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Pak. J. Bot., 49(1): 181-186, 2017.

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MODIFICATION OF PHOTO-THERMAL MODEL BY ACCOMMODATING LIGHT INTEGRALS USING ANTIRRHINUM FLOWERING AND LEAF NUMBER DATA

FROM RESTRICTED RANGE OF ENVIRONMENTAL CONDITIONS

MUHAMMAD MUNIR^1,3*, PAUL HADLEY¹, JAMES CAREW¹, STEVEN ADAMS² AND SIMON PEARSON¹

¹School of Plant Sciences, The University of Reading, Reading, RG6 6AS, UK

²Horticulture Research International, Wellesbourne, Warwick, CV35 9EF, UK

³King Faisal University, Al-Ahsa, Al-Hofuf, Kingdom of Saudi Arabia

^*Corresponding’s author email: m_munir04@yahoo.com

Abstract

 The objective of study was to quantify the flowering and leaf number response of Antirrhinum majus L. cv. Chimes White to different photoperiods, night temperatures and light integrals using photo-thermal model. Two experiments were conducted i.e. first one in February (under low ambient light integrals) and the second one in June (under high ambient light integrals). In each experiment plants of an early flowering cv. Chimes White were transferred (after 80% germination) to two night temperature suits (set-point temperatures 10 and 20°C), each having four photoperiod chambers (8, 11, 14 and 17 h.d^-1). Results revealed that plants flowered earlier at long photoperiod (17 h.d^-1), higher mean diurnal temperature (19.2°C in February and 23.4°C in June) and high ambient light integrals (8.26 MJ.m^-2.d^-1) and vice versa. These findings were successfully incorporated in to photo-thermal model, which was not reported before in Antirrhinum. The simple linear model hence updated, which would be helpful for growers to predict and quantify flowering time and leaf number (plant quality) of Antirrhinum well before their plantation to maintain its continual supply to the market.

Key words: Snapdragon, Antirrhinum majus L., Photoperiods, Night temperatures, Light integrals, Photo-thermal model, Flowering time, Leaf numbers.