Pecan | Subtropical and Temperate Fruit Production (HOR-MA201) - Unit 4 Notes - Chapter 18

Subtropical and Temperate Fruit Production

HORMA 201 - M.Sc. (Ag.) Horticulture

UNIT IV: Nuts- Walnut, Almond, Pistachio, Pecan

Table of Contents Commercial varieties of regional, national and international importance, Ecophysiological requirements, recent trends in propagation, rootstock influence, planting systems, cropping systems, root zone and canopy management, nutrient management, water management, fertigation, bioregulation, abiotic factors limiting fruit production, physiology of flowering, fruit set and development, abiotic factors limiting production, physiological disorders-causes and remedies, quality improvement by management practices; maturity indices, harvesting, grading, packing, precooling, storage, transportation and ripening techniques; industrial and export potential, Agri Export Zones(AEZ) and industrial support.

Chapter 18 -

🌰 PECAN (Carya illinoinensis)

Family: Juglandaceae
Chromosome number: 2n = 32
Origin: North America (Mississippi River Valley, Southern USA, Northern Mexico)
Type: Deciduous nut tree
Growth habit: Tall (20–30 m), deep-rooted, long-lived
Bearing habit: Terminal on current season’s growth
Edible part: Kernel

🔹 1. Commercial Varieties of Regional, National & International Importance

Region	Popular Varieties
USA	Stuart, Desirable, Western Schley, Wichita, Pawnee, Mahan, Cheyenne
Mexico	Western Schley, Wichita
South Africa	Wichita, Choctaw
India (Trial/Research)	Mahan, Stuart, Nellis – grown in Kashmir & Himachal Pradesh (Kullu, Solan)

• Stuart: Widely adapted, late maturing, medium-sized nuts

• Wichita: High yield, early bearing, but susceptible to scab

• Mahan: Large nuts, early maturing, poor shelling quality

🔹 2. Ecophysiological Requirements

• Climate: Subtropical to temperate, with long warm growing seasons

• Chilling requirement: ~400–600 hours below 7°C

• Temperature tolerance: –5°C to 40°C

• Soil: Deep, well-drained alluvial loams; pH 6.0–7.5

• Rainfall: 700–1,000 mm annually (requires irrigation in drier areas)

• Sunlight: Full sun exposure required

🔹 3. Recent Trends in Propagation

• Seedling propagation for rootstocks

• Patch budding and chip budding are standard

• Grafting (cleft or whip) done in early spring

• Micropropagation: Under experimental stage

• Clonal propagation helps in uniform orchards

🔹 4. Rootstock Influence

• Seedling rootstocks from vigorous, disease-free nuts

• No widely commercial clonal rootstocks yet

• Rootstock affects:

• Tree vigor

• Nut yield

• Resistance to diseases like pecan scab

🔹 5. Planting Systems

• Spacing: 12 × 12 m or 10 × 10 m (low density)

• High-Density: 8 × 8 m (temporary) → thinned later

• Pollinizer ratio: 1 pollinizer for every 8–10 trees

• Training: Central leader system

• Pollination: Wind pollinated and protandrous/protogynous (requires cross-pollination)

🔹 6. Cropping Systems

• Mono-cropping in commercial orchards

• Intercropping during juvenile stage: legumes, vegetables

• Takes 8–10 years to start bearing, full bearing after ~15 years

🔹 7. Root Zone & Canopy Management

• Deep-rooted → avoid shallow tillage

• Annual pruning for air circulation and light penetration

• Remove weak branches, dead wood, water sprouts

🔹 8. Nutrient Management

Nutrient	Dose (Mature tree/year)
N	500–700 g/tree
P₂O₅	250–300 g/tree
K₂O	300–400 g/tree

• FYM: 30–40 kg/tree

• Micronutrients: Zinc (deficiency is common) – foliar spray of ZnSO₄ (0.5%)

• Apply N in split doses: before flowering and during nut development

🔹 9. Water Management

• Moisture stress at nut filling leads to poor kernel development

• Irrigation critical during:

• Flowering

• Nut filling

• Drip or basin irrigation systems are beneficial

🔹 10. Fertigation

• Drip fertigation effective in modern orchards

• Water-soluble NPK + Zn, Fe, B

• Improves growth and kernel yield

🔹 11. Bioregulation

Bioregulator	Function
GA₃	Breaks dormancy, promotes uniform shoot growth
NAA	Improves fruit retention
Boron	Enhances pollination and nut set

• Zinc essential for leaf and shoot development

🔹 12. Abiotic Factors Limiting Fruit Production

• Late spring frost: Damages flowers and new growth

• Waterlogging: Root rot and poor aeration

• Drought stress: Poor kernel filling

• High humidity: Increases scab incidence

🔹 13. Physiology of Flowering, Fruit Set & Development

• Monoecious: Separate male (catkins) and female flowers on same tree

• Pollination: Wind; need synchrony between pollen release and female receptivity

• Fruit: Drupe (nuts) with green husk (shuck) that splits at maturity

• Kernel forms inside the lignified shell

🔹 14. Physiological Disorders – Causes & Remedies

Disorder	Cause	Remedy
Poor nut filling	Nutrient/water deficiency	Timely irrigation, balanced nutrition
Kernel shriveling	Drought or Zn deficiency	Foliar Zn spray
Shuck decline	Poor pollination, pests	Use pollinizers, pest control

🔹 15. Quality Improvement by Management Practices

• Maintain proper pollinizer ratio

• Zinc nutrition crucial

• Prune for light penetration and pest control

• Use of improved, scab-resistant varieties

🔹 16. Maturity Indices

• Shuck splits open and turns brown

• Nut shell color changes from green to brown

• Time: ~180–220 days after flowering

🔹 17. Harvesting, Grading, Packing

• Harvested by tree shaking or pole beating

• Collect nuts before they fall to avoid pest/disease

• Dry nuts to ~4–5% moisture

• Graded by:

• Kernel % recovery

• Shell thickness

• Nut size

• Packed in moisture-proof containers

🔹 18. Precooling, Storage & Transportation

• Store at 0–2°C, low RH

• Shelf life: up to 6–12 months

• Protect from mold and insects

• Use of vacuum or nitrogen-flushed packaging

🔹 19. Ripening Techniques

• Natural ripening on tree

• No artificial ripening used

• Timely harvest critical to avoid nut drop or quality loss

🔹 20. Industrial & Export Potential

• Uses:

• Confectionery, baked goods, roasted nuts, pecan pies

• Kernel oil (rare)

• By-products:

• Shells for fuel, mulch

• Exporting countries: USA, Mexico, South Africa

• India: Scope for import substitution and trial exports

🔹 21. Agri Export Zones (AEZ) & Industrial Support

• No defined AEZ yet in India for pecan

• Trials by IHBT Palampur and SKUAST in Himachal & Kashmir

• Government support under MIDH for temperate nut development

• Need for:

• Research on low-chill cultivars

• Nursery standardisation

• Cold chains for nut storage

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