Abstract
The effects of daylength (elongating day length) and night-break (interrupting night), by lighting with a homolux lump, on the shoot and fruit growth of ‘Pione’ grapes which were grown to harvesting twice a year in a heated plastic house were examined. Experiments were conducted from August 21 to November 6 during the second growing season in 1995.
The effects of a 14-hour daylength, 16-hours daylength, and night-break for 2 hours from 11 p.m. were compared. However, the effect of the 14-hours daylength was not significantly different from the control, the strongest effect on the growth of ‘Pione’ grapes being obtained by a night-break for 2 hours. The number of leaves on the lateral shoots and the average berry weight were significantly increased by a night-break for 2 hours and a 16-hour daylength. The lignification of primary shoots was delayed by this treatment but ultinately occurred.
The effects of night-break for 2 hours from 8:00 p.m., from 11:00 p.m. and from 2:00 a.m. were compared. Each night-break treatment promoted lateral shoot and berry growth and delayed lignification of primary shoots. The strongest effect on the growth of ‘Pione'’ grapes was obtained by night-break from 11:00 p.m..
