Influence of Herbicides on Respiration of Young Pinus Seedlings

Abstract

FIELD and greenhouse studies with a number of herbicides have demonstrated various degrees of growth inhibition of young gymnosperm seedlings. The effects vary greatly with the chemicals and dosage used, species, age of plants, manner of herbicide application, and environmental conditions^1–4. Considerable work has been carried out on herbicidal influences on metabolism of herbaceous plants, but very little information is available for the responses of woody plants. Triazine herbicides are generally accepted as inhibitors of photosynthesis^5,6. Metabolism is probably altered by atrazine in red kidney bean⁷ and by simazine in barley roots⁸. The extensive literature on 2,4-D and 2,4,5-T shows that metabolism varies greatly with species, age of plant, and tissues tested^9–12. Ingle and Rogers¹³ have shown that dalapon may reduce phosphate uptake while it does not alter respiration materially. EPTC causes some increase in respiration of mung beans and corn embryos after relatively long exposure to the herbicide¹⁴. Experiments have now been extended to evaluate the short-time effects of the active and inert ingredients of commercial formulations of several herbicides on respiration of tissues of woody plants. Herbicides and corresponding commercial formulations were obtained as: 2,4-D (esteron 10-10), 2,4,5-T (esteron 2,4,5-OS), 2,4-DEP (falone 44-E), EPTC (‘Eptam 6 E’), CDEC (‘Vegadex’), CDAA (‘Randox’), simazine (simazine 50 W), atrazine (atrazine 50 W), ipazine (ipazine 25 E), prometone (prometone 25 E), dalapon (‘Dowpon’), and sesone (sesone).