Uptake and Translocation of Paclobutrazol and Implications for Orchard Use

Quinlan, J. D.; Richardson, Phyllis

doi:10.17660/actahortic.1986.179.69

Cited by 22 publications

(9 citation statements)

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“…Effectiveness of uniconazole in controlling vegetative growth of elaeagnus was greater with drench application than with foliar application. Differences in effectiveness of uni-conazole due to site of application concur with earlier research (Keever et al, 1990;Quinlan and Richardson, 1986;Warren, 1990), and are probably due to differences in root and foliar uptake or differences in the ability of uniconazole to be translocated in the xylem and phloem. Root-applied retardant is acropetally transported to the leaves and shoot apex primarily via the xylem (Richardson and Quinlan, 1986).…”

supporting

confidence: 87%

“…Once inside the leaves, foliarly applied chemical would have to move through the phloem to the stem, where it might be translocated to the xylem (Barrett and Bartuska, 1982). However, in other research, no foliar-applied triazole retardant was translocated to stems or roots (Quinlan and Richardson, 1986;Wang et al, 1986), and only slight inhibition of growth resulted from leaf-lamina application (Quinlan and Richardson, 1986).…”

mentioning

confidence: 84%

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Response of Established Landscape Plants to Uniconazole

Keever¹,

West²

1992

horttech

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Uniconazole was applied once as a soil drench (15, 30, or 45 mg a.i./plant) or foliar spray (500, 1000, or 1500 mg liter-1, about 175 ml/plant) to established, field-grown thorny elaeagnus (Elaeagnus pungens Thunb. Fruitlandii) and leyland cypress [× Cupressocyparis leylandii (A.B. Jacks. & Dallim.) Dallim. & A.B. Jacks]. At the end of the second growing season following treatment, shoot dry weights (SDW) of thorny elaeagnus decreased with increasing rates of drench-applied uniconazole, while SDW of plants receiving the foliar application were not affected by increasing rates. Growth indices of leyland cypress, determined twice during the first growing season and at the end of the second growing season, were not influenced by application method or rate. Uniconazole applied as a soil drench at 15 to 45 mg a.i./plant suppressed growth of established thorny elaeagnus for at least two growing seasons, but leyland cypress was not affected by uniconazole drench or foliar spray at tested rates. No phytotoxicity was observed on either species in any treatment during the experiment.

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confidence: 87%

mentioning

confidence: 84%

Response of Established Landscape Plants to Uniconazole

Keever¹,

West²

1992

horttech

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“…The lack of response in other years may be attributed to an increase in fruit set. Although PB may inhibit gibberellin biosynthesis (Hedden and Graebe, 1985), which is known to reduce flowering, the mobility and redistribution of PB in the tree is very limited (Quinlan and Richardson, 1986). Most likely, insufficient PB was translocated to the seeds, which is the primary source of gibberellins that inhibit flowering in a bearing tree.…”

Section: Discussionmentioning

confidence: 99%

Reduced Rates and Multiple Sprays of Paclobutrazol Control Growth and Improve Fruit Quality of `Delicious' Apples

Greene¹

1991

jashs

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`Gardiner Delicious'/MM.lO6 apple (Malus domestics Borkh.) trees were initially sprayed in 1985 with paclobutrazol (PB) at 250 mg.liter-1 at tight cluster and again on 10 and 25 June and 29 July. From 1986 through 1988, PB sprays of 85 or 100 mg·liter-1 were applied at either petal fall (PF) + 2 or PF + 4 weeks and one to two additional sprays were applied per year when growth resumed. Promalin was applied to one group of trees that received PB starting at PF + 2 weeks. PB reduced terminal, lateral, and total shoot growth the year of application and in subsequent years. Although average shoot length of lateral and terminal shoots was reduced, the greatest reduction in growth occurred because PB prevented spurs from growing into lateral and terminal shoots. Compared to unsprayed trees, PB reduced pruning time in all 4 years by 23% to 70%. PB increased bloom only the first year after application, but increased fruit set for 2 years due to a carryover effect. Application of PB in 1985 caused a reduction in fruit size, sometimes in soluble solids concentration, length: diameter (L : D) ratio, and pedicel length. Promalin either overcame the reduction in the ratio or increased it in 1986. Reduced rates of PB in subsequent years caused few adverse effects on the fruit. PB increased flesh firmness when applied at PF + 2 weeks but not at PF + 4 weeks. Trees treated with PB produced fruit with higher flesh Ca and less bitter pit, cork spot, and senescent breakdown following regular air storage. Chemical names used: ß -(4 -chlorophenyl)methyl α -(1,1-dimethylethyl) -1H-l,2,4-triazole-1-ethanol (paclobutrazol, PB); gibberellins A4+7 plus N-(phenylmethyl) -1H-purine-6-amine (Promalin).

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“…[ 14 C]PAC has been shown to move through the plant via the transpiration stream (Quinlan and Richardson 1986) to the leaves where it is not exported but rather degraded (Early and Martin 1988). These authors even suggested the possibility that the stems, trunks, and roots could serve as potential reservoirs for PAC carryover in trees, although they did not examine this directly, nor did they consider that PAC could appear in the roots of a plant only if transported there by the phloem.…”

mentioning

confidence: 99%

Paclobutrazol Is Phloem Mobile in Castor Oil Plant (Ricinus communis L.)

Witchard

1997

J Plant Growth Regul

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It is commonly believed that the synthetic triazole growth regulator paclobutrazol (PAC) is exclusively xylem mobile within plants. By contrast, the triazole amitrole and many natural growth regulators are phloem mobile. This raises some doubt as to whether PAC must necessarily be exclusively xylem mobile. PAC was introduced into castor oil plants (Ricinus communis L.) through their hollow petioles. PAC was detected in xylem and phloem sap collected above the point of introduction but not in xylem sap below this point. This finding shows that PAC is not exclusively xylem mobile as believed previously. These results also raise the possibility of introducing PAC into plants in a different way so that it is carried by both the xylem and phloem and thus optimizing its effectiveness.

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Uptake and Translocation of Paclobutrazol and Implications for Orchard Use

Cited by 22 publications

References 0 publications

Response of Established Landscape Plants to Uniconazole

Response of Established Landscape Plants to Uniconazole

Reduced Rates and Multiple Sprays of Paclobutrazol Control Growth and Improve Fruit Quality of `Delicious' Apples

Paclobutrazol Is Phloem Mobile in Castor Oil Plant (Ricinus communis L.)

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