Effects of Photoperiods on the Length and Number of Epidermal Cells in Runners of Strawberry Plants

Abstract

Experiments were conducted to assess the importance of the length and the number of epidermal cells in regard to runner length in June-bearing strawberry plants (Fragaria × ananassa, cv. Donner).
When the elongation rate of proximal internode (I-1) reached the highest rate, the distal internode (I-2) started to elongate exponentially. The elongation pattern of each internode was represented by a single sigmoid curve. The cell division in I-2 continued for about 5 days longer than that in I-1.
I-1 and I-2 under a 16-hr day (LD) grew longer than did those which grew under a 9-hr day (SD). The increase in the internode length of I-1 was attributed to the increase in the epidermal cell length, whereas, the increase in the internode length of I-2 was attributed to the increase in the number of epidermal cells. The differences between I-1 and I-2 of strawberry runners in photoperiodic response to the length and number of epidermal cells may be attributed to the difference of developmental stages in each internode at the onset of the photoperiodic treatments.
In photoperiodic response to the length and number of epidermal cells, there was a similarity between runners and petioles.