The response of ‘Hosui’ Japanese pear to time of hand thinning and chemical thinning agents

Burge, G. K.; Spence, C. B.; Dobson, B.G.

doi:10.1016/0304-4238(91)90069-b

Cited by 4 publications

(11 citation statements)

References 9 publications

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“…Ethephon is an effective chemical thinner of Japanese pear, but it decreases fruit weight by 10-20% (Burge et al, 1991;Kaneko and Sakamoto, 1977). In our experiments, there was no significant difference in fruit weight at harvest between PDJ treatments and the control.…”

Section: Discussionmentioning

confidence: 99%

“…In apple (Yokota, 1988) and satsuma mandarin (Kamuro and Hirai, 1982), chemical thinning is successfully done in commercial orchards in Japan. In Japanese pear, the thinning effects of bendroquinone (Miki et al, 1981), lecithin (Yamazaki et al, 1987), ethephon (Burge et al, 1991;Kaneko and Sakamoto, 1977;Kim et al, 1988), and calcium formate (Hiratsuka et al, 2002) have been studied. However, at present, there are no thinners that can be used commercially for Japanese pears.…”

Section: Introductionmentioning

confidence: 99%

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Thinning Effect of Jasmonic Acid Derivative, n-Propyl Dihydrojasmonate on Japanese Pear ‘Hosui’

Ohkawa¹,

Ohara²,

Kurita³

et al. 2006

J. Japan. Soc. Hort. Sci.

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The fruit thinning effect of Jasmonic acid derivative, n-propyl dihydrojasmonate (PDJ) on Japanese pear 'Hosui' was investigated. During the 1996 season, PDJ at 500, 1000, or 2000 ppm was applied to flower clusters at 17 or 12 days before full bloom (DBFB), at full bloom (FB), or at 7 days after full bloom (DAFB). During the 1998 season, PDJ at 500 or 750 ppm was applied to the whole tree at 18 or 14 DBFB. All PDJ treatments before full bloom induced fruit abscission and resulted in a thinning effect. The best results were obtained with 500 to 750 ppm PDJ applied at 17 or 18 DBFB. In these treatments, the proportion of clusters that had two or fewer fruits was about 64%, compared to the control which was 16%. In addition, the position of dropped fruit on the inflorescence axis in a cluster differed among treatments. In PDJ treatment, from the 1st to 3rd fruits from the base of the floral axis in the cluster tended to abscise easily. Abscission of the 1st and 2nd basal fruits was observed in about 90% of the clusters. There were no significant differences in fruit weight, flesh firmness, brix, and titratable acidity at harvest. PDJ did not inhibit pollen tube growth in the style of the pistil, but in flowers treated with PDJ there were many abnormal ovules at FB. These findings indicate that an application of PDJ at 500 or 750 ppm, 17-18 DBFB budbreak has a consistently good thinning effect. Histological examinations revealed that PDJ causes fruit thinning by preventing fertilization and/or causing seed abortion.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thinning Effect of Jasmonic Acid Derivative, n-Propyl Dihydrojasmonate on Japanese Pear ‘Hosui’

Ohkawa¹,

Ohara²,

Kurita³

et al. 2006

J. Japan. Soc. Hort. Sci.

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“…The relationship between fruit size during the growing season and size at harvest is well-known; small fruit will never catch up in size to larger fruit [14,69]; hence, the basis for hand thinning should be fruit size rather than spacing. In nashi, the benefits of early thinning were noted by Burge et al [70], who reported a 17% increase in fruit size following flower thinning but no increase in trees thinned 26 days after full bloom (dAFB). However, McArtney and Wells [71] found that hand thinning as late as 56 dAFB, leaving one fruitlet at each fruiting site, increased fruit weight of 'Nijisseiki' and 'Hosui' and increased return bloom in 'Hosui'.…”

Section: Hand Thinningmentioning

confidence: 91%

“…In New Zealand trials on nashi, the application of 600 mg L −1 ethephon applied 9 dBFB has been shown to reduce fruit set in 'Hosui', but 300 mg L −1 had no thinning effect [70]. These authors also reported that Kim et al [86] found a greater thinning response to ethephon applied 14 and 21 dAFB than earlier applications at FB or 7 dAFB on 'Chojuro'.…”

Section: Ethephonmentioning

confidence: 96%

Crop Load Management in Nashi Pear—A Review

Bound

2022

Horticulturae

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Most nashi cultivars require heavy thinning, and this has traditionally been performed by the time and labour-intensive practice of hand thinning. Crop load management is a key cost driver for nashi production, but there are limited cost-effective options available for nashi growers compared to other pome fruit, especially apples and, to a lesser extent, European pears. There is, however, potential to adapt some of the thinning tools and techniques used in apples and European pears to reduce the labour requirements and high cost of thinning in nashi, thus improving industry profitability. Several chemical thinning agents have potential for nashi, and an understanding of the optimal application rates, times and weather conditions for each chemical, as well as the conditions/factors that impact the tree carbon balance, will improve the predictability of chemical thinning. However, it is difficult to target specific flowers/fruitlets within a cluster with chemicals, and the flowers that produce the preferred fruit shape and size are in the middle of the flower cluster. Mechanical thinning during the flowering period with either Darwin or BAUM-style string thinners has potential, particularly as these devices can be used as early as flower emergence. As for chemical thinning, the issue of non-selectivity needs to be addressed; however, the development of mechatronic systems should overcome most problems that occur with the currently available mechanical thinners. Shading at critical times is an avenue that could be explored further to ascertain the critical stage when developing fruit are susceptible to enable the determination of the optimal timing and duration of shading. Targeted pruning and bud thinning during the dormant winter period to reduce the floral bud numbers is a valuable option for the precise placement of fruit in optimal positions and to set up the required number of clusters. This review highlighted several tools/techniques that, with further work, can be incorporated into a systematic approach to crop load management in nashi while reducing the risk and cost.

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“…For example, carbaryl was a standard thinner for apple production in many countries, but it caused severe environmental problems and hence was banned in some countries (Bound, 2006 ). Ethephon is a chemical thinner of Japanese pear, but it was reported to cause fruit weight decrease by 10–20% (Burge et al, 1991 ). Therefore, new effective flower or fruit thinning techniques, which have no detrimental effects and meet modern environmental and food quality guidelines, are required.…”

Section: Introductionmentioning

confidence: 99%

5-Aminolevulinic Acid Thins Pear Fruits by Inhibiting Pollen Tube Growth via Ca2+-ATPase-Mediated Ca2+ Efflux

Duan

et al. 2016

Front. Plant Sci.

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Chemical fruit thinning has become a popular practice in modern fruit orchards for achieving high quality fruits, reducing costs of hand thinning and promoting return bloom. However, most of the suggested chemical thinners are often concerned for their detrimental effects and environmental problems. 5-Aminolevulic acid (ALA) is a natural, nontoxic, biodegradable, and environment-friendly plant growth regulator. One of its outstanding roles is improving plant photosynthesis and fruit quality. Here, results showed that applying 100–200 mg/L ALA at full bloom stage significantly reduced pear fruit set. Both in vivo and in vitro studies showed that ALA significantly inhibited pollen germination and tube growth. ALA decreased not only cytosolic Ca2+ concentration ([Ca2+]cyt) but also “tip-focused” [Ca2+]cyt gradient, indicating that ALA inhibited pollen tube growth by down-regulating calcium signaling. ALA drastically enhanced pollen Ca2+-ATPase activity, suggesting that ALA-induced decrease of calcium signaling probably resulted from activating calcium pump. The significant negative correlations between Ca2+-ATPase activity and pollen germination or pollen tube length further demonstrated the critical role of calcium pump in ALA's negative effect on pollen germination. Taken together, our results suggest that ALA at low concentrations is a potential biochemical thinner, and it inhibits pollen germination and tube growth via Ca2+ efflux by activating Ca2+-ATPase, thereby thinning fruits by preventing fertilization.

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The response of ‘Hosui’ Japanese pear to time of hand thinning and chemical thinning agents

Cited by 4 publications

References 9 publications

Thinning Effect of Jasmonic Acid Derivative, n-Propyl Dihydrojasmonate on Japanese Pear ‘Hosui’

Thinning Effect of Jasmonic Acid Derivative, n-Propyl Dihydrojasmonate on Japanese Pear ‘Hosui’

Crop Load Management in Nashi Pear—A Review

5-Aminolevulinic Acid Thins Pear Fruits by Inhibiting Pollen Tube Growth via Ca2+-ATPase-Mediated Ca2+ Efflux

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