Growth and oxidative defense response to silicon application on rice (Oryza sativa L. ‘Sembada Merah’) under salinity stress

Abstract

Salinity stress inhibits plant growth because of the high dissolved salt content in the soil. Silicon (Si) is a beneficial nutrient that helps plants protect against biotic and abiotic stress. The purpose of this study was to determine growth and oxidative defense response to silicon application on rice (Oryza sativa L. ‘Sembada Merah’) under salinity stress. Research method used a completely randomized design with two factors, calcium silicate doses (0 mM, 2 mM, 4 mM) and salinity stress (0 dS/m: control, 3 dS/m: low, 7 dS/: moderate, 10 dS/:high). The growth parameters included plant height, number of leaves and tillers measured up to 6 weeks after treatment. Oxidative defense response was determined by measuring the activity of superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT). We also determined malondialdehyde (MDA) and proline levels. The result showed that high salinity 10 dS/m inhibited the growth of rice ‘Sembada Merah’ as indicated by decreasing of number of leaves and tillers compared to control. Salinity stress caused oxidative stress by increasing SOD. Application of exogenous Si increase growth on salinity stress of rice 'Sembada Merah' by reducing MDA. Summarized of this study, the control plants without Si application showed a decrease in the growth, while application exogenous Si doses 4 mM caused the plant to maintain growth in high salinity stress. Si application reduces the negative impact of salinity stress by increasing SOD and CAT activity and proline level.