生物炭对水稻土壤微域环境和根功能影响及调控机制研究

Biochar can rebuild soil water conservation and fertilizer conservation, cation exchange capacity (CEC), surface sorption capacity and soil enzyme activity when added to soil. Biochar additioned to soil also have the potential to influence soil microbial community structure and function, and further affect on root activity and yield. However, biochar have the different properties under different carbonization conditions such as type of materials, carbonization temperature and so on. The different biochar impact on soil microenvironments and root function may different. In view of problems about the root of seedling are poor growth and high-yielding rice root is easy to premature senility in the late growth stage, we selected different root type of japonica rice varieties as materials, different properties biochar, input mode and application rates were treatments. The key research the effects of biochar on soil physical and chemical properties, soil microecology, root distribution and physiological characteristics and functional metabolism by location test of the rice before and after transplanting. This experiment makes clear the relationship between different input mode, application rates of biochar, fertilizer management and rice root growth. Explore a long-term mechanism of root morphological and physiological by biochar. Reveal the interaction of dependence and restriction between above-ground and underground of rice. Scientific evaluation the effects of biochar on soil properties and rice root structure and function. Reveal the regulation mechanism of rice root growth by biochar, which to provide a scientific basis for new nursery substrate, paddy soil improvement and improve rice potential productivity.

生物炭输入土壤能重塑土壤保水保肥能力、CEC、吸附力和酶活性，影响土壤微生物群落结构和功能，进一步影响根系活力，改变作物产量。然而，不同炭化条件（原材料类型、炭化温度等）所产生的生物炭理化性质差异较大，其对水稻土壤微域环境和根功能的影响也可能不同。针对目前水稻秧苗根系生长不良及高产水稻生育后期根系易早衰等问题，本研究拟选用不同根型粳稻品种、不同性质生物炭、不同输入方式、不同输入炭量为处理，通过秧田期和本田期定位试验，重点研究生物炭对水稻土壤理化特性、土壤微生态、根系形态分布、生理特性和功能代谢等的影响及调控机制。明确生物炭输入方式及输入量、肥料运筹与水稻根系生长的相互关系。探索生物炭调控根系形态生理的长效作用机制。揭示水稻地上和地下部依存制约的互动规律。科学评价生物炭对水稻土壤特性和水稻根系结构与功能的影响，为生物炭创制水稻新型育苗基质、改良稻田土壤、提升稻作生产潜力提供科学依据。

针对我国滨海稻区盐碱重，育秧取土难、难取土，秧苗根系生长不良及高产水稻生育后期根系易早衰等问题，本研究通过秧田期和本田期定位试验，开展了生物炭对水稻秧苗生长发育及育苗基质创制的研究，并从根系发育特征、生理特性、秧苗素质等方面入手，重点研究了生物炭对水稻土壤理化性质、根系形态结构、耐盐生理等方面的影响及调控机制。通过田间定位（水田、根箱）研究了水稻根系在炭化还田中的形态分布与生理响应及干物质积累、氮素利用率和产量形成规律。结果表明：添加生物炭（30%～40%）明显增加了营养土中阳离子交换量和电导率，降低了容重，显著提升了通气和持水性能；显著提高了秧苗地上部（叶龄、叶长、叶宽、株高、假茎宽和根冠比）和根系（总根长、根表面积、根体积、根平均直径、根尖数和根分支数）生长能力；随施炭水平的增加，叶片、假茎和根系中的内源激素（IAA、GA3、CTK）含量呈先升后降趋势，而ABA则相反。根系解剖结构表明：生物炭促使根半径、根截面积、根表皮厚度、根皮层厚度、皮层腔面积、根导管数量及导管横截面积等性状指标明显增加。水培实验结果表明：生物炭浸提液能够提高盐胁迫下（200 mmolL-1 NaCl）水稻种子的萌发率，地上部的鲜重、叶绿素含量、幼苗存活率、活性氧清除系统酶活性，说明生物炭浸提液通过提高水稻幼苗的抗氧化能力、减少活性氧物质的积累来提高水稻幼苗对盐胁迫的耐受能力。通过大量重复配比筛选基质及多年多点评比试验，创制出以生物炭为核心的水稻育苗基质，并进行了示范应用。通过田间定位（水田、根箱）研究表明，不同时期植株（根、茎、叶、鞘）干物质积累、氮素利用率、有效穗数、穗长、二次枝梗数、每穗颖花数及产量均随施炭量增加而增加；耕层0-25cm全层施炭更有利于根系生长发育；施炭量和施氮水平两者存在显著互作。综合分析表明，适量添加生物炭有利于改善土壤和基质微域环境，提高秧苗综合素质，延缓根系衰老，从而为粮食生产安全提供可持续保障。