Paclobutrazol application effects on plant height, seed yield and carbohydrate metabolism in canola

The mechanical harvesting of canola seeds requires a suitable plant height. The appropriate time of paclobutrazol application can reduce canola plant height. To evaluate the best application time of paclobutrazol, a field experiment was conducted with the paclobutrazol applied at stalk heights of 10, 20, 30, 40 and 50 cm. Plants without paclobutrazol application were taken as control. The results indicated that the plant height was reduced by 27% with paclobutrazol applied at 10 cm stalk height as compared with the control. The seed yield was significantly improved by mean increment of 21%. The increased branching ability contributed to yield improvement. The total soluble sugar, sucrose, and starch content in the stem, leaf and bud organs were significantly increased by paclobutrazol application at the initial flowering stage. Paclobutrazol enhanced the sucrose synthesis by sucrose phosphate synthase as well as the catalysis via sucrose synthase, neutral invertase, and in particular acid invertase. The amount of carbohydrates during harvesting remained significantly lower in the root after paclobutrazol treatment, thereby indicating the high-efficiency of carbohydrate utilization by the canola plants in comparison with the control plants. Thus, paclobutrazol applied at 10 cm stalk height takes advantages to control plant height and improve seed yield through enhancing carbohydrate utilization efficiency, which is useful in future for canola mechanical harvesting. © 2014 Friends Science Publishers