铁胁迫下不同基因型大豆根系调控及对Fe-EDDHA应答生理机制

Calcareous soil is widely distributed in North China, Northwest China, as well as the western area of Northeast China, which characterized by high pH and dramatically decreased effective iron (Fe) content. As one of the major crops in North China and Northwest China, soybean yield and quality have been restricted severely by Fe deficiency in these areas. Aiming at the burning problems in research of soybean Fe nutrition and the practice of agricultural production, our research group plan to take various Fe efficiency soybean genotypes as experimental materials, through the hydroponic experiment, their difference in root morphological characteristics, Fe3+ reduction ability, H+ secretion and organic acid secretion under Fe deficiency are to be studied, clearing the contribution of soybean Fe nutrition to various adaptive mechanism. In calcareous soil, Fe efficiencies of 185 soybean cultivars will be fine evaluated by combining method of cholorophyll content and seed Fe content, to develop standards for soybean grading and identifying. And the effect of supplying Fe-EDDHA on physiological characteristics of genotypes with different Fe efficiencies will be studied for clarifying their physiological mechanism, which include root morphological characteristics, leaf cholorophyll content, chlorophyll fluorescence parameters, photosynthetic rate and related indicators, dry matter accumulation dynamics, Fe distribution in different organs, as well as yield and its components. It will be a guidance for breeding Fe-efficient soybean varieties, and lay a foundation for correcting Fe deficiency of soybean in calcareous soil.

中国北方广泛存在石灰性土壤，其土壤特点是pH值高，有效铁含量大大降低。大豆作为东北和华北主要作物之一，其部分区域缺铁黄化严重，已成为限制大豆产量和品质重的重要因子。本课题针对大豆铁营养研究与农业生产实践中亟待解决的问题。以不同铁效率大豆品种为试材，通过水培试验，研究铁胁迫下，其根系形态特性、Fe3+还原能力、H+分泌量和有机酸分泌差异，明确各适应机制对大豆铁营养的贡献。在石灰性土壤条件下，采用叶绿素含量和籽粒含铁量相结合鉴定方法，对185个品种进行铁效率精确评价，制定大豆铁效率分级、鉴定标准。同时研究Fe-EDDHA对不同铁效率大豆品种根系形态特性，叶片叶绿素含量、叶绿素荧光参数、光合速率等光合相关指标，干物质积累动态，不同器官铁元素分配，产量及产量构成等生理特性影响，阐明Fe-EDDHA调控不同铁效率大豆品种生理机制。最终指导大豆铁高效育种，同时为我国石灰性土壤大豆缺铁黄化矫正奠定基础。

中国东北西部和华北石灰性土壤分布广泛，土壤有效铁含量大大降低，大豆作为本区域主要作物之一，出现了大面积缺铁黄化现象，已成为限制大豆产量和品质的重要因子。本研究针对大豆生产中亟待解决缺铁黄化的问题，主要开展以下内容研究：研究大豆不同铁效率品种鉴定简易指标；根据品种叶绿素含量和单株生物产量，对收集品种进行铁效率鉴定分级；通过水培试验，研究缺铁胁迫下不同铁效率大豆品种根系形态和生理的差异；通过大田试验，研究铁胁迫下不同铁效率大豆品种产量及相关性状对Fe-EDDHA肥响应；探讨了磷水平与大豆铁高效利用之间的平衡规律。主要结果如下：（1）苗期为大豆叶片缺铁黄化敏感时期，可将苗期和生殖生长期的叶绿素含量共同作为大豆铁效率鉴定指标，株高、单株荚重、单株粒重、单株生物量可作辅助鉴定指标。（2）将收集的126个品种分为5个级别，1级到5级抗黄化能力逐渐减弱，分别占参试品种总数14.3%、26.2%、23.8%、21.4%、14.3%，1-2级类别品种可在缺铁土壤区域种植推广。（3）水培铁胁迫条件下，铁高效品种的PhiPSII、ETR、Fv/Fm以及SOD、POD和CAT活性显著高于铁低效品种。通过主成分分析发现，地上部光能吸收因子和根系形态因子的贡献率最高，且提高光合作用以及根系表面积有助于提高大豆耐低铁能力。（4）不同铁效率品种产量及相关性状对Fe-EDDHA肥响应存在显著差异。为使不同铁效率大豆品种农艺及产量相关性状不降低，铁高效品种到铁敏感品种对铁肥需求逐渐增大，铁高效品种需施铁肥0-3 kg/公顷，铁中效品种需施铁肥3-6 kg /公顷，铁敏感品种需施铁肥6-9 kg/公顷，可使不同类型大豆品种不减产。产量相关性状对铁肥响应大小不同，表现为单株粒重＞单株荚重＞R2期SPAD值＞V3期SPAD＞株高＞百粒重。（5）根系发达水平在磷铁互作过程中发挥着重要作用，在高磷条件下，铁高效品种根系的干物质积累能力强于铁低效品种，但高磷处理干物质积累平均速率和最大速率是最低的，过量施磷无益于产量增加。