ISHS Acta Horticulturae 587: International Symposium on Asian Pears, Commemorating the 100th Anniversary of Nijisseiki Pear
SEASONAL CHANGES IN THE ICE NUCLEATION ACTIVITY OF VARIOUS TISSUES IN JAPANESE PEAR (PYRUS PYRIFOLIA NAKAI) IN RELATION TO THEIR FREEZING BEHAVIOR AND FROST INJURY |
| Authors: | Y. Sekozawa, S. Sugaya, H. Gemma, S. Iwahori, M. Ishikawa |
| Keywords: | ice nucleation activity, ice formation, cold hardiness, spring, frost injury, Pyrus pyrifolia, pears |
| Abstract:
Seasonal changes in the ice nucleation activity of various tissues of Japanese pear ‘Kousui’ were investigated with the aim of studying the manner of freezing, which is an important mechanism for cold hardiness. The ice nucleating temperatures of outer scales and inner scales were maintained at between -7°C and -5°C throughout the winter months, while those of florets and bracts markedly increased from -12.6°C to -6.0°C and from -10.4°C to -5.6°C, respectively from late October to February. In winter flower buds exposed to subfreezing temperatures showed ice crystals located in the space between florets and bracts and within scales where ice nucleation activity was fairly high. After blooming, high ice nucleation temperatures were observed in the petal, receptacle, sepal and pedicel while those of both the stamen and pistil remained very low. Injury by spring frosts occurred mainly in the pistil where ice nucleation activity was low, while the tissues with high ice nucleating activity showed more resistance to spring frost. The more sensitive tissues to spring frosts were different from the sites where ice nucleation activity is high. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
