Pear (Pyrus L.) Genetic Resources from Northern Japan: Organoleptic Evaluation of Ornamental Pear Trees K. Yamada1, C. Uematsu2 and H. Katayama3,a 1 Department of Agriculture, Forestry and Fisheries, West Branch, Tokushima, Prefect. Gov., Miyoshi, Tokushima, Japan 2 Kisaichi Botanical Gardens, Osaka City University, Katano, Osaka, Japan 3 Food Resources Center, Kobe University, Kasai, Hyogo, Japan Keywords: ‘Iwateyamanashi’, germplasm collection, ornamental pear, principal component analysis, Pyrus ussuriensis var. aromatica Abstract Although ornamental pear trees (Pyrus calleryana) are popular in North America and Australia, we have no ornamental pear cultivar in Japan. Two pear accessions available for ornamental trees were selected from ‘Iwateyamanashi’ (Pyrus ussuriensis var. aromatica) endemic in northern Japan. 95 accessions deposited as germplasm collection at Kobe University were selected first with the PCA based on the 9 floral morphological traits such as numbers of petal, stamen, stigma, flowers per bud, pedicel length, flower diameter, colour of petal edge, petal length and petal width, and flowering date, tree form, fruits quality and autumnal leaf colouration. And then 30 accessions were chosen from evenly considering PCA score plot. Finally two accessions of ‘i1717’ and ‘i1525’ were organoleptically evaluated by 123 panelists for full size pictures of flower, corymb and flowering branch. They had longer petal length, flower diameter, and petal width compared to those of other accessions and the petal shapes were circle. By PCA and the organoleptic evaluation, ‘i1525’ and ‘i1759’ were selected. The former showed rose pink petal edge, better fruit quality, and compact tree form. The latter possessed better fruit quality and compact tree shape, and the leaf turned a deep red colour in the fall. Two accessions had unique ornamental traits not found in Japanese pear cultivars (Pyrus pyrifolia). Pear genetic resources collected from the northern part of Japan will provide new resources for breeding and industry. INTRODUCTION Distribution area of Pyrus L., endemic in the northern part of Japan including ‘Iwateyamanashi’, (Pyrus ussuriensis var. aromatica) has been rapidly decreasing, thus conservation and evaluation are urgently needed. 750 pear accessions were collected and deposited at Kobe University in an ex situ field genebank. Although ornamental pear trees (Pyrus calleryana Decne.) are popular in North America and Australia (Culley and Hardiman, 2009), there is no ornamental pear cultivar in Japan. In this study, we investigated accessions, conserved as pear germplasm collection, from the point of view of ornamental usage by means of morphological measurement and organoleptic evaluations. MATERIALS AND METHODS Plant Materials Ninety-five accessions including P. ussuriensis var. aromatica (‘Iwateyamanashi’) and hybrid progeny between ‘Iwateyamanashi’ and P. pyrifolia were evaluated. A Japanese pear cultivar (‘Hosui’), P. calleryana and P. fauriei were examined as standards. Those materials were collected from northern Japan and deposited at Food Resources a
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Proc. XII International Pear Symposium Eds.: T. Deckers and J. Vercammen Acta Hort. 1094, ISHS 2015
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Center, Kobe University. Measurement of Morphological Traits Ninety-five accessions were evaluated based on the 9 floral morphological traits such as number of petal, stamen, stigma, number of flowers per single inflorescence, pedicel length, flower diameter, petal length, petal width, and colour of petal edge (Fig. 1). Also petal shape, waving degree of petal, flowering date, leaf colour on full bloom, tree form, fruits quality and autumnal leaf colouration were investigated. Some of these data were categorized (Fig. 2). Principal Component Analysis The measured data were analyzed with Principal Component Analysis using evenly considering PCA score plots (Fig. 3). PCA was performed using the program JMP 8 (SAS Institute Inc., Cary NC, USA). Based on this analysis, 30 accessions harbouring typical phenotype were chosen for an organoleptic evaluation. Organoleptic Evaluation Selected 30 accessions were arranged as an evaluation board (Fig. 4) with pictures of flower, inflorescence and branch in blooming. The pictures were printed on a B0 size (1,030×1,456 mm) photo paper. 123 panelists selected their favorite accession. They gave 2 points to the most preferable accession, and 1 point to up-to-five preferable accessions. The panelists’ preference of flower appearances was calculated and compared by ANOVA. Also, correlation coefficient between morphological traits and organoleptic evaluation were displayed. RESULTS AND DISCUSSION Diversity of Floral Morphological Traits The accessions preserved at the gene bank showed diversity in flower diameter, numbers of stamen, petal shape, flowering date, etc. As for flower number per single inflorescence, those with more than 9 flowers are also observed while 62% possessed 6 to 8 flowers (Fig. 1A). P. calleryana had 19 small flowers of 21 mm in a bud. Numbers of petal is 5 for 40% of the 95 accessions. ‘i0031’, ‘i0801’ and ‘i1725’ had 8 petals per flower. ‘i847’ showed the most, 13 petald in a flower (Fig. 1B). Correlations between PCA Score Plot Position and Evaluation Value Obtained evaluation values for flower appearance of 30 accessions were shown in Table 1. ‘i1717’ gained the highest score, and ‘i1525’, ‘i0031’, ‘i1759’ and other 5 accessions were also so favoured. The PCA score plot position of the highly evaluated accessions shows what kind of flower appearance is normally preferred. Those had higher PC 1 score, which means flowers with bigger petals and of longer diameter were more preferable. Another tendency is that the accessions with low PC 2 score were more preferred. PC 2 has strong negative correlation with petal length width ratio. That shows those flowers with round or wider petal shape are more preferred. CONCLUSIONS Out of 30 accessions, ‘i1525’ and ‘i1759’ were most highly evaluated by full-scale picture of an individual flower (Table 2 and Fig. 5). ‘i1525’ showed rose pink on petal edge, and compact tree form suitable as an ornamental tree. Furthermore its fruit quality was good. In case of ‘i1759’, flowers were setting densely, tree shape was compact, and leaf turned deep red in autumn. The fruit quality was also good. Two accessions had unique traits suitable for ornamental plants that were not found in Japanese pear (Pyrus pyrifolia) cultivars. The pear germplasm collection, maintained at Kobe University, collected from northern part of Japan will provide new 118
resources for breeding and industry. ACKNOWLEDGEMENTS Thanks are due to S. Kakehi, T. Fudan, Y. Watanabe and T. Tanikawa in the Food Resources Research and Education Center, Kobe University, for maintenance of plant materials. This work was supported in part by Grant-in-Aid (No. 25430191) for Scientific Research from the Ministry of Education, Science and Culture, Japan. Literature Cited Culley, T.M. and Hardiman, N.A. 2009. The role of intraspecific hybridization in the evolution of invasiveness: a case study of the ornamental pear tree Pyrus calleryana, Biol. Invasions 11:1107-1119. Kajiura, I. and Sato, Y. 1990. Recent progress in Japanese pear (Pyrus pyrifolia Nakai) breeding, and descriptions of cultivars based on literature review. Bull. Fruit Tree Res. Stn. Extra No. 1:28-29. Tables Table 1. Preferences of a flower appearance quantified by ANOVA analysis with Tukey-Kramer HSD test. Accession i1717 i1525 i31 i1759 i801 i853 i134 i458 i52 i981 157Y i847 i77 i353 i163 i1009 i1010 i1725 i1712 122 i1003 i1720Y i219 i845 i108 i957 i469 i423 i961 i452
a b b b b b b b b
c c c c c c c c c c
d d d d d d d d d d d d
e e e e e e e e e e e e e e e e
f f f f f f f f f f f f f f f f f f
g g g g g g g g g g g g g g g g g g
h h h h h h h h h h h h h h h h h h
i i i i i i i i i i i i i i i i i i i i
j j j j j j j j j j j j j j j j j j j j j
Mean 0.78 0.49 0.39 0.34 0.31 0.28 0.27 0.27 0.26 0.18 0.18 0.16 0.14 0.13 0.12 0.10 0.10 0.10 0.10 0.08 0.06 0.05 0.04 0.04 0.03 0.03 0.02 0.02 0.02 0.01
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Table 2. Important characters for accessions selected as the candidates of ornamental tree. Accession
Overall rate ranking
1525
1
2
16
medium
moderate
pink
good
-
1717
2
1
8
broomy
moderate
white
inedible
-
Flower ranking Colymb ranking
Tree Flower setting architecture tendency
Petal edge colour
Fruit taste
Fall leaf
847
3
12
2
medium
moderate
white
inedible
-
1759
4
4
11
broomy
strong
white
good
good
157Y (P. calleryana)
5
11
1
broomy
moderate
pink
inedible
good
353
6
14
9
spreading
strong
pink
inedible
-
31
7
3
7
broomy
moderate
pink
edible
-
1712Y
8
19
4
broomy
strong
white
inedible
-
134
9
7
5
spreading
moderate
white
edible
-
458
10
8
14
broomy
strong
pink
inedible
-
Figures
(A)
(B)
i0491
P. calleryana
i0031
i1003
i0847
Fig. 1. Diversity of flower number per single inflorescence (A), and petal number (B) in 95 accessions used in this study.
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Colour of petal edge
Petal shape
Waving degree of petal
Leaf colour on full bloom
White
Pink
1759
1525
long
Long -round
Long -constricted
Round
Constricted
Wavy
Wide-round
1009
353
514
157Y
1525
469
52
Nil
Slightly
Medium
Considerably
77
1525
845
423
Green
Reddish green
Red
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845
1003
Fig. 2. List of categorized floral morphologies for PCA.
Fig. 3. PCA score plot position of highly evaluated accessions concerning principal component 1 and 2.
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Fig. 4. Evaluation board showing 30 accessions with pictures of flower, inflorescence and branch in blooming used for organoleptic evaluation by 123 panelists.
‘i1759’
‘i1525’ Pink Petal edge
Compact tree shape
Compact tree shape & beautiful leaf
Abundant flower setting
6 cm
4 cm
Fig. 5. Characteristics of two accessions, ‘i1525’ and ‘i1759’ selected by organoleptic evaluation.
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