[If] one uproots turnips or radishes from his own [field] to replant in [another section of] his own [field] for [their] seeds, he is obligated [to tithe them], because it is their “goren.”  Onions, once they have taken root in the attic, become cleared of [their] capacity to convey tumah. [If] debris fell on [the onions], and they are uncovered, they are [treated] as though they were planted in a field.