生物炭添加量对冬小麦花后干物质积累及转运的影响

Amending Soil with Biochar to Improve Accumulation and Translocation of Dry Matter after Anthesis in Winter Wheat

【目的】提高微咸水灌溉效率并降低土壤盐渍化风险。【方法】以冬小麦为研究对象,设计避雨条件下不同微咸水-生物炭处理(CK,淡水;B0,5 g/L微咸水;B15,5 g/L微咸水及15 t/hm^(2)生物炭;B30,5 g/L微咸水及30 t/hm^(2)生物炭;B45,5 g/L微咸水及45 t/hm^(2)生物炭)的田间试验,探讨了微咸水灌溉下生物炭添加量对土壤特性和冬小麦花后干物质积累及转运的影响机制。【结果】生物炭添加后土壤表层(0~20 cm)体积质量降低了2.27%~8.33%,总孔隙度增加了4.52%~13.47%,有机质量增加了30.02%~111.12%,土壤表层(0~20 cm)及主根区(0~40 cm)钠吸附比降低了23.88%~33.27%和22.34%~30.80%;15 t/hm^(2)能够促进盐分淋洗,降低了微咸水灌溉下土壤含盐量,然而高剂量时将加剧盐分累积。单独微咸水灌溉下冬小麦生长受抑,最终产量下降了12.04%。生物炭能够缓解盐胁迫下叶片早衰,促进光合作用能力,并增加花前干物质转运量及花后干物质积累量,进而获取了更高的籽粒质量和收获指数。B15、B30、B45处理的最终产量较B0处理分别增加9.18%、7.73%、2.74%。【结论】15 t/hm^(2)添加量的生物炭效果最佳,可促进微咸水资源的农业利用。

【Background】Winter wheat is a staple crop in China,but in many parts of the country rainfall during its growth season cannot meet its demand for water.Irrigation is,therefore,essential to safeguarding winter wheat production.The increasing disparity between water supply and demand has become a challenge in food production,and using saline water and brackish water as a supplementary irrigation water source has thus attracted increasing interest despite their risk of soil salinization.【Objective】The purpose of this paper is to experimentally investigate the feasibility of amending soil with biochar to ameliorate the risk of soil salinization induced by irrigation with saline water.【Method】The experiments were conducted in a rain-shelter and compared different combinations of biochar amendment and saline water with salt content 5 g/L:Freshwater irrigation(CK),saline water irrigation without biochar amendment(B0),saline water irrigation with 15t/hm^(2) biochar amendment(B15),saline water irrigation with 30 t/hm^(2) biochar amendment(B30),saline water irrigation with 45 t/hm^(2) biochar amendment(B45).In each treatment,we measured the change in soil properties and dry matter accumulation and translocation after the anthesis stage.【Result】Biochar amendment significantly improved soil properties,with bulk density of the top 0~20 cm soil decreasing by 2.27%~8.33%,and the associated porosity,organic matter increasing by 4.52%~13.47%and 30.02%~111.12%,respectively.In the meantime,it also reduced the sodium adsorption ratio in the top 0~20 cm and the root zone(0~40 cm)soils by 23.88%~33.27%and 22.34%~30.80%respectively.Amending soil with biochar at 15 t/hm^(2) facilitated salt leaching and reduced salt accumulation in the topsoil induced by saline water irrigation,but when the applied biochar exceeded a threshold,a further increase in biochar application could increase salt content and salt accumulation in the topsoil.It was also found that amendment with biochar under salt stress could alleviate premature senescence,promote photosynthesis,in addition to maintaining high leaf area index,leaf area duration and stomatal conductance.Biochar was able to improve dry matter accumulation and translocation in the vegetative organs before the anthesis stage,and maintain a good dry matter production capacity after the anthesis stage,thereby improving grain weight and harvest index.Compared with B0 without biochar amendment,B15,B30 and B45 increased grain yield by 9.18%,7.73%and 2.74%,respectively.【Conclusion】Biochar amendment can improve soil properties and increase the yield of winter wheat when irrigated with saline water,but it needs to be used with care as over-application biochar could lead to salt accumulation and inhibit plant growth.In our study,applying biochar at 15 t/hm^(2) is optimal to reduce salt accumulation and improve crop yield.