Studies on the effect of herbicides on the physiology of Chenopodium album

Dunleavy, P.J., 1983. Studies on the effect of herbicides on the physiology of Chenopodium album. PhD, Nottingham Trent University.

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The physiology of Chenopodium album stomata in relation to bentazone application has been studied in whole plants and isolated epidermal peels. Porometry has demonstrated that when grown in a controlled environment stomata of this species display a marked circadian rhythm of opening and closure. Bentazone treatment causes appreciable stomatal closure and disruption of the rhythm more quickly after application at 0930 h, when stomata are wide open, than at 1230 h, when they are partially closed. This response is correlated with plant damage and C. album epidermal peel studies indicate that the stomatal closure is unlikely to result from photosynthetic inhibition.

Penetration of 14C-bentazone into intact C. album leaves is found to be very slow, particularly if applied when stomata are closed. However, incorporation of the oil adjuvant Actipron improves uptake under these conditions and overrides any time of day differences. Moreover, independent IRGA investigations show that photosynthesis and transpiration in this species are inhibited concurrently by bentazone and that maximum stomatal closure occurs in advance of complete inhibition of Co2 assimilation. Inclusion of Actipron reverses this response and it is suggested that the normally poor bentazone penetration may result in a major portion remaining on the leaf surface where significant photosynthetic inhibition may be caused by stomatal closure. Actipron may enhance bentazone movement to the mesophyll, thus by-passing any stomatal contribution to the herbicidal mode of action.

The mechanism of bentazone action on C. album stomata is shown by epidermal peel studies to be complex. Normal responses to potassium ions, ambient CO2 concentration and exogenous nucleotides are disrupted by the herbicide causing differential opening and closure. These effects are discussed in relation to those produced by other chemicals with stomatal activity and in the context of a potential anti-transpirant use for bentazone and its derivatives.

Item Type: Thesis
Creators: Dunleavy, P.J.
Date: 1983
ISBN: 9781369315998
Divisions: Schools > School of Science and Technology
Record created by: Linda Sullivan
Date Added: 24 Sep 2020 13:40
Last Modified: 16 Aug 2023 10:54

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