//调用

 return producePlantlst.Distinct(new item_collection_DistinctBy_item1()).ToList();

//方法

    public class item_collection_DistinctBy_item1 : IEqualityComparer<FMDS_ProducePlantInfo>

    {

        public bool Equals(FMDS_ProducePlantInfo x, FMDS_ProducePlantInfo y)

        {

            if (x.TaskAreaName == y.TaskAreaName && x.FarmPlotName == y.FarmPlotName && x.PlantYear == y.PlantYear && x.FarmerName == y.FarmerName && x.FarmProductClassName == y.FarmProductClassName)

            {

                return true;

            }

            else

            {

                return false;

            }

        }

        public int GetHashCode(FMDS_ProducePlantInfo obj)

        {

            return ;

        }

    }