title: Water balance and N-metabolism in broccoli (Brassica oleracea L. var. Italica) plants depending on nitrogen source under salt stress and elevated CO2.
abstract: Elevated [CO2] and salinity in the soils are considered part of the effects of future environmental conditions in arid and semi-arid areas. While it is known that soil salinization decreases plant growth, an increased atmospheric [CO2] may ameliorate the negative effects of salt stress. However, there is a lack of information about the form in which inorganic nitrogen source may influence plant performance under both conditions. Single factor responses and the interactive effects of two [CO2] (380 and 800ppm), three different NO3(-)/NH4(+) ratios in the nutrient solution (100/0, 50/50 and 0/100, with a total N concentration of 3.5mM) and two NaCl concentrations (0 and 80mM) on growth, leaf gas exchange parameters in relation to root hydraulic conductance and N-assimilating enzymes of broccoli (Brassica oleracea L. var. Italica) plants were determined. The results showed that a reduced NO3(-) or co-provision of NO3(-) and NH4(+) could be an optimal source of inorganic N for broccoli plants. In addition, elevated [CO2] ameliorated the effect of salt exposure on the plant growth through an enhanced rate of photosynthesis, even at low N-concentration. However, NO3(-) or NO3(-)/NH4(+) co-provision display differential plant response to salt stress regarding water balance, which was associated to N metabolism. The results may contribute to our understanding of N-fertilization modes under increasing atmospheric [CO2] to cope with salt stress, where variations in N nutrition significantly influenced plant response.
authors.affiliation: Laboratoire Aridoculture et Cultures Oasiennes, Institut des Régions Arides, Route de Djerba Km 22.5, Médenine 4119, Tunisia.
authors.forename: Chokri
authors.initials: C
authors.lastname: Zaghdoud
authors.affiliation: Department of Plant Nutrition, Centro de Edafología y Biología Aplicada del Segura (CEBAS-CSIC), Campus de Espinardo, Edificio 25, E-Murcia, 30100, Spain.
authors.forename: Micaela
authors.initials: M
authors.lastname: Carvajal
authors.affiliation: Laboratoire Aridoculture et Cultures Oasiennes, Institut des Régions Arides, Route de Djerba Km 22.5, Médenine 4119, Tunisia.
authors.forename: Ali
authors.initials: A
authors.lastname: Ferchichi
authors.affiliation: Department of Plant Nutrition, Centro de Edafología y Biología Aplicada del Segura (CEBAS-CSIC), Campus de Espinardo, Edificio 25, E-Murcia, 30100, Spain. Electronic address: mballesta@cebas.csic.es.
authors.forename: María
authors.initials: M
authors.lastname: Del Carmen Martínez-Ballesta
mesh_terms: D001937:Brassica / Q000502:physiology*; D002245:Carbon Dioxide / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D054712:Salinity; D013312:Stress, Physiological; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water; D002245:Carbon Dioxide; D009584:Nitrogen
keywords: Abiotic stress; Ammonium assimilation; Brassica oleracea; N fertilization; Nitrate reduction; Water relations