Báo cáo lâm nghiệp: " period of glyphosate treatment on oak seedlings: phenological and physiotogical aspects"

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Effects of theperiod of glyphosate treatment on oak seedlings: phenological and physiotogical aspects 2 Dizengremel 1 C. Fabert H. Frochot 1 P. 1 Station de Sylviculture, INRA-CRF, Champenoux, 54280 Seicham,os, and 2 Laboratoire de I, BP 239, 54506 Physiologie V6g6tale et Forestibre, Universit6 de Nancy Vandceuvre-les-Nancy, France Materials and Methods Introduction 1 yr old oak seedlings (Quercus petraea (M.) oak trees very sensitive to Young are grown on fertilized peat in Liebl.) were weed competition, especially brambles individual containers. Each treatment and (Rubus fruticosus L.). Bramble control is control consisted of 24 seedlings. essential during the first years of esta- Experiments were carried out in a climate of oak blishment regenerations. chamber simulating autumn and winter conditions during 8 periods of 14 d each. These Glyphosate (N phosphonomethylglycine) periods were characterized by ranges of enables good control when applied in medium (1, 5, f!), high (2, 4, 6) and low (3, 7) winter to green brambles (Frochot and temperatures (Fig. 1The seedlings were Wehrlen, 1983). accidental period of low subjected to an temperature indicated by an asterisk. The However, the tolerance of oak seedlings day-night regime was established as follows: 8 to the glyphosate treatments during the h d at a temperature equal to the maximum vegetative rest period was not clearly average temperature of the corresponding established. Previous studies demon- period (cf. Fig. 1). ). strated that glyphosate applied during the All seedlings were subjected to the same dormant period did not affect poplar climatic sequences (1-8). 8 groups of seedlings were subjected to a single herbicide application growth (Netzer and Hauser, 1983). Unfor- at 8 different periods, treatment Tn being tunately this herbicide sometimes causes applied in the middle of the period of injuries to oak seedlings. Young oaks were temperature n. Glyphosate 2160 g/ha (6 1/ha shown to be as equally affected by Roundup) in aqueous solution was applied with automatic sprayer. glyphosate applied at the beginning as at an the end of the rest period (Frochot et al., The height of main shoots was measured during the following July. Some enzyme 1981).). In this study, we analyzed the activities linked to carbohydrate breakdown effects of the period of herbicide appli- pathways were measured in leaves (nkat-mg- I cation on phenological and physiological protein) during the spring following the characteristics of oak seedlings. herbicide application: NAD-gal-3-PDH or NAD-
particularly marked in the first treatments gluyceraldehyde-3-phosphate dehydrogenase (cytosolic glycolysis) and NADP-gal-3-PDH or (T! and T and decreased from T to T28 . ) 2 NADP-glyceraldehyde-3-phosphate dehydro- Only a few alterations were still apparent genase (chloroplastic pathway) (Heber et al., in the last treatment (T ). 8 1963). Fumarase (Hatch, 1978) and NAD-malic (NAD-ME) (Grover et al., 1981; Gerant et al., 1989) were used as mitochondrial markers. A Enzyme activities in leaves pentose phosphate pathway enzyme (G-6-PDH or glucose-6-phosphate dehydrogenase) was also measured (Pitel and Cheliak, 1986). Decreases in the activities of NAD-ME, fumarase, NAD- and NADP-gal-3-PDH (Fig. 3), especially for the observed were spring treatments. In contrast, autumn and Results the G-6-PDH activity was strikingly stimu- lated by treatments T! and T The mag- . 2 Phenological effects nitude of the changes in enzyme activities marked for autumnal treatments was more than for winter treatments. All showed a significant treatments effect on shoot elongation as depressive compared to the control (Fig. 2). A maximum effect was observed for T! and Discussion T and later for T! and T 8’ Glyphosate , 2 caused symptoms of phytotoxicity, stretch- period of 6 mo separated the winter gly- ing and thickening of the leaves, and A shortening of the shoots. Damage was phosate treatments from the physiological
and carried out and later with application just before bud- phenological analyses after bud-break. These results show break. They indicate a possible seasonal clearly that effects of glyphosate were effect. However, the temperatures used never correlated with temperature. On the during the experiment did not take into other hand, maximum depressive effects account possible peaks of low tem- perature or moisture variations. appeared following application autumn
for6t pendant la saison froide. In: 12e A decrease in all enzyme activities en was Conference Columa, Unesco, Paris. 3, 345-352 commonly observed except for treatments T! and T when herbicide was applied in , 2 Frochot H., Pitsch M. & Wehrlen L. (1981) S61ectivitd du glyphosate en fonction de la dose autumn with normal and high tem- appliqu6e et du stade v6g6tatif des jeunes peratures. This corresponds to deep plants forestiers, r6sineux et feuillus. In: 11 e growth disturbances. The increases in G- Conf6rence Columa, ANPP, Paris. 2, 545-553 6-PDH activity observed in the first 2 Gerant D., Citerne A., Fabert C. & Dizengremel treatments might be linked to severe P. (1989) Extraction and study of enzymes stress, possibly revealing the synthesis of linked to malate metabolism in tree leaves. compounds linked to thick cellular growth, Ann. Sci. For. 46 suppl., 811 s-814s as has often been observed (Dizengremel Grover S.D., Canellas P.F. & Wedding R.T and Citerne, 1989; Koziol et al., 1988). (1981 ) Purification of NAD malic enzyme from potato and investigations of some physical and These preliminary results show that kinetic properties. Arch. Biochem. Biophys. 209, there is a cortical penetration of glypho- 396-407 sate during the cold season, particularly Hatch M.D. (1978) A simple spectrophotometric important at the end of the summer growth assay for fumarate hydratase in crude tissue period and just before bud-break. The extracts. Ann. Biochem. 85, 271-275 marked changes in enzyme activities re- Heber U., Pon N.G. & Heber M. (1963) veal a sensitivity of oak seedlings to Localization of carboxy dismutase and triose glyphosate, as shown clearly by shoot phosphate dehydrogenase in chloroplasts. growth reduction, mainly when the her- Plant Physiol. 38, 355-360 bicide was applied at the beginning of the Koziol M.J., Whatley F.R. & Sheivey J.D. (1988) autumnal period. An integrated view of the effects of gaseous air pollutants on plant carbohydrate metabolism. In: Air Pollution and Plant Metabolism. (Schulte- Hostede S., Darrall N.M., Blank L.W. & Wellburn A.R., eds.), Elsevier, London, pp. 148- References 168 Netzer D.A. & Hauser E.A. (1983) Controlling Dizengremel P. & Citerne A. (1988) Air pollutant weeds in poplar by dormant season glyphosate effects on mitochondria and respiration. In: Air overspray. North Central Weed Control Con- Pollution and Plant Metabolism. (Schulte- ference 38, 141-142 Hostede S., Derrall N.M., Blank L.W. & Wellburn A.R., eds.), Elsevier, London, pp. 169- Pitel J.A. & Cheliak W.M. (1986) Effectiveness 188 of protective agents for increasing activity of Frochot H. & Wehrlen L. (1983) Efficacit 6 five enzymes from vegetative tissues of white d’herbicides sur la ronce (Rubus fruticosus L.) spruce. Can. J. Bot. 64, 39-44