Concept:Mechanical harvesting of cereals is most efficient when the crop canopy is even and uniform.
Explanation:Combine harvesters and other mechanical reapers are set to cut the crop at one fixed height from the ground.
When all cereal plants have uniform height, the cutting bar operates at a consistent level across the entire field.
This ensures that every plant is harvested at the correct position, reducing losses of grains or heads that are too low or too high.
Uniform height also minimises the amount of straw entering the machine, so the threshing and cleaning systems work more smoothly.
It allows the harvester to move continuously without frequent adjustments, saving time and fuel.
Making cereals disease-resistant or free from pests improves yield and quality, but does not directly affect the physical cutting process.
Uniform maturity is important for grain quality, but maturity differences do not solve the height mismatch that hampers mechanical cutting.
Therefore, the key agronomic practice that makes mechanical harvesting easier is ensuring all plants reach the same height.
Answer:C. ensure they all have uniform height