EFFECTS OF NITROGEN FERTILIZATION AND STALK POSITION ON CHLOROPHYLL, CAROTENOIDS, AND CERTAIN LIPIDS OF THREE TOBACCO GENOTYPES

Abstract

Tobacco (Nicotiana tabacum L.) cv. Burley 21 and its breeding lines for low alkaloid, LA Burley 21, and low-polyphenol, LP Burley 21, were grown with rates of 112, 224, and 336 kg/ha of N fertilizer. Air-cured leaves from three stalk positions were analyzed for chlorophyll, carotenoid pigments, sterols, total and free fatty acids, and certain fatty acid esters. LA Burley 21 was highest in chlorophyll, carotenoids, and total sterols, while Burley 21 was lowest in chlorophyll and carotenoids and LP Burley 21 was lowest in sterols. The total fatty acid content was highest in LA Burley 21 and lowest in Burley 21. Palmitic acid was the major fatty acid of the free fatty acids and fatty acid ester groups. In general, N fertilization had only minor influences on the quantitative and qualitative composition of the lipid components. Stalk position, however, showed major effects. Crude lipid, chlorophyll, and carotenoids were higher in the top leaves than in bottom leaves. Total sterol content, however, was highest in bottom leaves, and free stigmasterol was the major component that accounted for this increase. The fatty acids in leaves from all stalk positions were similar from a quantitative and qualitative standpoint. A N fertilization × stalk position interaction was observed for total sterol and palmitic acid. Also, a genotype × stalk position interaction was found for contents of sterols, carotenoids, and chlorophyll.