Combinações de Nitrato e Amônio alteram a fotossíntese e crescimento de pimenta-de-cheiro

Abstract

Nitrate (NO₃⁻) and ammonium (NH₄⁺) are the main forms of nitrogen (N) absorbed and metabolized by plants. These forms directly influence metabolism, nutrient absorption, and plant growth. Thus, this study investigated the effect of different N-NO₃⁻/N-NH₄⁺ ratios on the nutritional, physiological, biochemical, and growth performance of two cultivars of sweet pepper (Capsicum chinense Jacq.). We used a completely randomized design with seven treatments (six ratios of NO₃⁻:NH₄⁺ and one control without N supply), totaling 56 experimental units. After 120 days, ratios of 60:40% and 80:20% favored photosynthesis, nitrate reductase activity, and the accumulation of macro- and micronutrients, especially in the roots and aerial parts of the De Cheiro cultivar. The Lupita cultivar showed greater sensitivity to high concentrations of NH₄⁺, with a reduction in chlorophyll fluorescence parameters and lower growth. The results indicate that the balance between NO₃⁻ and NH₄⁺ is essential to optimize the physiological and nutritional performance of the cultivars, with a ratio of 60:40% recommended for the De Cheiro cultivar and 80:20% for the Lupita cultivar.