Suppose the seed line A contains an allele a, and a seed line B of the same crop species contains an allele b, for the same gene. With these controlled genetic groups, we might cultivate each variety (genotype) in a range of environments. This range might be either natural or controlled variations in environment. For example, an individual plant might receive either more or less water during its growth cycle, or the average temperature the plants are exposed to might vary across a range.