Differential effect of the nitrogen form on the leaf gas exchange, amino acid composition, and antioxidant response of sweet pepper at elevated CO2
It is well known that NH4+ used as the sole N source is toxic, and that the degree of toxicity depends on environmental factors. However, far too little is known about the effect of the use of different NO3−/NH4+ ratios when the CO2 concentration [CO2] is high. Therefore, this work evaluates the extent to which the optimal form of the N-supply can increase growth at elevated CO2. Sweet pepper plants (Capsicum annuum L., cv. Melchor) were grown at ambient or elevated [CO2] (400 or 800 µmol mol−1) with a nutrient solution containing different NO3−/NH4+ ratios (concentration percentages of 100/0, 100/0 plus foliar urea (100/U), 90/10, 50/50, or 25/75). The results show that a low dose of NH4+ (90/10) in combination with the elevated [CO2] had beneficial effects on the plants. These plants had greater growth, root respiration rates, water-use efficiency, and chlorophyll fluorescence. Additionally, total phenolic compounds and ascorbate peroxidase activity were affected differentially, while the amino acid profile was also altered. This study reveals the strong interaction between the N form and the [CO2] in relation to the uptake of N, which requires further analysis to establish better nutritional strategies for the future.
KeywordsCapsicum annuum L. Climate change Foliar urea Ammonium Nitrate
M.C. Piñero is the recipient of a pre-doctoral fellowship from INIA. The authors thank Miguel Marín, for his technical assistance, and Dr. David J. Walker, for assistance with the correction of the English. This work was supported by the European Regional Development Fund (ERDF) 80%—Región de Murcia (FEDER 1420-07).
- Ariz I, Asensio AC, Zamarreno AM, García-Mina JM, Aparicio-Tejo P, Moran JF (2013) Changes in the C/N balance caused by increasing external ammonium concentrations are driven by carbon and energy availabilities during ammonium nutrition in pea plants: the key roles of asparagine synthetase and anaplerotic enzymes. Physiol Plant 148:522–537CrossRefPubMedGoogle Scholar
- del Amor FM, Gómez-López MD (2009) Agronomical response and water use efficiency of sweet pepper plants grown in different greenhouse substrates. Hortscience 44:810–814Google Scholar
- Hachiya T, Watanabe CK, Fujimoto M, Ishikawa T, Takahara K, Kawai-Yamada M, Uchimiya H, Uesono Y, Terashima I, Noguchi K (2012) Nitrate addition alleviates ammonium toxicity without lessening ammonium accumulation, organic acid depletion and inorganic cation depletion in Arabidopsis thaliana shoots. Plant Cell Physiol 53:577–591CrossRefPubMedGoogle Scholar
- IPCC (2014) Climate Change 2014: Synthesis Report. In: Core Writing Team, Pachauri RK, Meyer LA (eds) Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. IPCC, Geneva, Switzerland, p 151Google Scholar
- Kowalska I, Sady W (2012) Effect of nitrogen form, type of polyethylene film covering the tunnel and stage of fruit development on calcium content in sweet pepper fruits. Acta Sci Pol Hortorum Cultus 11:91–100Google Scholar
- Magalhaes JR, Wilcox GE (1983) Tomato growth, nitrogen fractions, and mineral-composition as influenced by nitrogen form and light-intensity. Hortscience 18:856–856Google Scholar
- Marschner H (2011) Marschner’s mineral nutrition of higher plants, 2nd edn. Academic Press, LondonGoogle Scholar
- Porra RJ, Thompson WA, Kriedemann PE (1989) Determination of accurate extinction coefficients and simultaneous equations for assaying chlorophylls a and b extracted with four different solvents: verification of the concentration of chlorophyll standards by atomic absorption spectroscopy. Biochim Biophys Acta 975:384–394CrossRefGoogle Scholar
- Salsac L, Chaillou S, Morotgaudry JF, Lesaint C (1987) Nitrate and ammonium nutrition in plants. Plant Physiol Biochem 25:805–812Google Scholar
- Stewart GR, Larher F (1980) Accumulation of acids and related compounds in relation to environmental stress. In: Miflin BJ (ed) Biochemistry of plants. A comprehensive treatise. Academic Press, New York, pp 609–635Google Scholar