The Susceptibility of Pea (Pisum sativum L.) to Simulated Mesotrione Residues as Affected by Soil pH Manipulation

Ana Pintar,Ivan Magdić,Josip Lakić,Klara Barić,Dragojka Brzoja,Zlatko Svečnjak

doi:10.3390/agriculture11080688

Abstract

Variations in soil pH have been shown to affect mesotrione adsorption, which in turn, may have an impact on crop susceptibility. Therefore, a greenhouse experiment was conducted to evaluate the effect of simulated mesotrione residues on pea crop grown in the typical agricultural soil (gleysol) of north-western Croatia. The soil pH was manipulated to obtain neutral (pH 7.0) and acidic (pH 5.0) values. Simulated mesotrione residues were 1.1, 2.3, 4.5, 9.0, 18, 36 and 72 g a.i. ha−1. Crop visual injuries as well as reductions in chlorophyll fluorescence and aboveground dry biomass were higher at pH 7.0 than at pH 5.0. With increasing mesotrione residues, the reductions in chlorophyll fluorescence ranged from 38.8% to 89.7% at pH 5.0 and from 63.7% to 99.3% at pH 7.0. Compared to chlorophyll fluorescence, the reductions in dry biomass were smaller and ranged from 49.2% to 96.8% at pH 7.0 and from 32.0% to 82.6% at pH 5.0 for the mesotrione residues from 1.1 to 72 g a.i. ha−1. These results indicate that soil pH is an important factor determining the susceptibility of pea crop to simulated mesotrione residues.

Highlights

Mesotrione is a p-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting triketone herbicide commonly used for the control of broadleaf and grass weeds in corn pre- and post-emergence [1]
The reductions in dry biomass were smaller and ranged from 49.2% to 96.8% at pH 7.0 and from 32.0% to 82.6% at pH 5.0 for the mesotrione residues from 1.1 to 72 g a.i. ha−1. These results indicate that soil pH is an important factor determining the susceptibility of pea crop to simulated mesotrione residues
At 14 days after treatment (DAT), phytotoxic symptoms on pea were observed at the lowest level (1.1 g a.i. ha−1) of simulated mesotrione residues and it was 16.0% at pH 5.0 and 31.3% at pH 7.0 (Figure 1a)

Summary

Introduction

Mesotrione is a p-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting triketone herbicide commonly used for the control of broadleaf and grass weeds in corn pre- and post-emergence [1]. Mesotrione is characterized by favorable physicochemical properties and relatively short degradation time (DT50 = 4–44.3 days under standard laboratory conditions) [2] It is the third most commonly used herbicide in corn in Croatia [3]. Commercial fields previously treated with mesotrione may occasionally show symptoms of carryover injury This effect is most commonly observed in overlap areas and is characterized by bleaching of the plants followed by necrosis of the meristematic tissue [6,7]. In a similar field experiment, no phytotoxic effects were observed in barley, lettuce, pea, sugar beet, sunflower and wheat at mesotrione rates of 168 and 336 g a.i. ha−1 applied 12 months earlier [9]

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Conclusion