Saint-Modeste Nursery
By Denise Tousignant, Laurence Tremblay, Michel Rioux, Jean-Yves Guay, Alain Bonneau and Corine Rioux
Photos 1-2. Aerial view of the Saint-Modeste nursery (Photos Jocelyn Landry).
• The current scenario for HL cutting production is based on three consecutive harvests of cuttings on one-year-old stock plants grown in 4-L pots (Table 2). This approach yields up to 100 top-quality cuttings per stock plant. The stock plants used for this operation are available for reforestation the following spring.
• Growing stock plants in 4-L pots was done for the fi rst time in 2006. From a single year of harvest, we are able to attain a multiplication factor in the order of 60 shippable plants per stock plant. Using this scenario we only harvest cuttings from one-year-old stock plants, which have the highest rooting capacity.
At the same time, problems of plagiotropism and stem curvature, which occur when cuttings are taken from older stock plants and prevent attaining production standards, are eliminated.
• When stock plants are kept for a second year of cutting harvest, we can expect a reduction in rooting percentage (1-year-old stock plants: 85–90% rooting;
2- and 3-year old stock plants: 60–65% rooting) and in the quality of cuttings after transplanting, which translates into a higher proportion (up to 50%) of rejected plants (bent stems related to plagiotropism).
Table 2. Production calendar for hybrid larch stock plants at the Saint-Modeste nursery.
Year Month Production stage
1
Late April
Seeds sown in 15 700 containers (15 cavities of 700 cm3)
May – October
Growth in tunnel, ending with a hardening-off period in greenhouse
Transplant to 4-L pots.
Forced growth in greenhouse Early May 1st harvest
Mid June 2nd harvest Mid July 3rd harvest
• Softwood cuttings are collected during the active growth phase. The work is done manually, using scissors (Photo 3a), allowing the selection of cuttings within the optimal length range (7 to 10 cm) (Photo 3b). Shoots that are too short are left on the stock plants to continue growing.
• Cuttings are stuck in a 45 110 container (45 cavities of 110 cc) with a peat moss and perlite substrate (40%:60% v:v) (Photos 3e, f). Beforehand, each container is moistened (Photo 3c), and holes are preformed in the cavities (Photo 3d). During the cutting operation for HL, productivity is about 3,300 cuttings per person per day (harvesting, sticking and handling). In comparison, productivity
is about 4,300 per day for black spruce (BS) and up to 6,000 per day for white spruce (WS).
• Cuttings are then placed in double-walled enclosures and tightly sealed (Photos 3g, h). Water is applied with both a spray robot and a central misting line.
Irrigation control takes into account air temperature and relative humidity in each enclosure, in order to maintain needles moist and hold the vapour pressure defi cit below 1.0 to 1.5 kPa.
• After 12 weeks, 85% of the cuttings show new roots.
Following a period of acclimatization, the rooted cuttings are lowered to the fl oor and spend the winter outside. Transplanting for bareroot or large-dimension container stock is done the following spring. Cuttings are delivered to reforestation two years later as large-dimension plants.
• Rooting trials are underway using low-volume containers (Jiffy® 18 mm plugs) with hardwood (dormant) cuttings, and could lead to adjustments in the current methodology, especially by opening the way to mechanized transplanting.
Production of plants using somatic embryogenesis
The MRNF is working to establish an operational somatic embryogenesis technique (SE), used at Saint-Modeste since 2001. The fi rst phase involves white spruce, and hybrid larch is the second. Compared to traditional methods, and in complement to cutting propagation, SE allows the multiplication of very large numbers of plants and accelerates the use of improved or selected individuals. The main advantage of the technique is the ability to use liquid nitrogen (cryoconservation) to preserve material (embryonic tissue) being evaluated in plantations. Plants produced by SE are evaluated in the nursery and in clonal tests where the best individuals will be selected according to predefi ned criteria. These selected clones are then propagated to produce plants for reforestation. They can also be integrated into genetic improvement programs and in mating designs for the selection of the next generation of improvement.
Through SE it is possible to obtain a limitless number of somatic embryos from a single seed (= clone). These somatic embryos will become plants whose genotype will be identical to the initial seed. An example of the steps to produce white spruce plants by SE is presented in Table 3 and Figure 1. Figures 2 and 3 illustrate the integration of SE in the MRNF’s plant production chain.
Producing plants from SE will lead to the establishment of clonal tests, the production of stock plants for cuttings production and the study of clonal variability. To date the SE laboratory at Saint-Modeste has produced 13,000 plants from a single clone previous to 2004, and 3,860 plants from 80 clones in 2004. Among these clones, 52 will be planted on reforestation sites in 2007 to establish a fi rst clonal test. More than 9,000 plants produced from 163 new clones in 2005 are being grown to establish a second clonal test. In 2006, 300 new clones were selected to establish a third clonal test. In addition, all clones produced were frozen in liquid nitrogen at -196˚C (cryoconservation).
Photos 3 a-h. Production stages for hybrid larch cuttings using double-walled enclosures at the Saint-Modeste nursery:
a) First harvest of cuttings in May from greenhouse-forced stock plants; b) softwood cuttings collected at a length of about 7 cm; c) misting water to stabilize the water content of rooting containers; d) perforation of rooting medium and installation of containers on a conveyor; e) operation of cutting sticking; f) detailed view of inserting a cutting; g) exterior view of a double-walled rooting enclosure; h) interior view of a double-walled rooting enclosure. (Photos P. Lemay, N. Robert and D. Tousignant).
a
a b b
cc d d
e
e ff
g
g h h
Container production of conifer plants by cuttings
After having overwintered outside (Photos 4a, b), the cuttings are transplanted with the production of large-dimension plants as an aim (height of 35 cm or more with a balanced H/D ratio). To do this, cuttings are transplanted either bareroot or in larger containers (15-320 cc or 25-310 cc), and grown for two years in the nursery. Production goals for container-transplanted cuttings are in the order of 400,000 HL, 700,000 BS and 700,000 WS.
Transplanting takes place from May 10 to June 10, approximately. White spruce, the most sensitive species to transplant stress, is transplanted fi rst, while still dormant. It is followed by hybrid larch, for which we wait for bud break to occur, to correctly distinguish between live cuttings from those that have no roots.
Maintenance of rooted cuttings before transplanting
One or two fertilizations (3 to 4 mg N/plant/application) are carried out before beginning transplanting operations.
Irrigation is managed to maintain a minimum water content in the substrate of 40 to 50% of its weight at saturation.
Preparation of cuttings
Cuttings are extracted from their container, shaken to remove the substrate (Photos 4c, d), then placed in basins lined with moistened jute, a portion of which will be used to cover the roots. During extraction, the containers are always lain on their side to avoid tearing the roots that have grown under the container from the stem. This simple precaution prevents important losses, because HL cuttings are particularly fragile where new roots attach to the stem.
Because the HL cuttings have begun to break bud, they must remain in the basins for as short a time as possible (maximum of one night), or the foliage will quickly become moldy.
Selection and transplanting cuttings
At the time of transplanting, cuttings are chosen according to their vigour (presence of new foliage) and the presence of at least one root measuring 1 cm or more in length. To facilitate insertion in the new cavity, roots that are too long are trimmed to 7 to 10 cm, or the width of a hand. Each cutting is then transplanted with a fork, directly through
the silica (Photo 4f). The operation is carried out in the fi eld, with rolling tables that advance over the production area (Photo 4e).
The 25-310 or 15-320 containers are fi lled with a mixture of peat and vermiculite (80:20, v:v), with a layer of silica on the surface. The potting density is 0.10 g/cm3, with a moisture level of 75%. Before transplanting, the top of the containers is moistened.
If the weather is sunny, recently transplanted cuttings are irrigated for 15 minutes at noon and at the end of the day.
Care of plants after transplanting
Transplanted cuttings are grown for two years then shipped for reforestation in the spring of the third year (Photos 4g, h), as large-dimension plants. For a lot to be accepted, it must meet the MRNF quality standards for this type of plant, which is a minimum height of 35 cm, a maximum height: diameter ratio of 7.5, and an incidence of defects lower than 15%.
HL plants grown from cuttings, especially if they come from stock plants that are two years old or older, can show plagiotropism (10–15% of plants), forks or multiple leaders. Corrective pruning is done the fall after transplanting or the following spring. Plants are sorted before shipping to remove those with defects.
Containers are lifted 10 cm-high on metal lattices to prevent the roots from anchoring in the soil. In the fall, they are lowered to the ground to ensure winter protection.
Cultural management is similar to standard seedlings:
• irrigation: watering to saturation when the substrate reaches 40% moisture content;
• weed control: the fi rst year, one application of Devrinol® (8 kg/ha) is done after transplanting, followed by two to three manual weedings until autumn. In early May of the second year, a herbicide (Princep 9T®, 1.3 kg/ha) is applied, with one manual weeding done during the summer;
• insect control: if necessary, a treatment is done to suppress Lygus bug (Lygus spp.) in early July;
• disease control: each autumn, a fungicide (Senator®) is applied on the foliage to prevent winter molds.
Steps Description
Induction Production of embryonic tissue using a zygotic embryo extracted from a seed.
Maintenance Multiplication of embryonic tissue, which will remain at an early-embryo stage.
This tissue is placed in cryoconservation (in liquid nitrogen).
Maturation Development of somatic embryos at the cotyledonary stage.
Germination Development of somatic embryos into plantlets. This is comparable to germination of a seed (growth of functional shoot and root system).
Acclimatization Indispensable stage for the survival and growth of the plantlets.
Soil transfer Transfer to soil of acclimatized plantlets for growing in a greenhouse.
Table 3. Description of the principal steps involved to obtain plants by SE.
Figure 1. Example of the stages of plant production for white spruce by somatic embryogenesis (Laurence Tremblay).
Step 1: Induction (3 to 10 weeks)
Step 6: Transfer to soil
Cryoconservation
Somatic embryos are mature after 5 weeks of maturation Zygoticembryo
Megagametophyte Dissection of the
immature seed
Step 5: Acclimatation (1 week)
Growing the zygotic embryo
Obtaining embryogenic tissue
Multiplication of embryogenic tissue
Somatic plantlets obtained after 12 weeks of germination
Step 4: Germination (10 to 12 weeks)
Step 3: Maturation (4 to 6 weeks)
Step 2: Maintenance (unlimited multiplication)
Figure 2. Integration of SE in the plant production chain at the MRNF (Lamhamedi et al. 2006, 4e Atelier technique sur la production de plants forestiers au Québec, Québec, Canada).
Figure 3. Example of plants produced by SE, showing clonal variability. Characterization of morpho-physiological variables and the rooting aptitude for cuttings will be undertaken. (M. Lamhamedi).
Transfer and plant production
Controlled crosses
Induction, maintenance, maturation and germination of embryos
Immature or
mature seeds Cryoconservation
Clonal tests: Quality of pollen, seeds and plants
Characterization of controlled crosses
Clonal variability of plants
Multi-criteria selection High-productivity
plantations
Family variability Stock plant production Cutting propagation
Stock plant production Cutting propagation
New orchards Existing
Orchards
Clonal effect
Plants produced by SE, 1st season Plants produced by SE, 2nd season
Photos 4 a-h. The production stages of hybrid larch containerized plants produced from cuttings at the Saint-Modeste nursery: a) Cuttings that rooted the previous year and ready to be transplanted at the start of the season; b) Detailed view of hybrid larch cuttings ready to be transplanted; c) Shaking of cuttings to extract them from rooting containers;
d) detailed view of cuttings after shaking; e) transplanting operation of cuttings into 5–320 containers; f) detailed view of manual transplanting of cuttings; g) general view of a section of transplanted cuttings, after one growing season; h) general view of containerized production areas of transplanted cuttings of several species. (Photos P. Lemay, N. Robert and D. Tousignant).
a
a b b
cc d d
e
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g
g h h
•fertilization – fi rst year: after transplanting, only a minimal fertilization is done, because rapid growth of HL must be controlled to avoid having the plants reach an excessive height the following year. In mid-August, fertilization ceases to allow hardening off.
From late September to late October, fertilization is resumed to increase the nitrogen tissue content to about 2.2 to 2.3%. The mean height of plants borders on 15 to 18 cm, with a mean total mass of 2,400 mg;
•fertilization – second year: from early May to mid-June, a low dose of fertilizer is applied weekly.
Afterwards, fertilization is stopped until bud set, and is then continued until the end of the season until the percent nitrogen in the tissues reaches 2.2 to 2.3%. The average height at this time is 35 to 40 cm, with a mean total mass of 8,400 mg.
Containerized production of conifer seedlings
• The useable production area is 26,000 m2 of greenhouse tunnels, or the equivalent of 4.5 M large-dimension plants (Table 4). The different species produced are, in order of importance: white spruce, black spruce, larches, balsam fi r, Norway spruce, red spruce and red pine. The great majority of seedlings are produced as large-dimension plants.
Large-dimension white spruce is one of the most diffi cult species to produce because it requires a fi nely tuned production regime (Table 5).
Our production technique includes the following activities, throughout the two years of production:
•regular inspection of crops (presence of pathogens, insects and weeds);
•periodic monitoring of moisture in the substrate.
A too-abundant or too-light irrigation hinders the normal development of the root system and, consequently, the plant’s development. The aim is to maintain a 25% moisture content (v:v);
• establishment of production standards for each species and type of plant. These are references curves ajusted to the season, for height, diameter, biomass, and the concentration of minerals in the substrate and tissues. These standards are the basis for the fertilization schedule;
•monitoring the crop bi-weekly (substrate and tissue mineral content, stem and root biomass, height and diameter) assists in periodically revising the fertilization schedule;
• in the spring of the shipping year, all plants must be verifi ed for quality before leaving the nursery, using criteria based on morphology, size and quality.
Usually, classifi cation of plants is done before shipping because a minimum of 85% of shipped plants must pass the quality control standards. From a quality standpoint, there are 20 possible rejection criteria, of which one is “Insuffi cient roots” (for the plant to be accepted the rooting plug must be intact and able to undergo normal handling.
• our growing season is from late April to the end of October. We accumulate between 2,200 and 2,500 degree-days, above a 1°C threshold. The fi rst year, seedlings are grown in unheated greenhouse tunnels, and the second and last year of production they are grown outdoors.
Additional information:
LAMHAMEDI, M. S., F. COLAS, D. TOUSIGNANT, L. TREMBLAY, A. RAINVILLE, J. Y. GUAY, C. OUELLETTE, M. RIOUX. 2006.
Intégration de l’embryogenèse somatique dans la fi lière de production de plants forestiers du Québec. Affi che présentée dans le cadre du 4e Atelier technique sur la production de plants forestiers au Québec, Québec.
ISBN 2-550-46934-8.
TOUSIGNANT, D., P. PÉRINET et M. RIOUX. 1996. Le bouturage de l’épinette noire à la pépinière de Saint-Modeste.
Ministère des Ressources naturelles du Québec.
Pépinière de Saint-Modeste et Direction de la recherche forestière. 33 pages.
TOUSIGNANT, D. et M. RIOUX. 2002. Le bouturage des résineux à la pépinière de Saint-Modeste (Québec, Canada) : 10 ans de recherche, de développement et d’innovations. Dans : Verger, M. (éd.). Multiplication végétative des ligneux forestiers, fruitiers et ornementaux. Actes [CD-ROM]. Montpellier, France:
CIRAD-INRA, p. 65-86. Troisième rencontre du groupe de la Sainte-Catherine, 22-24/11/2000, Orléans, France.
Table 4. Categories of seedlings produced in containers, and indication of the morphological criteria desired at the time of shipping (quality A1).
Product
Table 5. Schedule of the main production techniques for large-dimension white spruce grown in containers.
Month First year (1+0) Second year (2+0)
End of winter
• Seed stratifi cation;
• Use of seeds of calibre 1–2–3 (excluding small seeds; calibre 4.
xRemoval of winter covers immediately after the snow melt;
xMoving containers to outdoor growing areas.
April • Seeding early in the season (late April 2.5 viable seeds/cavity);
• Growing substrate composed of 80% peat and 20% vermiculite (v:v). Volumetric density of the substrate: 0.10 g/cm3.
x Placing containers on raised supports at least 10 cm off the ground for aeration and cavity drainage. The root system develops only within the cavity and growing conditions are optimized;
xFertilization begins as soon as the substrate thaws.
May • Containers placed in greenhouse tunnels (covered with opaque polyethylene) on supports raised 10 cm off the ground;
xDaily surface irrigation during the germination phase;
xManual thinning to one plant per cavity (the most vigorous and the most centred);
xGTemperature management in sheltered areas (opening side panels when the temperature rises above 30˚C);
xLow-intensity supplementary lighting immediately upon starting the growing period to stimulate stem growth (18-hour photoperiod).
xThroughout the entire active growing period, fertilizations are divided (2 applications per week) to reduce the risk of leaching minerals;
xThe fertilization schedule incorporates the contract standards for minimum nitrogen concentrations in plants at the time of shipping.
June
July
August • Ceasing artifi cial lighting to initiate hardening off.
Sept. xClosure of aeration panels in greenhouse tunnels to maintain raised temperatures, stimulate root development and hardening off of the seedlings.
October xRemoval of polyethylene in greenhouse tunnels.
xContainers placed on the ground.
Nov. xInstallation of a winter cover to minimize risk of root freezing (If seedlings are 10 cm or more in height, there is a high risk of stem breakage);
x1+0 target size: biomass - 1200 mg, height - 9 cm, stem/root ratio – 3.0, tissue concentration of N close to 3%.
xInstallation of snow fencing to provide winter protection for the root system and the stem.
TREMBLAY L. et M. S. LAMHAMEDI, 2006. Embryogenèse somatique au ministère des Ressources naturelles et de la Faune du Québec: du laboratoire au site de plantation. Des plants et des Hommes 9 (3): 6-11.
TREMBLAY, L., J.-Y. GUAY, C. OUELLETTE et M. S. LAMHAMEDI. 2006. L’embryogenèse somatique au Québec: une technologie très prometteuse pour la foresterie multi-clonale de haute productivité. Affi che présentée dans le cadre du 4e Atelier technique sur la production de plants forestiers au Québec, Québec. ISBN 2-550-46934-8.
TREMBLAY L., M. S. LAMHAMEDI, F. COLAS, D. TOUSIGNANT, A. RAINVILLE, G. PRÉGENT, J.-Y. GUAY, M. RIOUX, et J. BEAULIEU, 2006. White spruce in Québec: a multidisciplinary approach for enhancing forest productivity. Dans 30e rencontre de l’Association canadienne des améliorateurs d’arbres (ACAA) / Canadian Tree Improvement Association (CTIA), Tree Seed Working Group, Charlottetown (Île-du-Prince-Édouard), 24 juillet 2006, p. 7 Section 6.
Information contacts:
Alain Bonneau, ing.f.
Nursery Director
(Pépinière de Saint-Modeste) alain.bonneau@mrnf.gouv.qc.ca 418 862-5511 poste 224 Jean-Yves Guay, tech. f. sp.
Technical Team Manager (Pépinière de Saint-Modeste) jean-yves.guay@mrnf.gouv.qc.ca 418 862-5511 poste 237 Corine Rioux, tech. f. sp,
Technical Manager for Container Production (Pépinière de Saint-Modeste)
corine.rioux@mrnf.gouv.qc.ca 418 862-5511 poste 229
Michel Rioux, tech. f. sp, B.Sc.
Manager of Cuttings Operations (Pépinière de Saint-Modeste) michel.rioux@mrnf.gouv.qc.ca 418 862-5511 poste 223
Denise Tousignant, biologiste, M.Sc.
Researcher, Cuttings and Tree Reproduction (Direction de la recherche forestière) denise.tousignant@mrnf.gouv.qc.ca 418 643-7994 poste 6527
Laurence Tremblay, biologiste, M.Sc.
Researcher, Conifer Somatic Embryogenisis
(Direction générale des pépinières et des stations piscicoles et Direction de la recherche forestière
laurence.tremblay@mrnf.gouv.qc.ca 418 643-7994 poste 6704
Arctic
Boreal
Temperate northern
Thanks to our sponsors!
The organisers of the Larix 2007 Symposium thank all the contributors for their valued collaboration and their support for funding.
The organisers of the Larix 2007 Symposium thank all the contributors for their valued collaboration and their support for funding.