Determination of the effect of Paclobutrazol applications on plant growth, seed yield and seed quality in Cephalaria syriaca L.

In this study, the effects of different doses of plant growth regulator with the active ingredient Paclobutrazol on plant development, seed yield and seed quality were determined in pelemir (Cephalaria syriaca L.) plant. The trials were carried out in the experimental areas of İkizce Research and Application Farm affiliated to the Field Crops Central Research Institute. In the study, the plant growth regulator Paclobutrazol (PBZ) commercially named Pacman was applied by foliar spraying method at doses of 0 ppm, 150 ppm, 300 ppm, 450 ppm and 900 ppm in two different phenological periods, post-emergence and post-emergence + pre-flowering, using the Karahan variety. As a result of the study; statistically significant differences were determined at the level of 1% on physiological maturity, plant height and thousand seed weight, and at the level of 5% on plant first branch height and crude oil yield. With the increase in the applied doses, a decrease was observed in plant height and first branch height, whereas an increase occurred in the number of branches and thousand seed weight. It has been determined that the application at 150 ppm dose and after emergence is the most suitable application method in terms of controlling plant height. In the composition of fatty acids, no significant difference was observed on fatty acids (Lauric, Myristic, Palmitic, Palmitoleic, Stearic, Oleic, Linoleic, Arachidic, Linolenic and Nervonic). In addition, no statistically significant difference was observed in the study in features such as the number of days to flowering, the number of branches, the number of heads, seed yield and crude oil ratio. However, an increase in the number of heads and a decrease in seed yield were observed depending on the increase in dose. Pelemir plant's characteristics such as being able to grow in dry conditions with low costs, having an oil content that can be evaluated as a biodiesel raw material and being suitable for harvesting with machinery make it stand out as an alternative oil plant. The research conducted in this context reveals the effect of paclobutrazol use in pelemir plant on shortening plant height and increasing lodging resistance and branch number, and points out the necessity of supporting similar studies with multi-year trials in different locations.