Determination of the influence of herbicides on dicotyledons plant transpiration using the sap flow method

Abstract

Physiological parameters are sensitive and provide information on the toxicity of herbicides in plants. The impact of herbicide application on plant transpiration was evaluated by the sap flow method during 2009–2011. The aim of this work was to verify the sap flow method for determining the effect of herbicides on the basis of continuous measurements of the transpiration flow. Helianthus annuus was used as a model plant species. The two different herbicides tested in this study differed by the effect of active ingredients bromoxynil and clopyralid. The water flow was measured using sap flow meter T4.2. The impact of herbicides was assessed by comparing measured transpiration rate (Q) after herbicide application with an extrapolation of transpiration rate of plants before herbicide treatment (Q<sub>calc</sub>). After treatment with bromoxynil the Q values decreased significantly compared to Q<sub>calc</sub>. For plants treated by clopyralid, the decline of actual transpiration (Q) compared with the modelled one (Q<sub>calc</sub>) was less substantial and the plants continued to transpire after the treatment. The effect of herbicides was also verified using infrared gas analyser and chlorophyll fluorescence meter.

Sap Flow and Water Consumption of Captain Cook Tree [Cascabela thevetia (l.) Lippold].

“…Similar studies related to sap flow have been reported in the Northern hemisphere for unwanted shrub and tree vegetation (Randall 2013, Brant et al 2014, Ferrell et al 2015 [2,15,16]. Randall (2013) indicated that although 'Cut-stump, Girdle, Frill-Hack-n-Squirt, and Hatchet chemical injection treatment can be made any time of the year, application made during periods of heavy sap flow in spring may result in poor control of unwanted shrubs or trees.…”

“…Ferrell et al (2015) also showed that the efficacy of the Hack and Squirt herbicide application for woody plant control during spring, can be reduced because of heavy sap flow pushing the herbicide from the cut surfaces. In Europe, Brant et al (2014) clearly demonstrated the applicability of the sap flow method for determining the effects of herbicides on plant transpiration of sunflower (Helianthus annus) plants.…”

Physiological and leaf ultrastructural characteristics of perennial ryegrass (Lolium perenne L.) biotypes from Tunisia under sulfonylurea herbicide application

“…While the ACCase inhibitor herbicide (Pinoxaden) provided 100% control of the ryegrass, during a 4-season treatment period, when used at its labeled rate (Malekian et al, 2013). On the other hand, according to Brant et al (2014), the effectiveness of herbicides could be expressed in terms of P N E and gs. In this context, our gas exchange results show that both herbicides proportionally affected photosynthetic parameters in the Tinja and Mateur ryegrass biotypes.…”