High [CO2] and Temperature Increase Resistance to Cyhalofop-Butyl in Multiple-Resistant Echinochloa colona.

João Paulo Refatti,Edinalvo Rabaioli Camargo,Reiofeli Salas-Perez,Nilda Roma-Burgos,Lewis Hans Ziska,Claudia Oliveira,Luis Antonio De Avila,Christopher Edward Rouse

doi:10.3389/fpls.2019.00529

Abstract

Changes in the environment, specifically rising temperature and increasing atmospheric carbon dioxide concentration [CO2], can alter the growth and physiology of weedy plants. These changes could alter herbicide efficacy, crop-weed interaction, and weed management. The objectives of this research were to quantify the effects of increased atmospheric [CO2] and temperature on absorption, translocation and efficacy of cyhalofop-butyl on multiple-resistant (MR) and susceptible (S) Echinochloa colona genotypes. E. colona, or junglerice, is a troublesome weed in rice and in agronomic and horticultural crops worldwide. Cyhalofop-butyl is a grass herbicide that selectively controls Echinochloa spp. in rice. Maximum 14C-cyhalofop-butyl absorption occurred at 120 h after herbicide treatment (HAT) with >97% of cyhalofop-butyl retained in the treated leaf regardless of [CO2], temperature, or genotype. Neither temperature nor [CO2] affected herbicide absorption into the leaf. The translocation of herbicide was slightly reduced in the MR plants vs. S plants either under elevated [CO2] or high temperature. Although plants grown under high [CO2] or high temperature were taller than those in ambient conditions, neither high [CO2] nor high temperature reduced the herbicide efficacy on susceptible plants. However, herbicide efficacy was reduced on MR plants grown under high [CO2] or high temperature about 50% compared to MR plants at ambient conditions. High [CO2] and high temperature increased the resistance level of MR E. colona to cyhalofop-butyl. To mitigate rapid resistance evolution under a changing climate, weed management practitioners must implement measures to reduce the herbicide selection pressure. These measures include reduction of weed population size through reduction of the soil seedbank, ensuring complete control of current infestations with multiple herbicide modes of action in mixture and in sequence, augmenting herbicides with mechanical control where possible, rotation with weed-competitive crops, use of weed-competitive cultivars, use of weed-suppressive cover crops, and other practices recommended for integrated weed management.

Highlights

Climatic projections by the Intergovernmental Panel on Climate Change (IPCC) indicate an increase in global mean temperature (2.6–4.8◦C) and CO2 atmospheric concentration ([CO2]) (730– 1000 μmol·mol−1) by the end of the 21st century (Gianessi, 2013; IPCC, 2014; Varanasi et al, 2015)
The objective of the current research was to quantify the effects of increased atmospheric [CO2] and temperature on the absorption, translocation, and efficacy of cyhalofop-butyl on multipleresistant and susceptible E. colona genotypes under simulated climate change conditions
Three days before herbicide treatment (HAT), nitrogen fertilizer was applied at the recommended field use rate for irrigated rice

Summary

Introduction

Climatic projections by the Intergovernmental Panel on Climate Change (IPCC) indicate an increase in global mean temperature (2.6–4.8◦C) and CO2 atmospheric concentration ([CO2]) (730– 1000 μmol·mol−1) by the end of the 21st century (Gianessi, 2013; IPCC, 2014; Varanasi et al, 2015). The rapidity of these changes is likely to have consequences on a number of human activities, including agriculture. Yield losses due to weeds ranged from 10 to 83% in North America and averaged 51% in Eastern Canada between 2007 and 2013 (Soltani et al, 2016). Overall, increasing [CO2] and temperature may alter dominant weed species and increase weed problems (Ziska and Dukes, 2011)

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