ISHS Acta Horticulturae 587: International Symposium on Asian Pears, Commemorating the 100th Anniversary of Nijisseiki Pear
PHENOLOGY OF INTRODUCED ORIENTAL PEARS GRAFTED ONTO A LOCAL PEAR CULTIVAR AND THEIR CARBOHYDRATE AND NITROGEN STATUS |
| Authors: | J. Rakngan, H. Gemma, S. Subhadrabandhu |
| Keywords: | Pyrus pyrifolia Nakai, Pyrus serotina Rehder, flower bud grafting, C/N ratio, TNC, TN |
| Abstract:
The improvement of oriental pear production in Thailand has several challenges: to increase the poor quality of pear fruits; to expand the number of high yielding commercial cultivars; and to supply the products into optimum marketing periods. New technologies and new cultivars were introduced to improve pear production in warmer countries. The flower bud grafting technique was used to investigate the phenology and adaptation of Japanese pear cultivars in Thailand. The experiment was conducted during 1998~2000 at the Oriental pear orchard, Royal Ang Khang Experimental Station, Chiangmai, Thailand, which is located at 1,400 meters above sea level. Flower buds of ‘Kousui’, ‘Choujuurou’, ‘Nijisseiki’, ‘Housui’ and ‘Niitaka’ were collected in Japan and grafted on Thai local rootstock. The results showed a low percentage of flowering and fruit setting due to insufficient chilling hours. However, normal growth and development of new shoots were observed. Endogenous substances such as total carbohydrate and total nitrogen of the oriental pear cultivars were analyzed and compared among three groups of pear used in this study. Thai commercial cultivars (low chilling requirement; C.R.) such as ‘Yokoyama Wase’ and ‘Xiang Sui’, introduced Taiwan hybrids, such as SH-029, SH-078, SH-085 (medium C.R.) and introduced Japanese cultivars (high C.R.), such as ‘Kousui’, ‘Choujuurou’, ‘Nijisseiki’ were grafted onto Thai local rootstock. The results showed that total nitrogen in each cultivar remained stable but carbohydrate content fluctuated during the period of study. C/N ratio gradually increased before the dormancy period which reflects the food reserve characteristics of each pear cultivar. Shoot and flower bud development of high chilling requirement cultivars was poorer than the others. Therefore, good flower bud formation was observed in the low chilling requirement Thai commercial cultivars and the Taiwan hybrid SH-085. In conclusion, this new Taiwan cultivar is suitable to be commercialized for Thailand market in the near future. | |
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