| Sumario: | Habanero pepper (Capsicum chinense Jacq.) is one of the most cultivated plants in the world. We evaluated the physiological and molecular behavior of three habanero pepper varieties seedlings, two from the Yucatan region (Mayan Ek and Mayan Chan) and one commercial variety (SEMINIS), subjected to 10 days of nitrogen (N) deficiency treatment. Growth parameters, N compounds, net nitrate absorption, and CcNRT2.1 (Capsicum chinense high affinity nitrate transporter) gene expression were evaluated at 0, 2, 6, 8 and 10 days of the treatment. Mayan Ek presented a higher total dry mass (0.266 ± 0.002 g) during treatment period, when compared to the other varieties (0.167 ± 0.002 g and 0.106 ± 0.001 g for Mayan Chan and SEMINIS, respectively). The N metabolite contents suggest that the adaptive mechanism in Mayan Ek involves a re-mobilization of N reserved when a deficit exists, mainly from root nitrate and amino acids from other parts of plant. Moreover, total amino acid content may be determinant in the final dry biomass for this species, regardless of variety and the degree of exposure to N (R2 = 0.89). Mayan Chan showed a higher high-affinity nitrate uptake when exposed to N deficit (8.22 ± 0.69 μmoles g-1 DW min-1); thereby, revealing a different adaptive mechanism. All varieties increased their transcript levels of CcNRT2.1 gene, but differed in their induction period. We identified significant morphological and molecular traits that may increase the productivity of habanero pepper growing on soils with restricted N phyto-availability.
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