management of seed production and storage: principles and...
TRANSCRIPT
Management of seed production and storage: principles and practices
Romke Wustman, 11 June 2012
Seed potatoes: structure of the lecture
1. Objectives of seed potato production 2. Main requirements for seed production 3. Crop fitting 4. Pre-sprouting 5. Stem and tuber numbers 6. Fertilization 7. Haulm killing 8. Storage
Objectives of seed potato growing
1. Production of healthy seed 2. High yield but most important: high multiplication rate 3. Seed potato production = balancing production cost,
yield and health 4. Basically: maximizing the benefit (or return) per kg
ware (!) potatoes (market value)
What is important in seed potato production
Healthy seed
Total yield: Number of production days Production per day
Large number of healthy tubers per hectare (or per m2)
Number of tubers
A large number of tubers depends on:
1. Cultivar 2. Physiological age of seed 3. Pre-treatment of seed 4. Plant density 5. Soil conditions (less sprout development in dry soil)
What is the desired stem density
Plants / ha
Stems / plant
Stems / m2
Tubers / ha
Multiplication rate
40,000 4,4 18 650,000 16
60,000 3,6 21 790,000 13
80,000 3,4 27 880,000 11
100,000 2,8 28 900,000 9
Experiment: cultivar Alpha, seed size 35 - 45 mm
Main requirements for seed production
Climate: preferably moderate Low aphid pressure Moderate temperatures
• Tuber formation and growth require cool (night) temperatures
Seed quality Healthy seed Right physiological age: multiple sprouts
Availability of irrigation positively affects: Stem and tuber number Common scab control Production rate
Control of diseases and pests in the foliage Insects: aphids, Colorado beetle Fungal diseases: late blight, early blight
Control of soil borne diseases and pests Black scurf: Rhizoctonia solani Potato Cyst Nematode (PCN)
Case 1:
What are in your opinion the absolute minimum requirements to succesfully grow seed potatoes ?
Assessment of crop requirements: crop type
Assessment of crop requirements: strategy
Required quality characteristics Healthy starting material Right physiological stage: multiple sprouts Seed size: large number of potential sprouts
Selection of suitable cultivars Meet the specifications of the market(s): quality
characteristics Crop type fitting in the cropping season
Nitrogen fertilizer Low - moderate N
Strategy = “crop fitting”
Important characteristics of a seed potato crop: Low disease levels
Soil borne: • Absence of Potato Cyst Nematode (PCN) • Low black scurf • Low common scab
Seed borne: • Bacterial diseases • Virus diseases
Early development Pre-sprouting Low - moderate nitrogen
Premature haulm killing to escape from: Increased aphid pressure Too large seed tuber size at harvest
Pre-sprouting: advantages and disadvantages
Pre-sprouted seed harvested before 1 August (in The Netherlands) produces a 5 ton/ha higher total yield than non-sprouted seed
Pre-sprouting leads to: Earlier emergence, earlier crop development Less aphids and less aphids = less virus diseased plants
Pre-sprouting is more laborious and more expensive and the planting capacity is lower
Pre-sprouting: leading to a short cycle crop
Cv. Seresta stored in dark at 9 oCelsius: weak sprouts
Apical dominance
Cv. Agria Cv. Désirée Calcium deficiency in tip
Cultivar Agria, stored in dark at 18 oC under moist conditions
Cv. Bintje, well pre-sprouted seed potatoes
• 4 oC in dark storage till half February
• Diffused light after storage period
Cv. Bintje with sturdy light sprouts and root primordia
Pre-sprouting
Diffused light stored seed potatoes
Pre-sprouting
Diffused light stored seed potatoes
Pre-sprouting / diffused light storage Diffused light stored seed potatoes
Pre-sprouting / diffused light storage
Diffused light stored seed potatoes
Pre-sprouting / diffused light storage
Physiologically young seed
Cv. Bintje 3 oC dark from
November No sprouts Planted 21 April Harvest 17 May
Physiologically old seed
Cv. Bintje 15 oC from November De-sprouted March 1 Pre-sprouted in light Planted April 21 Harvest May 17 Little potato disorder
starting
Physiologically too old (senile) seed
Cv. Bintje 15 oC from Nov. De-sprouted April 3 Planted April 21 Harvest May 17 Little potato disorder
clearly visible
Cv. Bintje, mini chitted seed potatoes
Planting potatoes
Planting potatoes
Nitrogen increases canopy development
More nitrogen induces long crop cycle
% soil coverage Lelystad 1990
0
10
20
30
40
50
60
70
80
90
100
21-m
ei28
-mei
4-jun
11-ju
n18
-jun
25-ju
n
2-jul
9-jul
16-ju
l23
-jul
30-ju
l6-a
ug13
-aug
20-au
g
BINTJE 0 N
BINTJE 100 N
BINTJE 200 N
BINTJE 300 N
BINTJE 400 N
Late maturing cultivar needs less nitrogen % soil coverage Lelystad 1990
0
10
20
30
40
50
60
70
80
90
100
21-m
ei28
-mei
4-jun
11-ju
n18
-jun
25-ju
n
2-jul
9-jul
16-ju
l23
-jul
30-ju
l6-a
ug13
-aug
20-au
g
BINTJE 200 N
BINTJE 300 N
MORENE 100 N
MORENE 200 N
Nitrogen delays skin set • Increased storage losses: water loss and fungal diseases
• Quality loss
Case 2
Your seed crop has to be harvested early. You already applied 100 kg of nitrogen per hectare, soil content was 20 kg.
Would you further increase the amount of nitrogen to increase the yield?
Case 3
Under similar conditions you are growing both seed and ware potatoes of the same cultivar. Would you apply more or less nitrogen to the seed crop as compared to the ware crop?
Case 4
You are switching to a new cultivar that is maturing later than the old cultivar. Would you apply more or less nitrogen to the new cultivar as compared to the old cultivar?
Case 5
An emerged crop (and all nitrogen has already been applied at planting) has severely suffered from frost damage. Would you apply additional nitrogen during hilling to stimulate growth?
Potassium (K) reduces bruising susceptibility
Phosphate
Deficiency causes reduced canopy growth and thus reduction of yield
Phosphate increases tuber number at low soil phosphate levels, not at high soil levels
Minor elements
Magnesium, Manganese In case of deficiencies, mainly effects on production
potential Mostly to be cured with foliar sprayings Combination of mineral (chemical) fertilizer and
organic fertilizer (animal manure) usually provides sufficiënt minor elements
Fertiliser application: amount
Crop oriented: aiming for sufficient crop growth Potential crop requirement minus
soil capacity green manure crops animal manure
Field oriented: also aiming to maintain or increase soil levels (potassium and phosphate)
Fertiliser application: timing and splitting
Phosphate pre-planting no splitting
Nitrogen pre-planting: at least enough for canopy closure splitting only at very long crop cycles: generally not for
seed
Potassium pre-planting
Haulm killing seed potatoes: why ? To keep the quality of the seed high = to keep the percentage of virus low
Harvest date 24/7 4/8 13/8 24/8
Total yield (ton/ha) 28 35 40 45
% potato virus Yn 0,2 0,7 2,0 5,9
Haulm killing seed potatoes: how ?
Two relevant methods in the Netherlands (% of acreage)
Flailing and chemical killing of stem ends (about
85%) Complete chemical haulm killing (about 10 %)
Important: NO REGROWTH !
Haulm killing by haulm pulling (5 %)
Haulm killing by burning the crop with propane (< 1 %)
Haulm killing by flailing and chemically killing the stem ends (85 %). Flailing machine in front of the tractor
Haulm killing by chemical haulm killing (10 %) - Important: No regrowth of the plants
Hand harvesting → mechanical harvesting
Harvesting process: manual ⇮ mechanical
Mechanical harvesting
Limit damage during harvesting as much as possible:
Damage leads to bruising low quality = low prices Damage allows pathogens (bacteria and fungi) to
enter the tubers Therefore: Reduce falling height in harvesting and transporting
system: from harvester to cart / wagon From cart / wagon into a store
Mechanical harvesting
Potato storage temperature regimes (in oC ) for long term storage:
Seed 3-4 Table 4-5 French fry 6-8 Chips (crisps) 7-9 Starch 4
Seed potato storage: technique and management
Phases during each storage period Drying Wound healing (suberization)
most optimal conditions: • 15 oC • 90-95 % RH
Cooling down to desired temperature Holding Warming-up Unloading
Seed potato storage: technique and management
Seed potato storage – drying and cooling
Forced ventilation system: Quick drying and cooling Low temperature fluctuation with store
Space ventilation: Slower drying an cooling Larger temperature fluctuation within store
Basic seed potato storage: technique and management
Temperate climate conditions and applicable in tropical regions:
Forced ventilation Temperature management
Outside air or refrigeration
Additional: permanent refridgerated cooling
Seed potato storage: technique and management
Box storage
• Air moves from bottom to top through boxes
• High value crops: table and seed
Seed potato storage: technique and management
Box storage
• Air is forced horizontally through boxes:
Potato store with space refridgeration
Seed potato storage: technique and management
Two types of refridgerated cooling
Cooling unit mounted on wall Flexible cooling unit
Space cooling in a 8,000 MT store
Seed potato storage: technique and management
Boxes in refrigerated space cooling
Computerized storage management: centralized temperature control and data registration
Storage
Requirements for forced ventilation using ambient air in N.W. Europe
Forced ventilation: 100 m3 air.m-3 potatoes.hour-1 Air distristribution system Insulation Temperature measurement
Storage
Storage systems used in modern potato chains bulk: high volume turnover = table and processing boxes (crates): seed and high quality table stock
Case 6
Implications for your conditions Which seed storage system under conditions of:
Five months storage Average ambient temperature 25 oC
Five months storage Ambient temperature 15 oC
Storability of seed potatoes
Time span of seed potato storability in months
average ambient temperature (oC) storability in months
light dark 5 12 8
10 8 - 9 4 15 7 3 20 4 1 - 3 25 3 1 30 2 1
Thank you for your attention
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