That person is just a peasant, so they know nothing about city life.
In the past, people were often ridiculed as mere peasants.
Standard mixed kana-kanji spelling. The prefix ど is derogatory.
Ateji spelling; the kanji 土 ('earth') is used phonetically for ど. Rarely used in modern writing.
Katakana spelling of the prefix ど, sometimes used for emphasis or in informal writing.
The prefix ど is a derogatory intensifier, possibly related to the prefix ど- in words like ど真ん中 (dead center) or どぎつい (harsh). The exact origin is uncertain. 百姓 originally meant 'common people' or 'farmers'.