Perm V eg: A Model to Design Crop Sequences for Permanent Vegetable Production Systems in the R ed R iver D elta, V ietnam

The constraints in current vegetable production systems in the R ed R iver D elta, V ietnam, in which vegetables are rotated with flooded rice, called for the design of alternative systems of permanent vegetable production. The practical model, P erm V eg, was developed to generate vegetable crop sequences for permanent vegetable production, as based on a set of rules and restrictions. Permanent vegetable production systems were designed based on the following five scenarios: (i) increased profit, (ii) reduced labour requirement, (iii) decreased costs of pesticide use, (iv) improved crop biodiversity and (v) selected crops with low‐perishable products. P erm V eg showed that theoretically all selected crop sequences in the different alternative systems increased farmers' income compared to the traditional system. The system with the highest profitability increased profit per hectare per day by a factor of three as compared to the traditional system. Labour requirement in days per hectare per day in a crop sequence also increased in all systems. Except for the system with low costs of pesticide use, permanent vegetable production systems had higher pesticide costs than the traditional, vegetable – flooded rice crop sequence. Given the model outcomes, permanent vegetable production systems can be an option to improve farmers' income, to provide labour opportunities, and, in the case of the high crop biodiversity system, to contribute to the development of sustainable production systems. The P erm V eg model can act as a practical tool to rapidly explore crop sequence options and to help farmers' decision‐making.