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1.
Effects of droplet size and carrier volume on foliar uptake and translocation of gibberellic acid (GA3) and 2,4-D were investigated. Simulated spray droplets were applied to primary leaves of 10-day-old Phaseolus vulgaris (cv Nerina) in droplet sizes and carrier volumes ranging from 0.5 to 10 μl and 10 to 200 μl per leaf, respectively. Doses of GA3 (2 μg per leaf) and 2,4-D (100 μg per leaf) were held constant. Total uptake of GA3 approached a penetration equilibrium within 24 h after application, but uptake of 2,4-D continued to increase. Decreasing droplet size and/or increasing carrier volume increased GA3 and 2,4-D uptake. Translocation to stem and roots was positively related to total uptake. A positive linear relationship between the logarithm of the total droplet/leaf surface interface area and 2,4-D uptake or translocation was found, but for GA3 this relationship was quadratic. Potential mechanisms of the effects of spray application factors on foliar uptake are discussed. © 1999 Society of Chemical Industry  相似文献   

2.
Bioassays were adapted to investigate effects of droplet size and carrier volume on performance of daminozide, gibberellic acid (GA3) and 2,4-D using Phaseolus vulgaris L. as a model system. Response to plant growth regulators was indexed by inhibition (daminozide), promotion of internode elongation (GA3) or ethylene production (2,4-D). Elongation of first plus second internodes above primary leaves was evaluated 14 days after treatment of primary leaves, while ethylene production was determined from head-space samples of incubated leaves 24 h after treatment. Daminozide inhibition of internode elongation was related to decreased cell size and number in pith and epidermis (range 49–70% of the untreated control). GA3 increased cell size and number in both tissues 2·3- to 4·8-fold. Responsiveness to daminozide and 2,4-D markedly decreased as seedling age increased from 8 to 12 days, but responsiveness to GA3 increased. Decreasing droplet size (10–0·5 μl) and increasing carrier volume (10–200 μl per leaf) at constant dose of daminozide (100 μg per leaf) and 2,4-D (100 μg per leaf) significantly increased performance, but had little effect on performance of GA3 (2 μg per leaf). Effects of application factors on performance were related to their effects on the interface area between droplets and leaf surface. Significant positive linear relationships were obtained between plant response and the logarithm of the droplet/leaf interface area for all growth regulators. © 1998 Society of Chemical Industry  相似文献   

3.
The effect of fungicide spray droplet density (droplet cm-2), droplet size, and proximity of the spray droplet deposit to fungal spores was investigated with Mycosphaerella fijiensis ascospores on the banana (Musa AAA) leaf surface for two contact fungicides: chlorothalonil and mancozeb. When droplet size was maintained at a volume median diameter (VMD) of 250 μm while total spray volume per hectare changed, M. fijiensis ascospore germination on the leaf surface fell below 1% for both fungicides at a droplet deposit density of 30 droplet cm-2. At a droplet deposit density of 50 droplet cm-2, no ascospores germinated in either fungicide treatment. When both droplet size and droplet cm-2 varied while spray volume was fixed at 20 litre ha-1, ascospore germination reached 0% at 10 droplet cm-2 (VMD=602 μm) for both fungicides. At lower droplet densities (2–5 droplet cm-2 VMD=989 μm and 804 μm respectively), ascospore germination on the mancozeb-treated leaves was significantly lower than on the chlorothalonil-treated leaves. The zone of inhibition surrounding a fungicide droplet deposit (VMD=250 μm) on the leaf surface was estimated to extend 1·02 mm beyond the visible edge of the spray droplet deposit for chlorothalonil and 1·29 mm for mancozeb. The efficacy of fungicide spray droplet deposit densities which are lower than currently recommended for low-volume, aerial applications of protectant fungicides was confirmed in an analysis of leaf samples recovered after commercial applications in a banana plantation. Calibrating agricultural spray aircraft to deliver fungicide spray droplets with a mean droplet deposit density of 30 droplet cm-2 and a VMD between 300 and 400 μm will probably reduce spray drift, increase deposition efficiency on crop foliage, and enhance disease control compared to aircraft calibrated to spray finer droplets. © 1997 SCI.  相似文献   

4.
The evolution of ethylene, induced by 1-naphthylacetic acid (NAA), was studied as a means of evaluating spray parameters using cowpea [Vigna sinensis (Torner) Savi] under defined conditions as a test system. The dose-response curve was linear over the range of 1.4-14 μg per leaf. The marked production of ethylene following treatment with an active auxin, 2,4-D (2,4-dichlorophenoxyacetic acid), and the absence of its production following treatment with an inactive analogue (3,5-dichlorophenoxyacetic acid), established that ethylene production was hormonally induced. The effect of application volumes of 10-100 μ1 and of droplet sizes of 1-10 μ1 were evaluated using a constant dose (5 μg NAA per leaf); NAA was more effective when delivered to the leaf in the larger volumes but in the smaller droplet sizes.  相似文献   

5.
BACKGROUND: Typical active ingredient (AI) residue patterns are formed during droplet drying on plant surfaces owing to the interaction of spray solution characteristics and leaf micromorphology. Currently, comparatively little is known about the influence of AI deposit patterns within a spray droplet residue area on the penetration and biological efficacy of glyphosate. A scanning electron microscope with energy dispersive X‐ray microanalysis has been used to characterise residue patterns and to quantify the area ultimately covered by glyphosate within the droplet spread area. RESULTS: The easy‐to‐wet weed species Stellaria media L. and Viola arvensis L., as well as the difficult‐to‐wet Chenopodium album L. and Setaria viridis L., differing in their surface micromorphology, have been used. Rapeseed oil ethoxylates (RSO 5 or RSO 60) were added to glyphosate solutions to provide different droplet spread areas. Addition of RSO 5 enhanced droplet spread area more than RSO 60, and both caused distinct glyphosate residue patterns. The biological efficacy of treatment solutions showed no significant correlation with the area ultimately covered by glyphosate. CONCLUSION: The results have implications on herbicide uptake models. This study shows that droplet spread area does not correspond to the area ultimately covered by glyphosate, and that the latter does not affect glyphosate phytotoxicity. Copyright © 2009 Society of Chemical Industry  相似文献   

6.
Uptake of [14C-phenyl]2,4-D-butyl by 4- to 6-week-old tomato plants was measured for vapour concentrations in the range 0.3–19 ng litre?1, for an exposure period of 4 h. Calculation of boundary layer thicknesses at the surface of the leaves, and depletion of the vapour concentration due to uptake by the plants, suggested that the plants experienced concentrations very close to the nominal values. Relationships between external vapour concentration and plant uptake, expressed in terms of fresh weight, leaf area, or on a whole plant basis, were linear in all cases. Twenty-four hours after the commencement of exposure, leaves contained 63–93% of the total herbicide in the plant; the proportion retained by the leaves was greater at low vapour concentrations. The largest amount of herbicide was present in leaves from the mid-position on the stem, but in terms of leaf area, the amount was greatest in leaves at the apex and decreased basipetally. It is not known whether this was due to a greater uptake rate per leaf area at the apex, or to translocation. As visible symptoms of phytotoxicity usually develop at the apex, both of these processes, together with the preferential retention of herbicide in leaves at low vapour concentrations, may all contribute to the development of vapour damage.  相似文献   

7.
Zabkiewicz 《Weed Research》2000,40(1):139-149
The influence of adjuvants on spray liquid behaviour and herbicide performance is reviewed. Total formulation efficacy can be expressed as a function of [deposition:retention:uptake: translocation:a.i. toxicity]. Adjuvants influence the physico-chemical and plant interactions involved for each factor. Deposition efficiency of spray droplets on to a target is dependent largely on the droplet spectrum, whereas retention performance is dependent on plant leaf surface character, orientation and canopy architecture, as well as droplet volume, velocity and dynamic surface tension effects. Uptake into plant foliage is affected by the leaf surface wax, cuticle age and composition and species variability. Uptake can be improved through appropriate formulation to provide either stomatal infiltration or much greater and faster cuticular absorption of the active ingredient. The inherent translocation capability of the a.i. is not affected directly by adjuvants, which are relatively immobile, but they can increase the mass of absorbed a.i. translocated, as a consequence of improved uptake or may reduce it as a result of localized contact phytotoxicity. Considerable progress has been made in developing models of spray droplet deposition, adhesion and retention, as well as uptake. In future, individual models may be combined to provide an integrated formulation efficacy decision support system.  相似文献   

8.
田间采用背负式机动弥雾机对70%吡虫啉水分散粒剂进行喷雾试验,证明若吡虫啉喷雾雾滴在小麦穗部形成一定的沉积密度即可有效防治麦蚜。当70%吡虫啉水分散粒剂用水稀释2 333倍(有效成分300 mg/L),雾滴密度在54,133和280个/cm2条件下,施药7 d后对麦蚜的防治效果分别为83.3% ,88.7%和93.7%;当药剂稀释1 167倍(有效成分600 mg/L),雾滴密度在75,142和291个/cm2条件下,7 d后对麦蚜的防治效果分别为88.1%,94.5%和96.5%。采用背负式机动弥雾机,采用常量150 L/hm2、低浓度(300 mg/L)喷雾时,小麦穗部、旗叶上的雾滴沉积密度分别为177±12,113±8个/cm2,沉积量分别为27.4±6.8,6.6±1.6 ng/cm2,地面流失率为12.8%,7 d后的防治效果为94.0%; 当采用低容量75 L/hm2、高浓度(600 mg/L)喷雾时,小麦穗部、旗叶上的雾滴沉积密度分别为127±13,91±7个/cm2,沉积量分别为29.8±1.2, 6.7±0.6 ng/cm2,地面流失率为10.6%,7 d后的防治效果为93.8%。生产中建议采用吡虫啉低容量75 L/hm2、高浓度600 mg/L喷雾,省工、省水、省时。  相似文献   

9.
The activity of imazapyr and glyphosate against Imperata cylindrica was studied in field and glasshouse experiments using two methods of direct contact application; a rope-wick wiper and a cloth soaked in herbicide solution. The effect of concentration and position of application on herbicide uptake and translocation was also measured. At the lowest dose of imazapyr (5 mg acid equivalent (a.e.) per plant), phytotoxicity was greater from applications by a rope-wick wiper than by a cloth. However, when the dose of imazapyr was increased, the cloth applicator was more effective than the rope-wick wiper. At all doses of glyphosate, rope-wick application was more effective than wiping with a cloth. Herbicide performance in the glasshouse was similar to that in the field. Radiotracer studies showed that increasing the concentration of imazapyr, while keeping herbicide dose constant, decreased uptake and translocation of radiolabel. In contrast, the rate of uptake of 14C-glyphosate increased with increasing herbicide concentration. Position of application did not significantly affect the amount of uptake and translocation of radiolabel to the rhizomes. It is concluded that rope-wick wipers are more effective than wiping with a cloth for applying imazapyr and glyphosate to I. cylindrica, provided that the concentration of imazapyr does not exceed 10 g a.e. l?1.  相似文献   

10.
The effect of droplet diameter (36-274 μm) and concentration (10-400 g litre?1) of permethrin on the knockdown and mortality of 2nd-instar Plutella xylostella larvae was investigated. Larvae were placed on brussels sprout leaf discs treated with residual deposits of permethrin applied as ULV or emulsion formulations. The LD50 of permethrin decreased with droplet size at all concentrations tested. This effect could not be accounted for solely by increased drop numbers per unit area of leaf, suggesting that for both formulations transfer of permethrin to larvae is more efficient for deposits composed of small drops. The concentration of permethrin in the ULV formulation could be reduced to approach a minimum quantity of toxicant per unit area to maintain 50 per cent mortality. The approach to the minimum dose varied with drop size and drop number per unit leaf area. The ULV formulation was approximately 2.7 times more effective at killing larvae than the emulsion, presumably as a result of greater availability of toxicant and transfer to larvae.  相似文献   

11.
A finite dose diffusion system was employed to study cuticular penetration of 2‐(1‐naphthyl) [1−14C]acetic acid (NAA) from simulated spray droplets through enzymatically isolated tomato fruit cuticles (Lycopersicon esculentum Mill cv Pik Red). Isolated cuticles were mounted on diffusion half‐cells with the cell wall surfaces facing a 20 mM citric acid receiver solution (pH 3.2, volume 2.9 ml, prepared with deionized water). A 5‐µl donor droplet containing NAA at 100 µM in 20 mM citric acid buffer (pH 3.2) was applied to the outer surface. Penetration was monitored by repeated sampling of the receiver solution. NAA penetration was characterized by (1) an initial lag phase of about 2.3 h, (2) a phase of nearly constant maximum rate of penetration averaging 6.3% of applied NAA h−1 (equivalent to 0.032 nmol h−1) and (3) a plateau phase approaching an asymptote at 81.2% of applied NAA (equivalent to 0.406 nmol) at 120 h. Within 1 h after application droplets appeared dry on visual inspection. Immediately after droplet drying, 7.0% of the applied NAA was sorbed to the cuticle, but only 0.5% penetrated into the receiver solution, indicating that penetration occurred almost exclusively from the apparently dry deposit. At 120 h, 5.2% of the NAA applied was associated with the deposit and 4.3% with the cuticle. The distribution of maximum rates of penetration was log‐normal, but penetration at 120 h followed a normal distribution. Cuticle thickness (estimated 5–25 µm) had no significant effect on NAA penetration. Maximum rates of penetration through pepper fruit and citrus and ficus leaf cuticles were 4.9‐, 2.6‐ and 0.1‐times that through tomato fruit cuticles. At 120 h, penetration averaged 85.5, 79.5 and 34.7% for pepper, citrus and ficus cuticles, respectively. Extracting epicuticular and embedded waxes increased NAA penetration rates through tomato fruit cuticle more than three‐fold, but had little effect on penetration at 120 h (71.0 vs 87.7% for cuticular vs dewaxed cuticular membranes). The maximum penetration rate and total penetration were found to be useful parameters in describing the penetration time‐course. © 2000 Society of Chemical Industry  相似文献   

12.
The effects of several herbicides for broadleaved weed control on glyphosate (n-phosphonomethyl glycine) phytotoxicity to wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and wild oats (Avena fatua L.) were studied in the greenhouse. In tank mixtures, dicamba (3,6-dichloro-o-anisic acid), 2,4-D (2,4-dichlorophenoxy-acetic acid) and bromoxynil (3,5-dibromo-4-hydroxy benzonitrile) reduced the phytotoxicity of threshold rates of glyphosate on all three species. With increasing rates of the herbicides for broadleaved weed control relative to a fixed rate of glyphosate, there was a general trend towards increased antagonism. Increasing glyphosate rates above the threshold level in mixtures containing a fixed rate of herbicides for broadleaved weed control overcame the antagonism. Both the inert and active ingredients of 2,4-D amine and ester appeared to be involved in the antagonism. There was no reduction in glyphosate phytotoxicity on the annual grasses when 2,4-D or bromoxynil were sprayed sequentially at various times in relation to glyphosate. When droplets of bromoxynil and glyphosate were placed side by side on a leaf, glyphosate phytotoxicity was not reduced, whereas when the two herbicides were mixed and applied as one droplet, considerable reduction in glyphosate phytotoxicity occurred. These results suggest that the reduction in glyphosate phytotoxicity caused by tank mixing with herbicides such as 2,4-D, bromoxynil and dicamba may be due to a physical or chemical incompatability within the tank mixture rather than to a biological interaction in the plant.  相似文献   

13.
The effect of non-ionic nonylphenol (NP) surfactants containing 4–14 ethylene oxide (EO) molecules on the distribution of asulam and diflufenican was investigated in Pteridium aquilinum L. Kuhn and Avena fatua L. The distribution of the herbicides was dependent on the EO content and concentration of surfactant and differed between plant species and herbicide. The surface properties of contact angle, droplet diameter and surface tension were examined. For solutions of asulam, the greatest reductions in contact angle, surface tension and greatest droplet diameter were obtained with surfactants of EO 6.5–10 (at 0.001–0.1%). For solutions of diflufenican, these responses were greatest when applied with surfactant of EO 4. Surfactants of EO 6.5–10 increased the uptake and translocation of [14C]asulam in P. aquilinum, particularly at surfactant concentrations of 0.01 % and 0.1 %. All surfactants increased uptake of [14C]asulam in A. fatua with no significant effects of surfactant EO number or concentration. For both species, there was a positive correlation between the optimum surface characteristics of the herbicide droplets and the uptake of asulam. With diflufenican, greatest uptake and translocation by mature frond tissue of P. aquilinum occurred at the highest concentration of surfactant EO 4; in A. fatua, however, uptake and translocation were not significantly affected by any of the surfactants.  相似文献   

14.
Root-fed or foliar-applied glyphosate [N-(phosphonomethyl) glycine] reduced uptake and translocation of Ca2+ and Mg2+, but not K+, by soybean [Glycine max (L.) Merr. “Hill”] seedlings as measured by atomic absorption spectrometry. Histochemical techniques revealed that cells of secondary roots that were formed after glyphosate treatment were deficient in Ca2+. The relative distribution of Ca2+ in control root and leaf cells was mitochondria > plastids > cytoplasm. Glyphosate severely reduced Ca2+ content and eliminated intracellular concentration of Ca2+ in the mitochondria of both root and leaf cells. Glyphosate had no effects on K+ distribution at the ultrastructural level. These results support the view that glyphosate effects on distribution of divalent metal cations may be related directly or indirectly to the phytotoxicity of the herbicide.  相似文献   

15.
Radiolabelled daminozide and maleic hydrazide (MH) were injected into American elm seedlings, kept in nutrient solution, to determine their translocation pattern and metabolic fate. Both compounds were rapidly translocated to all parts of the plant. After 21 days, 13% of the applied 14C was exuded into the nutrient solution from the roots of the plants treated with MH. Using gel-filtration and thin-layer chromatographic techniques, it was determined that daminozide did not form any metabolite, and that MH was converted into a MH-sugar complex. A significant amount of 14C was unextractable from the plant tissue.  相似文献   

16.
The uptake from foliar deposits of 10 14C-labelled compounds into each of 10 species of field-grown plants was measured 26 h after deposition by combustion of leaf tissue after removal of surface deposits. The compounds, which included eight pesticides, covered a wide range of lipophilicity and each was formulated in the same way; they were applied as droplets with a microsyringe. Uptake varied greatly between the species. All compounds were taken up well into maize and Xanthium pennsylvanicum, whereas relatively little entered the leaves of apple or orange. Uptake into the six other species varied according to the compound. Amongst the eight non-polar compounds, no relationship between the rate of uptake and molecular size was discerned, and only in X. pennsylvanicum was uptake related to the partition coefficient and water solubility. Considering all the compounds, weak relationships were observed between molecular cross-sectional area and uptake into four species. The range of the uptake rates (×130) was small compared with those of octan-1-ol-water partition coefficients (×1010) and water solublities (×107) shown by the 10 compounds. Possible reasons for the absence of correlations between the uptake and the molecular properties considered are discussed. The results are consistent with either separate routes of cuticular entry for non-polar and polar compounds, or a common route for both types of compound. The generally poor uptake by apple and orange leaves, which may be related to their thick cuticles, highlights the need to develop special formulations to optimise uptake into these species.  相似文献   

17.
The influence of water stress on the absorption and translocation of 14C-labelled fenoxapropethyl and imazamthabenz-methyl in Avena fatua L. (wild oat) was studied. The phytoioxicity to A. fatua of both herbicides with a droplet application was also examined under water stress conditions. The absorption of both fenoxaproethyl and imazamethabenz-methyl was reduced by waler stress when the plants were harvested within 24 h after herbicide application. Up to 48 h after the application, the translocation out of the treated lamina of both herbicides, based on percentage of applied 14C. was reduced under water stress conditions. When havested 96 h after herbicide application, however, water stress no longer significantly affeaed the absorption and translocation of either herbicide. When the herbicides were applied as individual droplets, water stress reduced the phytotoxicity of fenoxaprop-ethyl but not that of imazamethabenz-methyl. It is concluded that the changes in herbieide absorption and translocation may not be the major physiological processes associated with differential whole-plant response oi A faiua to fenoxaprop-ethyl and imazamefhabenz-methyl under water stress.  相似文献   

18.
Diphenamid (N,N-dimethyl-2,2-diphenylacetamide) in an aqueous solution in plastic bottles was partially detoxified when exposed to sunlight for 1 week. Varying spray volumes from 300 to 1,800 I/ha did not have an appreciable effect on the phytotoxicity of diphenamid, sprayed on a coarse or fine soil surface. The marked dissipation of diphenamid which occurred from the soil surface was attributed to photodecomposition and volatilization. Diphenamid phytotoxicity was greater when the first irrigation after spraying was applied in four increments of 100 m3/ha or two increments of 200 m1/ha than when it was applied in a single 400 m1/h watering; the latter caused more leaching of the herbicide. The diphenamid fraction leached out of a 4-cm soil layer increased as the organic matter content in the soil decreased, from 25% in peat (22.3% o.m.) to >88% in sandy loam (0.9% o.m.). The herbicidal activity remaining after leaching was lower in sandy loam and in peat than in soil with medium organic matter content (11.6% and 6.2%). Diphenamid degradation rate in soil at 50% field capacity moisture level, increased when temperature was increased from 10° to 30°C. After 4 months of incubation at 10°C, 40-50% of the original herbicide was detoxified, while at 20° and 30°C the loss exceeded 90%. Within the range of day-temperatures of 10° to 40°C in soil and of 10° to 35°C in nutrient solution, diphenamid phytotoxicity to tomato seedlings increased with temperature.  相似文献   

19.
Imazapyr absorption, translocation, root release and metabolism were examined in leafy spurge (Euphorbia esula L.). Leafy spurge plants were propagated from root cuttings and [14C]imazapyr was applied to growth-chambergrown plants in a water + 28% urea ammonium nitrate + nonionic surfactant solution (98.75 + 1 + 0.25 by volume). Plants were harvested two and eight days after herbicide treatment (DAT) and divided into: treated leaf, stem and leaves above treated leaf, stem and leaves below the treated leaf, crown, root, dormant and elongated adventitious shoot buds. Imazapyr absorption increased from 62.5% 2 DAT to 80.0% 8 DAT. Herbicide translocation out of the treated leaf and accumulation in roots and adventitious shoot buds was apparent 2 DAT. By the end of the eight-day translocation period only 14% of applied 14C remained in the treated leaf, while 17% had translocated into the root system. Elongated and dormant adventitious shoot buds accumulated 3.2- and 1.8-fold more 14C, respectively, 8 DAT than did root tissue based on Bq g?1 dry weight. Root release of 14C was evident 2 DAT, and by 8 DAT 19.4% of the 14C reaching the root system was released into the rooting medium. There was no metabolism of imazapyr in crown, root or adventitious shoot buds 2 DAT; however, imazapyr metabolism was evident in the treated leaf 2 and 8 DAT. Imazapyr phytotoxicity to leafy spurge appears to result from high imazapyr absorption, translocation to underground meristematic areas (roots and adventitious shoot buds), and a slow rate of metabolism.  相似文献   

20.
Aim of our study was to exploit the relation between deposit structure at the microscale and the uptake and biological efficacy of herbicides. For this purpose, we analysed the relevance of the deposit structure of diquat dibromide, as affected by surfactants, on the spatially resolved chlorophyll fluorescence (ChlF) and the desiccation of the leaves. The present study is a sequential work to our studies with the systemic compound glyphosate. On that basis, we hypothesized here that larger deposits of diquat are negatively related to the bio-efficacy of the compound. By using selected ethoxylated rapeseed oil adjuvants (RSO 5, RSO 10, RSO 30, RSO 60) we influenced the deposit properties of diquat dibromide droplet residue on the leaves of easy-to-wet Viola arvensis and the difficult-to-wet Chenopodium album species. With the spatially-resolved pulse amplitude modulated (PAM) ChlF technique we demonstrated the effect of diquat on the physiology of the tissue. As shown, the RSO surfactants did not affect the area of diquat residue on the easy-to-wet leaves of V. arvensis; this trend is similar to those observed for ChlF and the herbicide desiccation potential. In contrary, on C. album, decreased deposit area of diquat droplet was associated with increased effect on ChlF parameters and increased desiccation potential of the herbicide, thus explaining its higher foliar uptake.  相似文献   

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