Functional, reproductive and biochemical traits of invasive Chromolaena odorata in dry and moist sites of Ramechhap district, Nepal

Chromolaena odorata (Siam weed) is the worst invasive weed spreading in tropical and subtropical regions of the Old World invading different habitats even in stressful environments. Specific mechanisms regarding how the weed has developed adaptive traits for growing in adverse ecological circumstances such as dry environment are less explored. This study has evaluated morphological, reproductive and biochemical traits of C. odorata in invaded dry and moist sites. Specific leaf area (SLA), reproductive traits (floral branches, capitula, and seeds) and biochemical traits (chlorophyll, carotenoid, proline, and leaf nitrogen) were measured by sampling plants from dry and moist sites from Ramechhap district, Nepal. Analyzing the results, the SLA was high but photosynthetic pigments and leaf nitrogen were reduced in the dry site. The weed had an increased number of mature capitula and seed mass against reduction in the number of floral branches in dry sites. Elevated concentration of the osmolyte ‘proline’ was found in the dry sites. Reducing the number of floral branches might help energy allocation to earlier maturation of capitula and increased seed mass at the dry site. The results will be useful to understand the adaptive biology of C. odorata and will also have significance in understanding their trait plasticity, which ultimately can be applied for predicting future invasions.