Thallium Differentially Affects Macronutrients Concentration and Stoichiometric Ratios with Nitrogen in the Leaves of Chili Pepper Varieties

This study aimed to assess the effects of thallium (Tl) on the leaf concentration of macronutrients (N, P, K, Ca, Mg, and S) and the stoichiometric relationships of P, K, Ca, Mg, and S with N in three varieties of chili pepper (Capsicum annuum): Jalapeño, Poblano, and Serrano. Sixty-day-old seedlings of the three varieties were treated with Tl, in doses of 0, 5.5, and 11 nM in the nutrient solution. After 80 days of exposure to Tl treatments, the nutrient concentration in leaf tissue was determined. With the data obtained, an analysis of variance and comparison of means with Tukey’s test ([Formula: see text]) were carried out, and through a meta-analysis, the size and direction of the effect of the evaluated Tl doses were determined, in the leaf concentrations of macronutrients. The 5.5 and 11 nM Tl doses increased the leaf concentration of P in Serrano and that of N in Poblano, respectively. Applying 5.5 nM Tl significantly reduced the leaf concentration of K in Jalapeño and Serrano, that of Ca in Poblano, and that of Mg in Serrano. In Jalapeño, both Tl doses tested reduced the leaf Ca concentration. Low Tl doses (5.5 nM) caused significant and positive effects on the leaf K concentration in all three varieties. High Tl doses (11 nM) caused significant negative effects on the leaf concentration of Mg. In the three varieties evaluated, the addition of Tl increased the leaf N:K ratio, that of N:Mg in Poblano and Serrano, the N:Mg ratio in Jalapeño, the P:K ratio in Serrano, and the N:Ca ratio in Jalapeño and Poblano. There was no effect of Tl on shoot dry biomass in any variety evaluated. In Tl-treated plants, foliar concentration of this element varied from12.0 to 26.6 mg kg⁻¹ on a dry basis. The sum of principal component 1 and principal component 2 represented 80.8, 72.3, and 79.6% of the total variance of macronutrient concentration in leaves of the Jalapeño, Poblano, and Serrano varieties, respectively. We conclude that Tl had differential effects on the nutrient status among varieties of chili pepper, with Jalapeño being the most affected and Poblano the least.