Differential Effects of 1-Methylcyclopropene on Citrus Leaf and Mature Fruit Abscission

Pozo, Luis; Yuan, Runyu; Kostenyuk, Igor; Alférez, Fernando; Zhong, Guang Yan; Burns, J. C.

doi:10.21273/jashs.129.4.0473

Cited by 39 publications

(38 citation statements)

References 28 publications

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“…When abscission agents become available for routine mechanical harvesting of citrus, they will be used annually for the life of the tree (≥20 years). Several natural and synthetic abscission agents that loosen mature fruit have been assumed unacceptable because they caused up to 25% defoliation (Burns et al, 2003a;Burns et al, 2003b;Pozo et al, 2004a;Pozo et al, 2004b). These abscission agents may now become more promising since yield and tree health were not affected by this level of defoliation.…”

Section: Discussionmentioning

confidence: 99%

“…However, most abscission agents not only loosen fruit but also cause leaf abscission (Burns et al, 2003b). The use of abscission agents as a one-time application during harvest could result in defoliation of as much as 20% (Burns et al, 2003a(Burns et al, , 2003bPozo et al, 2004aPozo et al, , 2004b annually for the life of the tree. Little is known about effects of defoliation of mature citrus trees during harvest, and no data are available on effects of annual defoliation on tree growth or fruit yield.…”

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confidence: 99%

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Partial Defoliation Can Decrease Average Leaf Size but Has Little Effect on Orange Tree Growth, Fruit Yield and Juice Quality

Yuan¹,

Alférez²,

Kostenyuk³

et al. 2005

HortSci

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The effects of 2 consecutive years of annual defoliation during the harvest season on fruit size, yield, juice quality, leaf size and number were examined in trees of the midseason cultivar `Hamlin' and the late-season cultivar `Valencia' orange [Citrus sinensis (L.) Osb.]. In `Hamlin', removal of up to 50% of the leaves in late November had no effect on fruit yield, fruit number, fruit size, soluble solids yield, juice °Brix, and °Brix to acid ratio of juice the following year. In `Valencia', removal of 50% of the leaves in late March decreased fruit yield and soluble solids yield but did not affect Brix or the Brix to acid ratio of the juice. Leaf size of new flush was reduced by removal of 50% of the leaves in both cultivars but there was little effect on total canopy size. There were no measured effects of removing 25% of leaves from tree canopies. Thus, canopy growth, fruit yield, fruit quality, and leaf size were not negatively impacted when annual defoliations did not exceed 25% of the total canopy leaf area in `Valencia' and `Hamlin' orange trees for two consecutive years. Overall, fruit weight increased linearly with increasing ratio of leaf area to fruit number, suggesting that fruit enlargement can be limited by leaf area.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Partial Defoliation Can Decrease Average Leaf Size but Has Little Effect on Orange Tree Growth, Fruit Yield and Juice Quality

Yuan¹,

Alférez²,

Kostenyuk³

et al. 2005

HortSci

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“…The fact that abscission can occur in the absence of ethylene binding has been recently reported. Application of 1‐MCP was unable to stop mature fruit abscission in trees exposed to ethephon, an ethylene‐releasing agent (Pozo et al 2004). In this case, treatment with 1‐MCP 24 h before or after ethephon application still did not stop abscission.…”

Section: Discussionmentioning

confidence: 99%

Mechanical wounding and abscission in citrus

Kostenyuk

Burns

2004

Physiologia Plantarum

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Fruit detachment force (FDF), ethylene evolution, fruit and leaf drop were determined in Citrus sinensis for periods up to 96 h after mechanical wounding. Injury by removing a thin section of mature fruit flavedo reduced FDF, increased ethylene evolution and promoted abscission. Injuring flavedo 1 cm below the calyx was more effective at reducing FDF than injuring flavedo at the equator or the blossom‐end of mature fruit. Injuring the calyx or peduncle of mature fruit, or injuring three leaves closest to the mature fruit did not reduce FDF. Immature fruitlets either did not abscise or underwent low rates of abscission in response to mechanical wounding, depending on age. Inhibiting ethylene binding in wounded mature fruit with 1‐methylcyclopropene (1‐MCP) increased ethylene evolution compared with wounded fruit alone, but the reduction in FDF was similar. When an ethylene biosynthesis inhibitor (aminoethoxyvinylglycine, AVG) was used, reduction in FDF of wounded mature fruit exposed to AVG was similar to that of wounded fruit alone but ethylene production was markedly reduced. Wounding mature leaf blades in the presence or absence of 1‐MCP resulted in elevated but equal ethylene evolution up to 48 h after wounding, however, no leaf drop occurred. Thereafter, ethylene evolution was higher in 1‐MCP‐treated wounded leaves. Removing up to 77% of the total mature leaf area did not cause leaf drop, nor did wounding tissue across the laminar or petiolar abscission zones. Leaflets of 5 mm length reached nearly 100% abscission after mechanical wounding, whereas wounding leaves 20 mm length resulted in 15% abscission. The data suggest that mechanical wounding of flavedo results in mature fruit abscission, and ethylene binding may not be mandatory to initiate abscission in citrus fruit. The differential response of fruit and leaves at different ages to wounding may be related to potential contribution to carbohydrate accumulation, and production and sensitivity of tissues to an abscission signal(s).

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“…On the day of spray application (22 May 2004) and before harvesting commenced (25 May 2004), fruit detachment force (FDF) was measured from ten randomly selected fruit in each treatment plot. FDF was measured as previously described (Pozo et al, 2004). Trees in the hand-picked controls were harvested and the fruit weighed to calculate yield.…”

Section: Methodsmentioning

confidence: 99%

Late-season `Valencia' Orange Mechanical Harvesting with an Abscission Agent and Low-frequency Harvesting

Burns¹,

Roka²,

Li³

et al. 2006

HortSci

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An abscission agent (5-chloro-3-methyl-4-nitro-1H-pyrazole [CMNP]) at 300 mg·L–1 in a volume of 2810 L·ha–1 was applied to Valencia orange trees [Citrus sinensis (L.) Osb.] on 22 May 2004. At this time, immature and mature fruit were present on the tree simultaneously. Three days after application, fruit were mechanically harvested using a trunk-shake-and-catch system. The power to the shaker head was operated at full- or half-throttle (FT or HT, respectively), and the duration of trunk shaking was 2 seconds at FT or 4 seconds at FT and HT. Mature fruit removal percentage and number of immature fruit removed, and fruitlet weight and diameter were determined. Mature fruit removal percentage with 2 seconds at FT or 4 seconds at FT harvesting ±CMNP, or 4 seconds at HT + CMNP was not significantly different and ranged between 89% to 97%. Harvesting at 4 seconds HT without CMNP removed significantly less mature fruit than any treatment. CMNP did not affect immature fruit removal by the trunk shaker. Harvesting at 4 seconds at HT removed significantly less immature fruit than 2 seconds at FT or 4 seconds at FT. No significant difference in fruitlet weight or diameter was measured between any trunk shaker harvest operation and CMNP treatment. Trunk shaking frequency was estimated to be 4.8 and 8.0 Hz at HT and FT, respectively. Yield in 2005 was determined on the same trees used for harvest treatments in 2004. CMNP did not impact yield. No significant difference in yield was seen between the hand-picked control and 4 seconds at HT, whereas yield in the remaining treatments was lower. The results demonstrate that CMNP application combined with low frequency trunk shaker harvesting can achieve high percentage of mature fruit removal with no significant impact on return yield of the following crop.

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Differential Effects of 1-Methylcyclopropene on Citrus Leaf and Mature Fruit Abscission

Cited by 39 publications

References 28 publications

Partial Defoliation Can Decrease Average Leaf Size but Has Little Effect on Orange Tree Growth, Fruit Yield and Juice Quality

Partial Defoliation Can Decrease Average Leaf Size but Has Little Effect on Orange Tree Growth, Fruit Yield and Juice Quality

Mechanical wounding and abscission in citrus

Late-season `Valencia' Orange Mechanical Harvesting with an Abscission Agent and Low-frequency Harvesting

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