ABSTRACT
Enhancement of germination, early growth, biochemicals, and antioxidant enzymes in drought-sensitive Iraqi rice through seed nano-priming with SiO2 nanoparticles (SiO2NPs) under drought stress

Inas Jasim Alwan1, Rosimah Nulit1, 2*, Rusea Go1, and Mahmoud Hussein Hadwan3
 
Rice (Oryza sativa L.), a major staple providing nearly 20% of global dietary energy, is highly vulnerable to drought, threatening productivity and food security in Iraq. This study aims to evaluate seed nano-priming with SiO2NPs for improving germination, seedling growth, biochemical traits, and antioxidant activities in three drought-sensitive Iraqi rice genotypes, ‘Amber’, ‘Furat’, and ‘Yasmine’. The SiO2NPs was synthesized using sodium silicate and sulfuric acid methods and characterized by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction analyses. Seeds were primed with different SiO2NPs concentrations (2.5%, 3.0%, 3.5%, and 4.0%) for 8 h before being grown under drought condition in a completely randomized block design with five replicates. Germination traits of primed seed increased as germination percentage (100%) in all genotypes compared with 83.33% in unprimed. Shoot fresh weight increased up to 5-fold in ‘Amber’ (0.82 mg), while seedling dry weight increased up to 23-fold at 2.5% (0.21 mg). Shoot length increased 2-fold at 2.5%-3.0% (47.33 mg) compared to unprimed seeds (23.00 mg). Biochemical traits improved significantly (P < 0.05) particularly total sugar increased to 118.95 mg mL-1 in ‘Amber’ (4.0%) and 149.09 mg mL-1 in ‘Yasmine’ (3.0%); while malondialdehyde decreased with the highest (6.4-fold) in ‘Yasmine’ (59.82 µmol g-1 fwt) compared to unprimed (382.47 µmol g-1 fwt). Catalase activity increased nearly 4-fold (1.17 and 1.35 U g¹ fwt) in ‘Amber’ and ‘Yasmine’, respectively, while ascorbate peroxidase increased > 2-fold in both genotypes. As conclusion, SiO2NPs nano-priming demonstrating potential for sustainable rice production in drought-prone Iraq.
Key words: Antioxidant enzymes, drought tolerance indices, germination traits, Iraqi rice genotypes, nanoparticle solution (NPs), seed nano-priming.
1University Putra Malaysia, Faculty of Science, Department of Biology, 43400 Serdang, Selangor, Malaysia.
2University Putra Malaysia, Institute of Nanoscience and Nanotechnology, 43400 Serdang, Selangor, Malaysia.
3University of Babylon, College of Science, Department of Chemistry, Hilla 51002, Iraq.
*Corresponding author (rosimahn@upm.edu.my)
Received: 12 May 2026; Accepted: 7 September 2026, Available online: 29 October 2026.