Silicon-Mediated Adjustments in C:N:P Ratios for Improved Beetroot Yield under Ammonium-Induced Stress

• Published in: Agronomy (Basel) Vol. 14; no. 6; p. 1104
• Main Authors: Olivera-Viciedo, Dilier, Salas Aguilar, Daimy, de Mello Prado, Renato, Peña Calzada, Kolima, Calero Hurtado, Alexander, de Cássia Piccolo, Marisa, Bomfim Soares, Mariana, Lizcano Toledo, Rodolfo, Alves, Guilherme Ribeiro, Ferreira, Daniele, Rodrigues, Rosane, de Moura Zanine, Anderson
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.06.2024
• Subjects: abiotic stress; Amino acids; Ammonium; ammonium toxicity; Beta vulgaris; C:N:P stoichiometry; Dry matter; Fertilizers; Flowers & plants; Hydroponics; Nitrogen; nutrient balance; Nutrients; Nutrition; plant growth; Shoots; Silicon; Stoichiometry; Sugar beets; Toxicity; Brazil; Germany
• ISSN: 2073-4395; 2073-4395
• DOI: 10.3390/agronomy14061104

Nitrogen (N) holds a prominent position in the metabolic system of plants, as it is a main constituent of amino acids, which are the basic building blocks of proteins and enzymes. Plants primarily absorb N in the form of ammonium (NH4+) and nitrate (NO3−). However, most plants exhibit severe toxicity symptoms when exposed to NH4+ as the sole N source. Addressing NH4+ stress requires effective strategies, and the use of silicon (Si) has shown promising results. However, there is a lack of underlying studies on the impact of NH4+ toxicity on C:N:P stoichiometric balance and the role of Si in these ratios. In this study, we explored the effects of varying NH4+ concentrations (1, 7.5, 15, 22.5, and 30 mmol L−1) on the C:N:P stoichiometry and yield of beetroot in hydroponic conditions. Additionally, we investigated whether the application of Si (2 mmol L−1) could mitigate the detrimental effects caused by toxic NH4+ levels. The experiment followed a randomized block design based on a 5 × 2 factorial scheme with four replicates. Results revealed that in the presence of Si, both [N] and [P] significantly increased in shoots and roots, peaking at 15 mmol L−1 of NH4+ in the nutrient solution. While shoot [C] remained stable, root [C] increased with NH4+ concentrations of 22.5 and 30 mmol L−1, respectively. Moreover, shoot and root [Si] increased with higher NH4+ levels in the nutrient solution. The findings underscored homeostatic instability under the highest NH4+ levels, particularly in plants cultivated without Si in the nutritive solution, leading to a reduction in both shoot and root dry matter production.