少花蒺藜草异型种子对光照和水分条件的差异化适应策略研究OA

Seed heteromorphism is a critical adaptive strategy for invasive plants to cope with environmental het-erogeneity.To investigate the response mechanisms of heteromorphic seeds of Cenchrus spinifex,we examined germination characteristics of its two seed types(M-type:larger;P-type:smaller)under varying light(com-plete darkness vs.12 h light/12 h dark)and moisture conditions(simulated by PEG gradients).Subsequent seedling growth,biomass allocation,and phenotypic plasticity were analyzed in response to the interaction between water availability(normal,mild,and severe drought)and light intensity(high and low intensity).The results showed that germination was unaffected by light but strongly inhibited by water stress;under severe drought,M-type seeds outperformed P-types in root length,bud length,and biomass.As seedlings,M-type plants showed higher phenotypic plasticity in morphological traits(plant height,tiller number,leaf area),favor-ing increased aboveground resource investment for rapid life cycle completion,whereas P-type plants exhibited greater plasticity in biomass allocation,enhancing stress tolerance through increased root biomass proportion.In summary,the complementary germination and growth strategies of heteromorphic seeds in C.spinifex repre-sent an effective"bet-hedging"mechanism,which is crucial for its successful invasion and spread across envi-ronmentally stressful and variable habitats.