Efficiency and Response to Nitrogen Use in Maize Genotypes for Silage Production in Tropical Climate

Aims: This study aimed to select efficient and responsive maize genotypes to the use of nitrogen for silage.

Study Design: The experimental design was randomized blocks in a 2 x 11 factorial scheme, the first factor being two nitrogen levels: 165 kg ha-1 of N and 15 kg ha-1 of N, and second factor eleven maize genotypes: BRS 3046, M 274, AG 8088PRO2, ANHEMBI, PR 27D28, AG 1051, P33-16, P33-11, P29-M12, P36-19, and P40-8.

Place and Duration of Study: The experiment was carried out in the 2017/18 harvest at Sítio Vitória (8º18'32" S, 50º36'58" W), located in the municipality of Santa Maria das Barreiras, southern region of Pará state, Brazil.

Methodology: Sowing fertilization was performed in the furrow with 300 kg ha-1 of NPK 5-25-15. Topdressing nitrogen fertilization was performed only at high N, having as source urea (45% N) at a dose of 150 kg ha-1 of N. Parceled in stages V4 and V8. The shoot fresh mass was evaluated at stages R4 and R5, with the cut performed 20 cm from the soil.

Results: The highest shoots fresh masses were obtained in treatments with high use of N, with a general mean of 628 g plant-1. The mean response of 1.87 g of plants per kg of N applied. Genotypes M 274, AG 8088PRO2, PR 27D28, AG 1051 and P 36-19 were efficient to use N. Genotypes AG 8088PRO2, PR 27D28, P29-M12, and P 36-19 were classified as responsive to N application.

Conclusion: Genotypes AG 8088PRO2, PR 27D28 and P36-19 were efficient in use and responsive to nitrogen application. And they are recommended for cultivation with low and high technological level.