Ministry of Agriculture & Lands
Tree Fruit Leader, Vol. 3(2) July 1994
Siberian C Rootstock Increases Peach Cold Hardiness and Yield
H.A. Quamme Research Scientist, Summerland Research Station
A trial of six peach rootstocks conducted for eight years at the Summerland Research Station demonstrated the benefits of using a hardy rootstock to increase flower bud hardiness and yield. The scion variety used was Redhaven. Three of the rootstocks that were tested, Siberian C, Bailey and Halford, come true-to-type from seed. Two clonal rootstocks, GF 655-2 and Citation, a plum and a peach-plum hybrid, respectively, were also included. The sixth rootstock was Redhaven on its own roots. The trial was planted and grown using management practices common to commercial orchards.
Yield and Tree Size
Siberian C combined small tree canopy volume with high cumulative yield (Table 1). Only Citation and GF 655-2 were as small in tree canopy volume and produced about as much fruit per unit canopy volume. These rootstocks, however, had serious defects. GF 655-2 suckered prolifically and Citation exhibited symptoms of graft incompatibility. Bailey, self-rooted Redhaven, and Halford had the lowest yields per unit canopy volume. Halford produced the largest trees of all rootstocks.
Table 1. Performance of six peach rootstocks after eight years in the orchard.
| Rootstock | Cumul- ative Yield/ Tree (kg) |
Final Tree Canopy Volume (m3) | Yield Efficiency (kg/m3) | Flower Bud Survival, 1989, % | Flower Bud Survival, 1991, % |
| Siberian C | 279 a | 29.1 bc | 9.7 a | 48.9 a | 35 a |
| Halford | 267 a | 46.7 a | 6.5 b | 30.6 b | 28 ab |
| Self-rooted | 236 a | 36.8 b | 6.7 b | 30.6 b | 13 c |
| Bailey | 230 a | 34.7 b | 6.9 b | 40.0 ab | 30 ab |
| Citation | 181 b | 20.7 c | 9.0 a | 32.8 b | 25 bc |
| GF 655-2 | 178 b | 23.5 c | 8.1 ba | 43.9 ab | 18 bc |
Flower Bud Hardiness
Flower bud survival was recorded after two winters in which temperatures were low enough to cause flower bud injury, 1988-89 and 1990-91 (Table 1). On both occasions, flower bud survival was greatest for Siberian C rootstock. Flower bud survival for other rootstocks, except for Bailey, was lower on one or both years. Siberian C has also been reported to increase flower bud hardiness in studies carried out at the Harrow Research Station, Agriculture and Agri-Food Canada, Ontario.
Comparison of annual yield, expressed on a per metric volume of canopy to take into account differences in tree size (Fig. 1), indicated during the two years in which flower bud injury occurred, yield per unit volume did not drop as much with Siberian C as other rootstocks. In 1991, the yield advantage of Siberian C over Halford seedling was almost 0.5 kg/cubic meter of canopy. The greater flower bud survival probably contributed to the better cumulative yield performance of Siberian C. Thus, prevention of yield loss from winter injury by using a hardy rootstock, such as Siberian C, is important to economics of peach growing in cold climates where flower bud injury is frequent.
Importance to Peach Production
This study confirms the value of using Siberian C as rootstocks for growing peaches in B.C. Both have been selected for resistance to winter injury to the roots. The main defect of Siberian C is that it is more susceptible to the root lesion nematode than other rootstocks. If it is used, the soil should be fumigated before planting to ensure establishment. In extensive trials in Ontario, in which fumigation was used and winter injury was absent, Siberian C performed similarly to Bailey. Contact your BCMAFF district horticulturists for information on fumigation.
A new rootstock, Tzim Pee Tao, being developed at the Harrow Research Station has promising cold hardiness and a high level of nematode resistance. However, trials to determine if it transfers cold hardiness to the scion and affects yield potential have not been completed at Harrow and have been only recently begun at Summerland. Siberian C is considered the standard to meet in these trials.
Summary
Siberian C rootstock produced the highest yields in a trial of six rootstocks with Redhaven as the scion variety. The high yields of Siberian C were shown to be, in part, the result of rootstock influence on flower bud hardiness. This effect appears to be an important consideration in evaluation of new rootstocks. Siberian C remains a useful rootstock if soil fumigation at planting time is carried out to ensure the root lesion nematode does not affect tree growth.
