Factors affecting the absorption of gibberellin A3 by sour cherry leaves

Knoche, Moritz; Lownds, Norman K.; Bukovac, Martin J.

doi:10.1016/0261-2194(92)90080-o

Cited by 12 publications

(11 citation statements)

References 20 publications

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“…While, in our experiments, deposit characteristics allowed for nearly complete penetration, markedly lower total uptake has been reported in a large number of foliar uptake studies, in some as low as a few per cent of the amount of AI applied 39. Mechanistically, low penetration plateaus are indicative of deposit‐restricted penetration, where deposit properties are such that (1) a fraction of the AI in the donor is not available for sorption to the CM and subsequent penetration (immobilization) or (2) the composition of the deposit favours AI partitioning into the deposit rather than the CM.…”

Section: Discussioncontrasting

confidence: 64%

Finite dose diffusion studies: I. Characterizing cuticular penetration in a model system using NAA and isolated tomato fruit cuticles

2000

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A ®nite dose diffusion system was employed to study cuticular penetration of 2-(1-naphthyl) [1À 14 C]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 halfcells 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-ml donor droplet containing NAA at 100 mM 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 À1 (equivalent to 0.032 nmol h À1 ) 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 lognormal, but penetration at 120 h followed a normal distribution. Cuticle thickness (estimated 5±25 mm) had no signi®cant effect on NAA penetration. Maximum rates of penetration through pepper fruit and citrus and ®cus 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 ®cus 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.

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Section: Discussioncontrasting

confidence: 64%

Finite dose diffusion studies: I. Characterizing cuticular penetration in a model system using NAA and isolated tomato fruit cuticles

2000

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“…The effect of donor pH on NAA penetration may be expected, since the residual solution of the deposit must have been an aqueous system. Similar pH responses of penetration of other organic acids have been documented 8. 17, 25, 26 Such effects have been related to (1) Donnan exclusion of the NAA anion at high pH owing to a negative net charge of the CM and (2) increased polarity of the active ingredient as a result of dissociation 27.…”

Section: Discussionsupporting

confidence: 54%

“…Field evidence suggests that increasing dose by increasing the concentration of herbicides, insecticides, fungicides and growth regulators generally yields an increased response as long as the dose applied is higher than the no‐effect level, but lower than the maximum response level (for example, see References 5 and 6). This is confirmed by numerous laboratory studies on foliar uptake from simulated spray droplets which have demonstrated that the amount of AI taken up is positively related to the concentration applied 7–9. Since the rate‐limiting step in foliar uptake is a diffusive process—the cuticular membrane (CM) representing the primary barrier—penetration increases as the concentration gradient across the CM is increased 10.…”

Section: Introductionmentioning

confidence: 57%

“…11 However, the fraction penetrating from the droplet during the liquid phase was often small compared with the penetration occurring from the deposit formed after droplet drying 7. 8, 12, 13 Furthermore, Knoche et al 14 demonstrated that NAA penetration occurred almost exclusively from the macroscopically dry deposits formed after droplet drying and, hence, that deposits were effective donors for penetration. While concentration dependence may be valid for penetration from deposits as well as liquid phases, the mechanism by which concentration dependence of penetration from deposits occurs is not clear.…”

Section: Introductionmentioning

confidence: 99%

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Finite dose diffusion studies: II. Effect of concentration and pH on NAA penetration through isolated tomato fruit cuticles

Knoche

Bukovac

2000

Pest Manag. Sci.

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The effects of NAA [2-(1-naphthyl)acetic acid] concentration and pH on penetration of NAA from aqueous droplets (5 ml) through isolated tomato (Lycopersicon esculentum) fruit cuticles were studied using a ®nite dose diffusion system. Penetration time-courses were characterized by a lag phase, which generally extended beyond the time of droplet drying. Initially penetration rates increased, reached a maximum penetration rate, remained constant for several hours, and then decreased with time. Penetration approached a plateau within 120 h after droplet application. Increasing NAA concentration in the donor droplet increased NAA penetration in both the presence and absence of the citric acid buffer (20 mM, pH 3.2). Maximum rates of penetration and the total amount of NAA that penetrated at 120 h were both linearly related to the initial concentration of the donor droplet (ranging from 0.001 to 0.1 mM NAA). The apparent ®rst-order rate constants for the concentration dependence of NAA penetration rates were greater with buffer than without (0.94 Â 10 À8 vs 0.50 Â 10 À8 m s À1 , respectively). While pH of the receiver solution (pH 6.2 vs 2.2) did not affect penetration, decreasing donor pH from 6.2 to 2.2 increased NAA penetration at 120 h.

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“…Time‐course studies have shown that penetration rates are highest during and shortly after droplet drying, and then decrease 4–6. However, the total amount of AI penetrating while aqueous spray droplets are still liquid is often small compared with the fraction penetrating from the residue after evaporation of the aqueous phase 4–6. Thus, the deposit often represents a significant donor for penetration.…”

Section: Introductionmentioning

confidence: 99%

Finite dose diffusion studies: III. Effects of temperature, humidity and deposit manipulation on NAA penetration through isolated tomato fruit cuticles

Knoche¹,

Bukovac²

2001

Pest Management Science

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Effects of temperature, humidity, rewetting and removal of deposits on penetration of NAA [2-(1-naphthyl)acetic acid] through isolated tomato (Lycopersicon esculentum Mill) fruit cuticles were studied using a finite dose diffusion system. In this system, an aqueous 5-microliter droplet (0.1 mM NAA in 20 mM citric acid buffer) is applied to the outer surface of a cuticle, which is mounted in a glass diffusion half-cell. The cell wall surface is in contact with a receiver solution (20 mM citrate). Penetration is monitored by repeated sampling of the receiver solution. Droplets appeared dry on visual inspection within 1 h of application, but significant NAA penetration continued after droplet drying. Maximum rates of NAA penetration increased exponentially as temperature was increased (from 5 degrees to 35 degrees C), the energy of activation averaging 153 (+/- 11.6)kJ mol-1. At 35 degrees C, penetration reached a plateau within 10 h of application (at 91.1 (+/- 1.0)% of dose applied) while at 5 degrees C penetration after 800 h reached only 30.2 (+/- 7.5)%. Increasing relative humidity from 20 to 80% increased maximum rates [from 1.0 (+/- 0.21) to 2.7 (+/- 0.80)% h-1] and penetration at 120 h after application [from 36.8 (+/- 2.1) to 64.3 (+/- 3.7)%]. Rewetting deposits at 120, 240 and 360 h after application resulted in increased NAA penetration. However, amounts and rates of NAA penetration progressively decreased with each subsequent rewetting. Removal of deposits by cellulose acetate stripping at various times after droplet application resulted in a rapid decrease in NAA penetration. NAA penetration following deposit removal was always less than 6.1% of the amount of NAA applied and averaged 0.5 (+/- 0.2)% when deposits were removed immediately after droplet drying.

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Factors affecting the absorption of gibberellin A3 by sour cherry leaves

Cited by 12 publications

References 20 publications

Finite dose diffusion studies: I. Characterizing cuticular penetration in a model system using NAA and isolated tomato fruit cuticles

Finite dose diffusion studies: I. Characterizing cuticular penetration in a model system using NAA and isolated tomato fruit cuticles

Finite dose diffusion studies: II. Effect of concentration and pH on NAA penetration through isolated tomato fruit cuticles

Finite dose diffusion studies: III. Effects of temperature, humidity and deposit manipulation on NAA penetration through isolated tomato fruit cuticles

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