Influence of Drought on Graminicide Phytotoxicity in Wild Oat (Avena fatua) Grown under Different Temperature and Humidity Conditions |
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Authors: | H S Xie A I Hsiao W A Quick |
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Institution: | (1) Agriculture and Agri-Food Canada, Research Station, Regina, SK S4P 3A2; and Department of Biology, University of Regina, Regina, SK S4S 0A2, Canada, CA |
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Abstract: | Controlled environmental experiments were carried out to determine the phytotoxicity of several graminicides on wild oat
(Avena futua L.) as influenced by combination of drought and temperature stress or drought and low relative humidity. Compared with unstressed
conditions (20/15°C plus adequate soil moisture), imazamethabenz phytotoxicity to wild oat was reduced significantly when
plants were exposed to a combination of drought and high temperature (30/20°C) stress. Imazamethabenz phytotoxicity was reduced
almost as much by high temperature stress alone as by a combined temperature and drought stress. When herbicides were applied
to wild oat plants subjected to drought alone or to drought plus high temperature, the observed reduction in phytotoxicity
from greatest to least was: fenoxaprop = diclofop > flamprop > imazamethabenz. Fenoxaprop performance was most inhibited by
the combination of drought plus high temperature, although drought alone and to a lesser degree, high temperature alone, inhibited
fenoxaprop action. High temperature had an adverse effect on the efficacy of fenoxaprop at lower application rates. Raising
fenoxaprop application rates to 400 g ha−1 overcame the inhibition caused by high temperature alone but only partially alleviated the effect of drought combined with
high temperature. When plants were grown under a low temperature regimen the imposition of drought stress had little effect
on imazamethabenz phytotoxicity but did reduce fenoxaprop phytotoxicity. At 25/15°C drought reduced the phytotoxicity of fenoxaprop
and diclofop greatly but had no significant impact on the performance of any of the herbicides examined, regardless of soil
moisture regimen.
Received April 14, 1997; accepted September 22, 1997 |
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Keywords: | , Diclofop—,Drought—,Fenoxaprop—,Flamprop—,Humidity—,Imazamethabenz—,Multiple stress—,Phytotoxicity—,Temperature—,Wild oat |
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