Why must vegetable seed crops be grown in isolated conditions?

In vegetable farming, growing crops under isolated conditions is essential to ensure the purity of the seed yield.1

When vegetables are raised for seed production, isolation prevents unwanted cross-pollination from other varieties or wild relatives. Many vegetable species are naturally cross-pollinated by wind or insects, which transfer pollen between different plants. If a seed crop is not isolated, foreign pollen can fertilize the flowers, leading to genetic contamination and resulting in seeds that do not maintain the desired characteristics of the parent variety. By maintaining isolation, farmers ensure that the resulting seeds are true-to-type and meet quality standards.12