Populus (tremuloides)

John T. Harrington Professor New Mexico State University-Mora Research Center P. O. Box 359 Mora, New Mexico 87732-0359 575-387-2319 575-387-9012 (fax) joharrin@nmsu.edu www.arborday.org

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Family Scientific Name:	Salicaceae
Family Common Name:	Willow family
Scientific Name:	Populus tremuloides (Michx.)
Common Name:	Quaking aspen, trembling aspen
Species Code:	POTR
General Distribution:	P. tremuloides (Michx.) has the broadest range of any North American tree. P. tremuloides (Michx.) occurs in Alaska and throughout Canada from the Pacific coast to the Atlantic coast. In the United States the species occurs throughout the Western United States, primarily in montane areas from Washington eastward through Montana and southward to California eastward to the Trans-Pecos region of Texas. The species also spans portions of the Great Plains eastward to West Virginia, western Virginia, Pennsylvania, and New Jersey. Quaking aspen is also found in the mountains of Mexico, as far south as Guanajuato. The species occurs throughout the mountainous regions of New Mexico.
Propagation Goal:	plants
Propagation Method:	seed
ProductType:	Container (plug)
Stock Type:	164ml conetainers
Time To Grow:	Weeks
Target Specifications:	Height 30 to 40 cm; firm root plug.
Propagule Collection:	Seeds were purchased from a commercial supplier. Both fresh, currant year, collections and seed stored for 2 years under refrigerated conditions (2 - 40C) have been successful.
Propagule Processing:	Seeds are typically sown in late June.
Pre-Planting Treatments:	None. Seeds are sown dry using a moistened needle or are placed in water and a syringe is used to allocate droplets of water containing the seed. Both methods have proven effective.
Growing Area Preparation/ Annual Practices for Perennial Crops:	Propagation (Establishment phase) occurs in a greenhouse and the active growth phase occurs in both a greenhouse and a shade house. The hardening phase occurs in the shade house and the dormant seedlings are over-wintered in a cold frame (small poly-topped greenhouse). After 6 to 8 weeks in the greenhouse and once they reach 25 - 35 cm in height, the plants are moved outside to the shade house facility. Seedlings are kept here until dormant and leaves have been shed, which typically occurs in late October in northern New Mexico. At this point the seedlings are moved into the cold frame for over wintering. Growing media is a 2:1:1 (v:v:v) peat moss: perlite: vermiculite mixture. Controlled release fertilizer 14-14-14 (N-P-K) 3-4 month is incorporated into the media at a rate of 4 kg/m3. Greenhouse irrigation is provided via mini-sprinklers. The irrigation heads are spaced to provide head to head coverage. Shade house and cold frame irrigation is provided via a sub-irrigation system; generally every 4-5 days. In the greenhouse seedlings are fertilized using a fertigation system, which utilizes the irrigation system. Seedlings are not fertilized in the shade house or cold frame.
Establishment Phase:	(Greenhouse) Seed is placed on top of the media using the methods described above. A 2-5 mm layer of perlite is placed of the media/seed. The containers are misted 3-5 minutes 3-5 times a day to keep the surface of the media moist, and maintained until vigorous shoot and root growth is apparent. Note, regardless of the technique employed to sow the seed, multiple seed are sown in each container and thinning of germinates is required. Containers are irrigated periodically to keep the media evenly moist. Greenhouse night temperatures range from 12 to 21oC and day temperatures range from 15 to 26oC. No supplemental light is provided. Thinning of germinants to one seedling per cell begins after 14 days. Seed lots we have used have highly variable germination rates so the establishment phase can be protracted.
Length of Establishment Phase:	2 to 4 weeks
Active Growth Phase:	(Greenhouse/Shade house) The first portion (4 to 8 weeks) of the active growth phase is performed in the greenhouse. Containers are irrigated as needed, which progressively increases as the seedlings grow. Typically, irrigation intervals involve irrigating once every 3 to 4 days for the first two weeks after rooting is complete, then once every 2 to 3 days through the next several weeks, then once every one to two days for the remainder of the active growth period in the greenhouse. Containers are allowed to dry down to a moderate state between irrigations. This irrigation regime is used to help minimize root disease problems. All irrigations are done early in the morning, which allows foliage to sufficiently dry before nightfall, minimizing foliar disease problems. During the active growth phase, seedlings are fertigated every irrigation with a liquid based fertilizer (20-10-10; N-P-K). Fertilization rates applied progressively increase throughout the active growth phase. Applications rate begins at 25 ppm N for the first 2 weeks and progressively increases by 25 ppm every two weeks. By week thirteen seedlings begin receiving 175 ppm N and this rate is held until the seedlings are moved to the shade house. During the greenhouse portion of the active growth period greenhouse temperatures during the day are 21 to 26oC and during the night 18 to 22oC. Ambient photoperiod is supplemented with 60 min light interruptions at the mid point of the dark cycle (10 - 14 hrs) from 75 watt incandescent lights suspended 2 meters above greenhouse benches and from 1,000 watt high pressure sodium vapor lights suspended 3.5 meters above the crop. Once transferred outside, ambient temperature and light regimes are utilized. The remaining 4 to 6 weeks of the growth phase occur in the shade house. Seedlings are irrigated once every other day using a sub-irrigation system. No supplemental fertilizers are used during this portion of the active growth phase.
Length of Active Growth Phase:	8 to 14 weeks
Hardening Phase:	(Shade house) This phase begins in late summer (end of August typically) to early fall as soon as seedlings attain their target shoot height. A series of incrementally increasing water stresses is applied to restrict any further height growth. In Mora, NM, ambient day temperatures are still quite warm but nights begin cooling markedly. The interval between irrigations becomes progressively longer due to seedlings becoming acclimated to water deficits and the gradual cooling associated with the onset of fall. Seedlings are considered "hardened" once buds have formed and leaves have been shed.
Length of Hardening Phase:	8 to 10 weeks
Harvesting, Storage and Shipping:	(Cold Frame) Seedlings are moved from the shade house into a cold frame (low-tech, twin-walled poly-topped greenhouse) in late October to early November. This step is necessary as the diurnal fluctuations in temperatures throughout the winter can result in daily freeze/thaw episodes which can damage the seedlings. The temperature in the cold frame ranges from 2 to 4oC day and night. Seedlings are irrigated on an as needed basis based on moisture levels in the root plug. No supplemental light is provided. Seedlings are kept in the cold frame until shipped which is typically in late February or early March.
Length of Storage:	5 months
References:	Carter, J. L. 1997. Trees and Shrubs of New Mexico. Mimbres Publishing 464 pp. [ITIS] Integrated Taxonomic Information System. 2008. (On-line database). http://www.itis.gov Perala, D.A. 2004. Quaking Aspen. In (R.M. Burns & B.H. Honkala Tech. Coords.) Silvics of North America. Volume 2. Hardwoods.

Citation:

Harrington, John T. 2010. Propagation protocol for production of Container (plug) Populus tremuloides (Michx.) plants 164ml conetainers; New Mexico State University-Mora Research Center Mora, New Mexico. In: Native Plant Network. URL: https://NativePlantNetwork.org (accessed 2024/07/02). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.