The effects of temperature on endodormancy completion in Japanese pear (Pyrus pyrifolia Nakai) and modeling the relationship

• Published in: Journal of Agricultural Meteorology Vol. 53; no. 4; pp. 285 - 290
• Main Authors: Sugiura, T. (National Inst. of Fruit Tree Science, Tsukuba, Ibaraki (Japan)), Honjo, H
• Format: Journal Article
• Language: English; Japanese
• Published: Tokyo The Society of Agricultural Meteorology of Japan 1997; Japan Science and Technology Agency
• Subjects: Developmental rate; DORMANCY BREAKING; Endodormancy; EXPERIMENTACION EN CAMPO; EXPERIMENTACION EN LABORATORIO; EXPERIMENTATION AU CHAMP; EXPERIMENTATION EN LABORATOIRE; FIELD EXPERIMENTATION; FORECASTING; GROWTH RATE; INDICE DE CRECIMIENTO; Japanese pear (Pyrus pyrifolia); LABORATORY EXPERIMENTATION; LEVEE DE DORMANCE; MODELE; MODELOS; PYRUS PYRIFOLIA; SALIDA DE LA LATENCIA; TAUX DE CROISSANCE; TECHNIQUE DE PREVISION; TECNICAS DE PREDICCION; TEMPERATURA; TEMPERATURE
• ISSN: 0021-8588; 1881-0136
• DOI: 10.2480/agrmet.53.285

The effects of temperature on endodormancy were investigated in flower buds of Japanese pear (Pyrus pyrifolia Nakai cv. ‘kosui’) for the purpose of developing a model estimating endodormancy completion. Potted trees were chilled at constant temperatures (0, 3, 6, 9 and 12°C) from late October for different hours in temperature-controlled dark room. After the chilling treatments, each tree was forced in growth chamber adjusted to 25°C. The endodormancy completion was judged from the percentage of flowering and normal flower after forcing. The chilling for 750h at 0-6°C was necessary to complete endodormancy and 1160h at 9°C was necessary. While at 12°C the endodormancy can not completed. The DVR (Developmental Rate) at each temperature was calculated in the form of reciprocal of the number of chilling hours that were necessary to complete endodormancy (Fig. 3). The model estimating endodormancy completion was obtained from the relationship between the measured DVR and temperature. In order to test the validity of the model, endodormancy completion dates and air temperatures were observed for three years in open field, and the observed hourly temperatures were applied to the model. The model was justified by comparisons between observed and estimated endodormancy completion dates in the field.