Asian Pear Research Articles

Occurrence of Anthracnose on Fruits of Asian Pear Tree Caused by Colletotrichum acutatum

Anthracnose symptoms often occurred on fruits of Asian pear trees grown in Anseong, Naju, Seonghwan and Pyeongtaek in Korea during the harvesting period from 2000 to 2005. A total of 28 isolates of Colletotrichum sp. were obtained from the anthracnose symptoms. Ail the isolates were identified as Colletotrichum acutatum based on their morphological and cultural characteristics. Four isolates of the fungus were tested for pathogenicity to fruits of Asian pear tree by artificial inoculation. All the isolates induced anthracnose symptoms on the fruits by wound inoculation but not by unwound inoculation. The anthracnose symptoms induced by artificial inoculation were similar to those observed in the orchard. This is the first report of anthracnose of Asian pear tree caused by Colletotrichum acutatum.

The use of sap flow measurements for scheduling irrigation in olive, apple and Asian pear trees and in grapevines

We evaluated three approaches for scheduling irrigation in wine grape vineyards and in olive, apple and Asian pear tree orchards, based on sap flow measurements and models of plant transpiration. In the first approach, we analysed how the shape of the sap-flow profile changed in response to root-zone soil water conditions and potential evaporative demand. The second approach was based on a transpiration ratio, as defined from the actual daily water use of a target plant divided by the potential daily water use of similar-sized plants under non-limiting soil water conditions (“well-irrigated” plants). Values of the actual plant water use were always determined from measured sap flow. Two independent methods were assessed for the calculation of potential plant water use; either sap flow was measured in well-irrigated plants or we used a leaf-area based model of plant transpiration. On some occasions water stress was found to modify the shape of the sap velocity profile. However, most of the time the velocity profile was found to be an insensitive indicator for triggering irrigation. The transpiration ratio method, using measured sap flow in well-irrigated plants, was more useful for irrigation scheduling, at least for the two species (i.e. olive and grape) that were investigated here. Nonetheless, realization of such an approach in a commercial orchard may not be practical due to problems associated with irrigation management e.g. excessive vegetative growth may occur on the reference plants over time. Besides, irrigating the orchard to maintain non-limiting soil water conditions is not always the best option for water and nutrient management. The alternative transpiration ratio method based on a leaf-area based model of plant water use, yielded the best results. Modelled transpiration rates always provided reliable information not only for well-irrigated plants, but also for deficit-irrigated plants. This result lends support to the use of the method for irrigation scheduling of vineyard and orchard trees. However, the use of models does require detailed microclimate data as well as a user-friendly technique to quantify plant leaf area. From a practical viewpoint the method should encompass the spatial variability of the soil and plants within the orchard. Accurate quantification of these factors is a cornerstone of precision horticulture and such information would help to minimise risks associated with insufficient as well as excessive irrigation applications.

Ultrastructural study on scab resistance expressed in epidermal pectin layers of pear leaves

Proliferation and collapse of subcuticular hyphae of Venturia nashicola race 1 were studied ultrastructurally, after inoculation of susceptible Japanese pear cv. Kousui, resistant Japanese pear cv. Kinchaku, resistant Asian pear strain Mamenashi 12 and nonhost European pear cv. Flemish Beauty leaves, to understand the nature of the resistance mechanism. After cuticle penetration by the pathogen, the hyphae were observed at lower frequency in epidermal pectin layers and middle lamellae of leaves of the three resistant plants than in those of susceptible ones. This result suggested that fungal growth was suppressed in the incompatible interaction between pear and V. nashicola race 1. In the pectin layers of all inoculated plants, some hyphae had modifications such as breaks in the plasmalemma with plasmolysis, necrotic cytoplasm and degraded cell walls. More hyphae had collapsed in the leaves of the three resistant plants than in those of the susceptible cv. Kousui. In collapsed hyphae, the polymerized cell walls broke into numerous fibrous and amorphous pieces, showing that the scab resistance might be associated with cell wall-degrading enzymes from pear plants.

Characterization of a leucine-rich repeat receptor-like protein kinase (LRPK) gene from Japanese pear and its possible involvement in scab resistance

A gene encoding a leucine-rich repeat receptor-like protein kinase (LRPK) was identified from Japanese pear (Pyrus pyrifolia var. culta) using reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) PCR. The Japanese pear LRPKp protein was composed of a leucine-rich extracellular ligand-binding domain, a transmembrane-spanning segment, and a cytoplasmic kinase domain; it had the highest sequence homology with apple LRPKm and Arabidopsis receptor-like protein kinase (RLK). Southern blot analysis revealed that the LRPKp belongs to a multigenic family, and a polymorphism in restriction fragment length was observed among Asian and European pear cultivars. The LRPKp transcripts were present at a high level in leaves and at a low level in flowers, while no expression was detected in fruits. The expression pattern of LRPKp was also studied by real-time RT-PCR in the scab susceptible cv. Kousui and resistant cvs. Kinchaku and Flemish Beauty after challenge inoculation with Venturia nashicola, the causal agent of Japanese pear scab. Transcripts of LRPKp were transiently enhanced in both the susceptible Kousui and to a great extent in the non-host-resistant Flemish Beauty. However, in resistant Kinchaku, expression of this gene was only weakly enhanced. Moreover, treatment with a resistance inducer, acibenzolar-S-methyl (ASM), which significantly reduces scab severity on potted trees of Kousui, was also able to induce and to potentiate the expression of this gene after inoculation. This suggests that the LRPKp gene is possibly involved in ASM-induced resistance.

‘Hanhong’ Pear

‘Hanhong’ (Pyrus ussuriensis Maxim × P. bretschneideri Rehd.) is a new high-quality Asian pear with excellent firmness and crispness and a long shelf life. Fruit of ‘Hanhong’ are very attractive and the tree is very winter-hardy. The fruit and leaves are resistant to pear scab (Venturia pirina Aderh) and black spot (Alternaria kikuchiana Tannka) disease.

Genetic diversity and similarity of pear (Pyrus L.) cultivars native to East Asia revealed by SSR (simple sequence repeat) markers

Simple sequence repeat (SSR) markers were used to assess genetic diversity and relationship of Pyrus L. cultivars native mainly to East Asia. A total of 168 putative alleles were generated from six primer-pairs (BGA35, KU10, BGT23b, NH004a, NH011b and NH015a). All the SSR markers showed a high level of genetic polymorphism with a mean of 28 putative alleles per locus and the heterozygosity of 0.63. The Dice’s similarity coefficient between cultivars ranged from 0.02 to 0.98 and Occidental pears generally had low affinities to Asian pears. Ten major groups were generated from all the accessions by UPGMA clusters analysis. Chinese sand pears consisted of four groups with Chinese white pears and Japanese pears, of which Chinese sand pears occurred in all four groups, presenting a large genetic diversity, Chinese white pears were included in three groups, and Japanese pears only fell into one group. In the dendrogram, Chinese sand pears and Chinese white pears did not form discrete group, even subgroups. Some Japanese pear cultivars had high affinities to Chinese sand pear cultivars. These findings supports the authors’ previous viewpoints of Chinese white pears as a variety or an ecotype of Chinese sand pears (P. pyrifolia var. sinensis (Lindley) Y. Teng et K. Tanabe) and the progenitor of Japanese pears coming from China. Cultivars of P. ussuriensis Maxim. were clustered together with one clone of P. hondoensis Nakai et Kikuchi, a relative species of P. ussuriensis. Cultivars of P. communis L. and other Occidental species formed three independent groups and were distant from most Asian pears, except for P. betulaefolia Bge.

Gymnosporangium spp. (non‐European)

<i>Gymnosporangium</i> spp. (non‐European)

Genetic differences between blight-causing Erwinia species with differing host specificities, identified by suppression subtractive hybridization.

PCR-based subtractive hybridization was used to isolate sequences from Erwinia amylovora strain Ea110, which is pathogenic on apples and pears, that were not present in three closely related strains with differing host specificities: E. amylovora MR1, which is pathogenic only on Rubus spp.; Erwinia pyrifoliae Ep1/96, the causal agent of shoot blight of Asian pears; and Erwinia sp. strain Ejp556, the causal agent of bacterial shoot blight of pear in Japan. In total, six subtractive libraries were constructed and analyzed. Recovered sequences included type III secretion components, hypothetical membrane proteins, and ATP-binding proteins. In addition, we identified an Ea110-specific sequence with homology to a type III secretion apparatus component of the insect endosymbiont Sodalis glossinidius, as well as an Ep1/96-specific sequence with homology to the Yersinia pestis effector protein tyrosine phosphatase YopH.

Microsatellites are Used to Examine Apple and Pear Identities and Genetic Relationships

Simple Sequence Repeat (SSR) markers developed in apple and pear were used to determine genetic relationships among heritage apple and pear cultivars from Portugal's Azore Islands, and to develop identity fingerprints for European and Asian pear accessions at the USDA–ARS National Clonal Germplasm Repository (NCGR). We used 11 SSR markers (six from apple and five from pear) to examine 18 heritage apple and 9 heritage pear cultivars from the Azores. Eight additional Portuguese and economically important cultivars of apple and eight of pear were used as standards. Cluster analysis separated the apple and pear accessions into two distinct groups. Among apple genotypes, 12 unique accessions and five groups of synonyms were identified, while, in pear, seven unique genotypes and three pairs of synonyms were found. None of the accessions obtained from the Azores corresponded to widely grown standard Portuguese apple or pear cultivars. To examine 144 NCGR pear accessions, we used nine polymorphic SSR loci that were developed from GenBank sequences. Cluster analysis identified five sets of synonyms (four in P. communis L. and one in P. ussuriensis Maxim.) and four pairs of homonyms (three in P. communis and one in P. pyrifolia Burm. f. Nakai), and confirmed three clonal sets. Morphological evaluations and additional SSR markers will be used to confirm these results, and to genetically document the identities of pear genotypes. SSR markers will greatly assist the management of ex situ pome fruit germplasm collections by helping to eliminate duplicate accessions and expanding the genetic diversity represented.

(95) Fruit Characteristics, Phenolic Compound, and Antioxidant Activity of Asian Pear Fruit from an Organically Cultivated Orchard

Pear (Pyrus pyrifolia) fruits of `Whangkeumbae' were produced from the organic orchard at Yongam, southwestern Korea, which was managed by spraying with chitin incubated solution (CIS) 15 times from petal fall stage, mid-April to late August, to control pests and diseases during the growing season. The CIS contained about 50 kinds of chitin digestive and/or effective microorganisms and other organic/inorganic biologically active substances by incubating the mixtures at 30 °C for 7 days. The soil had standard levels of chemical and physical properties in Korea, as well as 3.0% to 4.0% organic matter. The organic fruits showed higher soluble solid contents, and fruit firmness was increased in comparison to conventional fruits. The organic fruit skin changed in color from yellow to brown, and black spot occurred; however, there was no difference in flesh tissues in terms of colors and textures. The phenolic compounds were significantly increased in organic fruits and leaves, with especially higher levels for fruit skin than for flesh tissues. Free radical levels dropped sharply in organic fruit, but slowly in conventional fruits. The results showed that the organic pear fruits have higher levels of antioxidant activity, and also showed the phenomena related to the change in fruit skin color from yellow to brown.

HYBRIDS OF EUROPEAN AND NASHI PEARS: A NEW FRUIT FOR EUROPE?

In the attempt to combine the positive characteristics of European pears (P. communis) and Asian pears (P. pyrifolia), crossings were made in 1993 and 1994 to create a new pear type for the fresh fruit market in Europe. Approximately 10 hybrids of the crossing P. communis 'Harrow Sweet' × P. pyrifolia 'Nijisseiki' show promising characteristics worth further investigation. Five of these interspecific hybrids are described in respect to external and internal fruit quality parameters. In addition, a sensory evaluation was carried out between the fruit of European pears, Nashis and the interspecific hybrids. This first study shows a higher consumer acceptance of the hybrids in terms of aroma, acidity and general popularity in comparison to the two other species. These first results indicate a potential for market diversification. The requirements for producing, trading and marketing of the new fruit will be discussed.

European and Asian Pears: Simple Sequence Repeat–Polyacrylamide Gel Electrophoresis-based Analysis of Commercially Important North American Cultivars

The genus Pyrus (pear) includes species and cultivars of great diversity. We have tested the feasibility of a polyacrylamide gel eletrophoresis (PAGE)-based +/– simple sequence repeat (SSR) screen as a means of defining relationships amongst pears of commercial importance in North America. The screen included 28 pear accessions, including economically important cultivars, numbered selections from breeding programs and interspecific hybrids. It relied on 18 SSR primer pairs, each of which produced polymorphic banding patterns in all the genotypes examined. Fragments were scored for presence or absence within genotypes. The results show that amplification and analysis of a small number of SSR loci enable identification of cultivars and reasonable definition of genetic relationships in North American pears. Seven primer pairs were sufficient to distinguish the 28 pear cultivars. Analyses using both distance and parsimony criteria grouped cultivars in a manner consistent with known pedigrees and sites of origin.

Effect of Particle Size and Quality of Pruning Wood Residues of Asian Pear (Pyrus pyrifolia and Pyrus communis) On C-And N-Mineralisation in Soils of Contrasting Textures

A laboratory incubation study (22 o C ± 2 oC) with pruning residues of Asian pear (P. pyrifolia, cv. Hosui) was carried out to determine the effects of residue particle size (< 0.5 mm, 0.5-2 mm and 2-4 mm), residue quality (defined as C-to-N ratio, and total fibre content of each size class) and soil texture on C- and N-mineralisation in two Chilean soils. Particle size had a significat impact on C-mineralisation; however, no differences were observed for N-mineralisation. After 10 days of incubation, particles < 0.5 mm evolved more C-CO 2 than medium (0.5-2 mm) and coarse particles. Thereafter, no significant (P < 0.05) differences were observed for the smaller particles, while coarse sizes showed low C-CO 2 evolution during the all incubation period, except at the last sampling where C-CO 2 tended to be similar than < 0.5 and 2-4 mm particles. The higher C-CO 2 evolved from the smallest particles coincided with their low C-to-N ratio and low fibre content. There was no effect of soil texture on C and N-mineralisation. These results were explained on the basis of residue quality rather than soil type.

Balanço de carboidratos em gemas florais de dois genótipos de pereira sob condição de inverno ameno

As pereiras européias e asiáticas, cultivadas sob condições de inverno ameno, como na região Sul do Brasil, apresentam problemas de adaptação. Durante o inverno, as oscilações térmicas e o baixo acúmulo de frio têm sido referidos por alguns autores como causas do abortamento de gemas florais. O objetivo deste trabalho foi determinar o balanço de carboidratos em tecidos de gemas florais de duas cultivares de pereiras: Kieffer (P. communis x P. pyrifolia) e Housui (P. pyrifolia). Os tecidos de gemas florais e da base de gemas foram coletados mensalmente, de fevereiro a setembro de 2002, de plantas de pomar da Embrapa Clima Temperado, Pelotas-RS, coordenadas 32°51' S e 52°21'O, localizado a 230 metros de altitude. O material vegetal foi analisado separadamente quanto às concentrações de açúcares solúveis (por cromatografia gasosa) e porcentagens de amido (por espectrofotometria). Em ambas as cultivares, observou-se que a base da gema é um importante local de reserva. Ocorreram significativos aumentos de açúcares solúveis nas gemas das duas cultivares na fase que antecede a brotação. Em setembro, os açúcares solúveis totais na matéria seca (MS), nas gemas florais da cv. Housui (38,33 mg g-1), foram menores do que os observados nos tecidos da cv. Kieffer (50,39 mg g-1), cultivar melhor adaptada às condições climáticas. O açúcar-álcool sorbitol, seguido da sacarose, foi o açúcar solúvel mais abundante nos tecidos das duas cultivares.

Diagnóstico biológico e molecular e análise da seqüência de nucleotídeos do gene da proteína capsidial de um isolado do Apple stem pitting virus

O Apple stem pitting virus (ASPV) foi detectado por RT-PCR em amostras de cultivares de pereiras européias (Pyrus communis L.) cvs. Starkrimson e Abate Fetel, e asiáticas (P. pyrifolia var. culta) cvs. Kousui e Housui coletadas no início do outono de 2003 em pomar da Estação Experimental da Embrapa Uva e Vinho, Vacaria, RS. Utilizando várias combinações de oligonucleotídeos, foram amplificados fragmentos de DNA de 269 e 1554 pb, este último contendo o gene completo (1131 nt) da proteína capsidial do ASPV. Outro fragmento amplificado de 291 pb compreende parte do gene da polimerase viral. Estes fragmentos constituem-se em um excelente instrumento de diagnóstico do ASPV em pereiras. A comparação das seqüências de nucleotídeos do gene da proteína capsidial do ASPV com seqüências do banco de dados GenBank, revelou identidades de 89% com seqüências de um isolado alemão de macieira e de 85 a 88% com isolados poloneses, de pereiras. A indicadora herbácea Nicotiana occidentalis cv. 37B, inoculada mecanicamente com extrato foliar da cv. Housui, apresentou lesões locais necróticas, necrose foliar marginal e das nervuras. O ASPV também foi detectado por dot-ELISA nas cvs. Abate Fetel e Kousui, na cv. Starkrimson por imunoblot, e em Pyronia veitchii (Trabut) Guill. por enxertia de borbulhas da cv. Abate Fetel infetada.

Hosts of Plum Curculio,Conotrachelus nenuphar(Coleoptera: Curculionidae), in Central Georgia

Potential host plants for the larvae of plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), in central Georgia's peach producing region were surveyed. This fruit-attacking curculionid is reported to have a broad host range, including many plants in the Rosaceae and other families. However, our collections indicated that in this region plum curculio largely is limited to peach (Prunus persica) and plum (P. angustifolia and P. umbellata). Abandoned peach orchards and wild plum thickets are important hosts for the spring generation of plum curculio and are sources of subsequent infestations of managed peach orchards. However, only abandoned peach orchards were available to the summer generation of plum curculio. May haw, Crataegus aestivalis, was also a host, but other species of Crataegus were not used. Although the plum curculio was reported to be a significant pest of blueberries (Vaccinium spp.) in North Carolina, New Jersey, and Delaware, they were only rarely used as a host in central Georgia. Apple (Malus domestica) and Asian pear (Pyrus pyrifolia), when available, were ovipositional hosts of plum curculio in central Georgia; however, no larvae emerged from these hosts. We report the first records of plum curculio developing in Vaccinium stamineum and Vitis rotundifolia. Our results are compared with a previous survey conducted in the northeastern United States, as well as to data reported in the literature.

Native Mediterranean Pyrus Rootstock, P. amygdaliformis and P. elaeagrifolia, Present Higher Tolerance to Salinity Stress Compared with Asian Natives

The salt tolerance of native Asian pear species, Pyrus betulaefolia Bunge., P. pyrifolia Nakai, and P. xerophila Yu, and native Mediterranean ones, P. amygdaliformis Vill. and P. elaeagrifolia Pall., were examined by irrigating them with 75 mM and 150 mM NaCl solutions for 30 days. Native Mediterranean species did not develop leaf injury during the 30-day NaCl treatments, but native Asian species developed leaf injury. Concerning the shank, fine roots, and whole plant, bioregional differences in Na and Cl contents were small. However, the Na and Cl contents of the leaves of native Mediterranean species were markedly less than those of native Asian species in both NaCl concentrations. Therefore, the native Mediterranean P. amygdaliformis and P. elaeagrifolia may have some salt exclusion mechanisms in the shank which restrict Na and Cl transport to the leaves. The stem water potential and Ci/Ca ratios were decreased by NaCl treatments in native Mediterranean and native Asian species. Thus, the photosynthetic decline by NaCl treatment observed in these species might have been caused by stomatal closure, which is likely to be induced by decreased water potential in the plant body. However, the photosynthetic rate of native Mediterranean species under NaCl stress was higher than native Asian species. Therefore, low concentrations of Na and Cl in the leaves of native Mediterranean species might prevent crucial decreases of photosynthetic rates under NaCl stress. The present results imply that native Mediterranean P. amygdaliformis and P. elaeagrifolia have a higher salt tolerance than native Asian P. betulaefolia, P. pyrifolia and P. xerophila. These native Mediterranean species would be useful in providing genetic resources as salt-tolerant rootstock for the Japanese pear.

Responses of Two Asian Pear Rootstocks (Pyrus spp.) to Fe-deficiency Chlorosis Induced by Addition of Bicarbonate to Nutrient Solution

To evaluate the tolerance of two Asian pear rootstock species, Pyrus xerophila Yü and Pyrus betulaefolia Bunge, to lime-induced Fe chlorosis, seedlings were grown in a nutrient solution with or without bicarbonate. After 20 days in the bicarbonate solution, P. betulaefolia seedlings became chlorotic, a symptom of Fe-deficiency, whereas those of P. xerophila did not. Leaves of the P. xerophila had higher chlorophyll (SPAD value) while the stem amassed more Fe than did those of P. betulaefolia, which indicates that the former may be more tolerant to lime-induced Fe chlorosis than may be the latter. Furthermore, higher Fe3+-chelate reductase activity in root tips was observed in two pear rootstocks grown in the bicarbonate solution; seedling of P. xerophila had twice the activity than had those of P. betulaefolia seedlings. Hence, we propos that Fe3+-chelate reductase activity in roots tips may be a useful physiological index to select rootstock genotypes that are tolerant to Fe-deficiency chlorosis.

Photosynthetic gas exchange characteristics in three different almond species during drought stress and subsequent recovery

Three different drought stress levels (water potential of the nutrient solution, Ψ s = −0.6, −1.2 and −1.8 MPa, respectively), and a control treatment ( Ψ s = −0.1 MPa), were applied during 2 weeks to three almond species, followed by 3 weeks of recovery. The selected test species were Prunus dulcis (Miller) D.Webb (bitter almond) and two wild almond species, P. lycioides (Spach) C.K. Schneider and P. scoparia (Spach) C.K. Schneider. All three are species native to Iran, and can be used as rootstock, but only P. dulcis is actually used for commercial almond production. In the absence of drought stress, maximum net assimilation rate ( A max) is highest for P. scoparia and lowest for P. dulcis. For all species A max was above 16 μmol CO 2 m −2 s −1. A similar relationship between A max and dark respiration rate ( R d), was observed for all species. This relationship suggests that optimisation of the carbon budget is independent of species. The three investigated species seem to have a different reaction to a similar stress, indicating different drought stress coping strategies. P. scoparia lost all its leaves during the experiment, while P. lycioides only kept some leaves, however, the remaining leaves were almost totally wilted and did not allow for any photosynthesis measurement. P. scoparia did not recover during the experiment, as no new leaves were developed once Ψ s was restored to pre-drought stress levels. However, this species has green stems, indicating that stem photosynthesis might play an important role in the plants’ overall carbon balance. This species is an opportunistic one ( sensu [Higgins, S.S., Larsen, F.E., Bendel, R.B., Radamaker, G.K., Bassman, J.H., Bidlake, W.R., Alwir, A., 1992. Comparative gas-exchange characteristics of potted, glasshouse-grown almond, apple, fig, grape, olive, peach and Asian pear. Sci. Hortic. 52 (4), 313–329]), where assimilation is seriously limited by non-stomatal processes as evidenced by measurements of intercellular CO 2 concentration, eventually resulting in total leaf loss. All P. lycioides leaves almost completely wilted during the experiment, but this species recovered rather quickly. Leaves, newly formed at the end of the experiment, obtained maximal assimilation rates under control Ψ s levels, equivalent to those measured in the control treatment. Finally, P. dulcis did keep at least part of its leaves during drought stress. However, assimilation rates after 2 weeks of drought treatment and 3 weeks of recovery were only about half of those measured in the control treatment. Of the three investigated species, non-stomatal limitation of assimilation seems to be the least important in P. dulcis. Intrinsic water use efficiency, defined as the ratio of assimilation rate over stomatal conductance, increased for P. dulcis with increasing drought stress, while a different pattern was observed for P. lycioides and P. scoparia, indicating non-stomatal processes prevail over stomatal limitations of the assimilation process. It was concluded that P. dulcis is the species most tolerant to drought. P. scoparia tries to avoid drought, whereas P. lycioides has an intermediate behaviour. Besides P. dulcis, also P. lycioides seems to have some potential for use as rootstock for commercial almond production.

(338) Effect of Germanium Supply by Trunk Injection on Tree Growth and Fruit Quality of `Niitaka' Asian Pear (Pyrus pyrifolia)

Many trials to supply germanium to fruit have been carried out since tests have confirmed germanium's role as a medical substance. Supplying germanium in orchards by soil and foliar application was not effective because of loss from rainfall. In order to increase germanium absorption by fruit, this study carried out tree trunk injections during the growing season. Two types of germanium, GeO (inorganic type) and Ge-132 (organic type), in concentrations of 5, 10, 25, and 50 mg·L–1 were supplied to `Niitaka' pear trees by trunk injection (1.5 L/tree), four times at 15-day intervals from June 2004. The treatment with 50 mg·L–1 GeO showed decreased fruit weight, but 50 mg·L–1 Ge-132 showed no difference to the control and other treatments. Fruit lenticels were increased in size by all of the Ge treatments in comparison to control fruit. Soluble solids as well as Hunter value `a' of the fruits of all Ge treatments were higher than that of the control. Flesh browning after peeling the fruit was delayed by the germanium treatment, and polyphenoloxidase (PPO) activities were lowered. Postharvest potentials were maintained at high levels for fruit firmness, physiological disorders, and decayed fruit during cold storage at 0 to 1 °C for 2 months.