Urea retention and uptake by avocado and apple leaves

Klein, I.; Zilkah, S.

doi:10.1080/01904168609363538

Cited by 6 publications

(2 citation statements)

References 10 publications

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“…Up to 85% of the applied urea can be taken up by the avocado leaf within 2 to 5 days (16). In this study, translocation of 15N to the inflorescence was proportional to the quantity applied (Table 1), substantiating rapid urea uptake and its N translocation out of the leaf before the leaves abscissed.…”

Section: Discussionsupporting

confidence: 67%

“…Foliage-applied urea N reportedly increased fruit set in avocado (1) and other species, presumably when the internal pools of N were limiting (8,13,18,22). Foliar uptake, metabolism, and translocation of urea is rapid in avocado (16) and other species (7,13,15,18,22). Using isotopically labeled N, it has been possible to demonstrate that rapidly developing inflorescences and fruits are a strong N sink (15).…”

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confidence: 99%

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Translocation of Foliar-applied Urea 15N to Reproductive and Vegetative Sinks of Avocado and Its Effect on Initial Fruit Set

Zilkah

Klein

Feigenbaum

et al. 1987

J. Amer. Soc. Hort. Sci.

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Translocation of 15N from foliar-applied urea to vegetative and reproductive sinks of avocado (Persea americana Mill, cvs. Fuerte and Hass) was evaluated during inflorescence development and the early stages of fruit set. Urea (2%) increased the number and the total dry weight of the lateral inflorescence per shoot. The concentration of 15N in avocado inflorescences increased proportionately to the concentration of urea applied to the old leaf surface. The amount of 15N translocated was not affected by the proximity of the source leaf to the “terminal” inflorescence. 15N translocated to developing fruit and to new sprouting leaves in similar amount. Urea N was translocated basipetally from current flush leaves to developing fruit. Removing the vegetative sink reduced N influx to the reproductive tissue and increased initial fruit set by a factor of 1.7 to 2.1 in urea-treated and -untreated shoots, respectively. These data indicate that shoot growth does not limit fruit set in avocado via competition for N.

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Section: Discussionsupporting

confidence: 67%

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confidence: 99%

Translocation of Foliar-applied Urea 15N to Reproductive and Vegetative Sinks of Avocado and Its Effect on Initial Fruit Set

Zilkah

Klein

Feigenbaum

et al. 1987

J. Amer. Soc. Hort. Sci.

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Organosilicone surfactants as adjuvants for agrochemicals

Stevens

1993

Pestic. Sci.

150

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The literature has been reviewed and 160 references are presented to provide an overview of organosilicones as adjuvants for agrochemicals. Early studies (1973–1981) elucidated the special properties of these compounds, notably their extreme spreading and, by virtue of the exceptionally low surface tensions of their aqueous solutions, the ability to induce infiltration of spray formulations into foliage via stomata. Subsequent research at the New Zealand Forest Research Institute explored these and other properties in‐depth, and demonstrated that they enabled the herbicide glyphosate to be used as a cost‐effective alternative to 2,4,5‐T for the control of forest scrubweeds. As a result, in 1985, ‚Silwet’︁ L‐77 was the first organosilicone adjuvant to be commercialised, and various other products have subsequently been introduced. The chemistry and synthesis of these organosilicones have been detailed. A mechanistic approach has been adopted to consider the effects of the distinctive properties of organosilicones in each of the processes involved in spray application of agrochemicals. Commencing with spray formulation, the topics of foaming, hydrolytic stability and interactions with coformulants are discussed. Progressing to spray application, consideration is given to the effects of organosilicones on atomisation and impaction (wetting, adhesion/reflection, spreading, retention/run‐off), and the resultant influences on the activity of protectant agrochemicals. An assessment of the use of organosilicones with systemic agrochemicals includes examination of effects on foliar uptake, via both cuticular and stomatal pathways, and the rainfastness which the latter provides. Also considered is the physiological behaviour of organosilicones, specifically phytotoxicity and effects on translocation of active ingredients. The current and potential future use of organosilicones with herbicides, foliar nutrients, growth regulators, insecticides and fungicides is discussed, as is the specificity of their effects. Additionally, the potential application of organosilicone chemistry to adjuvant classes other than the spreader/penetrant type investigated to date is considered. Finally, the issues of registration, handling hazards, both toxicological and chemical, and environmental impact are discussed. The literature reviewed demonstrates the sound science base on which this novel class of organosilicone adjuvant chemistry rests.

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Fertilization of Temperate-Zone Fruit Trees in Warm and Dry Climates

Klein

Weinbaum

2000

Temperate Fruit Crops in Warm Climates

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Urea retention and uptake by avocado and apple leaves

Cited by 6 publications

References 10 publications

Translocation of Foliar-applied Urea 15N to Reproductive and Vegetative Sinks of Avocado and Its Effect on Initial Fruit Set

Translocation of Foliar-applied Urea 15N to Reproductive and Vegetative Sinks of Avocado and Its Effect on Initial Fruit Set

Organosilicone surfactants as adjuvants for agrochemicals

Fertilization of Temperate-Zone Fruit Trees in Warm and Dry Climates

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