Nitrogen nutrition of hedged stock plants of Loblolly Pine. I. Tissue nitrogen concentrations and carbohydrate status

• Published in: New forests 2002-07, Vol.24 (1), p.39-51
• Main Authors: ROWE, D. Bradley, BLAZICH, Frank A, RAPER, C. David
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Carbohydrates; Evergreen trees; Fundamental and applied biological sciences. Psychology; Nitrogen; Pine trees; Softwoods; Spring; Summer; Tissue analysis; Trees; Winter
• ISSN: 0169-4286; 1573-5095
• DOI: 10.1023/A:1020551029894

Hedged stock plants of four full-sib families [27-2 × 27-5, 27-3× 27-1, 27-2 × 27-1, and 27-6 × 27-1 (designated B, G, R, andW)] of loblolly pine (Pinus taeda) were fertilized dailywith a complete nutrient solution containing N supplied fromNH^sub 4^NO^sub 3^ at either 10, 25, 40, 55, or 70mg·L^sup -1^. In May (spring softwood), July(summer softwood), and January (winter hardwood) terminal stem cuttings weretaken for tissue analysis and rooting studies. Averaged over families, meantissue concentrations of N were higher in spring (1.8%) and summer (1.7%) thanin winter (1.3%). Concentrations of N increased linearly with increasing levelsof applied N. Concentrations of total nonstructural carbohydrates (TNC) inwinter (32.8%) were twice those in spring (17.1%) or summer (16.3%), but wererelatively unaffected by N application. In contrast, starch concentrations weresignificantly higher during spring and summer than winter. The greatest numbersof orthotropic shoots ≥ 9 cm in length were produced for thespring, followed by summer, and then winter hedgings. Number of shoots producedper hedge increased with increasing applied N rates, and family B producedsignificantly more shoots than the other three families at all applied N levels.Genetic differences among families were evident as several interactions with Nrates were observed.[PUBLICATION ABSTRACT]