Naphthalic anhydride decreases persistence of alachlor and atrazine and elevates tolerance of maize

Mamdouh M Nemat Alla,Nemat M Hassan

doi:10.1016/j.heliyon.2020.e05172

Abstract

The present study aimed at alleviating the impacts of alachlor (Ala) or atrazine (Atr) on maize growth by seed-dressing with naphthalic anhydride (NA, 0.4% w/w by seed weight). The dressed and undressed seeds were germinated for 10 days and treated with Ala or Atr at 3.2 or 1.8 kg ha−1, respectively, then the herbicide residues were determined in shoots one day after treatment. Atr residues were higher than Ala and remained in the same level for the 2nd day then retracted consistently up to 12 days. Meanwhile, GSH and GST were significantly induced while growth parameters were reduced; the effect of Atr was higher than Ala. Nonetheless, ABA, phenolics and anthocyanins as well as PAL, TAL and CI were increased but IAA was decreased coincidently with enhanced IAA-O and peroxidase. The immediate detection of the herbicide residues could conclude that growth reduction as elucidated from the decreased IAA concomitant with elevating ABA, phenolics and anthocyanin contents and enzyme activities are consequences of the herbicide persistence. The drop of IAA was preceded by the stimulation of IAA-O and peroxidase while the increased phenolics and anthocyanins followed PAL, TAL and CI stimulation confirming the regulatory roles of these enzymes. The application of NA greatly lowered the herbicide residues concurrently with ameliorations in growth parameters, GSH, GST, and maintained the balancing of secondary metabolites and plant growth regulators. Lowering Ala and Atr residues by NA in synchronization with enhanced GSH and GST could conclude that NA encouraged the detoxification of the herbicide. Moreover, the balances of IAA, ABA, phenolics and anthocyanins were mostly maintained in normal levels concomitantly with growth ameliorations suggesting that phytohormones and secondary metabolites are involved in the elevation of maize tolerance to Ala and Atr.

Highlights

Ala and Atr herbicides are widely used for the control of annual grasses and broadleaf weeds in maize fields
Residues of Ala and Atr herbicides were determined in shoots of 10day-old maize seedlings after one day of treatment up to the following 12 days
The persistence of Ala and Atr was highest during the first 2 days representing about 97 % on the 2nd day relative to values detected on the first day

Summary

Introduction

Ala and Atr herbicides are widely used for the control of annual grasses and broadleaf weeds in maize fields. Ala is an α-chloroacetanilide herbicide inhibits some metabolic processes during initial seed germination and further development such as protein synthesis (Sharp, 1988). Herbicides drastically influence all aspects of primary and secondary metabolism in crop plants when given to control weeds. A number of enzymatic systems are able to detoxify herbicides in plants. These include GST that adds the tripeptide GSH to herbicides and cytP450 that hydroxylates herbicides. Like other α-chloroacetanilide and S-triazine herbicides, Ala and Atr are mainly detoxified in higher plants by their conversion into GSH derivatives by the catalytic activity of GST. Zabalza et al (2007) detected that the enhancement of GSH in imazethapyr-treated pea roots can be related to the detected increase of glutathione reductase activity

Methods

Results

Conclusion