Preheat oven to 350 degrees F. Grease and flour 13- by 9- by 2-inch pan. Mix sugar, nuts, melted butter and cinnamon until crumbly and set aside for topping.

In a separate bowl, cream together brown sugar, shortening and egg. Add flour, soda and salt to creamed mixture alternating with sour cream. Stir in rhubarb. Pour mixture into pan and sprinkle with topping.

Bake for 45 to 50 minutes. Cut in squares and serve warm or cool.