Pengaruh Pemberian Silika terhadap Ekspresi Gen OsNHX1 pada Tanaman Padi (Oryza Sativa L.) Selama Fase Pemulihan dari Cekaman Salinitas

Abstract

This thesis examines the effect of silica application on OsNHX1 expression in rice plants (Oryza sativa L.) during the recovery phase from salinity stress. The study used three varieties, namely IR64 (sensitive), Pokkali (tolerant), and local swamp rice, with induction of 150 mM NaCl for 14 days followed by spraying of 1.5 mM silica Si(OH)₄ during the recovery period. The results showed that salinity stress inhibited physical growth (plant height and root length), reduced photosynthetic pigments, and increased oxidative stress as indicated by the accumulation of hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and electrolyte leakage. IR64 was the most susceptible variety, while Pokkali and local swamp rice showed higher levels of tolerance. The recovery phase using silica application provided a very significant improvement effect. Silica application was proven to improve morphological parameters, restore chlorophyll and carotenoid levels, and effectively reduce membrane tissue damage by lowering H₂O₂ and MDA levels. At the molecular level, silica application significantly increased OsNHX1 expression, which encodes a protein responsible for transporting toxic Na⁺ ions into the vacuole. The highest peak of gene induction was observed in the Pokkali variety, followed by local swamp rice, and the lowest in IR64. In conclusion, silica plays a crucial role in accelerating the overall recovery of rice growth through the enhancement of the Na⁺/H⁺ exchange pathway and the stability of cellular ion homeostasis.