Nitrogen Use and Assimilate Partitioning Ability for Grain Yield in Some Selected Maize (Zea mays L.) Inbred Lines Genotypes

Breeding for high grain yield in maize under natural soil Nitrogen condition is of high importance to reduce the heavy usage of nitrogen base fertilizer to enhance productivity and encourage safety of the environment and consumer health. Nine maize inbred lines viz; 1393, KU1414, 5057, 5012, 9030, 9450, SW1, SW6 and SW4, were characterized in a field experiment under natural soil nitrogen 1.81 g/kg. Data were collected on plant growth parameters (plant height, number of leaves, leaf area and stem girth); phenology (percentage emergence, day to anthesis, day to silking and days to grain harvest); total nitrogen uptake and yield (plant wet weight, plant dry matter, cob weight and total seed weight). Parameters were paired and correlated to determine their relationships patterns. Positive relationships were obtained from all paired intra-parameter correlations from plant growth, phenology and yield, and from paired inter-parameter correlations between plant growth and yield. Negative relationships were obtained for paired inter-parameter correlations between phenology and growth and between phenology and yield. Total nitrogen uptake gave positive correlations with all parameters. Relative performance grouping analysis revealed that maize genotype 1393 had high n-uptake, high assimilate partitioning and high performance in Plant wet weight, cob weight and plant dry matter at grain harvest. KU1414, 5057 and 9030 had high n-uptake, low assimilate partitioning and low performance in plant wet weight, cob weight and plant dry matter at grain harvest . 5012 had low n-uptake, low partitioning and high performance. 9450 had low n-uptake, low assimilate partitioning and low performance; and SW1, SW6 and SW4 had low n-uptake, high assimilate partitioning and high performance. Hence, 5012 and SW genotypes expressed efficient Nitrogen-use for high grain yield and better growth and phenological performances.