots, while increase them in roots; besides, the dry to fresh matter ratio was increased under deficit water in all the plant parts of all studied genotypes indicating the ability to drought tolerance. Besides that, the results showed high efficiency of some primers used in SSR technique on detection genetic differences within and among genotypes such CH01H02, Hi04g05, O2b1 and CH01f02. The genetic similarity was high among each genotype and its progenies, whereas, it was low between genotypes. On the other hand, the plants derived from the local apple genotype 'Sukari 2' were distinguished with a high number of plants have 4 genes among the studied genotypes, while the genotype B showed the lowest number of plants revealed the 4 genes in comparison with the other studied genotypes. Likewise, the highest percentage of resistant plant for woolly apple aphid was in genotype H, while the highest percentage of susceptible plants was in genotype C. Additionally, the NZsn_O05 and NZSc_E01 markers were more efficient to distinguish resistant plants for woolly apple aphid