Ecophysiology of Striga hermonthica Seed Germination in Response to Strigolactone Analogs from Host Root Exudates

Abstract

Striga hermonthica is a highly destructive parasitic weed causing severe yield losses in cereal production systems across tropical and subtropical regions. Germination of S. hermonthica seeds is strongly dependent on chemical signals, particularly strigolactones released from host root exudates. The present study investigated the ecophysiological responses of S. hermonthica seed germination to different strigolactone analogs under controlled environmental conditions. Preconditioned seeds were exposed to synthetic and naturally derived strigolactone analogs at varying concentrations to evaluate their effects on germination percentage, germination rate, and early seedling development. Environmental factors including temperature, moisture, and light conditions were also examined to determine their influence on germination responses. The results demonstrated that strigolactone analogs significantly stimulated seed germination of S. hermonthica, with germination responses varying according to analog type and concentration. Certain analogs exhibited strong germination-inducing activity even at low concentrations, indicating high sensitivity of the parasitic seeds to host-derived chemical cues. Temperature and moisture conditions significantly influenced seed responsiveness, with optimal germination occurring under warm and adequately moist conditions favorable for host root activity. The interaction between environmental factors and chemical stimulants regulated dormancy release and germination behavior of the parasite seeds. Variability in germination response suggested ecological adaptation of S. hermonthica populations to different host environments and agroecological conditions. The findings improve understanding of host–parasite interactions and the physiological mechanisms regulating parasitic weed germination. This study provides valuable insights for the development of sustainable management strategies targeting germination processes through manipulation of strigolactone signaling and reduction of parasitic weed establishment in cereal-based cropping systems.