Variability in the production traits and nutritional efficiency of coffee cultivars when submitted to low soil nitrogen
Extensive use of nitrogen fertilizers in coffee crops increases production costs and environmental pollution. Developing cultivars more efficient in nitrogen (N) utilization could contribute to reduce the need for N fertilization and promote sustainable production. We evaluated the variation in production characteristics among 20 coffee cultivars grown in nutrient solution with low N concentration (1.0 mmol.L-1), aiming to identify combinations to compose future populations to be used in breeding programs and obtain cultivars more efficient in N utilization. Morpho-agronomic traits and rooting, absorption, translocation, biomass production, and N utilization efficiencies were evaluated. The clustering methods Unweighted Pair Group Method with Arithmetic Mean (UPGMA) and canonical variables were employed. Cultivars presented differentiated responses at low N concentrations, except for nitrogen absorption efficiency. The UPGMA and canonical variables methods presented similar results, forming five cultivar clusters. Total dry mass contributed the most in the total dissimilarity. Significant genetic variability was detected among coffee cultivars grown at low N availability. Hybrids generated from cultivars Icatu Precoce 3282, Icatu Vermelho IAC 4045, and Acaiá Cerrado MG 1474 were found to be the most promising to obtain a segregating population or heterotic hybrids, aiming at greater N utilization efficiency.