2,4-D Hormesis Effect on Soybean

J.R.O Silva,J.N.R Marques,C.V.C Godoy,C.P Ronchi,A.A Silva,L.B Batista

doi:10.1590/s0100-83582019370100146

J.R.O Silva, J.N.R Marques + Show 4 more

Open Access

https://doi.org/10.1590/s0100-83582019370100146

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Journal: Planta Daninha	Publication Date: Jan 1, 2019
Citations: 7	License type: CC BY 4.0

Affiliation: Universidade Federal de Viçosa

Abstract

ABSTRACT: The hormesis effect of 2,4-D, applied at two stages of soybean development, on the physiological components of crop yield, was investigated. Soybean seeds of the cultivar ‘AG 3680 IPRO’ were sown in pots containing 7 L of a substrate and kept in a greenhouse. A randomized complete block design with four replicates was used. Eighteen treatments were tested, arranged in a split-plot scheme. The plots consisted of two stages of herbicide application (V4 and V6), and the split-plots were arranged by nine 2,4-D doses (0, 5, 10, 15, 20, 25, 30, 40, and 50 g ha-1). At the time of harvest, 100 days after sowing, significant interactions between crop development stages and 2,4-D doses were observed for the number of nodes in the main stem (NNMS) and the number of pods per plant (NPP). Both NNMS and NPP were not affected by 2,4-D during V6, but they increased with doses up to 20.2 g ha-1 and 22.5 g ha-1, respectively, during V4 and declined at higher doses according to a quadratic model, thus characterizing hermetic effect. Regardless of the application stage, the number of grains per plant and weight of a thousand grains were reduced as doses increased. However, the grain number and grain mass per plant reached maximum values for doses of 20.3 g ha-1 and 12.9 g ha-1, respectively. It was concluded that 2,4-D causes hormesis effects on the soybean crop ‘AG 3680 IPRO’ pot-grown in greenhouse conditions, regardless of the application stages herein tested.

Highlights

Hormesis is the term used to designate the stimulus to the development of an organism generated by the application of small doses of molecules, which in normal doses would cause an inhibitory or lethal effect on these organisms (Calabrese and Baldwin, 2002)
The hormetic effect can be promoted by many substances, such as herbicides (Duke et al, 2006)
Herbicides have been used in agriculture since the middle of the last century (Cobb and Reade, 2010) to control weeds in agricultural and nonagricultural areas, in pre- or post-emergence applications, which can be selective to certain species of plants of human interest

Summary

Introduction

Hormesis is the term used to designate the stimulus (beneficial effect) to the development of an organism generated by the application of small doses (or sub-doses) of molecules, which in normal doses would cause an inhibitory or lethal effect on these organisms (Calabrese and Baldwin, 2002). This term, coined in 1942, is derived from the Greek word “hormo,” which means hormone, and was first used to describe the stimulus to fungal growth generated through application of a low concentration of antibiotics that in high concentrations suppressed the growth of fungi (Luckey, 1991; 2006). Some examples of herbicides that have shown hormetic effect are glyphosate and 2,4-D

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