Historically speaking, both the introduction of double-cross hybrids and use of single crosses have caused the increase in grain yield and significantly improved agricultural practice. Nowadays, the uniformity of crops is regarded as an advantage of modern agriculture, since the uniformity of products is crucial in global market. Thus, uniformity of crop maturation provides both planning and efficient mechanized harvest. F₁ single-cross hybrids of maize, which is an allogamous species, not only exploit heterosis, but also impose homogeneity.