Postharvest Physiological Changes and Structural Characteristics of Fruits, Vegetables, and Cut Flowers

Postharvest Physiological Changes and Structural Characteristics of Fruits, Vegetables, and Cut Flowers

• 1.
  Structure of fruits,vegetables and cut flowers related to physiological changes after harvest Umesh Timilsina Assistant Professor Department of Horticulture CNRM, Bardibas, Mahottari Agriculture and Forestry University
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  Relation of FruitStructure to Postharvest Life Characteristic Effect Thick peel Longer shelf life Thin peel Rapid water loss High moisture Quick spoilage Hard tissues Better transportability Soft tissues Easily bruised
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  Examples • Banana Thin peel Highrespiration Short shelf life • Citrus Thick peel Lower respiration Longer shelf life
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  STRUCTURE OF VEGETABLES •Vegetables may consist of different plant parts. A. Root Vegetables • Storage organ = Root • Examples: Radish Carrot Beetroot • Structure • Periderm (Skin) ↓ Cortex ↓ Vascular Tissue ↓ Pith
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  • Postharvest Characteristics Highmoisture content Susceptible to shriveling Mechanical injury causes decay B. Tuber Vegetables • Examples: Potato Sweet potato Potato Structure Periderm ↓ Cortex ↓ Vascular Ring ↓ Pith
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  • Eyes • Axillarybuds present on potato. Importance: Sprouting Propagation C. Bulb Vegetables • Examples: Onion Garlic • Onion Structure • Dry Scales ↓ Fleshy Scales ↓ Basal Plate
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  Postharvest Importance • Dryscales reduce water loss. • Improper curing increases rotting. D. Stem Vegetables • Examples: • Asparagus • Kohlrabi (Knolkhol)
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  E. Leafy Vegetables •Examples: Spinach Lettuce Cabbage • Leaf Structure Cuticle Epidermis Palisade Tissue Spongy Tissue Vascular Bundles • Postharvest Characteristics Highest respiration rate Rapid wilting Very short shelf life
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  F. Flower Vegetables •Examples: Cauliflower Broccoli • Structure Immature flower buds attached to stalk. • Postharvest Characteristics Highly perishable Sensitive to ethylene Rapid yellowing
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  G. Fruit Vegetables •Examples: Tomato Brinjal Chilli Cucumber • Structure similar to fruits.
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  STRUCTURE OF CUTFLOWERS Components of a Flower Stigma │ Style │ Ovary │ ---------------- Petals (Corolla) ---------------- Sepals (Calyx) │ Peduncle
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  • Floral Parts 1.Calyx Made of sepals. Functions: Protect flower bud 2. Corolla Made of petals. Functions: Attract pollinators Ornamental value 3. Androecium Male reproductive part. Components: Anther Filament
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  4. Gynoecium Female reproductivepart. Components: Stigma Style Ovary 5. Peduncle Flower stalk. Function: Water transport Nutrient transport
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  Cut Flower-Water Relations •Water movement occurs through xylem. Vase Solution ↓ Stem Base ↓ Xylem ↓ Flower • Blockage causes: Wilting Bent neck Reduced vase life Bent Neck in Rose and Gerbera
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  PHYSIOLOGICAL CHANGES AFTERHARVEST • After harvest, produce remains alive. A. Respiration Most important physiological process. • Equation • Glucose + Oxygen ↓ Carbon dioxide + Water + Energy • Effects Heat production Weight loss Faster ripening
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  B. Transpiration Loss ofwater from produce. Effects Wilting Shriveling Loss of freshness C. Ethylene Production Natural ripening hormone. Functions Ripening Degreening Senescence
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  D. Ripening Changes include: •Physical Softening Color development • Chemical Starch → Sugar Acid reduction E. Senescence Final deterioration stage. Symptoms: Yellowing Tissue breakdown Flower fading
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  STRUCTURAL FACTORS AFFECTINGSTORAGE LIFE 1. Cuticle Thickness • Thicker cuticle: Less water loss Longer shelf life • Examples: Citrus Pumpkin 2. Surface Area High surface area: Higher transpiration • Examples: Spinach Coriander
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  3. Stomata Large numberof stomata: Greater water loss 4. Tissue Firmness Firm tissues: Longer storage • Examples: • Apple • Citrus Soft tissues: Short storage • Examples: Strawberry Papaya 5. Presence of hairs  Higher the no. of hairs, higher will be the transpiration  E.g. Rambutan, Kiwi
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  Comparison of Fruits,Vegetables and Flowers Character Fruits Vegetables Flowers Main tissue Ovary Various organs Floral organs Respiration Moderate High High Water loss Moderate High Very high Shelf life Moderate Short Very short Ethylene sensitivity Moderate Variable Very high