Morphophysiological Characterisation of Guayule (Parthenium argentatum A. Gray) in Response to Increasing NaCl Concentrations: Phytomanagement and Phytodesalinisation in Arid and Semiarid Areas

Daniela Di Baccio; Aurora Lorenzi; Andrea Scartazza; Irene Rosellini; Elisabetta Franchi; Meri Barbafieri

doi:10.3390/plants13030378

Morphophysiological Characterisation of Guayule (Parthenium argentatum A. Gray) in Response to Increasing NaCl Concentrations: Phytomanagement and Phytodesalinisation in Arid and Semiarid Areas

Plants (Basel). 2024 Jan 27;13(3):378. doi: 10.3390/plants13030378.

Authors

Daniela Di Baccio¹, Aurora Lorenzi¹, Andrea Scartazza^{1

2}, Irene Rosellini¹, Elisabetta Franchi³, Meri Barbafieri^{1

2}

Affiliations

¹ Research Institute on Terrestrial Ecosystems, National Research Council of Italy (IRET-CNR), Via G. Moruzzi 1, 56124 Pisa, Italy.
² National Biodiversity Future Center (NBFC), Piazza Marina 61, 90133 Palermo, Italy.
³ Eni S.p.A., R&D Environmental & Biological Laboratories, Via Maritano 26, San Donato Milanese, 20097 Milan, Italy.

Abstract

Water and soil salinity continuously rises due to climate change and irrigation with reused waters. Guayule (Parthenium argentatum A. Gray) is a desert perennial shrub native to northern Mexico and the southwestern United States; it is known worldwide for rubber production and is suitable for cultivation in arid and semiarid regions, such as the Mediterranean. In the present study, we investigated the effects of high and increasing concentrations of sodium chloride (NaCl) on the growth and the morphophysiological and biochemical characteristics of guayule to evaluate its tolerance to salt stress and suitability in phytomanagement and, eventually, the phytodesalinisation of salt-affected areas. Guayule originates from desert areas, but has not been found in salt-affected soils; thus, here, we tested the potential tolerance to salinity of this species, identifying the toxicity threshold and its possible sodium (Na) accumulation capacity. In a hydroponic floating root system, guayule seedlings were subjected to salinity-tolerance tests using increasing NaCl concentrations (from 2.5 to 40 g L^-1 and from 43 to 684 mM). The first impairments in leaf morphophysiological traits appeared after adding 15 g L^-1 (257 mM) NaCl, but the plants survived up to the hypersaline conditions of 35-40 g L^-1 NaCl (about 600 mM). The distribution of major cell cations modulated the high Na content in the leaves, stems and roots; Na bioconcentration and translocation factors were close to one and greater than one, respectively. This is the first study on the morphophysiological and (bio)chemical response of guayule to different high and increasing levels of NaCl, showing the parameters and indices useful for identifying its salt tolerance threshold, adaptative mechanisms and reclamation potential in high-saline environments.

Keywords: biomass partitioning; chlorophyll fluorescence; growth analysis; mineral composition; photosynthetic pigments; phytodesalinisation; saline and hypersaline conditions; sodium chloride; sodium concentration factor; sodium translocation.

Grants and funding

The research was supported and fully funded by Eni S.p.A., contract CNR-ENI: “Salt tolerant plants for produced water management” (no. 3500047415, within the framework agreement no. 4400003660).