GROWTH AND DEVELOPMENT RESPONSE OF RICE PLANTS DURING THE NURSERY STAGE TO SALINITY AND PYRITE STRESS

Abstract

Salinity and heavy metal contamination, including pyrite, are environmental pressures that frequently limit plant growth. This study was designed to examine how salinity and pyrite, both individually and in combination, influence the early growth performance of rice seedlings. The experiment was arranged using a completely randomized design with two treatment factors. Salinity was applied at three concentrations: 0 mM (control), 50 mM, and 100 mM. Pyrite was also tested at three levels: 0 mg (control), 200 mg, and 400 mg. Each treatment combination was replicated four times, resulting in 36 experimental units. Every plot contained 25 plants, from which 10 plants were selected as samples for observation. In total, 900 plants were involved in the experiment. Growth observations included stem length, stem diameter, leaf length, chlorophyll content, root volume, fresh weight, dry weight, and leaf color. The results demonstrated that salinity imposed a stronger and more consistent negative effect on rice growth than pyrite. Increasing salinity concentrations led to marked reductions in stem length, leaf length, chlorophyll content, and total biomass accumulation. Although pyrite also suppressed growth, particularly by reducing stem length and fresh weight, its overall impact was less extensive than that of salinity. A significant interaction between salinity and pyrite was detected for fresh weight, indicating that the combined stresses altered plant growth responses beyond the effects observed under single-stress conditions. These findings suggest that salinity serves as the main limiting factor in the early growth phase of rice, while elevated levels of pyrite can aggravate growth suppression, especially under saline conditions.