Piperidine alkaloids in nitrogen fertilized Pinus ponderosa

Citation
Ea. Gerson et Rg. Kelsey, Piperidine alkaloids in nitrogen fertilized Pinus ponderosa, J CHEM ECOL, 25(9), 1999, pp. 2027-2039
Citations number
39
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
JOURNAL OF CHEMICAL ECOLOGY
ISSN journal
0098-0331 → ACNP
Volume
25
Issue
9
Year of publication
1999
Pages
2027 - 2039
Database
ISI
SICI code
0098-0331(199909)25:9<2027:PAINFP>2.0.ZU;2-V
Abstract
We fertilized individual, pole-size ponderosa pine trees at two low-quality sites and pine saplings at a relatively high-quality site, with ammonium n itrate. Six to 12 months later, we measured total %N and 2,6-disubstituted piperidine alkaloids in the foliage. The N additions raised foliar %N above deficiency levels (i.e., from 1.0-1.1% to 1.4-1.6%) at the low-quality sir es, but did not elevate foliar %N in saplings at the higher quality site, w here it was already (1.9%) well above critical levels. In control trees wit h foliar N below a threshold of 1.1%, we detected no more than trace levels of alkaloids, indicating that alkaloid production is highly constrained by N deficiency. The N additions increased mean concentrations of the predomi nant alkaloid, pinidine, at all three sites. Mean total alkaloid concentrat ions for fertilized trees at the two low-quality sites were 12 and 155 mu g /g dry wt higher than controls (relative increases of 12x and 4.5x, respect ively). For saplings at the high-quality site, the mean total increased by 584 mu g/g dry wt (1.6x) with the N additions. Allocation of foliar N to al kaloids was highest in fertilized saplings (0.81%) compared to control sapl ings (0.53%). These findings demonstrate that foliar alkaloid concentration s can be increased by nitrogen fertilization of forest trees growing on bot h low- and high-quality sites. Fertilizing for the purpose of inhibiting po tential herbivores may be more successful at higher quality sites where alk aloid levels are enhanced relative to food quality (foliar %N).