Stem sinuosity in loblolly pine with nitrogen and calcium additions

► Stem sinuosity is a deformation that has been associated with nutritional and physiological disorders. ► Nitrogen additions caused significant increases in stem sinuosity. ► Calcium additions reduced stem sinuosity and mitigated the negative effect of N addition when it was applied with N. ► An appropriate nutrient balance is important for growth and acceptable stem form when managing pine species. Stem sinuosity is a deformation that occurs in loblolly pine ( Pinus taeda L.), and in many other pine species, that frequently affects the quality of the wood and hence, the final products. This deformation occurs mainly on the stem and has been associated with nutritional and physiological disorders. Nitrogen (N) and calcium (Ca) are two important elements affecting the formation, growth, membrane stability and maintenance of tree cell integrity. We hypothesized that high N and low Ca availability could be a cause for sinuous growth in young loblolly pine. A trial was established in the Coastal Plain of South Carolina using different loblolly pine genotypes to evaluate sinuosity when nitrogen fertilizer was applied with and without calcium additions. Eight genotype blocks were fertilized with N (224 kg ha −1) as (NH 4) 2SO 4 and Ca (168 kg ha −1) as CaSO 4. Nutrient concentrations from flushing shoot tissue were examined and then correlated with stem sinuosity. Nitrogen additions caused significant increases in both stem sinuosity and N concentrations. Calcium additions reduced stem sinuosity and mitigated the negative effect of N addition when it was applied with N. The magnitude of the effect of nutrient additions observed in the eight genotypes used, however, suggests that long-term trials composed of more genotypes need to be established in order to confirm the effect of Ca, N and genotype on stem sinuosity found on this study. Our findings infer that the appropriate nutrient balance and selection of genetic material are important to provide good growth and acceptable stem form when managing stands of loblolly pine.