What are the regulations for partnership in a grape cultivation project, and is it permissible to give the investor a variable percentage of the price difference for a limited period instead of him being a full capital partner?

An agreement with an investor to be a partner with an undivided share in the entire project is considered a type of partnership. In such a case, losses are divided between the two partners according to each one's capital. As for profit, it is distributed according to their agreement, and it is permissible to allocate an additional share of the profit to the working partner in exchange for his labor. The first method mentioned by the questioner is not permissible as a Mudarabah (profit-sharing partnership) because the invested capital cannot be precisely determined to ascertain its profit or loss, especially the capital of the crop owner. Therefore, the legitimate method for investment is participation with an undivided share in the project's capital.