不同耕作制下水田土壤有机质氧化铁含量的研究

以第四纪红色粘土发育的旱土为供试土壤,淹水种稻,进行水田耕作制模拟试验,研究对土壤有机质、氧化铁含量的影响。结果表明:有机质的增加是冬泡区>冬绿区>冬油区,但只施化肥的冬泡区有机质增加量少;无定形铁的含量及氧化铁的活化度均逐年增加,其增加速度是冬泡区>冬绿区>冬油区:无定形铁含量与有机质含量之间存在一定的相关性。     

二系杂交水稻制繁种中利用标记辅助去杂技术

在二系杂交水稻种于生产中，由于母本雄性不育不彻底，往往造成自交种子污染；在不育系繁种时，由于与外源花粉串粉杂交或机械混杂，因此难以保证不育系纯度。作者选用叶绿素缺失突变体为模式标记，讨论了标记性状必需具备的条件及其应用方法。最后以一个转绿型白化突变体为例，证明了标记性状对当代及Ｆ＿１杂种优势无负效应，从而证实了这一去杂体系具有一定的应用前景。     

红壤的磷肥有效性差异及其土壤化学特点的初步研究

用发育于玄武岩和花岗岩的红壤及其水稻土作水稻盆栽试验研究红壤的磷肥有效性差异及其土壤化学特点，试验表明，花岗岩发育的红壤及其水田的磷肥有效性与Ｆｅ，Ａｌ有关，而玄武岩发育者，不仅占Ｆｅ，Ａｌ，而且还与Ｍｎ有密切关系，对土壤－植物系统中磷肥有效性与Ｆｅ，Ｍｎ元素相互作用及其机理进行了讨论。     

添加铬、铁及葡萄糖对土壤中异化铁还原的影响

采用水稻土为供试土壤,通过添加氧化铁、铬酸盐和葡萄糖的模拟试验,在厌氧培养条件下测定了土壤中可浸提态的亚铁和铬( )浓度的变化,探讨了有机碳源及Cr( )、Fe对厌氧条件下水稻土中微生物铁还原的影响及Fe( )和Cr( )还原的竞争关系。结果表明,添加碳源和氧化铁后,能有效促进厌氧条件下水稻土中铁的异化还原过程,显著减小土壤中铬( )浓度;添加Cr( ),将导致土壤中铁还原滞后;厌氧水稻土中Fe( )和Cr( )的竞争还原机制为,有机电子供体导致氧化铁发生微生物还原,产生的Fe( )引起土壤中Cr( )的化学还原。     

拔节和挑旗期缺磷对两小麦品种体内磷分配的影响

 采用石英砂培养方法,研究了拔节和挑旗期缺磷对大穗型小麦CA9325和多穗型晋麦2号（JM2）生长后期体内磷分配和成熟期磷利用效率的影响。结果表明,随着生长的延续,两品种供磷植株的主茎、有效分蘖和整株中的磷含量均呈"S"型增加,峰值在灌浆期。两品种所有处理的植株主茎中的磷在整株中所占比例不断增加,而无效分蘖和根系中的磷所占比例不断下降。两品种缺磷植株的有效分蘖中磷含量也呈下降趋势;对照CA9325主茎的籽粒含磷量及其在主茎中所占比例高于有效分蘖;而对照JM2主茎的籽粒含磷量低于有效分蘖,这与二者分属不同穗型小麦有关。缺磷的两品种主茎和有效分蘖营养器官和颖壳中的磷含量均低于同期的对照植株,使得籽粒中磷占主茎和有效分蘖中磷的比例高于对照。尽管如此,主茎和有效分蘖的籽粒含磷量低于对照;到成熟期,两次缺磷均显著降低两品种的籽粒产量。供磷的CA9325磷吸收效率和各处理的CA9325的收获指数均高于JM2,但前者各处理的磷利用效率低于后者。对两品种小麦体内磷利用的差异进行了讨论。     

全磷和缺磷条件下甘蔗叶悬浮细胞主要生长指标的比较

研究了以甘蔗基因型US66-56-9的心叶为材料，对甘蔗愈伤组织进行诱导和建立甘蔗叶片悬浮细胞系，并对悬浮细胞进行全磷和缺磷处理，然后对二者的生长曲线，细胞含水率及培养基pH等变化进行了比较，结果表明；与全磷条件相比，缺磷胁迫抑制细胞的生长，导致细胞含水率较高，使培养基的pH值在生长过程中基本保持酸性状态。     

华中地区水旱轮作酸性土磷、铁形态转化及机理

为探讨华中地区水旱轮作体系酸性土壤磷与铁的形态转化以及磷生物有效性变化,本研究于2018年和2019年水稻收获后采集该区域典型酸性红壤（低磷铁比）和黄棕壤（高磷铁比）,采用张守敬-杰克逊无机磷分级方法和梯度扩散薄膜（DGT）技术,对干湿交替培养样品磷形态、生物有效性磷（DGT-P）与铁（DGT-Fe）、Fe（Ⅱ）及无定形氧化铁（Fe_ox）等进行定量分析。结果表明：淹水过程中黄棕壤和红壤pH逐渐升高趋于中性;二者氧化还原电势（Eh）在淹水期间降低,土壤环境呈明显的还原条件。淹水过程黄棕壤和红壤中Fe²⁺与Fe_ox均增加,干燥后均明显降低。黄棕壤与红壤磷形态以铁结合态磷（Fe-P）与闭蓄态磷（Oc-P）为主,干湿交替过程中黄棕壤Oc-P向Fe-P转化,红壤Fe-P向Oc-P转化。在水-土界面以下120 mm土壤垂直剖面内,黄棕壤DGT-P和DGT-Fe释放水平先增加后减少;红壤DGT-Fe增加,DGT-P减少,黄棕壤P和Fe的同步释放相关性更显著。研究表明,干湿交替条件下酸性土壤磷形态主要是Fe-P与Oc-P之间转化,低P/Fe红壤以磷闭蓄化为主,高P/Fe黄棕壤Fe-P增加,以铁吸附磷为主;淹水导致DGT-P含量增加,生物有效性增加;干燥过程磷闭蓄化加深,但磷有效性并无明显降低,这与土壤磷水平有关。     

Potential for the alleviation of arsenic toxicity in paddy rice using amorphous iron-(hydr)oxide amendments

Abstract

A pot culture experiment was conducted to investigate the effects of amorphous iron-(hydr)oxide (Am-FeOH) amendments on arsenic (As) availability and its uptake by rice (Oryza sativa L. cv. BR28) irrigated with As-contaminated water. A rhizobag system was established using 3.5 L plastic pots, each containing one central compartment for plant growth, a middle compartment and an outside compartment. Three levels of laboratory-synthesized Am-FeOH (0, 0.1 and 0.5% w/w) were used to amend samples of the As-free sandy loam paddy soil placed into each compartment of the rhizobag system. The soils were submerged with a solution containing 5 mg L^?1 As(V). Two-week-old rice seedlings were planted in the central compartments and cultured for 9 weeks under greenhouse conditions. The addition of 0.1% Am-FeOH to the soil irrigated with As-contaminated water improved plant growth, reduced the As concentration in the plants and enhanced Fe-plaque formation on the root surfaces. Analysis of soil solution samples collected during the experiment revealed higher pH levels and lower redox potentials in the soils amended with Am-FeOH at the onset of soil submergence, but later the soil solution collected from the 0.1% Am-FeOH treatment was slightly acidic and more oxidized than the solution from the 0% treatment. This indicated active functioning of the roots in the soil treated with 0.1% Am-FeOH. The concentrations of As(III) in the soil solution collected from the central compartment were significantly reduced by the Am-FeOH amendments, whereas in the soil treated with 0% Fe, As(III) accumulated in the rhizosphere, particularly during the late-cultivation period. The improvement in plant growth and reduction in As uptake by plants growing in the Am-FeOH treated soil could be attributed to the reduction of available As in the soil solution, mainly as a result of the binding of As to the Fe-plaque on the root surfaces.     

Effects of Iron Deficiency on Thylakoid Membrane Structure and Composition in the Alga Dunaliella salina

Abstract

The unicellular green alga Dunaliella was previously proposed as a model photosynthetic organism for adaptation to iron deficiency. The purpose of this study was to find out how iron limitation affects the structure and composition of the photosynthetic system of Dunaliella salina. Iron deprivation did not retard proliferation of D. salina cells, but was associated with a decrease in cell volume and chlorophyll content, and with a four‐fold reduction in iron content and a two‐fold increase in Cu content. Electron microscopic analysis revealed shrinkage of the chloroplast and decrease in stacked thylakoid membranes. Measurements of chlorophyll fluorescence induction in the presence of DCMU and of 77 K chlorophyll fluorescence emission spectra indicated gross changes in the photosynthetic efficiency of reaction centers and in the organization of their associated light harvesting antenna. Differential analysis of protein composition led to the identification of a major thylakoid membrane protein (Tidi), that was specifically induced under iron deprivation. Partial sequencing suggests that Tidi is a novel type of a chlorophyll a/b binding protein. These results clearly show that iron limitation is associated with extensive reorganization of the photosynthetic system in Dunaliella.     

内蒙古河套灌区春玉米推荐施肥指标体系研究

【目的】建立河套灌区春玉米施肥指标体系,指导科学施肥。【方法】2006—2008年在河套灌区分高、中、低肥力水平设置春玉米“3414”肥料肥效试验236个。【结果】通过对数据进行整理分析表明：河套灌区春玉米N、P2O5、K2O的农学效率平均分别为10.6 kg•kg-1、9.9 kg•kg-1、6.7 kg•kg-1,肥料增产作用依次为：氮肥＞磷肥＞钾肥,随着土壤肥力水平的降低,施肥增产率升高,但单位养分增产量下降。河套灌区春玉米的土壤养分丰缺指标为：全氮,极低（＜0.42 g•kg-1）、低（0.42—0.67 g•kg-1）、中（0.67—1.08 g•kg-1）、高（1.08—1.72 g•kg-1）、极高（＞1.72 g•kg-1）;有效磷,极低（＜3.6 mg•kg-1）、低（3.6—7.6 mg•kg-1）、中（7.6—16.0 mg•kg-1）、高（16.0—33.7 mg•kg-1）、极高（＞33.7 mg•kg-1）;速效钾,极低（＜70 mg•kg-1）、低（70—103 mg•kg-1）、中（103-151 mg•kg-1）、高（151—222 mg•kg-1）、极高（＞222 mg•kg-1）。河套灌区春玉米施肥模型为：F(N)=-78.13×lnS(N)+155.85,F(P2O5)= -54.621×lnS(P)+250.2,F(K2O) =-42.4071×lnS(K)+272.91。【结论】农学效率、施肥肥效、养分丰缺指标、施肥模型均为推荐施肥的重要依据。