The Influence of Three Herbicides on the Sensitivity of Greenhouse-grown Flue-cured Tobacco (Nicotiana tabacum)Plants to Ozone

Abstract

TwoNicotiana tabacumL. cultivars, ‘North Carolina 88’ and ‘Coker 319′, were grown in a charcoal-filtered greenhouse and treated with three different herbicides according to the herbicide labels. Labeled rates (X) for diphenamid (N,N-dimethyl-2,2-diphenylacetamide), isopropalin (2,6-dinitro-N,N-dipropylcumidine), and pebulate (S-propyl butylethylthiocarbamate) were 9.2 kg/ha, 2.3 kg/ha, and 6.2 kg/ha, respectively. Three weeks after treatment with 1/2X, X, or 2X rates of herbicide, half of the plants were fumigated with 15 μl/liter ozone for 2.5 h for four consecutive days. North Carolina 88 and Coker 319 grew equally well and were equally sensitive to ozone injury. Ozone reduced plant height and levels of reducing sugars and total nonstructural carbohydrates of both cultivars. Isopropalin, at X and 2X, reduced the ozone sensitivity and growth of both cultivars, while the X rate of pebulate reduced the ozone sensitivity of North Carolina 88. The chemical composition of the plants was not correlated with the sensitivity of the tobacco plants to ozone-induced injury. The major factors governing fleck intensity, growth, and chemical compositions were ozone and herbicide treatments.

Ozone-Metolachlor Interactions on Corn (Zea mays), Bean (Phaseolus vulgaris), and Soybean (Glycine max)

“…Antagonistic interactions between metolachlor and O3 on bean and soybean are difficult to explain. Other investigators have reported that selected herbi cides can protect plants such as tobacco against O3 injury (14,18). However, the exact mechanism by which these herbicides neutralize the effects of 0 3 on tobacco and other plants is unknown.…”

“…For example, pebulate (5-propyl butylethylcarbamothioate) and chloramben (3-amino-2,5-dichlorobenzoic acid) can in teract synergistically with O3 on selected cultivars of tobacco (Nicotiana tabacum L.) (1). The herbicides benefin [N-butyl-N-ethyl-2,6-dinitro-4-(trifluoromethyl)benzenamine] and diphenamid (A^-dimethyl-a-phenyl benzeneacetamide) interacted antagonistically with O3 in selected tobacco cultivars (14,18).…”

Ozone-Herbicide Interactions on Sorghum (Sorghum bicolor) and Velvetleaf (Abutilon theophrasti) Seedlings

“…needles to 0 3 . has been reported to increase the activity of several enzymes involved in phenol metabolism such as phenylalanine-ammonia lyase and polyphenoloxidase (22). Ozone-injured plants and water-stressed plants possess several features in common (2), and stimulation of the activity of enzymes involved in hydrolysis and metabolic degradation has been reported to occur in plants exposed to moderate or severe water stress (24).…”

“…Ozone may interact with. selected herbicides on certain crop plants, thereby modifying either the plant response to herbicides (1,15,18,22) or the metabolism of herbicides in fumigated plants (5,6,7,8,9). For example, pebulate (S -propyl butylethylthiocarbamate), chloramben (3 -amino -2,5 -dichlorobenzoic acid), and metribuzin [4-amino-6-tertbutyl-3-(methylthio)-astriazin -5 (4H) -one] have been reported to interact synergistically with 0 3 on selected cul tivars of tobacco tNicotiana tabacum L.) and tomato (Lycopersicon esculentum Mill.…”

“…, and isopropalin (2,6 -dinitro -N, Ndipropylcumidine) were reported to interact antagonistically with 0 3 on selected tobacco cultivars (18,22). Preliminary studies by Hodgson (5) indicated that fumigation of intact corn (Zea mays L.) and sor-, ghum plants with 0 3 altered the metabolism of atrazine [2 -chloro-4-(ethylamino) -6 -(isopropylamino) -striazine] in those plants.…”