Effects of drought stress induced by D-Mannitol on the germination and early seedling growth traits, physiological parameters and phytochemicals content of Tunisian squash (Cucurbita maxima Duch.) landraces

Wassim Saadaoui; Neji Tarchoun; Insaf Msetra; Ourania Pavli; Hanen Falleh; Chadha Ayed; Roua Amami; Riadh Ksouri; Spyridon A Petropoulos

doi:10.3389/fpls.2023.1215394

Effects of drought stress induced by D-Mannitol on the germination and early seedling growth traits, physiological parameters and phytochemicals content of Tunisian squash (Cucurbita maxima Duch.) landraces

Front Plant Sci. 2023 Jul 31:14:1215394. doi: 10.3389/fpls.2023.1215394. eCollection 2023.

Authors

Wassim Saadaoui¹, Neji Tarchoun¹, Insaf Msetra¹, Ourania Pavli², Hanen Falleh³, Chadha Ayed¹, Roua Amami¹, Riadh Ksouri³, Spyridon A Petropoulos⁴

Affiliations

¹ Research Laboratory LR21AGR05, High Agronomic Institute of ChottMariem, University of Sousse, Sousse, Tunisia.
² Laboratory of Genetics and Plant Breeding, Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Volos, Greece.
³ Laboratory of Aromatic and Medicinal Plant, Centre of Biotechnology of Borj Cedria, Tunis, Tunisia.
⁴ Laboratory of Vegetable Production, Department of Agriculture, Crop Production and Rural Environment, University of Thessaly, Volos, Greece.

Abstract

Introduction: Drought stress is one of the most devastating environmental stressors, especially in the arid and semi-arid regions of the world. Considering the major constraints that drought stress poses to crop production and the consequent yield losses in food crops, breeding for climate-resilient crops is an efficient means to mitigate stress conditions.

Materials and methods: This study aimed at evaluating the response of four squash (Cucurbita maxima Duchesne) landraces to drought stress at germination and at plant stage. Drought stress was induced by different concentrations of D-mannitol (-0.24, -0.47 and -0.73 MPa). The tested parameters at germination stage included germination percentage, seedling vigor index, seed water absorbance and seedling growth potential. At the plant stage, leaf chlorophyll and carotenoids content, chlorophyll fluorescence, evapotranspiration, photosynthesis activity and several biomarkers, namely malondialdehyde, proline, total phenols content, total flavonoids content and DPPH radical scavenging activity were evaluated in both roots and leaves.

Results and discussion: Our results indicate a magnitude of drought stress effects reflected via repression of germination and seedling growth as well as adjustments in physiological functions at later growth stages, in a genotype depended manner. Among landraces, "751" and "746" showed better performance, as evidenced by higher seed germination and seedling growth potential even at high stress levels (-0.47 and - 0.73 MPa), whereas "747" was the most sensitive landrace to drought stress at both tested stages. In conclusion, our findings highlight the importance of squash landraces selection for the identification of elite genotypes with increased tolerance to drought stress.

Keywords: Cucurbita maxima Duchesne; carotenoids; chlorophyll fluorescence; seed germination; seedling vigor; total phenols content; water stress.

Grants and funding

The project is funded by the General Secretariat for Research and Technology of the Ministry of Development and Investments under the PRIMA Programme. PRIMA is an Art.185 initiative supported and co-funded under Horizon 2020, the European Union’s Programme for Research and Innovation (Prima2019-08). This research was also jointly founded by Prima project and National research laboratory LR21AGR05.