Tall wheatgrass response toward phosphorus deficiency: a constraint to its use as a forage resource in marginal soils

Abstract

Tall wheatgrass is cultivated for pasture in marginal areas around the world due to its tolerance to abiotic stress including seasonal droughts and floods, as well as saline and alkaline soils. However, there is concern about its biomass productivity, which often does not exceed that of natural pastures. In this work we hypothesize that tall wheatgrass is a plant more sensitive to low P availability than commonly assumed. A glasshouse sand culture experiment was conducted to analyze morpho-physiological responses of tall wheatgrass to different P availability levels: 1 µmol L⁻¹ phosphorus (severe deficiency, P1), 10 µmol L⁻¹ phosphorus (representative value of soil solution in the region, P10) and 500 µmol L⁻¹ phosphorus (full P supply, P500). Our results show that both limiting P conditions strongly decreased plant development and biomass accumulation, and altered above- and below-ground morphology, in comparison with P500 plants. The latter, in turn, had relative growth rate values comparable to those of other cultivated grasses under non-limiting conditions. In both P-deficient treatments, plant development was severely delayed starting from leaf number 3, even when P concentration in the pseudostem at early stages was similar or even higher than that of P500 plants. Our results suggest that developmental inhibition of tall wheatgrass at low P supply may be the consequence of a specific plant response to P concentration in soil solution, rather than to direct P starvation in plant tissues, and underlines the need of improvement of this species to enhance productivity in this environment.

Keywords:

• Abiotic stress
• phosphorus nutrition
• plant development
• root growth
• soluble carbohydrates
• tillers

Acknowledgements

We thank Drs S. Pellerin and L. Aguirrezábal for generously supplying the laboratory facilities. Dr M. Lorenzo is warmly acknowledged for his technical assistance and the quality of the data obtained.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Universidad Nacional de Mar del Plata (Projects 15/A548-AGR544/18 and 15/A600-AGR596/19) and Programa de Cooperación Argentino–Francesa de Formación para la Investigación Científica y Tecnológica MINCyT – Ecos (Project A06B01).