PROPAGATION FACILITY
Plant propagation requires controlled environment for:
I. STRUCTURES1. Temperature
2. Light
3. Moisture
4. Gases (O2, CO2 )
5. Mineral nutrition (fertilizer)
6. Cleanliness
A.
Cold frames
-semi controlled environment (passive system)
-used mainly for hardening seedlings and rooted cuttings
-also used for vernalizing herbaceous perennials
B. Hotbeds
C. Greenhouses
1) Types--Quonset, ridge and furow (gutter-connected), lean-to(attached)
2)
Heating
a. Steam (centralized)- pipes (including fin-type), heat exchanger
b. Hot water (central, local)- pipes (fin-type), even distribution of heat
3)
Cooling---Natural
ventilation
Pad and Fan system (evaporative cooling system)
4) Automatic Controls
a. temperature (heating, cooling)
b. watering (timer)
c. CO2 injection
5)
Glazing
Materials (covers)
a. glass ($1.00/sq. ft)
b. plastic :
Flexible
-polyethylene film (poly 6mil) $0.15/ 2layer . sq ft
-polyvinylfluoride (PVF, Tedlar)--UV resistant
-polyvinylchloride (PVC film, popular in Japan)
Ridgid
-fiberglass (corrugated)--Tedlar coated (cumbstable)
-acrylic (plexiglass, exolite) --doulbe layer $3/sq. ft
-polycarbonate (polygal, Lexan)--- $0.75/sq ft
6)
Propagation
Structures within Greenhouse
a. 'Wardian' Case- covered bench or structure (spore gernination, grafts)
b. Germination chamber- 'Sweat Chamber' (high humidity, temp, lowlight)
bedding plant seeds
c. Mist house- cutting propagation (bottom heat)
low pressure mist, high pressure fog
II. GROWING MEDIA
A. Requirements
-water retention
-good aeration
-nutrient holding (CEC)
-neutral pH
-free of toxicity
B. Amendments
1)
Soil--Heavy,
requires sterilizaation, high CEC
2) Sand--No CEC, inert, heavy
used for improving aeration
3) Peatmoss--Sphagnum or hypnum peatmoss (~70% decomposed)
usually low in pH, high CEC, high water holding capacity, provides some
nutrients
4) Vericulite--expanded mica mineral
high water holding, good CEC, good buffering
5) Perlite-- expanded volcanic silicaceous rock (1400°
F, vacuum)
very light, inert, no CEC, no buffering
6) Pumice--crushed volcanic rock (heavier than perlite)
similar properties as perlite--mainly used for nursery crops in CA
7) Bark, wood shavings, sawdust
problem with phenolics, tannins
use after decomposition
8) Rockwool --shredded, sheets, cubes
no CEC, no buffering, inert
III. MIXTURES FOR CONTAINER GROWING
A. Mixtures Containing Soil
1)
Heavy
soil (clay or clay loam)
1 part soil
2 parts perlite or sand
2 parts peat
2) Medium soil (silt loam)
1 part soil
1 part perlite or sand
1 part peat
3) Light soil (sandy loam)
1 part soil
1 part peat
For 1, 2, and 3-- Add Base fertilizers (per bushel)
8oz. dolomite (Ca, Mg)
10oz. Superphosphate (P, S)
B. The U.C. Mixes (Nursery Crops)
1) Used mostly for nursery crops (woody)
No. % sand
% peatmoss
A 100
0
B
75
25
C
50
50 (most common)
D
25
75
E
0
100
Base Fertilizers
For mix C, use (per cubic yd)
4oz. potassium nitrate (KNO3)
4oz. potassium sulfate (K2SO4)
2.5oz single superphosphate
7.5lb. dolomite (CaCO3. MgCO3)
2.5lb. limestone (CaCO3)
C. The Cornell Peat-Lite Mixes (soil-less mix)
Soilless mix or peat-lite mix (most flower crops)
Bushel/yd3
Peat Perlite
Vermiculite Bark
Peat-lite Mix A
11
--
11 --
Peat-lite Mix B
11
11
-- --
Foliage Plant Mix
11 5.5
5.5 --
Epiphytic
Mix (Orchid) 7.3
7.3 --
7.3
Base fertilizers: ground limestone, superphosphate, calcium or potassium
nitrate,
Iron sulfate, Fritted trace elements, wetting agent
Most commercial mixes are based on cornell peat-lite mixes
Example: Sunshine Mix #1 (with base fertilizers)--many crops
Sunshine Mix #2 (no base fertilizers)
Sunshine Mix #3 (base fertilizers)--bedding plant seed germination
Promix, Metromix, etc.
IV. PASTEURIZATION OF GROWING MEDIA
A. Steam Sterilization
-Moist heat
-30 min at 180° F (82° C)
-Kills pathogen, weed, seed
-Ammonium toxicity in heavy soils
Ammonifying bacteria
Nitrifying bacteria
Nitrifying bacteria
OM Actinomycetes
> NH4+
Nitrosomonas >
NO2 Nitrobacter
>NO3-
Crop residue
Ammonium
Nitrite
Nitrate
Remedy- Allow less OM in soil before sterilizing
-Aeration before use
B. Chemical Sterilization
Chemicals------Chloropicrin
(Tear gas)
Methyl bromide (Restricted)
Vapan
Problems Some plants are sensitive
i.e. Dianthus to Methyl Bromide
Long aeration time (~14 days)
V. pH ADUSTMENTS
A. To Lower
pH
-Sulfur powder
-Aluminum sulfate
-Iron sulfate
-Also use acids
Sulfuric acid
Phosphoric acid
Nitric acid
B. To Raise
pH
-Lime (CaCO3)
-Dolomite (CaCO3. MgCO3)