This lecture provides a comprehensive overview of Papaya (Carica papaya L.), focusing on its soil and climate requirements, water and nutrient management, propagation, and the extraction and uses of papain. Emphasis is placed on cultivation practices, pest and disease management, and the economic significance of papaya in tropical and subtropical agriculture. The lecture also addresses the physiological and reproductive biology of papaya, highlighting its importance in sustainable horticultural production.
Introduction and Economic Importance
- Papaya (Carica papaya L.) belongs to the family Caricaceae and has a chromosome number of 2n=18.
- Native to Tropical America, papaya was introduced to India in the 18th century and is now widely cultivated in tropical and subtropical regions.
- Major producing states in India include Bihar, Assam, Maharashtra, Madhya Pradesh, and Andhra Pradesh, with a cultivation area of approximately 34,000 ha.
- Papaya is valued for its high vitamin A content (2000 IU/100g) and is consumed fresh or processed into products like jam, jelly, and nectar.
- The fruit is a significant source of the proteolytic enzyme papain, which has diverse applications in medicine and industry.
Botanical Characteristics and Sex Expression
- Papaya plants exhibit dioecious, hermaphrodite, and gynodioecious sex forms, influencing fruit set and orchard management.
- Dioecious types have separate male and female plants, while hermaphrodite and gynodioecious types bear both flower types on the same plant.
- Male flowers are borne on long panicles; female flowers are solitary and larger, with a prominent ovary.
- Fruit morphology varies: globular from female flowers and elongated from bisexual flowers.
- Sex expression is influenced by environmental factors (temperature, day length) and growth regulators (e.g., GA, ethrel, SADH, phosphon-D).
Soil and Climate Requirements
- Papaya thrives best in deep, well-drained loamy soils with uniform texture up to 1.8 m depth.
- Good drainage is essential; even brief water stagnation can cause collar-rot disease.
- Optimal temperature range is 35–38°C; papaya is sensitive to frost and extreme heat.
- Windbreaks are recommended in areas prone to strong winds to prevent tree damage.
- Regions with mild temperatures and low incidence of viral diseases, such as Tamil Nadu, are ideal for year-round cultivation.
Propagation and Planting
- Papaya is primarily propagated by seeds, which are collected from mature, healthy fruits and cleaned before sowing.
- Seedlings are raised in nursery beds or polythene bags; the latter method produces more vigorous plants.
- For dioecious varieties, 2–3 seedlings per pit are planted to ensure sufficient female plants; excess males are removed after sex identification.
- Planting is done in pits of 45 x 45 x 45 cm at 1.8 x 1.8 m spacing, accommodating about 3000 plants/ha.
- The best planting time coincides with the onset of the South-West monsoon or during mild weather periods.
Nutrient and Water Management
- Papaya requires regular and balanced fertilization due to its rapid growth and continuous fruiting habit.
- Recommended nutrient application includes 10 kg FYM/plant as basal and 50 g each of N, P, and K per plant bimonthly, or 250 g N, 250 g P2O5, and 500 g K2O per plant/year in split doses.
- Peak nutrient uptake occurs between flowering and harvesting stages.
- Regular irrigation is essential, typically every 8–10 days, but waterlogging must be avoided to prevent root diseases.
- Intercropping with short-duration vegetables is possible during the pre-bearing stage.
Harvesting, Yield, and Post-Harvest Handling
- Fruits mature 12–14 months after planting, with continuous cropping possible for up to 2 years.
- Harvesting is done when fruits change from green to yellowish-green, using careful hand picking to avoid damage.
- Average yield per tree ranges from 50 to 100 fruits; high-yielding varieties can produce 100–160 t/ha.
- Fruits for local markets are stored in straw layers; for distant transport, they are packed in straw-lined bamboo baskets.
- Yield and fruit quality depend on the proportion of female and hermaphrodite trees in the orchard.
Papain Extraction and Uses
- Papain is a proteolytic enzyme extracted from the latex of unripe, fully developed green papaya fruits.
- Latex is collected by making shallow incisions on the fruit surface, preferably using non-metallic tools to prevent discoloration.
- Collected latex is sun-dried or artificially dried at 50–55°C, then powdered and stored in airtight containers.
- Papain is used in medicine (digestive aid, ulcer treatment), food industry (meat tenderizer, beer clarification), textiles, cosmetics, and other industrial applications.
- Factors affecting papain yield include fruit size, maturity, and varietal characteristics; potassium metabisulphite may be added to improve quality and shelf life.
Pest and Disease Management
- Papaya is susceptible to several diseases, notably collar-rot, mosaic virus, and leaf curl virus, especially in poorly drained or virus-prone areas.
- Good field sanitation, use of disease-free seeds, and resistant varieties are key preventive measures.
- Regular weeding and removal of infected plants help reduce disease incidence.
- Common pests include fruit flies, aphids, and red spider mites; integrated pest management strategies are recommended.
- Windbreaks and proper irrigation management also contribute to reducing pest and disease pressure.
Objective Questions
Q1. Which of the following statements about papaya sex expression is correct?
A. Gynodioecious papaya plants bear both female and bisexual flowers on the same plant.
B. Dioecious papaya plants have both male and female flowers on the same plant.
C. Hermaphrodite papaya plants never produce male flowers.
D. All papaya plants are monoecious by nature.
Answer: A
Q2. What is the recommended fertilizer dose per plant per year for higher yield in papaya according to the Indian Institute of Horticulture Research, Bangalore?
A. 250 g N, 250 g P2O5, 500 g K2O in six split applications
B. 100 g N, 100 g P2O5, 200 g K2O in two split applications
C. 50 g N, 50 g P2O5, 100 g K2O in one application
D. 500 g N, 500 g P2O5, 1000 g K2O in twelve split applications
Answer: A
Q3. Which of the following is NOT a recommended use of papain extracted from papaya?
A. Clarifying beer
B. Tenderizing meat
C. Increasing fruit sweetness
D. Pre-shrinking wool
Answer: C
Q4. What is the main reason for providing wind breaks in papaya cultivation?
A. To prevent wind damage to trees
B. To increase soil fertility
C. To enhance fruit sweetness
D. To control pest infestation
Answer: A
Q5. Which of the following factors does NOT influence sex expression in papaya?
A. Growth regulators like GA and ethrel
B. Season of planting
C. Soil drainage
D. Environmental temperature
Answer: C
Q6. What is the preferred method of propagation for papaya and why?
A. By seeds, because vegetative methods are not economical
B. By cuttings, because it ensures true-to-type plants
C. By grafting, because it increases fruit size
D. By tissue culture, because it is faster
Answer: A
Q7. During papain extraction, why are non-metallic instruments preferred for tapping and collecting latex?
A. To prevent discoloration of the latex
B. To increase latex yield
C. To avoid contamination with soil
D. To reduce labor cost
Answer: A
Q8. Which papaya species is known as 'mountain papaya' and thrives at elevations between 1500 to 2000m in the Western Ghats?
A. Carica candamarcensis
B. Carica monica
C. Carica papaya
D. Carica pubescens
Answer: A
Q9. What is the main consequence of failing to use controlled pollination (sib mating) in papaya seed production?
A. Deterioration of variety and mixed progeny types
B. Increased fruit size
C. Higher papain content
D. Reduced need for irrigation
Answer: A
Q10. According to TNAU recommendations, what is the basal application of farmyard manure (FYM) per papaya plant?
A. 10 kg per plant
B. 1 kg per plant
C. 25 kg per plant
D. 50 kg per plant
Answer: A
