Effect of paclobutrazol on growth and yield of continuous cropping Tartary buckwheat

This study aimed to explore the regulatory effect of exogenous paclobutrazol treatment on alleviating the damage of Tartary buckwheat caused by continuous cropping. Buckwheat variety JQ 2 was used as the experimental material, and multiple cropping was carried out in the experimental area of continuous cropping for 2 years. Different concentrations of paclobutrazol (0, 100, 150, 200, and 250 mg/L) were sprayed on the leaves at the squaring stage to study its effects on the growth, physiology, and yield of continuously cropped Tartary buckwheat. The results showed that the plant height decreased significantly, and the stem diameter increased significantly after paclobutrazol treatment. The total root length, root surface area, root volume, and average diameter increased first and then decreased with the increase in paclobutrazol concentration, whereas the root activity significantly increased. With the increase in paclobutrazol concentration, the contents of chlorophyll and soluble protein and the activities of superoxide dismutase, peroxidase, and catalase in the leaves increased first and then decreased, whereas the contents of malondialdehyde and superoxide anion radical decreased. The grain number per plant, grain weight per plant, and 1000-grain weight increased first and then decreased with the increase in paclobutrazol concentration. Compared with the control, the continuously cropped Tartary buckwheat had increases in yield by 3.32%, 14.53%, 32.20%, and 17.88% when treated with 100, 150, 200, and 250 mg/L of paclobutrazol, respectively. In conclusion, suitable concentration of paclobutrazol treatment could alleviate the damage of Tartary buckwheat caused by continuous cropping and increase the yield. Particularly, the treatment of 200 mg/L has the best effect, so it is recommended to use in production.