Interactive Effects of Vernalization, Photoperiod and Light Intensity on Reproductive Development of Wheat Cultivars

475 Abstract: The interactive effects of vernalization, photoperiod and light intensity on the length of the apex or spike and main shoot, and the diameter of the main shoot of five different wheat (Triticum aestivum L.) cultivars (Çukurova-86, Atay-85, Lancer, Haymana79 and Bezostaya-1) having different biological characters were investigated. The research was carried out in four independent experiments, which were the combinations of two different photoperiods (12 and 16 h.d.-1) and light intensities (200μmol m-2s1 and 500μmol m-2s-1 PFD) with different vernalization periods. At the end of each photoperiod and light intensity treatment, supplementary illuminance, which was arranged to be 35% of main light regime, was applied for two hours. Vernalization treatment was applied for 0, 15, 30, 45 and 60 days at 2 ±1 ̊C in a dark cold room at 80% humidity and also 90 days only in the short daylow light intensity experiments. In all experimens; ear emergence was completed in Çukurova-86 and Atay-85 in the control and all vernalization treatments while it was completed in Lancer, Haymana-79 and Bezostaya-1 in 30, 45 and 60 days of vernalization treatment. Since the spike development was slow in short day conditions and the required radiation was provided by high light intensity, the longest spike was obtained in the short day-high light intensity experiment. The shortest spike was obtained in the long day-high light intensity experiment. Low light intensity accelerated the transition of the apex from the vegetative to the reproductive stage through an effect probably similar to that of vernalization, only in short day conditions. The length of the main shoot increased because of a longer flower development stage in low light intensity than that in the high light intensity, independent photoperiod. The thickest diameter of all cultivars was obtained in short day-high light intensity. The length of the apex or spike, main shoot, and diameter of main shoot decreased with increasing vernalization periods in spring type cultivars, but increased in winter cultivars with increasing vernalization periods because winter cultivars were in their vegetative phase until they reached the required vernalized period. After these periods, the length of apex or spike and diameter of main shoot decreased with increasing vernalization periods.