Comparison of Chemical Blossom Thinners Using ‘Golden Delicious’ and ‘Gala’ Pollen Tube Growth Models as Timing Aids

Reducing apple crop load during bloom can increase fruit size and promote annual bearing when compared with crop reduction at later timings. In this study, we compared the efficacy of chemical blossom-thinning strategies on ‘Golden Delicious’ and ‘Gala’ apple trees. Several blossom-thinning treatments were evaluated, including 1) unthinned control (control), 2) hand-thinned (HT) at bloom, 3) liquid lime sulfur + Stylet-Oil (LS + SO), 4) ammonium thiosulfate (ATS), 5) endothall (ET), and 6) naphthaleneacetamide (NAD). Chemical treatments were applied twice during bloom, using a predictive model to determine application timings. Blossom thinner effects on pollen tube growth, fruit set, and yield responses were evaluated. LS + SO and ATS reduced the number of pollen tubes that entered the style for ‘Golden Delicious’ by 75% and 63%, respectively. ET and NAD did not affect the number of pollen tubes that entered the style. In one of 2 years, LS + SO resulted in a near-ideal crop load and increased fruit weight. ATS was effective in reducing initial fruit set in ‘Golden Delicious’ and ‘Gala’, but did not reduce whole-tree crop density. ET reduced crop load in all experiments but caused excessive spur leaf injury and negatively affected fruit size of ‘Gala’ but not ‘Golden Delicious’. NAD had limited efficacy on ‘Golden Delicious’ at the concentrations and application timings used in this trial. When used as the sole method of crop load management, none of the chemistries evaluated over-thinned or increased fruit injury. However, ET caused excessive thinning when evaluated as part of a commercial crop load management program on ‘Gala’. Of the products evaluated, LS + SO provided the best overall thinning response.

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Effects of Temperature and the Combination of Liquid Lime Sulfur and Fish Oil on Pollen Germination, Pollen Tube Growth, and Fruit Set in Apples

HortScience ◽

10.21273/hortsci.44.5.1277 ◽

2009 ◽

Vol 44 (5) ◽

pp. 1277-1283 ◽

Cited By ~ 14

Author(s):

Keith Yoder ◽

Rongcai Yuan ◽

Leon Combs ◽

Ross Byers ◽

Jim McFerson ◽

...

Keyword(s):

Pollen Tube ◽

Pollen Tube Growth ◽

Pollen Germination ◽

Fruit Set ◽

Pollen Tubes ◽

Tube Growth ◽

Pollen Tube Growth Rate ◽

Golden Delicious ◽

Effects Of Temperature ◽

Increasing Temperature

Effects of temperature and the combination of liquid lime sulfur (LLS) and fish oil (FO) applied during bloom on pollen germination and pollen tube growth in flowers and fruit set were examined in apples (Malus ×domestica Borkh.). Percent germination of pollen of ‘Manchurian’ crabapples and ‘Golden Delicious’ apple flowers on the stigmatic surface of ‘Golden Delicious’ pistils increased with increasing temperature from 13 to 29 °C in the first 24 and 48 h after pollination, respectively, but not thereafter. Pollen tube growth rate in the style increased quadratically with increasing temperature from 13 to 29 °C. ‘Manchurian’ was a more effective pollenizer of ‘Golden Delicious’ than was ‘Golden Delicious’ pollen. For example, at 24 or 29 °C, some ‘Manchurian’ pollen tubes grew to the base of ‘Golden Delicious’ styles by 24 h after pollination. On the other hand, no ‘Golden Delicious’ pollen tube grew to the base of a ‘Golden Delicious’ style regardless of temperature and time. Pollen tube growth rate in the style increased with increasing day/night temperature from 7/0 to 24/7 °C. The time required for pollen tubes to grow to the base of styles decreased with increasing day/night temperature from 13/2 to 24/7 °C. Only ≈36 h was required for pollen tubes to grow to the base of style at 24/7 °C, whereas pollen tubes grew very slowly and no pollen tubes grew to the base of style at 7/0 °C regardless of pollen source. LLS + FO, applied 4 or 24 h after pollination, inhibited pollen germination, pollen tube growth in the style, fertilization, and fruit set, but it had no effect when applied 48 h after pollination. These results suggest that LLS + FO applied at this bloom stage causes flower or fruit abscission most likely by inhibiting pollen germination, pollen tube growth in the style, and fertilization.

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Pollen Tube Growth and Fruit Set in Apple

HortScience ◽

10.21273/hortsci11511-16 ◽

2017 ◽

Vol 52 (8) ◽

pp. 1054-1059 ◽

Cited By ~ 4

Author(s):

Khalil R. Jahed ◽

Peter M. Hirst

Keyword(s):

Pollen Tube ◽

Pollen Tube Growth ◽

Pollen Germination ◽

Fruit Set ◽

Pollen Tubes ◽

Tube Growth ◽

Physiological Basis ◽

Golden Delicious ◽

Malus Floribunda ◽

Seed Crops

Pollination is an essential prerequisite for the production of many fruit and seed crops, including apple. In apple, successful fertilization requires pollen transfer to the stigma, pollen germination, and successful pollen tube growth resulting in fruit set. Precise selection of the most effective pollinizers for commercial orchards is not possible however, until these processes are more fully understood. The present study was undertaken to compare pollinizers in terms of pollen tube growth and fruit set. On trees of ‘Honeycrisp’, ‘Fuji’, and ‘Gala’ from which bees were excluded, flowers were hand-pollinated using pollen collected from crabapple (‘Ralph Shay’ or Malus floribunda), ‘Delicious’ and ‘Golden Delicious’. Flowers were harvested at one, two, three, and four days after pollination (DAP). Pollen source had a significant influence on pollen germination on the stigmatic surface, number of pollen tubes penetrating the stigma, distance of pollen tube growth down the style, and pollen tubes reaching the base of the style. In ‘Honeycrisp’ and ‘Gala’, ‘Golden Delicious’ pollen grew the fastest, followed by ‘Delicious’ and crabapple. Neither ‘Ralph Shay’ nor Malus floribunda were effective pollinizers for ‘Honeycrisp’ and resulted in low fruit set suggesting incompatibility may be involved. However, both these crabapples were effective pollinizers for ‘Fuji’ and ‘Gala’. These results indicate that pollen source can have a tremendous impact on pollen tube growth and fruit set. The physiological basis for these effects is not clear, but implications for pollinizer selection are obvious.

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Apple Pollen Tube Growth Rates Are Regulated by Parentage and Environment

Journal of the American Society for Horticultural Science ◽

10.21273/jashs03824-16 ◽

2016 ◽

Vol 141 (6) ◽

pp. 548-554 ◽

Cited By ~ 6

Author(s):

Candace N. DeLong ◽

Keith S. Yoder ◽

Leon Combs ◽

Richard E. Veilleux ◽

Gregory M. Peck

Keyword(s):

Growth Rate ◽

Pollen Tube ◽

Growth Rates ◽

Pollen Tube Growth ◽

Management Strategies ◽

Pollen Tubes ◽

Tube Growth ◽

Load Management ◽

Crop Load ◽

Pollen Tube Growth Rate

A greater understanding of apple (Malus ×domestica) pollen tube growth rates can improve crop load management in commercial orchards. Specifically, applications of caustic bloom-thinning chemicals need to occur when enough, but not too many, flowers have been fertilized to achieve crop load densities that balance yields with marketable fruit sizes. In this study, the pollen tube growth rates of five crabapple (Malus sp.) cultivars were measured in the styles of three maternal cultivars at 12, 18, 24, and 30 °C after 24 hours in a growth chamber. Pollen tube growth rates were greatest for ‘Selkirk’ and ‘Thunderchild’ at 12 °C, and greatest for ‘Indian Summer’, ‘Selkirk’, and ‘Thunderchild’ at 24 °C. Pollen tube growth increased with increasing temperatures until 24 °C. There were minimal pollen tube growth rate increases between 24 and 30 °C. Overall, ‘Snowdrift’ had the slowest pollen tube growth rate of the five evaluated crabapple genotypes. At 24 and 30 °C, ‘Indian Summer’ and ‘Thunderchild’ pollen tubes reached the base of the style most frequently, and ‘Snowdrift’ pollen tubes the least frequently. Pollen tube growth rate was also influenced by the maternal cultivar, with Golden Delicious having relatively faster pollen tube growth than Fuji at 24 and 30 °C. Interactions among paternal and maternal genotypes as well as temperature after pollination reveal complex biological and environmental relationships that can be used to develop more precise crop load management strategies for apple orchards.

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Pollen tube growth and fruit set in quince (Cydonia oblonga Mill.)

Spanish Journal of Agricultural Research ◽

10.5424/sjar/2020182-15551 ◽

2020 ◽

Vol 18 (2) ◽

pp. e0702

Author(s):

Aleksandar Radovic ◽

Radosav Cerovic ◽

Dragan Milatovic ◽

Dragan Nikolic

Keyword(s):

Pollen Tube ◽

Pollen Tube Growth ◽

Fruit Set ◽

Pollen Tubes ◽

The Self ◽

Tube Growth ◽

Open Pollination ◽

Self Pollination ◽

High Yields

Aim of study: To determine the self-compatibility level of eight quince cultivars.Area of study: The region of Belgrade (Central Serbia).Material and methods: Pollen tube growth in vivo and fruit set in two pollination variants (self- and open-pollination) were studied in eight quince cultivars. The quantitative parameters of pollen tube growth (average number of pollen tubes in the upper and middle third of the style, base of the style and in the ovary; the dynamics of pollen tube growth through these parts of the pistil) was determined using the fluorescence microscopy.Main results: The parameters of pollen tube growth and fruit set were primarily dependent on the genotype and variants of pollination. All studied parameters were significantly higher in the open-pollination variant compared with the self-pollination in all cultivars. In the self-pollination variant, ʻLeskovackaʼ and ʻVranjskaʼ had the highest number of pollen tubes that penetrated the ovary (2.10 and 0.54 in average, respectively), as well as the largest percentage of pistils with the penetration of pollen tubes in the nucellus of ovules six days after pollination (40.09% and 14.74%). Also, they had the highest percentage of initial fruit set (17.01% and 28.52%) and final fruit set (9.32% and 9.86%). Based on this, ʻLeskovackaʼ and ʻVranjskaʼ can be classified as self-compatible cultivars, while the others are self-incompatible.Research highlights: The majority of quince cultivars were self-incompatible. When establishing new orchards with these cultivars, care should be taken about the choice of pollenisers in order to achieve high yields.

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The Effect of Air Pollution on Developmental Stages and Pollen Germination, Pollen Tube Growth and Fruit Set of the Apple Cultivars ‘Golden Delicious’ and ‘Golab’

Gesunde Pflanzen ◽

10.1007/s10343-019-00468-4 ◽

2019 ◽

Vol 71 (4) ◽

pp. 237-247

Author(s):

Fatemeh Ahmadi ◽

Babak ValizadehKaji ◽

Ahmadreza Abbasifar

Keyword(s):

Air Pollution ◽

Pollen Tube ◽

Pollen Tube Growth ◽

Pollen Germination ◽

Fruit Set ◽

Developmental Stages ◽

Tube Growth ◽

Golden Delicious ◽

Apple Cultivars

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Heading Fruiting Shoots before Bloom Is Equally Effective as Blossom Removal in Peach Crop Load Management

HortScience ◽

10.21273/hortsci.37.4.642 ◽

2002 ◽

Vol 37 (4) ◽

pp. 642-646 ◽

Cited By ~ 5

Author(s):

Richard P. Marini

Keyword(s):

Prunus Persica ◽

Fruit Set ◽

Fruit Size ◽

Fruit Weight ◽

Load Management ◽

Full Bloom ◽

Crop Load ◽

Fruit Thinning ◽

Crop Density ◽

Net Profit

Three experiments were performed to determine if pruning treatments could reduce the need for peach [Prunus persica (L.) Batsch] fruit thinning without reducing average fruit weight. To determine if dormant shoot heading affected fruit size simply by reducing the number of flowers per tree, all 1-year-old shoots on `Cresthaven' trees were headed by 50% or blossoms were removed from the terminal half of each shoot. At 45 days after full bloom, all trees were hand-thinned to obtain predetermined crop densities. Average fruit weight was highest on trees with blossom removal, but crop value and net profit were highest for nontreated trees. To determine the influence of treatment severity on fruit weight, all shoots on `Cresthaven' trees were blossom-thinned or headed to remove blossoms on varying proportions of each shoot. Fruit set and the number of fruit removed during postbloom thinning decreased as the percentage of a shoot that was headed or blossom-thinned increased. Average fruit weight at harvest and crop value were higher for trees with blossom removal than for trees with headed shoots. Fruit weight and crop value were not affected by the percentage of the shoot treated. In the final experiment, all shoots on `Cresthaven' trees were headed by 50% or were not headed. Heading of shoots reduced fruit set, number of fruits removed at thinning, and thinning time per tree, but yield, crop density, and average fruit weight were not affected by heading. Profit was increased by shoot heading one of the 3 years. Results from this study indicate that heading peach shoots by 50% while dormant pruning can reduce thinning costs without reducing fruit size, but a similar level of labor-intensive blossom removal may reduce postbloom thinning costs and improve fruit size.

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STIGMATIC RECEPTIVITY AND POLLEN TUBE GROWTH IN RABBITEYE BLUEBERRY

HortScience ◽

10.21273/hortsci.40.3.891b ◽

2005 ◽

Vol 40 (3) ◽

pp. 891b-891

Author(s):

Patricio A. Brevis ◽

D. Scott NeSmith ◽

Hazel Wetzstein

Keyword(s):

Pollen Tube ◽

Pollen Tube Growth ◽

Fruit Set ◽

Pollen Tubes ◽

Tube Growth ◽

Limiting Factor ◽

Ripe Fruit ◽

Pollen Tube Growth Rate ◽

Growth Chambers ◽

Limiting Parameters

Effective pollination period (EPP) is the number of days during which pollination is effective to produce a fruit. The EPP is determined by ovule longevity, pollen tube growth rate and length of stigmatic receptivity. The objectives of this research were to establish the EPP of rabbiteye blueberry and to further the understanding of its limiting parameters. The experiments were conducted in growth chambers using blueberry plants of the cultivars Brightwell and Tifblue. Emasculated flowers were hand-pollinated at 0, 2, 4, 6, and 8 days after anthesis (DAA). Ripe fruit were harvested to record percentage fruit set. Stigmatic receptivity was evaluated as the number of germinated tetrads on the stigma 24 hours after pollination. Under day/night temperatures of 23/10 °C, the EPP was 7 days. Stigmatic receptivity was lowest on the day of anthesis and increased as flowers aged. Stigmatic receptivity was not positively correlated to fruit set, therefore, this parameter was not the most limiting factor of the EPP. Observations of pistils pollinated 3 DAA indicated that the fastest growing pollen tubes reached the bottom of the style 2 to 3 days after pollination. Self-pollination resulted in normal pollen tube growth in the style and inside the ovary. Self-pollen tubes were seen penetrating the micropile.

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Effects of Lime Sulfur and Fish Oil on Pollen Tube Growth, Leaf Photosynthesis and Fruit Set in Apple

HortScience ◽

10.21273/hortsci.41.2.357 ◽

2006 ◽

Vol 41 (2) ◽

pp. 357-360 ◽

Cited By ~ 10

Author(s):

Steven McArtney ◽

John Palmer ◽

Sue Davies ◽

Shona Seymour

Keyword(s):

Pollen Tube ◽

Fish Oil ◽

Pollen Tube Growth ◽

Fruit Set ◽

Pollen Tubes ◽

Tube Growth ◽

Dependent Manner ◽

Leaf Photosynthesis ◽

Total Carbohydrate ◽

Concentration Dependent Manner

The effect of liquid lime sulfur (LS) and fish oil (FO) application during bloom on leaf photosynthesis (Pn) and pollen tube growth in apple (Malus ×domestica) flowers were investigated in order to determine their mode of action as a bloom thinning agent. LS increased the percentage of flowers with fewer than 10 pollen tubes per flower to more than 64% compared to 5% or less in the control. Pollen tubes were completely absent from 27% to 48% of flowers following LS treatment compared with fewer than 4% of flowers having no pollen tubes on control trees. These data indicate that 30% to 50% of flowers that open on the day of LS application are unlikely to set a fruit due to the complete inhibition of embryo fertilization. Increasing the rate of LS from 0.5% to 4% increased the proportion of flowers with limited pollen tube number in a concentration dependent manner. LS suppressed the rate of light saturated Pn; successive LS sprays during the bloom period had an additive effect on suppression of Pn and fruit set. In one study the reduction in Pn was greatest 12 days after application of LS but Pn recovered by about 19 days after initial treatment. In a second study Pn of primary spur leaves had still not recovered when measured 57 days after the first of three applications. FO had no effect on the number of pollen tubes per flower, but reduced Pn and fruit set by about 10% and 20% respectively. An increase in the proportion of flowers with no pollen tubes, and therefore no embryo development, can account, at least in part, for the thinning response following application of LS to apples during bloom. It is likely that suppression of Pn contributes to the thinning response, although the importance of this mechanism will depend on perturbation of the total carbohydrate supply to developing fruit.

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Hyperoside promotes pollen tube growth by regulating the depolymerization effect of actin-depolymerizing factor 1 on microfilaments in okra

Horticulture Research ◽

10.1038/s41438-021-00578-z ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Biying Dong ◽

Qing Yang ◽

Zhihua Song ◽

Lili Niu ◽

Hongyan Cao ◽

...

Keyword(s):

Pollen Tube ◽

Pollen Tube Growth ◽

Pollen Germination ◽

Pollen Tubes ◽

Tube Growth ◽

Actin Depolymerizing Factor ◽

Specific Mechanism ◽

Promoting Effect ◽

New Research

AbstractMature pollen germinates rapidly on the stigma, extending its pollen tube to deliver sperm cells to the ovule for fertilization. The success of this process is an important factor that limits output. The flavonoid content increased significantly during pollen germination and pollen tube growth, which suggests it may play an important role in these processes. However, the specific mechanism of this involvement has been little researched. Our previous research found that hyperoside can prolong the flowering period of Abelmoschus esculentus (okra), but its specific mechanism is still unclear. Therefore, in this study, we focused on the effect of hyperoside in regulating the actin-depolymerizing factor (ADF), which further affects the germination and growth of pollen. We found that hyperoside can prolong the effective pollination period of okra by 2–3-fold and promote the growth of pollen tubes in the style. Then, we used Nicotiana benthamiana cells as a research system and found that hyperoside accelerates the depolymerization of intercellular microfilaments. Hyperoside can promote pollen germination and pollen tube elongation in vitro. Moreover, AeADF1 was identified out of all AeADF genes as being highly expressed in pollen tubes in response to hyperoside. In addition, hyperoside promoted AeADF1-mediated microfilament dissipation according to microfilament severing experiments in vitro. In the pollen tube, the gene expression of AeADF1 was reduced to 1/5 by oligonucleotide transfection. The decrease in the expression level of AeADF1 partially reduced the promoting effect of hyperoside on pollen germination and pollen tube growth. This research provides new research directions for flavonoids in reproductive development.

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