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Interactive effects of CO2 concentration elevation and nitrogen fertilization on water and nitrogen use efficiency of tomato grown under reduced irrigation regimes

Wei, Zhenhua, Du, Taisheng, Li, Xiangnan, Fang, Liang, Liu, Fulai
Agricultural water management 2018 v.202 pp. 174-182
Solanum lycopersicum, biomass, carbon dioxide, fertilizer application, greenhouses, irrigation management, leaves, nitrogen, nitrogen content, nitrogen fertilizers, nutrient use efficiency, photosynthesis, root zone drying, stomatal conductance, tomatoes, water use efficiency
The interactive effects of CO2 concentration elevation, N fertilization, and reduced irrigation regimes on water and nitrogen use efficiency (WUE and NUE) of tomato (Solanum lycopersicum L.) plants at both leaf and whole plant scales were investigated in a split-root pot experiment. The plants were grown in two separate climate-controlled greenhouse cells at atmospheric [CO2] of 400 (a[CO2]) and 800 (e[CO2]) ppm, respectively. In each cell, plants were fertilized at either 1.5 or 3 g N per pot. The leaf physiological parameters, C and N content in stem, leaf and fruit were determined, and both WUE and NUE were evaluated. Plants harvested from 3 g N per pot associated with e[CO2] environment possessed the greatest photosynthetic rate (Pn) and lowest stomatal conductance (gs) and transpiration rate (Tr), resulting in the highest WUE at stomatal and leaf levels. Especially alternate partial root-zone irrigation (PRI) strategy coupled with e[CO2] had the potential to synergistically reduce gs and Tr while sustain Pn and leaf water status, and further improve tomato leaf WUE. e[CO2] combined with sufficient N fertilization enhanced the biomass, C accumulation and N uptake of plants under reduced irrigation; yet the WUE and NUE at whole plant scale were affected solely by the N supply being greater in low N fertilizer. These findings provide useful knowledge on efficient irrigation and N management for adapting to the future water-limited and CO2-enriched environment.