ABSTRACT
Nano-priming with calcium silicate nanoparticles (CaSiO3NPs) promotes germination, seedling growth, and antioxidant enzyme activity in Iraqi rice genotypes under drought stress

Alwan Inas Jasim Alwan1, Rosimah Nulit1, 2*, Rusea Go1, and Mahmoud Hussein Hadwan3
 
Drought is a major abiotic stress limiting rice (Oryza sativa L.) cultivation in Iraq. This study aimed to enhance germination, early seedling growth, biochemicals, and antioxidant enzymes activity in Iraqi rice genotypes under drought stress through nano-priming with calcium silicate nanoparticles (CaSiO3NPs). Seeds of three rice genotypes: ‘Amber’, ‘Furat’, and ‘Yasmine’ were primed with CaSiO3NPs at 0.01%, 0.02%, 0.03%, and 0.05%, alongside a non-primed control. Results showed that primed seeds significantly improved, though differed among rice genotypes. ‘Furat’ showed the highest germination percentage (GP; 90%) and germination index (GI; 9.35 and 9.05) at 0.03%-0.05%, compared to control (GP 63.2% and GI 5.93). Shoot length increased in all genotypes, with ‘Furat’ showing more than a two-fold higher (8.78 cm and 9.08 cm) at 0.02%-0.03% compared to control (3.82 cm). ‘Yasmine’ showed the highest root length and seedling length at 0.02% (8.68 cm- four-fold that control 1.92 cm) and at 0.02% (18.79 cm vs. 11.24 cm in the control). Seed vigour was the highest in ‘Furat’ at 0.03%, showing 2.6-fold increase (12.0 vs. 4.6 in the control). Compared to control, total chlorophyll highest in ‘Yasmine’ (10.49 mg mL-1) at 0.03%, total sugar in ‘Furat’ (74.56 mg mL-1) at 0.05% showed more than one-fold higher while total protein three-fold higher in ‘Amber’ (21.36 mg g-1 fwt) at 0.03%. Catalase activity increased nearly two-fold in ‘Yasmine’ (0.42 U g-1 FW) at 0.03%. The ascorbate peroxidaseactivity increased in ‘Amber’ (0.32 U g-1 FW) and ‘Furat’ (0.34 U g-1 FW) at 0.01%. In conclusion, CaSiO3NPs nano-priming is a promising strategy to enhance rice cultivation in Iraq.
Keywords: Drought stress tolerance, early seedling growth traits, germination traits, Iraqi rice genotypes, 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)