Wheat is a major product, grown under irrigation and dry, which has a vital role in human nutrition by contributing to food pattern of 75 percent of world’s population. Before 1383, Iran was known as an importer of wheat but in 1383 became self-sufficient. In this article at first, the two-level models, the estimations of parameters’ using maximum likelihood (full and restricted) and bootstrap (parametric and nonparametric) methods and bootstrap confidence intervals for these models are described briefly. Thus, the effects of various factors on amount of wheat harvest using two-level model are discussed.