Micro-environment vs. Macro-environment
Plant breeders frequently differentiate the macro-environment from the micro-environment. Macro-environmental factors are those that are common to a given location at a given time. Examples are the amount of rainfall and average temperature during a growing season and the amount of fertilizer applied to a field.
Micro-environmental factors are those that are unique to a single plant or to a small group of plants. An important example of a micro-environmental factor is plant-to-plant spacing in a row. In Figure 4, the plants in the two rows have different micro-environments resulting from different plant spacings, and this difference will affect numerous phenotypes later in development. For example, the plants with greater spacing likely will produce larger ears than those with less spacing because of reduced competition for light, water, and nutrients.