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1.
A series of glasshouse experiments was conducted to evaluate the activity of fluazifop-butyl, butyl 2-[4-(5-trifluoromethyl-2-pyridyloxy)phenoxy] propionate, against Elymus repens. Foliar applications of doses 0·25–1·0 kg ha?1 consistently gave better control than did soil applications. The most obvious phytotoxic symptoms were chlorosis and necrosis, beginning with the youngest leaves 5–6 days after spraying, which spread to all leaves within 2 weeks. Translocation was measured by defoliating plants at different times after spraying and assessing regrowth and by evaluating rhizome-bud viability. At low doses (0·125 and 0·25 kg ha?1) translocation to rhizomes occurred mainly between 6 and 48 h. When fluazifop-butyl was sprayed at a dose range of 0·125–1·0 kg ha?1, at least 90% of the rhizome buds had accumulated a lethal dose within 72 h of spraying. In another experiment, with a dose of 0·25 kg ha?1, 31, 72 and 92% of rhizome buds were found to be non-viable when sampled 2, 24 and 48 h respectively after spraying. At 1·0 kg ha?1 all the buds had accumulated sufficient herbicide to prevent sprouting 48 h after spraying. 相似文献
2.
Examination of the fine structure of Rubus procerus leaves following application of 2.4.5-trichlorophenoxyacetic acid a field does shows that the chloroplast is a side of herbicide action and that by 1 week after spraying the leaves show changes indicative of accelerated senescence. Both aqueous and non-aqueous methods were used to isolate chloroplasts following treatment of leaves with radioactive 2.4.5-T. Chloroplast isolation using the non-aqueous method indicated an accmulation of radioactivity in that organelle. 相似文献
3.
The phytotoxicity of glyphosate(N-(phosphonomethyl glycine) to seedlings of white mustard (Sinapis alba) cultivated indoors was studied. Yellowing and wrinkling of leaves was observed, necrotic spots appeared and the elongation of the seedlings was significantly reduced at doses 0–49 kg ai/ha and above. Only when sprayed at 4–97 kg ai/ha was the effect of glyphosate 100% lethal (5–7 days after spraying) At the highest concentration of herbicide a marked decrease in chlorophyll content was found but with 0–49 kg ai/ha the chlorophyll content was found to be higher than that in the leaves of control plants. Two and fourteen days after spraying with glyphosate and the commercial product samples of leaf and stem were harvested for electron microscopy. Cellular defects in the leaves ranging from slight swelling to complete disruption of the chloroplasts were detected at the two highest herbicide doses 48 h after spraying. These defects were intensified with time und in addition other sub-morphological changes occurred: decrease in starch grain content, an increase in the number of dictyosomes and mitochondria, disruption of tonoplasts and increase of plastoglobuli In the more central parts of stem segments the commercial product resulted in greater cellular effects than did glyphosate. It is suggested that the differences may be due to the surfactant. 相似文献
4.
Fluazifop-butyl, haloxyfop and sethoxydim with adjuvant oil were applied for three successive growing seasons to established strawberries infested with Elymus repens. The weed was virtually eradicated by three applications of haloxyfop (0.8 kg a.e. ha?1) in successive years. A similar effect was given by five applications of haloxyfop (0.4 kg a.e. ha?1) and fluazifop-butyl (1.6 kg AI ha?1) in three growing seasons. Lower rates of haloxyfop and fluazifop-butyl, and a high rate of sethoxydim (1.6 kg AI ha?1) applied five times were less effective, the ground cover of E. repens shoots not being reduced by the end of the experiment although weight of living rhizome was only 10-30% of that on untreated plots. Fruit yields on treated plots generally reflected the level of E. repens control, but there was some evidence of crop phytotoxicity from herbicide treatments. During the experiment E. repens untreated plots increased from about 30-100% ground cover and reduced yield 13, 28 and 68% in successive years compared with weed-free plots. 相似文献
5.
Growth inhibition of pot-grown Elymus repens (L.) Gould by fluazifop-butyl was occasionally enhanced by pre-treatment with ethephon. Studies with 14C-labelled fluazifop-butyl showed that ethephon increased the accumulation of 14C in basal buds and proximal parts of the rhizome system. This potential modification in the distribution of fluazifop-butyl within E. repens rhizomes may have reduced regeneration and recovery of the E. repens, particularly from the basal buds, although there was no increase in the proportion of 14C translocated into the rhizome. Also, ethephon not only activated the sinks in the rhizome but in the foliage of E. repens as well, and could initiate buds without sinks. The effects of ethephon on fluazifop-butyl phototoxicity were irregular in their occurrence and degree, and possible reasons for this are discussed. Effets depré-traitements à I'étéphon sur la réponse de Elymus repens au fluazifop-butyl Lors d'expériences en pots, des pré-traitements & 1'étéphon augmentaient occasionnellement 1'inhibition de croissance d'Elymus repens (L.) Gould traité au fluazifop-butyl. Des etudes avec du fluazifop-butyl marqué au 14C ont montré que l'éléphon augmentait l'accumulation de 14Cdans les bourgeons de la base et dans les parties proximales des rhizomes. Bien que la proportion de 14C transportée dans le rhizome ne soit pas accrue, cette modification de la distribution du fluazifop-butyl à l'intérieur des rhizomes d'E. repens pourrait limiter la régénération et la reprise de croissance, en particulier à partir des bourgeons de la base. En outre, l'étéphon activait des puits métaboliques non seulement dans le rhizome mais aussi dans le feuillage d'E. repens et pouvait initier des bourgeons qui ne se comportaient pas comme des puits métaboliques. Tant 1'existence que 1'intensité des effets de 1'étéphon sur la phytotoxicité du fluazifop-butyl étaient irréguliers et les raisons possibles en sont discutées. Wirkung einer Vorbehandlung mit Ethephon auf die Reaktion von Elymus repens (L.) Gould auf Fluazifop-butyl In Gewächshausversuchen war die Wuchshem-mung von Elymus repens durch Fluazifop-butyl gelegentlich durch eine Vorbehandlung mil Ethephon verstärkt. Untersuchungen mil 14C-Fluazifop-butyl ergaben, daß Ethephon die Ak-kumulation von 14C in basalen Knospen und proximalen Teilen des Rhizoms förderte. Die so mögliche Veränderung der Verteilung von Fluazifop-butyl in den Quecke-Rhizomen kann zu der reduzierten Regeneration der Pflanzen geführt haben, vor allem aus den basalen Knospen, obwohl insgesamt keine groBere 14C-Menge im Rhizom gefunden wurde. Ethephon aktivierte nicht nur die Sinks im Rhizom, son-dern auch in den oberirdischen Teilen und kon-nte zur Ausbildung von Knospen ohne Sinks führen. Die Wirkungen des Ethephons auf die herbizide Wirkung des Fluazifop-butyls war unregelmaßig, und die moglichen Grunde dafiir werden diskutiert. 相似文献
6.
In this series of glasshouse experiments, several factors influencing the foliar activity of fluazifop-butyl, butyl-2-[4-(5-trifluoromethyl-2-pyridylox-y)phenoxy] propionate, against Elymus repens (L.) Gould (=Agropyron repens(L.) Beauv.) were investigated. The growth stage of the weed even up to about 16 weeks of age was not found to be a major factor affecting the performance, if a dose of 1.0 kg ai ha?1 is used. The activity of fluazifop-butyl was affected by low temperature, low humidity and water stress, all of which reduced the herbicide performance to varying extents. High post-treatment temperature or humidity favoured the activity of the herbicide, as measured from the regrowth ability of treated plants. Moderate water stress did not affect the activity significantly, but severe stress led to the plants becoming more tolerant of the herbicide. The effect of light/shade on foliar activity was not clear, bin showed a tendency of decreasing with increasing shade. Adverse effects of rain, probably due to wash-off of the retained spray droplets, reduced the performance of fluazifop-butyl, if rain fell within 6 h of spraying. Certains facteurs qui touchent à la performance du fluazifop-butyle contre Elymus repens (L.)Gould. (= Agropyron repens (L.) Beauv.) Cette expérimentation en serre a porté sur plusieurs facteurs qui influent sur l'activité foliaire du fluazifop-butyle, butyle-2–4-(5-trifluorométhyl-2-pyridyloxy)phénoxy proprionate, contre Elymus repens (L.) Gould (Agropyron repens (L.) Beauv.). Il en résulte que, même jusqu'à l'âge de 16 semaines, le stade végétal de l'adventice ne paraît pas jouer un rôle important dans la performance de l'herbicide à une dose de 1,0 kg ma ha?1. L'activité du fluazifop-butyle se trouve altérée en conséquence de température faibles, d'une faible humidité et de carence d'eau; tous ces facteurs ont amené une réduction plus ou moins grande dans la performance de l'herbicide. A en juger part la croissance nouvelle des plantes traitées, une température élevée, de même qu'une forte humidité suivant l'application, favorisent l'activité herbicide. La carence d'eau n'a exercé une influence significative sur l'activité herbicide que lorsqu'elle est devenue sévère; alors les plantes ont fait preuve d'une moindre tolérance. L'influence de la lumière sur l'activité foliaire est restée imprécise mais celle-ci a eu tendance à dimineur à mesure qu'augmentait l'ombre. Les effets néfastes de la pluie, grâce sans doute au lessivage des gouttelettes retenues sur les feuilles, ont diminué l'efficacité du fluazifop-butyle lors d'une précipitation moins de 6 heures après la pulvérisation. Einflüsse auf die Wirkung von Fluazifop-butyl auf Elymus repens (L.)Gould. (= Agropyron repens (L.) Beauv.) Verschiedene Einflüsse auf die Blattwirkung von Fluazifop-butyl Butyl-2-[4-(5-trifluormethyl-2-pyridiloxy)phenoxy]propionate auf die Gemeine Quecke wurden in einer Reihe von Versuchen im Gewächshaus untersucht. Das Entwicklungsstadium des Unkrauts war auch bei bis zu 16 Wochen alten Pflanzen ohne Einfluss auf die Wirkung, solange 1,0 kgAS ha?1 angewandt wurden. Niedrige Temperatur und Luftfeuchtigkeit sowie Wassermangel setzen die Wirkung des Herbizids, die am Wiederaustrieb gemessen wurde, herab. Hohe Temperatur und Luftfeuchtigkeit nach der Behandlung begünstigten die Wirkung. Schwacher Wassermangel beeinflusste die Wirkung nicht signifikant, aber bei starkem Wassermangel waren die Pflanzen widerstandsfähiger. Die Wirkung einer Beschattung der Pflanzen auf die Wirksamkeit des Herbizids war undeutlich, aber tendenziell zeigte sich eine Abnahme der Wirkung mit Zunahme der Beschattung. Regen innerhalb 6 Stunden nach der Behandlung verminderte die Wirkung von Ftuazifop-butyl, vermutlich wegen des Abwaschens des Spritzbelags von den Blättern. 相似文献
7.
D. COUPLAND 《Weed Research》1987,27(5):329-336
The performance of sethoxydim on Elymus repens (L.) Gould was studied under contrasting levels of humidity, light intensity, temperature, soil moisture and simulated rainfall using controlled environment chambers. Over a 24-h post-spraying period, increases in humidity and temperature markedly enhanced herbicide performance, while effects of light intensity were less pronounced. Soil moisture deficit significantly reduced herbicide performance, but there were no adverse effects of wet soil conditions (twice field capacity) on activity. The effects of simulated rain depended upon herbicide dosage, time interval between spraying and the onset of rain, and rain intensity. A low rain intensity of 0.5 mm h?1 did not reduce herbicide performance even when applied 10 min after spraying. The longer term studies, over 4 weeks, showed increases in herbicide activity with higher temperatures but lower light intensities. 相似文献
8.
Pre-harvest application of glyphosate in barley at 1·44 and 0·72 kg ha?1 was compared with post-harvest application at 1·44 kg ha?1 at six sites in south-east Scotland, three sprayed in 1980 and three in 1981. Both levels of pre-harvest application gave consistent 95–99% control of A. repens compared with 0–76% control from post-harvest application. Yields of crops grown in 1981 were significantly increased after all the 1980 pre-harvest treatments and after one post-harvest treatment. No significant depressions in grain germination were recorded from the lower rate of pre-harvest application but one significant depression was recorded from the higher rate. Combine harvesting throughput at a given grain loss level was significantly improved by pre-harvest application and moisture content of grain at harvest was significantly reduced by up to 2·5%. Wheeling losses from pre-harvest spraying ranged from 1 to 5%. Crop yield increases in the year after spraying compensated for herbicide and application costs plus any yield losses through tractor wheelings. 相似文献
9.
The effect of degree of water stress in Avena sativa on diclofop-methyl efficacy was assessed. Within 24 h of applying stress by adding mannitol to the root medium (0 to 12.5%), the rate of leaf extension of the youngest leaves (leaves 3 and 4) decreased with increasing mannitol concentration. Without water stress, application of diclofop-methyl had little effect on extension rate of leaves 3 and 4 during the first 4 days after spraying. Subsequently, it caused a significant decrease in the extension rate of leaf 4 with more pronounced effects on later leaves. Diclofop-methyl had little effect on leaf extension rate of plants given mannitol. Shoot dry weight at harvest for unsprayed plants decreased with increased mannitol concentration and for sprayed plants it was greater without mannitol than with mannitol (all levels). However, at mannitol concentrations greater than 4%, shoot dry weight for sprayed and unsprayed plants was not significantly different. Sprayed plants exposed to 2–8.5% mannitol produced seed heads but those at zero mannitol did not. When the root medium of all treatments was flushed of mannitol one week after spraying, then main-tained without mannitol, shoot dry weight at harvest for unsprayed plants decreased slightly with increased mannitol concentration applied initially. However, shoot dry weight for sprayed plants increased with increased mannitol concentration. Without mannitol two weeks after spraying, chlorophyll concentrations of leaves 3 and 4 were greater and water saturation deficit (WSD) values were lower for unsprayed plants than sprayed plants but there were no differences at 6.2% mannitol. It is proposed that tolerance to diclofop-methyl by A. sativa as a result of water stress, is primarily due to a decreased rate of leaf expansion resulting in lower demand for membrane synthesis and less strain on membranes damaged by the herbicide. 相似文献
10.
Andrea A. Zanini Liliana Di Feo Dario F. Luna Pablo Paccioretti Agostina Collavino Marianela S. Rodriguez 《Plant pathology》2021,70(1):195-205
Cassava common mosaic virus (CsCMV) is a potexvirus that causes systemic infections in cassava plants, leading to chlorotic mosaic and producing significant yield losses. To date, the physiological alterations and the mechanism underlying biotic stress during the cassava–CsCMV compatible interaction remains unknown. In this study, we found that CsCMV infection adversely modified chloroplast structure and had functional effects on chloroplasts in source leaves during the course of viral infection. Extrusion of the chloroplast membrane with amoeboid-shaped appearance and disorganized grana stacks were observed in infected mesophyll cells. These alterations were associated with up to 35% reduction of relative chlorophyll content, and a decline of CO2 fixation (13.5% and 24.2% at 90 and 210 days after planting, respectively). The effects of CsCMV infection on the performance index on absorption basis dropped up to 37%. The analysis of chlorophyll a fluorescence showed a progressive loss of both oxygen evolving complex activity and “connectivity” within the tripartite system (core antenna-LHCII-reaction centre). Here, we report the latter phenomenon for the first time in a viral infection. The oxidative stress process was observed in CsCMV-infected plants (20.8% reduction of antioxidant capacity with respect to noninfected plants). Other effects of the pathogen included reduction of starch and maltose content in source leaves, and a significant increase (24.7%) of the sucrose:starch ratio, which indicates an altered pattern of carbon allocation. Our results suggest that CsCMV induces chloroplast distortion associated with progressive chloroplast function loss and diversion of carbon flux in source leaf tissue, leading to the loss of cassava tuber yield. 相似文献
11.
Rapid chlorophyll fluorescence technique for the study of penetration of photosynthetically active herbicides into leaf tissue 总被引：2，自引：0，他引：2
A rapid and sensitive technique, involving analysis of chlorophyll a fluorescence induction kinetics, for the study of the penetration of photosynthetically active herbicides into leaves is described. A range of chlorophyll fluorescence parameters are examined for wheat leaves treated with diuron in order to determine the most appropriate parameter to use in herbicide penetration studies. The usefulness of the technique is demonstrated by examination of the effect of a range of commercially available additives on diuron penetration in wheat leaves. 相似文献
12.
D. COUPLAND 《Weed Research》1989,29(4):289-297
The performance of fluazifop-butyl against Elymus repens (L.) Gould was significantly influenced by the environmental conditions in which the plants had grown prior to treatment as follows: soil moisture deficit (greatest reduction of herbicide performance) > cool temperatures > low light intensity. The level of control under conditions in which none of these factors was reduced (so-called ‘standard’ conditions) was similar to that observed for‘low light’regime plants. Significant effects of environment on spray retention, foliar uptake and amounts of herbicide translocated to the roots and rhizomes were observed. The lowest rates of herbicide uptake were found with plants grown under cool conditions, the greatest amount of basipetal herbicide translocation being associated with low light intensities. Rates of herbicide de-esterification were much lower in plants grown under low light intensities, cool temperatures, or soil moisture deficits than in those plants grown under the ‘standard’ conditions. This result was confirmed by studies of herbicide deesterification using cell-free leaf homogenates. 相似文献
13.
A concentration of atrazine of 0?1 mm 1?1 in the nutrient solution resulted in complete inhibition of photosynthesis in intact leaves of susceptible biotypes of Amaranthus retroflexus L., Polygonum lapathifolium L., Chenopodium album L., Solanum nigrum L., Poa annua L. and Stellaria media (L.) Vill. within a few hours of treatment, whereas the inhibition of the resistant biotypes by the same concentration varied from small to moderate. In contrast, diuron (10 or 20 μm 1?1) produced only minor differences between resistant and susceptible biotypes. The influence of some other herbicides on photosynthesis of these resistant biotypes was also smaller than that on the susceptible biotypes. This cross-resistance was evaluated with the resistance factor for intact leaves of Brassica napus L., A. retroflexus, and S. nigrum. This factor is equal to the ratio of the herbicide concentration in leaves of the resistant biotype to that in leaves of the susceptible biotype with inhibition to half-maximum rate of photosynthesis. This concentration in the leaves was calculated from the concentration in the nutrient solution, and the total transpiration divided by leaf area from the beginning of the herbicide treatment until the moment of half-maximum of photosynthesis. The resistance factors for intact leaves of A. retroflexus, S. nigrum and B. napus were 26–30 for atraton, 3–7 for metamitron, 2–9 for bromacil, 3–5 for monolinuron, 1 for diuron and < 1 for bentazone. For isolated chloroplasts much higher values have been reported. The reason for this discrepancy is not clear. A somewhat higher resistance factor (around 50–60) was derived after infiltration of detached leaves of these species with atraton solutions. 相似文献
14.
The imposition of water stress before or al the time of spraying diclofop-methyl reduced efficacy against wild oat (Avena fatua L.). Similar reductions in herbicide performance were obtained by application of 20 μg of the methyl ester of abscisic acid (ABA) to plants with three to four leaves before spraying with I kg ha?1 diclofop-methyl. Application of 40–100 μg ABA per plant effectively protected plants against damage from diclofop-methyl applied at 1 5–2 0 kg ha ?1. The application of 20 μg ABA induced rapid stomatal closure and a reduction in leaf extension rate, which were sustained for 7–8 days after treatment. These changes were associated with an overall reduction in shoot growth. ABA-treated plants that were additionally sprayed with diclofop-methyl sustained ABA symptoms, but no additional weight loss or leaf chlorosis. The mechanism of the protective action of ABA on diclofop-methyl has not been determined. 相似文献
15.
Herbicide pyrazolate causes cessation of carotenoids synthesis in early watergrass by inhibiting 4-hydroxyphenylpyruvate dioxygenase 总被引：1，自引：0，他引：1
HIROSHI MATSUMOTO MORIHIRO MIZUTANI TAKAHIRO YAMAGUCHI JUNJI KADOTANI 《Weed Biology and Management》2002,2(1):39-45
In aqueous solution, the herbicide pyrazolate [4‐(2,4‐dichlorobenzoyl)‐1,3‐dimethyl‐5‐pyrazolyl p‐toluenesulfonate] is rapidly hydrolyzed to destosyl pyrazolate (DTP), 4‐(2,4‐dichlorobenzoyl)‐1,3‐dimethyl‐5‐hydroxypyrazole, which is an active form of the herbicide. The objective of this study was to examine the effect of pyrazolate and DTP on carotenoids synthesis in susceptible weed, early watergrass (Echinochloa oryzicola Vasing.). Furthermore, their in vitro effect on 4‐hydroxyphenylpyruvate dioxygenase (HPPD) was determined. Roots of the plants at the two‐leaf stage were soaked for 24 h into pyrazolate (5 × 10–5 mol L?1) or norflurazon (10–6 mol L?1) solution containing 0.5% volume of acetone. At the first sampling time (3 days after treatment: 3 DAT), the chlorophyll content in the third leaves of pyrazolate‐treated plants were not different compared with the untreated control, but it was decreased between 3 and 6 DAT. The declining pattern of β‐carotene in the third leaf of early watergrass was very similar to that of chlorophyll. Both herbicides induced greater accumulation of phytoene in the third leaves of early watergrass 3 DAT, and the levels were kept until 9 DAT. However, feeding of homogentisate reduced the phytoene accumulation only in pyrazolate‐treated plants, suggesting the site of action of the herbicide located in the pathway of plastoquinone synthesis. In a HPPD assay, DTP revealed to inhibit the enzyme with an IC50 value of 13 nmol L?1 and that of pyrazolate was 52 nmol L?1. In the pyrazolate solution used in the assay, some of the herbicide possibly has been hydrolyzed to DTP. From the all results obtained, it is strongly suggested that pyrazolate inhibits carotenoids synthesis and causes bleaching on the developing leaves by the similar mechanism with norflurazon, but its action site is not phytoene desaturase and is HPPD. 相似文献
16.
Wild oat (Avena fatua L.) plants sprayed at the 2-or 3-leaf stages of growth with diclotop-methyl developed chlorosis over the entire leaf blade of all leaves. The leaves became necfrotic 7days after spraying Shool growth was inhibited. In wheat (Triticum aesicum L cv.Waldron) discrete chlorotic areas developed only where the herbicide convicted the 2nd or 3rd leaf with no visible injury so new growth uf'ter treutment. Growth inhibition of susceptible oat (Avena sativa L. cv. Garry) was sensitive to placement of diclutop-methyl near the upica and meristematic sites of the plant. Chlorosis and necrosis were independent of herbicide placement. Selective herbicide placement induced chlorosis only or both chlorosis and growth inhibition Root growth in wild oat and barley (Hordeum rulgare L. cv. Dickson) was strongly inhibited by 1–0 μM diclofop-methyl. Wild oat shoots were killed when seedlings were root-treated with 10 μM diclofop-melhyl. The 100 μM rool treatment killed barley shoots but only stunted the growth of wheat shoots by approximately 50%. In root-ireated wheat plants the shoots were turgid and developed a light purple colour, whereas in foliar-treated plants the shoots developed discrete chlorotic areas. 相似文献
17.
M. ANDREWS 《Weed Research》1990,30(5):331-340
Avena saliva cv. Amuri and A. fatua were sprayed with diclofop methyl (1.0 kg a.i. ha?1) alone and in combination with 2,4-D (1.1 kg a.i. ha?1), bentazone (1.0 kg a.i. ha?1), chlorsulfuron (15 g a.i. ha?1) or dicamba (0.3 kg a.i. ha?1). Effects of the herbicides on leaf extension rate during the first 8 to 10 days after spraying and subsequent growth (dry weight) after 57–75 days were determined by comparison with unsprayed plants. Diclofop-methyl applied alone did not cause a decrease in leaf extension rate of A. saliva or A. fatua until at least 4 days after spraying. All broadleaf weed herbicides in combination with diclofop-methyl caused a decrease in leaf extension rate of both species within 2 days of spraying. Ten days after spraying, leaf extension rates for plants sprayed with a broadleaf weed herbicide plus diclofopmethyl (all combinations) were lower than for unsprayed plants but greater than for plants sprayed with diclofop-methyl alone. With the exception of A. fatua sprayed with bentazone, long-term growth of plants sprayed with a broadleaf weed herbicide plus diclofop-methyl (all combinations) was lower than for unsprayed plants but greater than for plants sprayed with diclofop-methyl alone. Bentazone applied with diclofop-methyl caused a substantial decrease in leaf extension rate of A. fatua within 24 h of spraying but at harvest, dry weight of plants from this treatment was similar to or less than that for plants sprayed with diclofop-methyl alone. Application of diclofop-methyl with bentazone at a rate of 0.3 kg a.i. ha?1 also caused a reduction in leaf extension rate of A. fatua within one day of spraying. At this rate of bentazone, dry weight of plants at harvest was intermediate to that of unsprayed plants and those sprayed with diclofop-methyl alone. It is proposed that decreased leaf expansion rate during the first few days afte spraying is the cause of broadleaf weed herbicide antagonism of diclofop-methyl. 相似文献
18.
BACKGROUND: Changes in chlorophyll fluorescence have often been advocated as a sensitive biomarker of plant stress, assuming that any kind of plant stress serious enough to affect plant growth will also affect photosynthesis. Glyphosate affects photosynthetic electron transport indirectly by inhibiting sink processes. The question is how fast this inhibition can be observed on CO2 assimilation and ultimately on chlorophyll fluorescence? RESULTS: Experiments measuring CO2 assimilation, conductance and chlorophyll fluorescence using four Kautsky curve parameters on barley (Hordeum vulgare L.) exposed to increasing doses of glyphosate showed a total cessation of CO2 fixation and conductance without significant changes in chlorophyll fluorescence. The decrease in CO2 fixation and conductance was significant 1 day after spraying and corresponded well to the decrease in biomass 5–7 days after spraying. CONCLUSION: A total cessation of CO2 assimilation can take place without affecting chlorophyll fluorescence. Hypotheses concerning what happens to the energy from the photosynthetic apparatus that is not used for CO2 assimilation are discussed. The results question the use of chlorophyll fluorescence as a universal indicator of stress on photosynthetic processes. Also, they demonstrate that changes in gas‐exchange parameters are more sensitive biomarkers for glyphosate toxicity compared with chlorophyll fluorescence. Copyright © 2010 Society of Chemical Industry 相似文献
19.
The effects of paraquat and 2,4,5-T on the photochemical activities of chloroplasts from the leaves of the woody species Carissa spinarum, Maba buxifolia, Flacourtia sepiaria, Chomelia asiatica, Gymnosporia emarginata and Dodonaea viscosa were investigated by comparing the effects on isolated chloroplasts from untreated leaves with those on chloroplasts isolated from herbicide-sprayed plants. DCPIP and NADP reduction of chloroplasts incubated in paraquat or 2,4,5-T solution was inhibited, whereas that of chloroplasts isolated from most species sprayed with these herbicides was enhanced after 24 and 48 h. The enhancement was smaller or disappeared after 72 h. The cyclic and noncyclic photophosphorylation rates were suppressed in chloroplasts isolated from herbicide-treated plants, and also in those from most untreated plants incubated in the herbicide solutions. The differences in reactions of chloroplasts from herbicide-treated and untreated plants are discussed. 相似文献
20.
The chlorophyll production of wheat (Triticum vulgare L. cv. Mericopa), corn (Zea mays L. cv. Everta), and alfalfa (Medicago sativa L. cv. Saranac), treated with the herbicide 4-chloro-5-methylamino-2-(3-trifluoro-methylphenyl)pyridazin- 3-one (norflurazon) and grown under high light intensity (10 760 lux) was markedly reduced. Corn and wheat seedlings germinated and grown for 7 days in an agar medium containing 1 mg/1 norflurazon were almost completely bleached. Alfalfa was even more sensitive to norflurazon, 0.1 mg/1 causing almost complete chlorosis. Under low light intensity (10.76 lux) the influence of norflurazon on chlorophyll production was greatly reduced. It is thought that norflurazon inhibits carotenoid synthesis leaving the chlorophyll of the plant subject to photooxidation. Electron micrographs of chloroplasts from green, partially bleached, and bleached areas of corn leaves treated with norflurazon indicate that the herbicide causes progressive deterioration of the lamellar system. 相似文献