Comparative Germination Ecology of Herbicide-Resistant and Susceptible Biotypes of Raphanus raphanistrum

Abstract

Herbicide resistance in weed species is often associated with ecological and physiological adaptations that may influence germination behavior and early seedling establishment. The present study investigated the comparative germination ecology of herbicide-resistant and susceptible biotypes of Raphanus raphanistrum under different environmental conditions. Germination experiments were conducted under controlled laboratory conditions to evaluate the effects of temperature, light regimes, and moisture availability on seed germination percentage, germination rate, and seedling vigor. The results demonstrated significant differences in germination responses between resistant and susceptible biotypes across the tested environmental gradients. The resistant biotype exhibited a broader germination tolerance range and maintained relatively higher germination rates under suboptimal temperature and moisture conditions compared to the susceptible biotype. In contrast, the susceptible biotype showed higher germination synchronization under favorable conditions but reduced performance under environmental stress. Light conditions also influenced germination behavior, with both biotypes responding differently to light and dark regimes, indicating variation in photoblastic sensitivity. Temperature significantly affected germination velocity and final germination percentage, with optimal germination observed within moderate temperature ranges for both biotypes. Moisture stress reduced germination in both groups, however, the resistant biotype showed greater resilience to water-limited conditions. These findings suggest that herbicide resistance may be associated with subtle shifts in germination ecology that could influence population dynamics and field emergence patterns. The study provides valuable insights into the ecological fitness of resistant weed biotypes and supports the development of integrated weed management strategies that consider both chemical resistance and ecological adaptability.