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Lesson 190 min read
Crop Science
Plant Anatomy, Photosynthesis, C3/C4/CAM Plants & Philippine Crops
In This Lesson
Plant Anatomy
Root Systems
Taproot System
- * Single main root (primary root)
- * Smaller lateral roots
- * Deep penetration
- * Examples: carrots, mango, beans
Fibrous Root System
- * Many thin roots
- * Spread horizontally
- * Good for erosion control
- * Examples: rice, corn, grasses
Stem Functions
- * Support: Holds leaves, flowers, and fruits
- * Transport: Xylem (water up) and Phloem (sugars down)
- * Storage: Stores food and water
- * Photosynthesis: Green stems can photosynthesize
Leaf Parts
Blade (Lamina)
Flat, green part for photosynthesis
Petiole
Stalk connecting blade to stem
Stipules
Small appendages at base
Photosynthesis
Basic Equation
6CO₂ + 6H₂O + Light Energy → C₆H₁₂O₆ + 6O₂
Carbon dioxide + Water + Light → Glucose + Oxygen
Light Reactions
- * Occurs in thylakoid membranes
- * Requires sunlight
- * Produces ATP and NADPH
- * Splits water, releases O₂
Calvin Cycle (Dark Reactions)
- * Occurs in stroma
- * Does not require light directly
- * Uses ATP and NADPH
- * Fixes CO₂ into glucose
Factors Affecting Photosynthesis
Light Intensity
More light = more photosynthesis (up to saturation)
CO₂ Concentration
Higher CO₂ = faster photosynthesis
Temperature
Optimal range: 25-35°C for most crops
C3, C4, and CAM Plants
| Feature | C3 Plants | C4 Plants | CAM Plants |
|---|---|---|---|
| First Product | 3-carbon compound (3-PGA) | 4-carbon compound (OAA) | 4-carbon compound |
| Photorespiration | High | Low/None | Low |
| CO₂ Fixation | Day only | Day only | Night (stomata open) |
| Water Efficiency | Low | High | Very High |
| Examples | Rice, wheat, soybeans, trees | Corn, sugarcane, sorghum | Pineapple, cactus, orchids |
Key Points
- C3: Most common, less efficient in hot/dry conditions
- C4: Adapted to hot, sunny environments; more efficient
- CAM: Desert plants; conserve water by opening stomata at night
Major Philippine Crops
Rice (Palay)
- * Primary staple food crop
- * C3 plant
- * Requires flooded paddies
- * Two cropping seasons: wet and dry
- * Major varieties: IR64, RC222, PSB Rc18
Corn (Mais)
- * Second staple crop
- * C4 plant (efficient)
- * Used for food, feed, industry
- * Types: white corn, yellow corn
- * Major areas: Mindanao, Visayas
Coconut
- * "Tree of Life"
- * Multiple products
- * Major export crop
- * C3 plant
Sugarcane
- * C4 plant
- * Sugar production
- * Major in Negros, Batangas
- * Also for bioethanol
Banana
- * Major fruit export
- * Cavendish variety
- * Year-round harvest
- * Davao, Bukidnon
Planting Seasons
Wet Season (May-November)
- * Rice (main crop)
- * Corn
- * Root crops
- * Leafy vegetables
- * Natural rainfall irrigation
Dry Season (December-April)
- * Rice (with irrigation)
- * Vegetables (tomato, eggplant)
- * Legumes (mungbean, peanut)
- * Requires irrigation
- * Less pest pressure
Crop Production Basics
1
Land Preparation
Plowing, harrowing, leveling; removes weeds and aerates soil
2
Seed Selection
Choose certified seeds; consider variety, climate, market
3
Planting
Direct seeding or transplanting; proper spacing
4
Crop Care
Fertilization, irrigation, pest management, weeding
5
Harvesting
At proper maturity; minimize losses; proper handling
Key Takeaways
- ✓Taproot systems (deep) vs Fibrous root systems (spread out)
- ✓Photosynthesis: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
- ✓C3 (rice, wheat), C4 (corn, sugarcane), CAM (pineapple, cactus)
- ✓Rice is C3; Corn and Sugarcane are C4 (more efficient)
- ✓Wet season (May-Nov) and Dry season (Dec-Apr) cropping