Physiological responses of maize and sorghum to four different safeners for metazachlor

Abstract

The ability of the herbicide safeners. BAS-145138 (I "dichloroaL;etyl-hex.iihydrt)-3,3,8a-irimethylpyrrolo( 1.2a)pyrimidin-6(2/D-one), dichlormid (A'.N-dialIyl-2,2-diehloroacelamide), ilurazoie (phenylmethyl ester), and MG-191 (2-dichloromelhyl-2-metliyl-l.3-dioxolane) for preventing metazachlor Injury to maize (Zea mays L.) and sorghum (Sorghum hicotor L.) seedlings were compared with their effects on '""C-metazachlor metabolism lo a glutathione (GSH) conjugate, effects on non-protein thiol contents (mainly GSH) and effecls on giutathione .S-transferase (GST) activity in these two species.Sorghum shoot growth was redueed by 41'!';, and maize shoot growth was reduced by 54'' ;) by metazachlor concentrations in vermieulite nutrient culture of 0-6 fiM and 7-5 fiM, respectively. In this system, all four compounds had significant aetivity as safeners for metazachlor in both sorghum and maize seedlings. BAS-145138 and flurazole were the most effective saleners in maize and sorghum, respeetively. In the absence of safeners, the rate of non-enzymatic conjugation of nietazachlor and GSH was much greater than the enzymatic rate. However, the rate of t Correspondence: enzymatic conjugation of metazachlor with GSH was increased by safener treatment in both maize and sorghum. Safener effectiveness was highly correlated with Increases in ''*C-melazachlor uptake and metabolism in both species. Safener effectiveness was more highly correlated with safener effects on GST activity in maize or sorghum when '•'C-metazachlor was used as the substrate than when the non-specific CDNB (1ehloro-2.4-dinitrobenzene) was used as the substrate. Safener effectiveness was also strongly eorrelated with safener effects on GSH levels in sorghum, but not in maize, possibly because of the greater importance of non-enzymatic conjugation of metazaehlor with GSH in sorghum as compared to maize. Reponses physiologiques du mais et du sorgho a quatre phytoprotccteurs differents contre le metazachloreLa capacite des phytoproteeleurs. BAS-145138 (I-dichloro-acetyl-hexahydro-3,3,8a-trimethylpyrrolo (1.2a) pyrimidine 6 (2 H)-l); dichlormide (N, N-diallyl-2.2 dichloroaeetamide); flurazole (2-chloro-4-(trifluoromethyl)-5 thiazole-carboxylide aeide (phenyl methyl ester)); et MG 19 (2dichloromethyl-2-methyl-l,3-dioxlane); a proteger les plantules de ma'is (Zea mays L.) et de sorgho {Sorghum blcolor L.) contre les degats du metazachlor a ete mise en comparaison avec leurs effets sur le metabolisme du C-metazachlor pour seconjuguerauglutathion(GSH), les effets sur la teneur en thiol non prote'ique (principalement GSH) et les effets sur I'activitc de la glutathion-Stransferase chez ces deux especes (GST), La croissance des tiges de sorgho a etc rcduite de 41%. et eelie de eeile de mai's de 54' M) par des concentrations en metazachlore dans le milieu de eulture a base de vermieulite respectives de 0,6 /iM et 7,5 /iM. Dans ce systeme les quatre produits ont 182 Z. Ekler and G. R. Stephenson cu une activiie phytoprotectrice significative vis a vis du melazachlor a la...

Effects of herbicide mixtures on freshwater microalgae with the potential effect of a safener

“…2B). In this mixture, five other active compounds can form adducts with GSH (Ekler and Stephenson, 1989;Tal et al, 1993;Prade et al, 1998) and a loss of effect could also result of their conjugation to GSH through GSTs induction by BE.…”

Ultrastructural changes caused by metazachlor on maize seedling leaves and root cells

“…Metazachlor was also registered for use in maize in South Africa for some years. It is selective in maize when applied with a safener (Ekler & Stephenson, 1989). Lack of stable selectivity for maize led to the withdrawal of this herbicide from the South African market in 1999.…”

“…], sugarcane (Saccharum officinarum L.) and tobacco (Nicotiana tabacum L.). It is mainly used for the control of annual grass weeds and some broad leaf weeds (BASF, 1984;Ekler & Stephenson, 1989;Tomlin, 1994;Vermeulen et al, 1998). Metazachlor was also registered for use in maize in South Africa for some years.…”

Safeners Reduce Corn (Zea mays) Chloroacetanilide and Dicamba Injury Under Different Soil Temperatures

“…Several new dichloroacctamide safeners MON-13900, MON-4660, BAS-145138 {1-dichloroacetylhexahydro-3,3-8atrimcthyl-pyrrolo[ 1,2-a}pyrimidin-6-(2/1) -0 n e }, and CGA-154281 have recently been developed to increase corn tolerance to acetochlor, alachlor, 1l1ctolachlor, and mctazach 1or (2-chloro-N-(2,6-dimethylphcnyl)-N-( IHpyrazol-I-ylnlcthyl)acetamide), respectively. These~ichloroacetarnide safeners have demonstrated a potential for increasing corn tolerance to a variety of chloroacetanilides (4,5,16,20,25,26) as well as other hcrhicide chclnistrics (3). Although studies have shown that these safeners increase corn, but not sorghum (5,8), tolerance to chloroacetanilide herbicides, only a linlitcd alnount of work has been done to exallline their performance under conditions conducive to chloroacctanilide injury and in combination with other herbicides.…”

“…These~ichloroacetarnide safeners have demonstrated a potential for increasing corn tolerance to a variety of chloroacetanilides (4,5,16,20,25,26) as well as other hcrhicide chclnistrics (3). Although studies have shown that these safeners increase corn, but not sorghum (5,8), tolerance to chloroacetanilide herbicides, only a linlitcd alnount of work has been done to exallline their performance under conditions conducive to chloroacctanilide injury and in combination with other herbicides. Therefore, the objectives of these studies were to detertnine: whether MON-4660, CGA-154281, dichlornlid, and MON-13900 would increase alachlor, metolachlor, and acetochlor tolerance in corn grown at different soil temperatures~the effect of dicanlba.…”