Department of Horticultural and Landscape Architecture, National Taiwan University1
Pear Research Station, National Institute of Horticultural & Herbal Science2
Department of Horticulture, Sunchon National University3
Department of Horticulture and Biotechnology, Chinese Culture University4
Time-specific responses of flower bud differentiation were investigated in ‘Shinko’ (Pyrus pyrifolia Nakai) pear grown at different altitudes from July through December 2013 to determine their suitability as scions in a top-grafting system. Flower bud initiation and bud necrosis were monitored on each of three sections of one-year-old shoots: terminal, middle, and basal. Flower bud differentiation started in September in the highlands of the Lishan area, and in July in the lowlands of the Zhoulan area. In Lishan, flower bud differentiation was higher in the middle and basal segments; during leaf fall, however, flower bud differentiation occurred rapidly in the terminal segment. In Zhoulan, flower buds began to differentiate from the terminal section of the shoot, and severe flower bud necrosis was noted. In July, flower buds developed normally; however, in early August, some of the buds at the basal segment showed browning. During leaf fall, some flower buds showed symptoms of necrosis with rapid and complete browning. Flower bud necrosis began at the basal segment and progressed rapidly towards middle and terminal sections. Before leaf fall, flower buds fell off when scales swelled. The terminal and middle parts of the current-year shoots, with some flower buds, collected in October or later from the Lishan area could be used as scions for top-grafting of 'Shinko' pear. Each grafting scion was a 3-5 cm shoot with one flower bud. These results suggest that scions from the terminal and middle segments of stems of ‘Shinko’ pear from the Lishan area can be used as scions whereas those from Zhoulan area show necrosis and might not be suitable as scions.
1. Banno, K., S. Hayashi, and K. Tanabe. 1985. Relationships between flower bud formation and endogenous growth regulators in Japanese pear cultivars (Pyrus serotina Rehd.). J. Japan. Soc. Hort. Sci. 54:15-25.
2. Beutel, J.A. 1990. Asian pears, p. 304-309. In: J. Janick and J.E. Simon (eds.). Advances in new crops. Timber Press, Portland, OR, USA.
3. Byrne, D.H., S.K. Ou, and J.B. Storey. 1995. Annual grafting of Nashi pear in low chill areas of Taiwan. Fruit Varieties J. 49:103-106.
4. Chen, C., C.C. Huang, R.W. Chio, and C.C. Huang. 1997. The effect of shoot bending and other cultivation practices on the lateral flower bud formation of ‘Hosui’ pear grown in Taiwan highland area, p. 187-196. In: L.J. Chang and R.W. Chen (eds.). Proceedings of a symposium on enhancing competitiveness of fruit industry II. Taichung District Agricultural Improvement Station, Chunghua, Taiwan.
5. Fan, N.T. 1981. Studies on the flower-bud differentiation of apple and pear in Taiwan. I. Morphological change in bud. Nchu Hort. 6:9-16.
6. Faust, M., A. Erez, L.J. Rowland, S.Y. Wang, and H.A. Norman. 1997. Bud dormancy in perennial fruit trees: Physiological basis for dormancy induction, maintenance and release. HortScience 32:623-629.
7. Gemma, H. 1995. Dormancy breaking in Japanese pear grown in a heated greenhouse. Acta Hortic. 395:57-68.
8. Honjo, H. 2007. Effects of global warming on dormancy and flowering behavior of temperate fruit crops in Japan. Hort. Res. Jpn. 6:1-5.
9. Jackson, J.E. 2003. Biology of apples and pears. Cambridge Univ. Press, Cambridge, UK. p. 488.
10. Kim, J.K., S.H. Kim, Y.T. Yim, and H.H. Seo. 2004. Shoot growth and mineral concentration in ‘Niitaka’ pear trees with flower bud necrosis. Kor. J. Hort. Sci. Technol. 22:444-447.
11. Kim, J.K., S.H. Kim, Y.T. Yim, and H.H. Seo. 2006. Anatomical feature, sugar, carbohydrate, and hormone content of normal and abnormal flower buds in ‘Niitaka’ pear trees. Kor. J. Hort. Sci. Technol. 24:354-358.
12. Kingston, C.M., D.J. Klinac, and C.W van Epenhuijsen. 1990. Flower bud disorders of nashi (Pyrus serotina) grown in New Zealand. New Zealand J. Crop Hort. Sci. 18:157-159.
13. Klinac, D.J. and B. Geddes. 1995. Incidence and severity of the flower bud disorder ‘budjump’ on nashi (Pyrus serotina) grown in the Waikato region of New Zealand. New Zealand J. Crop Hort. Sci. 23:185-190.
14. Krisanapook, K. and S. Subhadrabandhu. 1995. Effect of some practices and hydrogen cyanamide on bud break of ‘Shinseiki’ pear. Acta Hortic. 395:149-152.
15. Lin, H.S., C.L. Lee, and C.O. Lin. 1987. Production of high chilling Asian pear in Taiwan’s lowland. Acta Hortic. 199:101-108.
16. Marafon, A.C., F.G. Herter, F.J. Hawerroth, and A.S. Silva. 2010. Occurrence time and intensity of flower bud necrosis and inflorescence duplication in pear trees ‘Housui’ (Pyrus pyrifolia (Burm.) Nak.) during the dormancy period in Pelotas - RS, Brazil. Acta Hortic. 872:97-100.
17. Motoshima, S., M. Kato, T. Nishio, and T. Kobayashi. 1983. Sap-transmissible viruses detected from imported pear plants. Res. Bull. Plant Prod. Ser., Japan 19:29-37.
18. Nee, C.C. 1980. Studies on the growth and flower bud differentiation of pear trees at low altitude district of Taiwan. Nchu Hort. 5:38-41.
19. Nee, C.C., C.H. Tsai, and D.D. Anstine. 2002. Asian pear germplasm future trends and current research in the industry. Acta Hortic. 587:61-69.
20. Oh, S.D. and D. Klinac. 2003. Relationship between incidence of floral bud death and temperature fluctuation during winter in Japanese pear (Pyrus pyrifolia cv. Hosui) under New Zealand climate conditions. J. Kor. Soc. Hort. Sci. 44:162-166.
21. Oh, S.D., S.N. Jin, and H.J. Lee. 2002. Growth, leaf nitrogen contents, and nitrate reductase activity of pear (Pyrus pyrifolia cv. Niitaka) trees as affected by different levels of nitrogen supply. J. Kor. Soc. Hort. Sci. 43:433-438.
22. Petri, J.L. and F.G. Herter. 2002. Nashi pear (Pyrus pyrifolia) dormancy under mild temperature climate conditions. Acta Hortic. 587:353-361.
23. Petri, J.L., G.B. Leite, and Y. Yasunobu. 2002. Studies of the causes of floral bud abortion of Japanese pear (Pyrus pyrifolia) in Southern Brazil. Acta Hortic. 587:375-380.
24. Rakngan, J., H. Gemma, and S. Iwahori. 1995. Flower bud formation in Japanese pear trees under adverse conditions and effects of some growth regulators. Jpn. J. Trop. Agr. 39:1-6.
25. Verissimo, V., F.G. Herter, A.C. Rodrigues. J.P. Gardin, and J.B. Silva. 2004. Characterization of pear flower bud (Pyrus sp.) and the relation with flower bud abortion. Rev. Bras. Frutic. 26:193-197.
26. Verissimo, V., J.P. Gardin, R. Trevisan, and F.G. Herter. 2002. Morphological and physical parameters of flower buds of trees of two Japanese pear cultivars grown at three different areas of Southern Brazil, and their relationship with flower bud abortion intensity. Acta Hortic. 587:381-387.
27. Wilkie, J.D., M. Sedgley, and T. Olesen. 2008. Regulation of flower initiation in horticultural trees. J. Exp. Bot. 59:3215-3228.
28. Yamamoto, R.R., Y. Sekozawa, S. Sugaya and H. Gemma. 2010. Influence of chilling accumulation time on “flower bud abortion” occurrence in Japanese pear grown under mild winter conditions. Acta Hortic. 872:69-76.