Appropriate Concentration of Rice Straw Decomposition Liquid Prompted Germination and Seedling Growth of Common Buckwheat

To address the problem of poor soil conditions and low straw return measures in Southwestern China, straw decomposition liquid was used to simulate the effects of straw return on common buckwheat seed germination and growth in the field. The high-yielding common buckwheat variety “Fengtian 1” was used as test material to study the effect of different rice straw decomposition liquid treatments (0, 6.25, 12.50, 25.00, 50.00, 100.00 mg mL− 1) on seed germination, root morphology and activity, antioxidant enzyme activity, and nutrient uptake and utilization of common buckwheat. The germination rate, germination potential, and germination index of common buckwheat seed with low concentration of rice straw decomposition liquid treatment were not significant difference from those of the control. The root activity, root surface area, and the root volume of seedlings increased significantly with the increase in treatment concentration, at the 12.50 mg mL− 1 concentration treatment with the best effect. As the concentration of rice straw decomposition liquid increased further, the seed germination indicators, seedling root indicators, and antioxidant activities significantly decreased. Meanwhile, the decomposition liquid ammonium nitrogen, available phosphorus, available potassium content and plant total nitrogen, total phosphorus, total potassium content, biomass (dry weight underground), root-to-shoot ratio, main stem length were increased with increasing the decomposition liquid concentration. The appropriate concentration of rice straw decomposition liquid will not inhibit the common buckwheat seed germination, while it can promote seedling growth and improve the efficiency of nutrient absorption. There was a better effect at 12.50 mg mL− 1 concentration treatment.