An experiment was carried out to verify the effect of vernalization period on the phyllochron (time interval between the appearance of two successive leaves) in lily (Lilium longiflorum Thunb), cv. 'Snow Queen'. The trial was conducted at Santa Maria, RS, Brazil. Treatments were bulbs stored at vernalizing temperatures of -0.5, 4, and 10ºC during periods of 2, 4, 6 and 8 weeks. Control treatment was unvernalized bulbs. Bulbs were planted inside a plastic greenhouse on December 05, 2002, and crop development was evaluated throughout the growing season. Phyllochron for each treatment was estimated as the inverse of the slope of the linear regression relating leaf number and accumulated thermal time above 1ºC after emergence. Results showed that the phyllochron is affected by vernalization. Unvernalized plants and plants with low vernalization treatments had greater phyllochron values compared to completely vernalized plants. Plants vernalized with 30 or higher effective vernalization days had a phyllochron value around 25 ºC days/leaf. This phyllochron can be used as a reference when vernalized bulbs are used in commercial croppings.
Lilium longiflorum Thunb.; phyllochron; vernalization; leaf unfolding; thermal time
