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The seeds being referred to in the manga are literal seeds of agriculture, for farming and crops. Luka's village is experiencing barren crops and low yields at the start of the volume, which is very fatal for a farming village. The "divine" seeds that Kuro talks about and eventually gets offered to the village are literal seeds as well, but bolstered through agricultural knowledge and persistent tests done by Kuro himself, so they are able to withstand any condition and climate. Think of it like modern-day GMO crops that are created through selective breeding.
Hope this helps! :)
can't comprehend about the seeds and harvests, but i do understand so well what seed that makes luka pregante