The main impact of nutrition is on this is on the numbers of grains per head.
Nitrogen will affect the number of grains that are set on individual ears. A high yielding crop of oats will have approximately 30-40 grains / ear, however if nitrogen supply is limiting this will be reduced.
The timing of the applied nitrogen is important as grain numbers are determined early from double ridge to floret initiation.
Early applications of nitrogen increases the number of grains / ear.
Manganese, zinc, copper and boron are the essential micro nutrients that affect the number of grains/ear and hence increase grain yield. Copper affects the quality of pollen and therefore the number of grain sites that set seed. Blind sites are associated with copper deficiency.
The number of eventual grains per ear varies from season to season and is affected by a number of factors including: