сев.-эст. KAER-KAERA, юж.-эст. KAUR-KAURA, сканд. HAVRE ("овёс") и...


Или прибалтийские финны зерна не знали? Да 5000 лет как растят:
https://www.helsinki.fi/en/news/culture/5000-year-old-barley-grain-discovered-aland-southern-finland-turns-researchers-understanding-ancient-northern-livelihoods-upside-down#:~:text=The%205%2C000-year-old%20barley,common%20wheat%20or%20club%20wheat.