Increasing N uptake in elevated [CO2] conditions through manipulation of NO3:NH4 ratio in fertigated tomatoes

M. Halpern, U. Yermiyahu, A. Bar-Tal

Research output: Contribution to journalArticlepeer-review


Elevated [CO2] (e[CO2]) causes an increase in biomass but a decrease in plant N concentration, leading to increased N deficiency. While increasing N fertilization may ameliorate e[CO2] induced N deficiency (eCIND), it is not necessarily environmentally feasible. In this study, we examine whether manipulation of the NO3:NH4 ratio can ameliorate eCIND. Tomato plants were grown in greenhouse chambers with 2 levels of [CO2] (400, 850 ppm) and 4 levels of NO3:NH4 in the irrigation water (100:0, 67:33, 33:67, 0:100). Biomass and leaf N concentration were measured. Total leaf N uptake and nitrogen use efficiency (NUE) were calculated. We found that e[CO2] caused a decline in N concentration. In the low N concentrations used in this experiment, manipulating the NO3:NH4 ratio did not change the N concentration in the leaves nor did it ameliorate the negative effect of e[CO2] on leaf N concentration. However, treatments that included a mix of NO3 and NH4 lead to greater N uptake in both ambient [CO2] and in elevated [CO2], leaving open the possibility of using NO3:NH4 manipulation as a tool for ameliorating eCIND in future e[CO2] conditions, perhaps in higher N conditions.

Original languageEnglish
Pages (from-to)387-391
Number of pages5
JournalActa Horticulturae
StatePublished - 1 Jan 2022
Externally publishedYes


  • Carbon dioxide
  • NO:NH ratio
  • Nitrogen

ASJC Scopus subject areas

  • Horticulture


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