TITLE: Transplanting Tobacco Seedlings in the Greenhouse
AUTHORS: Lynn Doran

[DESCRIPTION]
<div class = "text-blocks"><div class = "text-block">Protocol for transplanting and growing tobacco seedlings in the UIUC RIPE greenhouse.  Has been verified on Petite Havana and Samson cultivars.  </div><div class = "text-block">For additional information on growing tobacco for research purposes refer to UIUC RIPE greenhouse guide "Growing Tobacco (Nicotiana tabacum) under Greenhouse Conditions, RIPE Project UIUC Field and Greenhouse, 2020"</div></div>

[STEPS]
?. [Initial Transplant]
Select the appropriate pot size for transplanting. Typical pot sizes:If keeping all transplants or after making selections for final growout: Classic 400 PotIf making selections for final growout: 3" x 3" , 18 well planting flatIf preparing plugs for transplanting into the field: 1" x 1", 72 well planting flat
Tobacco can reach maturity even in a small pot if the proper fertilizer solution is provided. Tobacco can be top-heavy and a larger soil volume will prevent the plants from falling over.  Tobacco should not be allowed to dry out.  Smaller pots will require more frequent watering. Classic 400 pot (1gal) is standard  for tobacco. This size container allows enough soil to prevent fallen plants if watered properly and reduces soil waste after harvest
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If transplanting into the Classic 400 pot, it is advisable to mix the slow release fertilizer into the soil while filling the pots. For a medium fertilization rate of a 1 gallon container, use  of Osmocote® Plus 15-9-12. A tablespoon of Osmocote weighs about  so if application does not need to be exact, 1.5TBSP will suffice. Fill the pot half full with soil. Add recommended rate of Osmocote. Mix in well with hands.  Add remaining soil.More information on Osmocote recommended rates.
17 g
12 g
For the smaller planting flats, it is too difficult to properly mix in the appropriate amount of Osmocote.  Apply liquid fertilizer as needed in smaller planting flats.
?. [Initial Transplant]
Fill the appropriate sized pot completely full with soil.Use Berger BM6 HP Myco Organic Fertilized Peat Moss Mix soil if transplanting into Classic 400 pot or 3" x 3" 18 cell flat.Use Coco Loco if transplanting into 1" x 1" 72 cell flats for field propagation.
Coco Loco soil seems to help control the presence of fungus gnats.
?. [Initial Transplant]
Tamp the soil down firmly with your hands. Trying to make as level of a surface as possible.
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Using the super fine (0.5 GPM @ 40 PSI) fogg-IT drench nozzle, soak the soil until saturated to remove any air bubbles.  If the soil settles more than about an inch, add additional soil and rewet.  Do not overpack the soil.
?. [Initial Transplant]
Label pot twice. Once with sharpie on a plastic stake in the pot and once on the exterior of the pot using a sharpie and labelling tape or a laser printed label.
Laser printed labels are more robust.  Handwritten sharpie labels tend to fade over the growing season.
?. [Initial Transplant]
Poke a small hole in the middle of the pot using tweezers.
?. [Initial Transplant]
Choose a healthy looking seedling with one to two true leaves but that isn't too big.
The root system begins to develop rapidly after the first true leaves.  When the true leaves first appear, there is typically one branch in the root system making it easy to remove from the initial media if care is taken. Larger plants have larger root systems that can easily be damaged during transplanting. Damaging roots during transplant will drastically affect development and result in non-uniform plants.
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Pinch the tweezers closed and insert them into the soil about a quarter inch deep about an inch away from the selected seedling.
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Holding the tweezers closed, dig under and towards the selected seedling.  Slowly bring the tweezers up to the surface to loosen the soil.
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Once the soil has been loosened, use the tweezers to grab the plant by the stem as close to the roots as possible.
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Gently pull up on the seedling until the roots are free from the soil.
If the roots or stem break, discard the seedling and select a different one.  Additional seeds should have been sown at seeding to allow for breakage and provide more seedlings to select from.
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With the tweezers lay the intact roots of the seedling that was freed from the soil over the hole in the new pot.
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Use the tweezers to gently shove the roots of the seedling into the hole in the new pot.
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Use the tweezers and finger to gently firm the soil around the seedling. Try to plant the seedling to the same depth on the stem that it was growing in the previous pot and the seedling leaves should not be touching the soil when transplant is finished.
Fungus gnat larva may be present in the soil.  The larvae will eat the leaves if the leaves of the seedling touch the soil.  The larvae cannot climb the stem.
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Using the super fine (0.5 GPM @ 40 PSI) fogg-IT drench nozzle, soak the soil until saturated to remove any air bubbles and ensure good soil to root contact.
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Place the planting flat in a non-perforated propagation tray, or place the Classic 400 pot in a 10" saucer.  Fill tray with about 1" of water or fill saucer about half full with water.
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If using a planting flat, cover with a humidity dome for at least the first three days after transplanting.  Leave vents on dome half closed, half opened.  There are no humidity domes available for the Classic 400 pot.
?. [Initial Transplant]
After at least 3 days, remove humidity dome and grow transplants at ambient greenhouse conditions:  ,  , 300-750PAR, and light cycle 12 hours on/12 hours off. Check daily and add water to keep tray filled with approximately 1" water or Classic 400 pot saucer half full of water.  Apply liquid fertilizer to planting flats as needed, if plants show nutrient stress such as yellowing.  Most plants transplanted into planting flats will be transplanted into the field or transplanted again into Classic 400 pots with Osmocote before fertilizer is required. For plants in Classic 400 pots, slow release Osmocote fertilizer should be sufficient for remainder of the plant's life cycle.
23 °C
Following transplant the plant will not use much water but it is important that the soil does not dry. Water from the bottom by filling the saucer at least half full or the tray 1" full for the entire life of the plant. Under less than ideal conditions, i.e. high temps/low humidity, it may be necessary to water the plants from the top, but this has been found to promote sore-shin, a fungal disease that will rot the stem at the base from which the plant cannot recover.  Frequent watering is essential and plants should be monitored daily to maintain the healthiest possible plants.
If plants in planting flats require liquid fertilizer, dilute 600 g of Peter's Profession 20-10-20 in a 9 liter container of water. Then measure 150 ml of the diluted fertilizer into a watering can with 3 gal of water. Use a TDS meter to test total dissolved solids and adjust to 150 ppm by adding more diluted fertilizer or more plain water.
?. [Initial Transplant]
Keep original seedlings watered and growing in the greenhouse for one to two weeks after transplanting.  Replace any transplants that die with a new transplant from the respective seedling pot.
?. [Repotting]
If transplants were grown in a 3" x 3" planting flat, after 3 to 4 weeks and once selections have been completed, transplant selected plants into Classic 400 pots.  If transplants were planted directly into Classic 400s, maintain plants through necessary phenotyping or seed collection.
?. [Repotting]
Plants should be repotted from 3" X 3" planting flats to Classic 400 pots when their leaf spread diameter is approximately 1-2 inches.
Signs of stress that indicate a plant has grown too large for it's pot and should be repotted immediately include:Once plants show signs of stress, they will never grow or produce seed to their full potential even after repotting.  Repotting too late will create added variability and negatively affect research measurements.
?. [Repotting]
Prepare a Classic 400 Pot as described in
[through step #6.]
?. [Repotting]
Make a 3" by 3" hole in the center of the pot.
?. [Repotting]
Remove the plant with as much soil intact as possible from the 3" X 3" flat and place in the hole. Soil from the original pot and new soil should be level.
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Gently firm the soil around the base of the plant with your hands.
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Water thoroughly from the top down to ensure good root to soil contact.
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Maintain plants through necessary phenotyping or seed collection.