Press ReleasesCollaborative Development of Method for Consistent Production of High-quality Japanese PearsOur original technology helps enhance the rooting of cutting plantlets and
minimize occurrence of fruit physiological disorders

Nippon Paper Industries Co., Ltd.
Tochigi Prefectural Agricultural Experiment Station

Since 2006, Nippon Paper Industries Co., Ltd. (President: Yoshio Haga) and Tochigi Prefecture (Governor: Tomikazu Fukuda) have collaboratively researched a method for consistent production of high-quality Japanese pears (nashi). We recently developed production technology for effectively growing the seedlings of Japanese pears and minimizing fruit physiological disorders, a recent problem in this area.

Well-known varieties of Japanese pears are Kosui and Hosui, which collectively account for more than 60% of the total domestic production of the fruit. Tochigi is one of the major producers of Japanese pears and many of the fruit's trees in this prefecture were planted at least 30 years ago. The aging of the trees has brought about problems in deteriorating quality and yield. Japanese pear seedlings are supplied in the form of grafting, and those derived from seeds of wild species such as yamanashi (pyrus pyrifolia) and mamenashi (pyrus calleryana) are used as rootstock. The genetic diversity of seed-derived seedlings brings about problems such as variability in growth of Kosui, Hosui and other grafted seedlings, and symptoms of fruit physiological disorders like cork-like flesh disorder (Note 1) and watercore (Note 2). Especially in recent years, the abnormal summer weather has induced frequent occurrences of these disorders. Solutions to these problems are needed.

The propagation of Japanese pear cuttings is very difficult with traditional methods. Application of photoautotrophic culture technology (Note 3), Nippon Paper Industries' original rooting technology, improved the rooting of Kosui and Hosui by more than 60% and enabled efficient production of cutting plantlets. The Tochigi Prefectural Agricultural Experiment Station grew these cutting plantlets using earth-fill rhizosphere control technology (Note 4). Results confirmed that the plantlets grew better and more uniformly than traditional types of grafted seedlings, and that the occurrence of fruit physiological disorder could be reduced in Hosui.

Nippon Paper Industries and Tochigi Prefecture will continue to apply and extend this technology for consistent production of high-quality fruit as they pursue diffusion of good varieties of Japanese pears. Results of the collaborative research will be presented at the horticultural society's conference, which is scheduled to open in Okayama Prefecture on September 24.

  1. Note1:Cork-like flesh disorder
    A cork-like brown area forms within the fruit. This type of physiological disorder occurs in Akizuki, Hosui and Oshu (Appendix 1).
  2. Note2:Watercore
    A small or large area of the fruit appears as if it is immersed in water. As the disease progresses, the affected part of the flesh looks watery. Fruits with this disease may quickly rot and their product value significantly deteriorates (Appendix 1).
  3. Note3:Photoautotrophic culture technology
    High-concentration carbon dioxide, water and light are used instead of sugar, which becomes a source of energy after tissue culture. This culture method elicits a plant's photosynthetic capacity (Appendix 2).
  4. Note4:Earth-fill rhizosphere control technology
    A root-shading sheet is used to plant seedlings in a small volume of ridging (earth fill) isolated from the ground surface. This helps adapt irrigation to the growth of the trees. Since this technology makes dense planting possible, the yield of fruits per unit area can be larger (Appendix 3).

Appended documents: Appendices 1, 2 and 3