Potencies of Justicia adhatoda L. for its possible phytotoxic activity

Md Sirajul Islam Khan,Noorjahan Begum,Marzia Habib,Md Abdul Hakim,Mohammed Ariful Islam,Md Tazul Islam Chowdhury,Rokeya Begum,Md Abdul Kaium,Bittam Kumar Sarkar

doi:10.14719/pst.2021.8.2.1044

Abstract

The phytotoxic effects of Justicia adhatoda L. were investigated on cauliflower, broccoli, tomato, foxtail millet and barnyard grass. The experiments were carried out under laboratory and in pot experiments. Six different aqueous methanol extract concentrations (control, 0.001, 0.003, 0.01, 0.03 and 0.1 g DW equivalent mL-1 extract) were tested in the laboratory and six aqueous extract concentrations (control, 1.0, 2.0, 3.0, 4.0 and 5.0 g DW mL-1 extract equivalent) were evaluated in the pot experiment. Results showed a reduction in germination and growth (shoot length, root length and biomass weight) at higher extract concentration compared to control. The leaf extracts from J. adhatoda showed that the foxtail millet and barnyard grass are germinating below 50 % both in the laboratory condition and in the pot experiment at their maximum concentration. When maximum extracts have been applied, we have found less than 0.5 cm of shoot and root of foxtail millet and barnyard grass. Maximum dry weight reduction was observed in foxtail millet and barnyard grass at the same concentration. The findings show that J. adhatoda may have phytotoxic potential and thus contains phytotoxins. Therefore, J. adhatoda can be used in sustainable crop production as a mulch or soil additive to suppress weeds.

Highlights

The favourable or deleterious biochemical relationship between plants and microorganisms is known as phytotoxicity or allelopathy
Wide range of variability on the percentage of germination of cauliflower, broccoli, tomato, foxtail millet and barnyard grass was found in the aqueous methanol and aqueous extracts of J. adhatoda leaves (Supplementary Fig. 1 & 2)
With 0.1 g dry weight (DW) extract ml-1, 30% of germination was seen in cauliflower and barnyard grass in the laboratory

Summary

Introduction

The favourable or deleterious biochemical relationship between plants and microorganisms is known as phytotoxicity or allelopathy. It implies any direct or indirect effect of one plant species on another plant species or micro-organism by producing secondary metabolites [1, 2]. The population of the world growing difficulties to improve the crop productivity. Weeds are the key obstacles to effective crop production. Weeds caused greater yield losses (about 34%) to pests [3, 4]. Farmers generally depend on synthetic herbicides for managing weeds in their crop areas. Synthetic herbicides often cause overwhelming adverse environmental and human health impacts [5]

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