Crop Science Reviewer for ALE Philippines 2026 (Deep Dive)

Crop Science is the largest and most heavily tested subject in the Agriculture Licensure Examination. It covers the complete cycle of crop production from seed selection and land preparation through harvest and post-harvest handling. This deep dive reviewer goes beyond the basics and covers the specific technical knowledge that separates passing from failing ALE scores.

Plant Physiology: Understanding How Plants Work

Plant physiology questions appear throughout the ALE because understanding why a crop behaves the way it does is essential for making correct production and management decisions.

Photosynthesis and Plant Growth

Photosynthesis is the foundation of all crop production. Plants convert light energy, water, and carbon dioxide into glucose and oxygen.

Equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂

Light reaction (in thylakoids): Light energy is captured and converted to ATP and NADPH. Oxygen is released as a byproduct of water splitting.

Calvin cycle (in stroma): ATP and NADPH are used to fix CO₂ into glucose. This is where actual sugar production occurs.

C3 plants: Most crops including rice, wheat, soybean, and most vegetables. Fix CO₂ directly through the Calvin cycle. Less efficient in hot, dry conditions.

C4 plants: Corn, sugarcane, sorghum. Have a more efficient CO₂ fixation mechanism that reduces photorespiration. Better adapted to high temperature and high light intensity. This explains why corn yields are typically higher than rice per unit area under optimal tropical conditions.

Plant Hormones and Their Functions

Rice Production: The Most Tested Crop in the ALE

Rice is the most economically and culturally significant crop in the Philippines and the most consistently tested crop in ALE questions.

Rice Growth Stages

Vegetative phase: From germination to panicle initiation. Includes germination, seedling, tillering, and stem elongation stages. Duration varies by variety (typically 55 to 75 days for most Philippine varieties).

Reproductive phase: From panicle initiation to flowering. Duration is approximately 35 days. This is when the panicle (flower head) develops and flowering (heading) occurs.

Ripening phase: From flowering to maturity. Duration approximately 30 days. Grain filling and hardening occur during this phase.

Critical Growth Stages for Water Requirement

The two most critical stages for water in rice are tillering and the heading to flowering period. Water stress during these stages causes significant yield loss. This is a common ALE question.

Key Rice Varieties in the Philippines

The National Seed Industry Council (NSIC) registers approved rice varieties. Some key NSIC-registered varieties frequently referenced in ALE questions:

NSIC Rc 222 (Tubigan 18): Widely grown inbred variety. Good yield potential, intermediate amylose content, tolerant to tungro.

NSIC Rc 216 (Tubigan 14): High-yielding inbred variety. Resistant to bacterial leaf blight.

NSIC Rc 160 (Mestiso 7): Hybrid rice variety. Significantly higher yield than inbred varieties.

PhilRice

The Philippine Rice Research Institute (PhilRice) is the government agency responsible for rice research and development in the Philippines. PhilRice develops and releases NSIC-registered rice varieties.

Corn Production

Corn (Zea mays) is the second most important cereal crop in the Philippines after rice.

Types of corn:

Growth requirements: Corn is a C4 crop requiring high solar radiation. It is sensitive to waterlogging but moderately drought tolerant during vegetative stages. Critical water requirement period is during tasseling and silking.

Pollination: Corn is cross-pollinated. The tassel (male flower) at the top sheds pollen that falls onto the silks (female stigmas) below.

Coconut Production

The Philippines is one of the world's largest producers and exporters of coconut products.

Scientific name: Cocos nucifera

Products from coconut:

Philippine Coconut Authority (PCA): The government agency responsible for the development of the coconut industry in the Philippines.

Cropping Systems

Fertilizers and Crop Nutrition

The Primary Macronutrients (NPK)

Nitrogen (N): Most limiting nutrient for crop growth. Promotes vegetative growth and green color. Deficiency: yellowing starting from older leaves (chlorosis). Urea (46-0-0) is the most common N fertilizer.

Phosphorus (P): Essential for root development, flowering, and fruiting. Deficiency: purple or reddish discoloration of leaves, poor root development. Most available in slightly acidic soils (pH 6.0 to 6.5).

Potassium (K): Improves disease resistance, water use efficiency, and quality of fruits and grains. Deficiency: scorching and browning of leaf margins starting from older leaves.

Fertilizer Calculations

Fertilizer calculations are a reliable source of ALE questions. Practice the following formula:

Amount of fertilizer needed (kg) = (Required nutrient kg/ha) ÷ (Nutrient content of fertilizer as decimal)

Example: If a rice crop needs 90 kg N/ha and you are using urea (46-0-0):

Amount of urea = 90 ÷ 0.46 = 195.6 kg/ha

Complete fertilizer grade is expressed as N-P₂O₅-K₂O. A 14-14-14 fertilizer contains 14% each of N, P₂O₅, and K₂O.

Post-Harvest Technology

Post-harvest losses in the Philippines are estimated at 10 to 37 percent for rice and can be even higher for vegetables and fruits. Reducing these losses is a major food security goal.

Post-Harvest Loss Points

Harvesting (cutting, threshing losses), transport, drying, storage, and milling are the five main points where grain losses occur.

Moisture Content and Storage

Safe moisture content for long-term rice storage: 14 percent or below. Above this, molds and insects proliferate rapidly.

Equilibrium moisture content: The moisture level at which grain neither gains nor loses moisture to the surrounding air. Depends on relative humidity and temperature.

Grain Drying Methods

Sun drying: Traditional method. Simple and low cost but dependent on weather. Grain is spread on concrete or tarpaulin and raked periodically.

Mechanical drying: Uses heated air forced through the grain mass. Faster and weather-independent. Flatbed dryer and recirculating batch dryer are common types in the Philippines.

Practice What You Just Learned

Crop science questions in the ALE combine plant physiology, crop-specific production knowledge, and applied calculations. Practice now at LisensyaPrep. No account needed.

Practice Agriculture Questions at LisensyaPrep

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