METLA Production, transportation and storage of the seedlings for mechanized planting and extended planting season Nordic Nursery Conference 5-6 Sep. 27, NSFP Risto Rikala, METLA
Seedlings for the whole planting season Nursery aims to produce target size seedlings which stand stresses during transportation, storage and after planting and establish roots quickly into the site Tools to achieve these targets are Size of container Sowing time and scheduling of growing measures Short-day treatment, night break lighting Fertilization and irrigation Challenge: planting time from 15 June to 15 July Frozen stored seedlings can not be used SD-treated seedlings are not yet available Actively growing seedlings are still fragile and susceptible against mechanical stresses
Sowing date and height (first-year spruce seedlings) Height, cm 17.3. Sowing date Date
Seedling transportation from nursery to planting site in Finland Winter storage Longdistance transportation. Short distance transportation Nursery Cold/ frozen storage c. 4% Hardening compound c. 5% Intermediate storage (1-3 weeks) (local cool storage, shelters, open holding area) Growingcompound c. 2% Winter storage in forest 5-1% Storage by planting sites (on-site storage)(1-2 days) Planting Planting sites
Duration of transportation and storage before planting of frozen stored seedlings in Finland 35 3 25-5 6-1 11-15 16-2 21-25 26-3 31-35 36-4 41-45 46-5 Proportion, Osuus, % 2 15 1 5 Duration Kuljetus+varastointiaika, of transportation and vrk storage, days (Viitarinne 22, Rantala et al. 23)
Package and transportation Seedlings are packed: in cardboard boxes (open or closed), open perforated plastic trays (Lännen), plastic bags or they are transported in the container in which they are grown Seedlings are transported by trucks, deliver vans and passanger cars with trailers Intermediate and field storage requirements for proper storage: even base (for unloading), not frost sensitive, possibilities for watering, shade or covers maintenance and control of the storage: person responsible in charge watering rotation in storage (first in first out)
1 8 6 4 2 Annual cycle and planting time Shoot height Diameter Roots 1.1. 1.2. 1.3. 1.4. 1.5. 1.6. 1.7. 1.8. 1.9. 1.1. 1.11. 1.12. Roots Shoot Relative Suhteellinen growth kasvu 1.2. 1.3. 1.4. 1.5. 1.6. 1.7. 1.8. 1.9. 1.1. 1.11. 1.12. 1.1. -1-2 -3-4 -5 Frost Pakkaskestävyys, resistance, C C Spring Summer Autumn -6
Spring (15 April to 15 June) Environment Temperature is increasing, night frosts appear every 2nd or 3rd year Photoperiod is lengthening Air is dry and soil is moist, but cool until the beginning of June Seedlings Seedlings are dormant but deharden quickly, buds burst and frost hardiness decreases Transpiration is high but water uptake of seedlings is slow due to cold soil Instructions In open packages seedlings dry quickly thus daily watering is needed in sunny weather (max. storage time < 1 week) Storage must be sheltered from drought and frost and seedlings can be covered with reflected tarpaulins (which must not touch seedling tops). Frozen stored seedlings in closed boxes can be stored 2-3 weeks and they can be used until the middle of June
Risk for autumn frost injuries of frozen stored seedlings by shipping date in Central Finland (bases long-term (5 years) climatical data, assumptions: critical temperature sum to fulfill growth and hardening = 7 d.d. and frost tolerance of seedlings = 5 C) 1 Frost injury risk, % 8 6 4 2 1.6. 1.6. 2.6. 3.6. 1.7. 2.7. 3.7. Shipping date from frozen storage Hänninen, H., Luoranen, J., Smolander, H., & Rikala, R. 22
Root plugs of frozen stored seedlings must be thawed Height growth, mm New roots (5 weeks), mg Thawed Frozen Soil temperature, C (Helenius et al. 25)
Summer (15 June to 31 July) Environment: Soil is warm but both soil and air can be dry Long photoperiod Seedlings Shoot is elongateing (shoot is fragile) Root growth is active Frost resistance is low (-2-3 C) Leaf area is as largest and cuticula of needle is thin transpiration is high Instructions: Gentle handling and frequent watering (every day) Short storage time (few days) No closed packages!
Wet root plugs at planting assure the survival of seedlings over 2 weeks drought period Preplanting drying treatments: 1 day's drought (55-95%, dripping wet) 4 days' drought (4-75%) 8 days' drought (16-64%) Mortality, % 8 6 4 2 1 2 3 4 Length of drought period, weeks (Helenius et al. 25)
Autumn (August September) Environment High relative humidity, shortening photoperiod air temperature may decrease but soil temperature remain higher Seedlings Shoot elongation finish and hardening begins Root growth ceases Susceptibility against grey mold increases (surface wetness) Instructions: sufficient air circulation in seedling packages watering of seedlings is important also in late summer hardening requires light seedlings must not be stored in dark
Remember watering
Dormant seedlings, planted in late June, are rooted better than growing seedlings if very long dry periods occur after planting New roots, mg 3 2 1 Growing Dormant 1 2 3 4 Drought period, weeks Helenius et al. 25
Short-day treatment improves drought tolerance of spruce seedlings planted in late July Dry mass of new roots, mg 1 8 6 4 2 A A E a a B * * b * SD SD 2 SD 5 Photoperiod treatment and drought period, Luoranen et al. (27)
Both spruce and pine seedlings are most susceptible for mechanical injuries in June Injuries seedlings, % 1 8 6 4 Spruce 45 4 35 3 25 2 15 1 8 6 4 Pine 45 4 35 3 25 2 15 Height 2 1 5 2 1 5 No injury Slight injury Heasvy injury 24.5. 7.6. 21.6. 5.7. 19.7. 2.8. 16.8. Date of exposure Height Current shoot 24.5. 7.6. 21.6. 5.7. 19.7. 2.8. 16.8. Date of exposure (Helenius 22)