Oil palm (

We compared four oil palm (Elaeis guineensis Jacq.) progenies’ morphological growth characteristics to reveal genotypic differences in plant growth and assess their adaptability in Nigeria’s environment in response to different levels of potassium chloride (KCl) and kieserite fertilizer applications. The studied progenies (C1, C2 and C3 of Deli × La Mé origin and C4 of Deli × Yangambi origin) represent a wide genetic diversity of oil palm and have shown among a population of 116 different progenies, a contrasting K and Mg leaflet concentrations that covered the extreme ranges of leaflet concentrations in these minerals. The trial consisted of a completely randomized split-plot factorial design with six replicates, where progenies, considered as sub-factor were treated with combinations of 3 levels of potassium chloride (0, 1.5, 3.0 kg of KCl palm−1 year−1) and kieserite (0, 0.75, 1.5 kg of MgSO4 palm−1 year−1) fertilizers (main factor), respectively. Growth characteristics differed significantly among progenies, but not in all studied years. In all progenies, KCl treatments significantly increased the average annual collar girth increment and projected canopy area. Adding 3.0 kg palm−1 year−1 of KCl significantly increased the total leaf area of progeny C4. Kieserite applications did not have an effect on progenies’ growth characteristics whereas potassium showed to be the main mineral needed for oil palm growth. It was shown that with equal amounts of fertilizers applied, progeny C3 had better morphological traits than the other progenies, suggesting that the effective nutrient requirements should be assessed for each individual progeny and that fertilization should be adapted accordingly