Preparation Of Biochar-Wood Vinegar Derived Seed Coating And Its Effect On Maize Seedling Growth

Maize is one of the main food crops in dry cropland which has the largest yield and planting area in China. However, commonly used seed coating may contain organic materials with film properties and pesticides such as carbofuran and carbendazim, which has the potential of the environmental pollution and causes poisoning risk of human and animal. Therefore, pollution-free and environmental friendly seed coating are getting more and more attention.Biochar and wood vinegar derived from pyrolysis of maize straw were adopted as raw materials to make biochar-wood vinegar seed coating agents (BWSCA). The ratio of the components such as biochar-wood vinegar (1:1), sodium alginate and pH values were adjusted and a best formula of the BWSCA was prepared with its physic-chemical properties meeting the national standards and can be stably attached to the seeds. BWSCA and a conventional seed coating (consisted of 11.2% formalin, 8.0% carbofuran and 0.8% triadimefon) were used as coating agent of Zhengdan958 maize seeds, seeds without coating as control (CK). Germination experiment and pot experiment were conducted to study the effects of BWSCA on maize seeds vigor, seedling quality and physiological characteristics. The results of the study are as follows:(1) A germination experiment was conducted using BWSCA with five formulas (A1-A5) and maize seed without coating, the results showed that Al and A4 have significant effects on seed germination. Formula A4 increased germination potential and germination percentage by 22.1% and 9.7%, respectively.(2) Formula A4 was used as main BWSCA material and its ratio with biochar-wood vinegar, sodium alginate and pH were adjusted. The results showed that 5.0% biochar-wood vinegar significantly improved germination potential, germination index, vigor index of maize seeds and seedling length by 14.3%,13.8%,150.3% and 99.5%. When the sodium alginate0.5%, significantly improved germination potential, germination index, vigor index of maize seeds and seedling length were by 5.6%,12.7%, 124.3% and 109.8% in condition. When the pH of BWSCA was 6.5, the germination potential, germination rate, germination index, vigor index of maize seeds and seedling length were increased by 11.3%,12.5%,16.8%,85.6%, and 80.2%, respectively,Above all, the best formula of BWSCA was as follows:biochar-wood vinegar (1:1) 5.0%, sodium alginate 0.5%, pH 6.5 and bentonite 22.5%.(3) Effect on maize seed germination ability experiment showed that BWSCA significantly improved seed germination index and vigor index by 13.7% and 47.8%, respectively, compare with the control. Mean germination time was significantly decreased. In addition, BWSCA significantly improved maize seedling length, leaf area, root dry weight and root/shoot ratio by 22.3%,55.1%,17.4%, 30.3% and 9.7%, respectively, compare with CT; while the corresponding properties were increased by 39.7%,233.8%,37.5%,39.7% and 9.8%, respectively, compare with CK.(4) Effect on corn seedling growth and physiological and biochemical indexes experiments showed that BWSCA significantly increased the maize seed vigor index by 35.6% and 47.8%, respectively, compared to conventional seed coating and no seed coating; while no significant effects were found on seed germination power and germination rate. The results of pot experiment showed that BWSCA increased the height, leaf area and leaf fresh weight were by 26.4%,48.9% and 19.8%, respectively, compared to no seed coating; and by 14.0%,11.6% and 16.2%, respectively, compared to conventional seed coating, during 30d of the maize emergence. During the seedling stage, BWSCA increased underground CAT activity by 15.9%-40.1% and 7.8%～21.4%, compared to no seed coating and conventional seed coating. MDA concent was significantly reduced by 19.4%～42.1% and 16.9%～ 20.8% under BWSCA treatment compared to no seed coating and conventional seed coating except the 20d of maize emergence. Besides, N content was significantly increased in seedling root by 27.3% and 13.8% under BWSCA treatment compared to no seed coating and conventional seed coating, while there were no significant effects on P and K concentration.In conclusion, BWSCA has good coating effects on seed vigor, seedling quality and physiological characteristics. Meanwhile, the components such as biochar, wood vinegar, sodium alginate and bentonite are environmental friendly materials and they can be derived easily with relative low cost.This provide a good practice in agriculture sustainable development and provide new theoretical basis and practical technology.