Author(s)

Prince Emmanuel Norman^1*, Lansana Kamara^1,2, Aloysius Beah³, Kelvin Sahr Gborie², Francess Sia Saquee^4,5, Sheku Alfred Kanu², Fayia Augustine Kassoh², Yvonne Sylvia Gloria Ethel Norman², Abdul Salaam Kargbo²

¹Sierra Leone Agricultural Research Institute (SLARI), Freetown, Sierra Leone.
²School of Agriculture, Njala University, Njala Campus, Njala, Sierra Leone.
³School of Natural Resources Management, Njala University, Njala Campus, Njala, Sierra Leone.
⁴Department of Agro Biotechnology, Institute of Agriculture, RUDN University, Moscow, Russia.
⁵Faculty of Development Agriculture & Natural Resources Management, Eastern Technical University of Sierra Leone, Kenema, Sierra Leone.

This study evaluated the genetic and agronomic parameter estimates of maize under different nitrogen rates. The trial was established at the Njala Agricultural Research Centre experimental site during 2021 and 2022 in a split block design with three maize varieties (IWCD2, 2009EVDT, and DMR-ESR-Yellow) and seven nitrogen (0, 30, 60, 90, 120, 150 and 180 kg∙N∙ha⁻¹) rates. Findings showed that cob diameter and anthesis silking time (ASI) had intermediate heritability, ASI had high genetic advance, ASI and grain yield had high genotypic coefficient of variation (GCV), while traits with high phenotypic coefficient of variation (PCV) were plant height, ASI, grain yield, number of kernel per cob, number of kernel rows, ear length, and ear height. The PCV values were higher than GCV, indicating the influence of the environment in the studied traits. Nitrogen rates and variety significantly (p < 0.05) influenced grain yield production. Mean grain yields and economic parameter estimates increased with increasing nitrogen rates, with the 30 and 180 kg∙N∙ha⁻¹ plots exhibiting the lowest and highest grain yields of 1238 kg∙ha⁻¹ and 2098 kg∙ha⁻¹, respectively. Variety and nitrogen effects on partial factor productivity (PFP_N), agronomic efficiency (AEN), net returns (NR), value cost ratio (VCR) and marginal return (MR) indicated that these parameters were significantly affected (p < 0.05) by these factors. The highest PFP_N (41.3 kg grain kg⁻¹∙N) and AEN (29.4 kg grain kg⁻¹∙N) were obtained in the 30 kg∙N∙ha⁻¹ plots, while the highest VCR (2.8) and MR (SLL 1.8 SLL⁻¹ spent on N) were obtained in the 180 kg∙N∙ha⁻¹. The significant influence of variety and nitrogen on traits suggests that increasing yields and maximizing profits require use of appropriate nitrogen fertilization and improved farming practices that could be exploited for increased productivity of maize.

Nitrogen Rates, Genetic and Agronomic Estimates, Introduced Genotypes, Grain Yield, Zea mays

Norman, P. , Kamara, L. , Beah, A. , Gborie, K. , Saquee, F. , Kanu, S. , Kassoh, F. , Norman, Y. and Kargbo, A. (2024) Genetic and Agronomic Parameter Estimates of Growth, Yield and Related Traits of Maize (Zea mays L.) under Different Rates of Nitrogen Fertilization. American Journal of Plant Sciences, 15, 274-291. doi: 10.4236/ajps.2024.154020.