Crop Physiology Flashcards
7 cards from real Agronomy practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Crop Physiology flashcards as text
What is the Leaf Area Index (LAI)?
Answer: The ratio of total one-sided leaf area to ground surface area
LAI is the total one-sided leaf area per unit of ground area; it quantifies canopy light interception capacity and is closely related to crop productivity potential.
What does the harvest index (HI) measure in crop production?
Answer: The proportion of total biomass partitioned into the harvestable product
Harvest index is the ratio of economically harvestable yield (grain, fruit) to total above-ground dry biomass, indicating how efficiently a crop converts total growth into useful product.
Which environmental factor does NOT directly drive stomatal opening or closing?
Answer: Soil pH
Soil pH affects nutrient availability indirectly but does not directly signal guard cells; stomata respond directly to light (especially blue light), internal CO2 levels, and plant water status.
What is the directional growth of a plant shoot toward a light source called?
Answer: Phototropism
Phototropism is the directional growth response toward (positive) or away from (negative) light, mediated by asymmetric auxin distribution that causes differential cell elongation.
What is the primary carbon-fixing enzyme in C3 photosynthesis?
Answer: RuBisCO
RuBisCO (ribulose-1,5-bisphosphate carboxylase/oxygenase) catalyzes CO2 fixation in the Calvin Cycle and is the most abundant enzyme on Earth, though it can also bind O2, causing photorespiration.
What is the period of plant development from germination to the initiation of flowering called?
Answer: Vegetative phase
The vegetative phase spans from germination to floral initiation, during which the plant builds its root system, stems, and leaf canopy to accumulate resources for reproduction.
What is the microbial process that converts organic nitrogen in soil organic matter into plant-available ammonium (NH4+)?
Answer: Ammonification
Ammonification (mineralization) is the decomposition of organic nitrogen compounds (proteins, nucleic acids) into ammonium by soil bacteria and fungi, making nitrogen available for plant uptake.