Abstract

Poblano (Capsicum annuum var. annuum) and Chiltepin pepper (Capsicum annuumvar. glabriusculum) are considered closely related parent species. Poblano pepper is a cultivated species that has lost stress tolerance attributes, and Chiltepin is a wild species adapted to adverse environmental conditions, such as salinity stress. Differential physiological responses between the wild and cultivated species were compared in order to study the physiological and biochemical mechanisms of Chiltepin’s salinity tolerance. Salt stress treatments were applied to Chiltepin and Poblano and their growth, chlorophyll content, transpiration rate, and concentrations of anions and cations in leaves, stem and roots were measured. Dry weight and relative growth index decreased significantly with salt stress in Poblano, chlorophyll-a decreased significantly in both peppers and transpiration decreased in Chiltepin, with no significant changes evidenced by Poblano. Concentrations of Na⁺ and Cl^–increased in stems and roots, but K⁺ declined in stems for both peppers, evidencing changes proportionally associated to the salt treatments. The accumulation of Na⁺increased and the ratios K⁺/Na⁺, Ca²⁺/Na⁺, and Mg²⁺/Na⁺ decreased at all concentrations of NaCl. Sulfate, nitrate and phosphorus did not show significant differences in both species. We confirm that Chiltepin possessed salinity tolerance and also was physiologically more tolerant to salinity than Poblano.

Key words: Salt stress, Capsicum, physiological traits, ion uptake, peppers.