The 1981–2000 Studies of 13 C/ 12 C and 15 N/ 14 N Discrimination in the Metabolism of Higher Plants, and the Progress Since Then

Abstract

During 1981-2000, my research focused on the precise determination of the natural abundances of the 13 C/ 12 C and 15 N/ 14 N ratios (δ 13 C, δ 15 N) in many samples of plant tissues and metabolites. That research benefited from the previous work performed by pioneers in this field. My studies during that period provided the followings; (1) the identification of significant differences in the δ 13 C values in plant tissues and phloem sap affected by biotic (N acquisition, plant species and cultivars) and abiotic (drought) factors, (2) the discrimination of 15 N/ 14 N during the uptake, metabolism, and translocation of nitrate, ammonium and biologically-fixed N, and (3) the application of δ 13 C and δ 15 N tracing techniques for the quantification of plant residue dynamics (i.e., accumulation and degradation) in soils, plant N uptake from different sources (soils, chemical fertilizers , organic manures) and field biological N 2 fixation by legumes including trees and non-legumes such as sugarcane and sweet potato, respectively. Here I review my publications and findings which gave insight for a precise understanding of whole plant C/N metabolisms.