Complex sentence: The country grows more than 42 different types of maize, each of which has several varieties whose number is estimated at more than 3,000 by the International Center for the Improvement of Maize and Wheat (CIMMYT).
Split into simpler sentences: The country grows more than 42 different types of maize. In turn, each of these types has several varieties whose number is estimated at more than 3,000 by the International Center for the Improvement of Maize and Wheat (CIMMYT).