Effect of nitrogen addition on the architecture and biomass allocation of two invasive plant species (Ageratum conyzoides L. and Parthenium hysterophorus L.)

The present study was conducted to explore the potential role of nitrogen deposition in the success of exotic species in terms of their change in architecture, biomass allocation and growth responses. Two invasive species prevalent in India (Ageratum conyzoides L. and Parthenium hysterophorus L.) were selected for this purpose. Seedlings were grown with and without application of N at the rate of 80 kg ha(-1). N enrichment increased relative growth rate and net assimilation rate by 66% and 36% respectively in P. hysterophorus and 101% and 20% in A. conyzoides over control. N treated A. conyzoides showed 4.3% and 28% increase while P. hysterophorus exhibited 6.7% and 159% increase in specific leaf area and plant height respectively over the control plants. Overall the increase in various parameters was more pronounced in P. hysterophorus than A. conyzoides except for relative growth rate.