Germination Biology and Seedling Vigor of Cyperus difformis as Influenced by Light, Temperature, and Salinity Stress

Abstract

Cyperus difformis germination responses vary significantly under light, temperature and salinity gradients influencing seedling establishment in agro-ecosystems. Seeds were subjected to controlled laboratory assays evaluating germination percentage, mean germination time and seedling vigor index across varying photoperiods, thermal regimes and salinity concentrations. Maximum germination was recorded under alternating light conditions with moderate temperatures, while continuous darkness and extreme salinity significantly reduced germination potential and delayed emergence. Seedling vigor showed a positive correlation with optimal temperature ranges and low salinity stress, indicating sensitivity of early growth stages to environmental fluctuations. Statistical analysis revealed significant interaction effects among light, temperature and salinity treatments, highlighting their combined influence on germination ecology and establishment success. Findings emphasize the adaptive germination strategy of Cyperus difformis, supporting its persistence in rice-based and disturbed agricultural systems and informing integrated weed management approaches under changing climatic conditions. Light quality treatments including continuous light, red and far-red spectra further demonstrated differential germination responses, indicating phytochrome-mediated regulation of dormancy break. Salinity stress imposed through sodium chloride solutions progressively inhibited radicle elongation and reduced seedling dry biomass at higher concentrations. Temperature optima were identified between 25–30°C, beyond which germination rate declined sharply due to metabolic constraints. These physiological thresholds provide critical insights for predicting weed emergence patterns and improving timing of weed control interventions in cereal ecosystems. Overall, the species exhibits broad ecological plasticity enabling survival under variable field conditions, reinforcing its status as a problematic weed in irrigated and rainfed cropping systems supporting proactive integrated weed management strategies in sustainable agriculture.