Effect of paclobutrazol and triapenthenol on the growth and flower number of Gardenia jasminoides in relation to temperature and solar radiation

The effect of paclobutrazol doses of 5, 10 and 20 ppm and of triapenthenol doses of 70, 140 and 280 ppm on the growth and flower number of Gardenia jasminoides in relation to temperature and solar radiation was examined under greenhouse conditions. Higher concentrations resulted in lower plans height and flower number. Thus a statistically important difference was found to exist between the control plants and the plants treated with the growth retardants. In contrast, the differences between the flower number of the control plants and the flower number of plants treated with the lowest doses of the growth retardants were not significant. High correlation coefficients (R-2 = 0.86 to 0.98) were found to exist between the plant growth height (for control plants and those treated with the lowest doses), the mean air temperature and the total solar radiation. In addition, when the doses were higher, the coefficients were lower for the plants treated with paclobutrazol (R-2 = 0,98 to 0,53) and those treated with Triapenthenol (R-2 = 0.86 to 0.48). The best quality for sale had the plants which were treated with doses of 70 ppm Triapenthenol as their height was reduced by 55% and the number of their flowers remained the same.