The production of super-high-yield summer maize is an important strategic way to improve the production of maize and ensure the national food security. At present phenomenons such as excessive fertilizer(especially nitrogen)、unbalanced nutrient ratio、unreasonable fertilizer application times and so on were widespread. Therefore it has the important theoretical and practical value to clear the limiting nutrient factors、yield responses to applied NPK and balanced nutrient ratio、the characters of assimilation ...