In a large bowl, combine flour, the 3/4 cup sugar, the pecans, baking powder, salt, and baking soda.
In another bowl, beat together egg, orange peel, orange juice, and cooking oil. Stir in rhubarb. Make a well in the center of the flour mixture. Pour in the rhubarb mixture all at once. Stir until just moistened (batter should be lumpy).
Line muffin cups with paper bake cups. Fill 2/3 full. Sprinkle with the 1/4 cup sugar.
Bake in a 400 degree F. oven for about 20 minutes or until golden. Remove from pans; serve warm.