Invasiveness of Alternanthera bettzickiana – Is Allelopathy a Factor?

Aims: The aim of the experiment was to investigate the allelopathic potential of Alternanthera bettzickiana (Regel) Voss.

Study Design: Experiment on effect of aqueous extract, incorporation and mulching of A. bettzickiana on crop seedling growth was carried out in completely randomized design with five treatments replicated five times. Varying concentrations and time of application of weed extract were also tried in an experiment laid out in factorial completely randomized design with a total of twenty treatment interactions replicated thrice.

Place and Duration of Study: Experiments were carried out at Kerala Agricultural University, Thrissur, during 2021- 2022.

Methodology: Rice and cowpea were used as test crops in all the experiments. A laboratory study was carried out with test crops sown in petri plates to assess the effect of aqueous extract of the weed at 0%, 2%, 4%, 6% and 8% concentration on germination of the crops. Effect of mulching and incorporation of A. bettzickiana at the rate of 0, 1, 2, 4 and 6 tonnes per hectare on crop growth was studied as pot culture experiments. To assess the influence of time of application of weed extract on seedling growth, extracts at various concentrations of 0%, 2%, 4%, 6% and 8% were applied at 0, 6, 15 and 21 days after sowing of test crops in trays.

Results: Only the treatment of 8% aqueous extract of weed caused a significant reduction in seedling vigour of cowpea, while rice was found to be unaffected. Incorporation and mulching of A. bettzickiana showed no significant effect on germination and growth of both the test crops. Time of application of weed extract at various concentrations also had no significant effect on seedling growth of both rice and cowpea

Conclusion: Alternanthera bettzickiana possessed no strong allelopathic potential as exhibited by other species of the genera like A. philoxeroides, A. sessilis etc.