Growth and Physiological Responses of Miscanthus × Giganteus to Combined Salinity and Drought Stress

Abstract

Miscanthus × giganteus is a high-yielding, perennial C₄ grass recognized for its potential as a lignocellulosic biomass crop with a net-positive carbon footprint, ideal for sustainable bioenergy production. Its adaptability to grow on marginal lands, such as those in arid and semi-arid regions of Pakistan, highlights its potential to reduce pressure on fertile agricultural areas. However, salinity and water scarcity are major limiting factors in these environments. A three-month pot trial was conducted at MNS University of Agriculture, Multan, using a completely randomized factorial design with four replicates with the objective, to assess the effects of salinity and drought stress on Miscanthus growth, physiology and nutrient uptake. Treatments included two salinity levels i.e., 4 dS m⁻¹ (S1, moderate salinity) and 6 dS m⁻¹ (S2, high salinity), two irrigation regimes i.e., 100% field capacity (FC1) and 50% field capacity (FC2), and a non-saline control. Results showed that control plants under full irrigation (FC1) had significantly higher growth, biomass, photosynthetic traits, and nutrient uptake compared to stress treatments, with up to 65% higher biomass and substantially reduced electrolyte leakage. In contrast, plants under S2 with FC2 exhibited a 65% reduction in biomass. Nitrogen and phosphorus levels increased under moderate salinity (S1) with full irrigation (FC1), while potassium declined under all stress treatments. Overall, FC1 mitigated stress impacts significantly better than FC2. These findings suggest that Miscanthus can tolerate moderate salinity if sufficient water is available, making it a viable crop for saline-prone arid regions. Future studies should focus on long-term field evaluations and the development of effective management practices to enhance the resilience of Miscanthus × giganteus to salinity and drought stresses.