Phytotoxic effects of invasive Ageratina adenophora on two native subtropical shrubs in Nepal

Tej Bahadur Darji,Seeta Pathak,Khadka Bahadur Pal,Barsha Adhikari,Ramesh Raj Pant,Gunanand Pant,Shristi Neupane,Kiran Bishwakarma,Lal B Thapa,Tara Datt Bhatt

doi:10.1038/s41598-021-92791-y

Abstract

The response of native plants to allelopathic interference of invasive species may differ from species to species. In this study, the phytotoxic effects of Ageratina adenophora were tested on two native shrubs (Osbeckia stellata and Elsholtzia blanda) of Nepal. Both the shrubs were grown in pots under treatments of A. adenophora fresh leaves and root leachates, and litter. Then, the seedling length and biomass were compared among the treatments. The results show that A. adenophora litter has stimulatory effects but the leachates from fresh leaves and root are phytotoxic to the growth and development of native shrubs. Infrared Spectroscopy (IR) analysis confirmed the presence of O–H (Hydroxyl), N–H (Amines), C≡C (Alkynes), and C–H stretching (Aromatic) or C–O–C stretching (Ethers) in the leachates representing harmful allelochemicals. The invaded soil by A. adenophora had low pH and a high amount of organic matter, total nitrogen, phosphorus, and potassium than the uninvaded soil. The results indicate that the native O. stellata and E. blanda are harmed by A. adenophora in nature by leaching of allelochemicals and probably by reducing the soil pH. Overall, this study has provided valuable insights regarding the effects of A. adenophora invasion on native shrubs and revealing the potential mechanism of its invasiveness.

Highlights

Shoots of both the native species E. blanda and O. stellata were longer in A. adenophora litter treatment compared to the control plants
Ageratina adenophora litter showed positive effects on E. blanda seedling growth. Both the shoots and roots of native E. blanda were longer in A. adenophora litter treated plants compared to the control plants (Fig. 1)
It confirms that A. adenophora may have a supportive role in the growth and development of native E. blanda

Summary

Introduction

It has threatened the biodiversity of native forests, rangelands, and farmlands[4] This weed has the capability to regenerate by vegetative methods and reproduce from its minute seeds which are produced in huge numbers. In Nepal, it is locally called ‘Kalo Banmara’ meaning the ’Forest Killer Plant’ having dark green leaves It has been spreading throughout the country from tropical regions to northern border crossing through the subtropical mountain region[7]. The functional group analysis is one of the most satisfactory and applicable methods of determining organic compounds which lends towards the identification of organic c ompounds[27] Such analyses have significance in understanding the chemical nature of invasive weed’s allelochemicals. Such phenomena cannot be predicted by simple field observations

Methods

Results

Conclusion