ISHS Acta Horticulturae 51: Symposium on Protected Cultivation of Flowers and Vegetables
THE EFFECTS OF LONG DAYS ON THE FLOWERING OF SPRAY CARNATIONS |
| Author: | A. Beisland |
| Abstract:
Long-day treatment (subsequently referred to as LD) is known to give an earlier flower induction for standard varieties than that given by natural day-length. The purpose of this trial was to see whether LD had a similar effect on the induction of spray varieties. The varieties used were Sam's Pride, Scarlet Miniqueen and Royalette. When most of the shoots had between 7 and 9 expanded pairs of leaves, they were given incandescent light, 20 watts/sq.m. for 0, 2, 3 and 4 weeks, respectively. The treatment for all varieties started on the 14th of February and during the treatment period the plants received the light from dusk to dawn. Seen from the point of earliness, the best treatment was the 4-week LD. Sam's Pride, Scarlet Miniqueen and Royalette flowered after 4 weeks of LD - 23, 18 and 17 days-respectively, earlier than the control plot. The time from long-day start to flowering decreased gradually with increasing LD periods for Sam's Pride and Scarlet Miniqueen. For the latter variety the decrease in period to flowering was very small between the control and the 4 weeks of LD-treatment. The severe decrease occurred between the plot receiving 3 weeks of LD and the one receiving 4 weeks of LD. The shortest stems for all the varieties were noted at the plot which had received 4 weeks of LD. Between the other treatments, there were no differences. For all the varieties, there was a negative correlation between the number of LD weeks and the number of leaf-pairs formed prior to initiation. With increasing numbers of LD weeks, all the varieties showed a decreasing number of vegetative side-shoots. For Scarlet Miniqueen the decrease at 3 and 4 weeks of LD was of such a size that the following flush may well result in a low production. Sam's Pride and Royalette produced an increasing total amount of flowers and buds with the increasing number of LD weeks. For Scarlet Miniqueen there were only small differences between the plots. Royalette had the stiffest stems, the stiffness not being affected by 2 and 3 LD weeks. The stems became a little weaker after 4 LD weeks without however affecting the quality. Sam's Pride had the weakest stems, and it may well | |
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