In order to identify genetic and metabolic factors that regulate leaf senescence in response to whole plant development and N supply, chlorophyll content, root/shoot ratio, hormonal changes, anion levels, C/N ratio, transcriptomic and global metabolic rearrangements were analyzed in barley primary and 4th leaves at different nitrogen regimes. Moreover, phloem exudates of primary leaf were collected in EDTA solution and analyzed for sugar and amino acid levels to monitor export activity. The results showed that leaves undergoing senescence have a capacity to sense the availability of nitrogen and accordingly to modulate senescence progression and sustain barley plant growth. This is reflected by global hormonal (tZ and ABA), transcriptomic, and metabolic rearrangement in response to leaf development and N status. Especially, TCA cycle-components were affected under N deficiency condition. This metabolic rearrangement was also reflected by transcriptomic change. Such as, genes coding pyruvate kinase, pyruvate dehydrogenase, and pyruvate dikinase were regulated by senescence and N status.