Grain quality of Brazilian maize genotypes as influenced by nitrogen level

Maize (Zea mays L.) is an important crop in Brazil, and concerns about grain quality are increasingly important with increasing exports and use of grain for specific end-uses. A wide range of genotypes are grown and N application is required to produce high yields. The objectives of these studies were to: (i) determine N application effects on the kernel hardness and breakage susceptibility of a wide range of Brazilian genotypes ranging from dent to flint kernel types and (ii) determine relationships among kernel hardness and breakage susceptibility tests, yield and N and oil concentration. Three studies were conducted with a broad range of maize genotypes and N application rates of 0, 60, 120, and 180 kg ha(-1). Grain was harvested and yields corrected for water content, and grain was evaluated through a series of chemical and physical quality tests. Application of 180 kg ha(-1) N application increased grain yield by 747 to 1466 kg ha(-1), increased grain N concentration by 0.9 to 2.4 g kg(-1), and increased hardness to a lesser extent, while reducing breakage susceptibility by 1.9 to 6.9%. Genotype had a much larger influence on grain quality parameters than did N rate. The limited correlation between grain yield, grain N concentration, and grain oil concentration to kernel hardness suggests that development of further improved genotypes with high maize yields and excellent dry milling grain quality is feasible in Brazil. The large variation in grain yield and dry milling grain quality in intermediate kernel-type (semident, semiflint) genotypes used in Brazil presents short-term potential to select hybrids that produce both high yield and good dry milling grain quality.