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 drymilling 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

Physical-chemical characterization and wet milling yield of four maize hybrids

The influence of physical-chemical characteristics of maize grains and lactic acid concentrations on byproduct yields, generated by conventional wet milling, was studied during steeping, for four maize hybrids and two lactic acid concentrations (0.55 and 1.00%). For physical-chemical characterization, grain dimensions (length, thickness, and width) were determined, as well as mass of 100 grains, percentage of floating grains, volumetric mass, and centesimal composition. Statistical differences were found for percentage of floating grains (2.33 to 24.67%), volumetric mass (0.814 to 0.850 kg.L-1), mass of 100 grains (0.033 to 0.037 kg), water content (11.86 to 12.20%), proteins (8.21 to 9.06%), lipids (3.00 to 4.77%), and ashes (1.07 to 1.26%). There were no relationships of wet milling yields with maize appearance and physical-chemical characteristics. The addition of 1.00% lactic acid did not statistically improve byproduct yields; however, it favored separation of the grain components.Para verificar a influência da aparência e as características físico-químicas do grão de milho e da concentração de ácido lático durante a maceração nos rendimentos de subprodutos da moagem úmida convencional, quatro híbridos de milho foram caracterizados e macerados em duas concentrações de ácido lático (0,55% e 1,00%). Para a caracterização físico-química dos grãos, foram determinadas suas dimensões (comprimento, espessura e largura), massa de cem grãos, porcentagem de grãos boiantes, massa volumétrica e análise da composição centesimal. Diferenciaram-se estatisticamente entre os grãos a porcentagem de grãos boiantes (2,33% a 24,67%), massa volumétrica (0,810 kg L-1 a 0,850 kg L-1), massa de cem grãos (0,033 kg a 0,037 kg), teor de água (11,86% a 12,20%), proteínas (8,21% a 9,06%), lipídeos (3,00% a 4,77%) e cinzas (1,07% a 1,26%). Verificou-se que não há relação entre a aparência ou a composição química dos grãos com seus rendimentos de subprodutos na moagem úmida. A adição de 1,00% de ácido lático não proporcionou, estatisticamente, melhores rendimentos de subprodutos, entretanto facilitou a separação dos componentes do grão.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

FUM gene expression profile and fumonisin production by Fusarium verticillioides inoculated in Bt and non-Bt maize

This study aimed to determine the levels of fumonisins produced by F. verticillioides and FUM gene expression on Bt (Bacillus thuringiensis) and non-Bt maize, post harvest, during different periods of incubation. Transgenic hybrids 30F35 YG, 2B710 Hx and their isogenic (30F35 and 2B710) were collected from the field and a subset of 30 samples selected for the experiments. Maize samples were sterilized by gamma radiation at a dose of 20 kGy. Samples were then inoculated with Fusarium verticillioides and analysed under controlled conditions of temperature and relative humidity for fumonisin B1 and B2 (FB¬1 and FB2) production and FUM1, FUM3, FUM6, FUM7, FUM8, FUM13, FUM14, FUM15 and FUM19 expression. 2B710 Hx and 30F35 YG kernel samples were virtually intact when compared to the non-Bt hybrids that came from the field. Statistical analysis showed that FB¬1 production was significantly lower in 30F35 YG and 2B710 Hx than in the 30F35 and 2B710 hybrids (P 0.05). The kernel injuries observed in the non-Bt samples have possibly facilitated F. verticillioides penetration and promoted FB1 production under controlled conditions. FUM genes were expressed by F. verticillioides in all of the samples. However, there was indication of lower expression of a few FUM genes in the Bt hybrids; and a weak association between FB1 production and the relative expression of some of the FUM genes were observed in the 30F35 YG hybrid