Integration of seed priming with nano-sized chitosan-proline and biochar application improves salt tolerance in differentially responding alfalfa genotypes

Safaa Mohammed Al-Farsi; Abdullah Al-Sadi; Aman Ullah; Abdul Rehman; Muhammad Farooq

Just Accepted

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Integration of seed priming with nano-sized chitosan-proline and biochar application improves salt tolerance in differentially responding alfalfa genotypes

Safaa Mohammed Al-Farsi, Abdullah Al-Sadi, Aman Ullah , Abdul Rehman , Muhammad Farooq

Abstract

Context: Salinity is one of the major abiotic stresses challenging alfalfa production. Aims: In this study, the potential of nano-sized chitosan-proline (NsCP) seed priming and biochar application in enhancing the salt tolerance in alfalfa (Medicago sativa L.) was evaluated. Methods: Seeds of two alfalfa genotypes OMA-84 (salt-sensitive) and OMA-285 (salt-tolerant) were soaked for 18 h in aerated distilled water (hydropriming) or a solution of NsCP (100 mM) for seed priming. Alfalfa seeds were planted in plastic pots containing acid-washed pure sand supplemented with or without biochar (25 g kg-1 sand) and with or without salt stress (120 mM). Key results: Both genotypes experienced significant reduction in root/shoot growth, biomass production and carbon assimilation under salinity stress, with more pronounced effects on OMA-84. However, applying both NsCP priming and biochar significantly improved the biomass production and plant photosynthetic assessment traits. Notably, this combined approach proved more effective in enhancing salt tolerance than individual treatments. Biochar amendment increased the Na+ and Cl- concentration but it also contributed to salt tolerance by elevating K+ level, promoting proline accumulation, and antioxidant activities. Conclusions: The NsCP priming enhanced the salinity stress tolerance in alfalfa genotypes by facilitating osmotic adjustment (proline accumulation), maintaining ionic homeostasis (higher K+ and lower Na+ concentration), and increasing the levels of α-tocopherol, flavonoids, and the activities of antioxidant enzymes. Implications: Integrated application of NsCP and biochar significantly enhanced salt tolerance in alfalfa, demonstrating practical strategies for sustainable agriculture in saline environments by promoting ionic homeostasis, osmotic adjustment, and antioxidant defense mechanisms.

CP24222 Accepted 16 January 2025