Agronomy Crop Physiology 3

Question 1

What is the Leaf Area Index (LAI)?

Accepted Answer

The ratio of total one-sided leaf area to ground surface area

Answer

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.

Question 2

What does the harvest index (HI) measure in crop production?

Accepted Answer

The proportion of total biomass partitioned into the harvestable product

Answer

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.

Question 3

Which environmental factor does NOT directly drive stomatal opening or closing?

Accepted Answer

Soil pH

Answer

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.

Question 4

What is the directional growth of a plant shoot toward a light source called?

Accepted Answer

Phototropism

Answer

Phototropism is the directional growth response toward (positive) or away from (negative) light, mediated by asymmetric auxin distribution that causes differential cell elongation.

Question 5

What is the primary carbon-fixing enzyme in C3 photosynthesis?

Accepted Answer

RuBisCO

Answer

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.

Agronomy Practice Test

Agronomy Practice Test

Agronomy Crop Physiology 3