Malus sieversii, a wild apple species native to Central Asia has been recognized as the major progenitor of the domestic apple. Recent collection trips to Central Asia have verified that M. sieversii is very diverse and has all the qualities present in M. x domestica. Nearly 100,000 seeds from 700 wild M. sieversii trees were collected in seven distinct areas of Kazakhstan over two collection trips (1995/96). Nearly 20,000 of these seeds have been distributed to scientists worldwide who are evaluating seedlings for multiple traits under different environments. This investigation features a subset of 6yr-old seedlings originating from two areas in Kazakhstan: the northernmost (site 9); and southernmost (site 6). Seedlings were screened for resistance to Venturia inaequalis (apple scab) at the young seedling stage and planted as own-rooted seedlings in a high density orchard in Geneva, New York. Included are 14 elite populations (204 seedlings) out of the 85 seed lots collected at site 6, and 29 elite populations (388 seedlings) out of the 207 seed lots from site 9, as well as 12 grafted elite clones (mothers of some of the 388 seedlings) from site 9. Scab resistance of plants grown in Geneva was found in 40% of seedlings from site 6 and 47% of those from site 9. Natural infection with Erwinia amylovora (fire blight) was recorded, with those from site 9 showing significantly higher levels than those from site 6. In the 6(th) leaf, we characterized fruit using multiple descriptors on 55% of seedlings from site 6 and 28% from site 9. Among the many descriptors measured, individual fruit size was quite variable among the many trees, but generally much larger from site 9 than site 6. The range of fruit weight from different trees was: 17-72 g (site 6); 20-102 g (site 9); and 74-158 g (site-9 clones). We anticipate this germplasm, along with that from the broad M. sieversii evaluation project, will offer useful genetic diversity for crop improvement.
