Influence of glyphosate on leaf gas exchange and photosynthetic pigments of broomrape-infested tobacco plants

Mariyan Yanev and Shteliyana Kalinova

Abstract: Changes in the leaf gas exchange and photosynthetic pigments of Oriental tobacco plants, parasitized by Phelipanche ramosa L. and Phelipanche mutelii SCH, were determined after treatment with glyphosate. The study was carried out in two consecutive years. The plant samples were collected from the experimental field of the Institute of Tobacco and Tobacco Products in Markovo, Plovdiv region: leaves of untreated plants; leaves from the upper part of the plant, treated with 0.144 l/ha a.s. glyphosate; leaves from the lower part of the plant, treated with 0.144 l/ha a.s. glyphosate; leaves from the upper part of the plant, treated with 0.240 l/ha a.s. glyphosate; leaves from the lower part of the plant, treated with 0.240 l/ha a.s. glyphosate. It was found that the decrease in the rate of net photosynthesis in tobacco plants treated with glyphosate, was due to the decreased content of photosynthetic pigments. Under the conditions of the present study, the total content of chlorophyll A and chlorophyll B in the plants treated with 0.240 l/ha glyphosate was reduced from 16% to 18% compared to the untreated plants. The intensity of transpiration in tobacco plants was influenced more strongly by environmental conditions and less by the treatment with glyphosate. The differences in stomatal conductance values of untreated and glyphosate-treated tobacco leaves were small and did not show statistical significance.

Keywords: broomrape; gas exchange; glyphosate; leaf; photosynthetic pigments; tobacco

Date published: 2020-04-30