Morphophysiological and anatomical responses of rice to water deficit stress after silicon seed priming

Abstract

Importance of the work: Silicon acts as a priming agent that enhances plant tolerance
to water deficit stress.
Objective: To analyze the interactive effect of sodium metasilicate concentrations
and field capacity levels on the morphophysiological and anatomical responses of rice
(Oryza sativa L. ‘Inpari 24 Gabusan’) under drought stress.
Materials and Methods: A completely randomized design with three replications was
applied using four silicon priming concentrations (0, 20, 40, 60 mM) and three field
capacities (100%, 75%, 50%). Growth, pigment content, stress biomarkers and stomatal
characters were analyzed at 42 d after transplanting.
Results: Significant interaction effects were observed between silicon concentration
and field capacity for all measured parameters. The combination of 60 Mm Na2SiO3
and 100% or 75% field capacity enhanced plant height, root length, chlorophyll content
and membrane stability, while reducing malondialdehyde and proline accumulation.
In contrast, under 50% field capacity, the benefits of silicon were reduced but remained
superior to the untreated control. Stomatal density and aperture size peaked with
60 Mm Na2SiO3 at 100% field capacity, contributing to optimized water use and gas
exchange.
Main finding: Silicon priming at 60 Mm Na2SiO3 improved drought resistance in rice,
primarily through a synergistic effect with higher soil moisture levels. The results
from this study should provide valuable insights for developing rice varieties with
improved drought resistance.