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Pak. J. Bot., 47(5): 1717-1720, 2015. |
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Updated: 20-10-15 | ||||
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EFFECT OF CONSTANT TEMPERATURES AND NATURAL DAYLENGTH ON FLOWERING TIME AND LEAF NUMBER OF ANTIRRHINUM USING THE PHOTO-THERMAL MODEL
MUHAMMAD MUNIR1,3, PAUL HADLEY1, JAMES CAREW1, STEVEN ADAMS2, SIMON PEARSON1 AND BALAKRISHNAN SUDHAKAR3
Abstract: After 80% seed germination plants of an early flowering cultivar Chimes White of Antirrhinum were subjected to five set-point temperature regimes (14, 18, 22, 26 and 30°C) for two consecutive years to observe their effects on the flowering time and leaf numbers using photo-thermal model. Findings revealed a curvilinear response of flowering time to temperatures that is plants flowered after 34 (31.8°C), 35 (25.3°C), 37 (23.1°C), 43 (19.5°C) and 68 days (14.6°C) of transplantation in 2002 whereas in 2003 flowering time was recorded as 30 (31.5°C), 29 (27.5°C), 34 (24°C), 39 (22.5°C) and 67 days (15.1°C). Similarly, rate of progress to flower per day was increased linearly up to plateau at 28°C set-point temperature, thereafter, no changes in rate of progress to flower is observed which indicated that 28°C is the ceiling temperature for the flower initiation and development of cultivar Chimes White. A three to six days difference in flowering time was observed below ceiling temperature which might be due to the difference between the light integrals (0.9 MJ.m-2.d-1) in two years. Non-significant difference was observed regarding leaf numbers data in both years i.e. 9-10 leaves in 2002 and 8-9 leaves in 2003. Predicted data estimated from the photo-thermal model plotted against the actual data which showed a best fit, hence, the model application is validated which would assist growers to use it for plant scheduling.
Key words: Snapdragon, Antirrhinum majus L., Temperature, Daylength, Photo-thermal model, Flowering time, Leaf numbers.
1School of Plant Sciences, The University of Reading, Reading, RG6 6AS, U.K. 2Horticulture Research International, Wellesbourne, Warwick, CV35 9EF, U.K. 3Date Palm Research Center of Excellence, King Faisal University, Al-Ahsa, Kingdom of Saudi Arabia *Corresponding author e-mail: mmunir@kfu.edu.sa |
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