ISHS Acta Horticulturae 662: VII International Symposium on Temperate Zone Fruits in the Tropics and Subtropics
ESTIMATION OF EFFECTIVE CHILLING HOURS AND GDH°C REQUIREMENT AND ITS SIGNIFICANCE IN PREDICTING FULL BLOOM IN DELICIOUS APPLE |
| Authors: | M.S. Mankotia, P.S. Chauhan, A. Sud, K.K. Jindal |
| Keywords: | chilling hours, bloom, Delicious, Malus domestica |
| Abstract:
The effective chill units (CU) and GDH°C requirements of Delicious apple at Mashobra, Shimla located at 31.1°N with an elevation of 2286 m were estimated by adopting Utah model. The estimated CU and GDH°C were 1208 and 8893 respectively. Using the estimated constants and the Utah model suggested values of 1234 CU and 6933 GDH°C, the dates of full bloom were calculated for 9 years. The calculated dates and actual full bloom dates were compared. The range of differences in days using estimated constants was –8 to +7 days, whereas for the suggested values the range was –17 to +1 days. The average differences in days were +0.1 and -7.1 and standard deviation were 4.2 and 5.42 for the estimated and suggested constants respectively. The estimation of the constants are useful in determining the time of rest completion and modifying the bloom period through cultural amendments with a high degree of accuracy. | |
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