Effects of paclobutrazol’s pre-treatment on cold tolerance induction in soybean seedling (Glycine max L.)

Paclobutrazol is one of the growth regulators in plants. It is from the Triazoles group, which can protect plants from all kinds of tension. In order to investigate the effect of cold stress and paclobutrazol on physiological characteristics of soybean seedling (cv. Williams), a factorial experiment was conducted base on completely randomised design with three replications. The first factor involved applying cold tension at 5°C in four intervals times (0, 8, 16 and 24 h). The second factor involved pre-treatment of paclobutrazol in four concentrations (0, 100, 500 and 1000 μM). The results showed a significant increase in shoot’s dry weight by 100 μM paclobutrazol application compared to non-paclobutrazol in eight hours of cold tension. The highest amount of chlorophyll a and relative water content was shown by 100 and 500 μM paclobutrazol application, respectively. The increase in cold tension time to 24 h caused an increase in ion leakage and led to an increase in protein content, catalase and peroxidase antioxidant enzymes. The results of this study demonstrate that cold tension can cause reduction in shoot’s dry matter and change the physiological characteristics of soybean but application of 100 and 500 μM of paclobutrazol can partly induce tolerance to cold stress.