粪产碱菌耐铵工程菌与水稻联合共生固氮作用

粪产碱菌（ Ａａｅｃａｌｉｓｆａｅｃａｌｉｓ） 在ＬＷ 培养基下能产生植物激素ＩＡＡ。盆栽结果表明,接种Ａ．ｆａｅｃａｌｉｓ 显著提高了水稻的生长,接种Ａ１５０１ 和Ａ１５１３ 的水稻稻谷产量分别比未接种提高了８５％ 和１０３ ％ ,用１５ Ｎ 同位素稀释法估测水稻地上部总氮中来源联合固氮的百分率达９００ ％ 和１１５ ％ ,其结果与水稻地上部（ 茎叶及稻谷） 总氮量的增加幅度（８６ ％ 和１１６ ％ ）基本一致。研究还表明Ａ１５１３ 耐铵工程菌的产ＩＡＡ作用以及对水稻的生长和产量、联合固氮作用均优于原始菌株Ａ１５０１ 。     

固氮粪产碱菌（Alcaligenes faecalis）exoC基因的克隆及其特性

应用Ａ．ｂｒａｓｉｌｅｎｓｅ ｓｐ７的ｅｘｏＣ基因为探针，发现Ａ．ｆａｅｃａｌｉｓ Ａ１５０１具有与Ａ．ｂｒａｓｉｌｅｎｓｅ Ｓｐ７ ｅｘｏＣ基因同源的基因。Ａ．ｂｒａｓｉｌｅｎｓｅ ｅｘｏＣ基因能恢复Ａ．ｆａｅｃａｌｉｓ ＥＰＳ缺陷型（ＥＰＳ＾－）突变，表明粪产碱菌ＥＰＳ的产量为ｅｘｏＣ基因产物所调控。本工作已获得类似Ａ．ｂｒａｓｉｌｅｎｓｅ Ｓｐ７的ｅｘｏＣ－ｌｉｋｅ基因的克隆     

固氮粪产碱菌（Alcaligenes faecalis）表面蛋白变构作用的研究

采用电子自旋共振技术（ＥＳＲ），以马来酰亚胺自旋标记粪产碱菌野生型（Ａ１５０１）、胞外多糖突变株（ｅｘｏ＾－和ｅｘｏ＾＋＋）及工程菌（ｎｉｆ某Ａ和ｎｔｒＣ－ｎｉｆＡ重组子），监测由粪产碱菌表面多肽及些膜蛋白构象变化引起的ＥＳＲ波谱的变化。结果表明，粪产碱菌野生型菌株细胞表面特性显著不同于胞外多糖突变株及工程菌，根系粘质及ＮＨ４＾＋都能引起粪产碱菌表面蛋白的构象变化，标记后菌体ＥＳＲ参数τｃ的变化与     

固氮粪产碱菌（Alcaligenes faecalis）胞外多糖的分离纯化及成分分析

固氨粪产碱菌野生型Ａ１５０１菌株及其胞外多糖（ＥＰＳ）突变株Ｅｘｏ＋＋（Ａ１５３２）和ＥｘＯ－（Ａ１５３１）,以及ｎｉｆＡ和ｎｔｒＣ－ｎｉｆＡ转化子（Ａ１５１３和Ａ１５２３）的ＥＰＳ,由高分子量（２５０ｋＤ左右）组分（ＥＰＳＨ）和低分子量小于４０ｋＤ组分（ＥＰＳＬ）组成。两个组分中均含有葡萄糖、半乳糖、果糖和戊糖,其主要成分葡萄糖和半乳糖的分子摩尔比：Ａ１５０１－ＥＰＳＨ为２：１、ＥＰＳＬ为３：１;Ａ１５３１－ＥＰＳＨ为２：１、ＥＰＳＬ为１：１;Ａ１５３２－ＥＰＳＨ为８：１、ＥＰＳＬ为５：１;Ａ１５１３－ＥＰＳＨ和ＥＰＳＬ均为４：１;Ａ１５２３－ＥＰＳＨ为４：１、ＥＰＳＬ为８：１。高分子量ＥＰＳ中还含有多肤,其氨基酸组分在各突变株和转化子之间差异明显,而ＥＰＳＬ中仅含有痕量多肽。     

固氮粪产碱菌（Alcaligenes faecalis）胞外多糖突变株的筛选及特性

应用Ｔｎ５转座子对粪产碱菌野生型菌株Ａ１５０１进行诱变处理，用荧光增白剂及ＴＴＣ为标记筛选，分别获得胞外多糖缺陷型和丰富型突变株。激光共聚焦观察证实，ＥＰＳ突变株确实具有与野生型不同的表面特性，贴根试验表明，突变株贴根菌数均少于野生型，胞外多糖生成过多或过少均影响菌体与根表的有效结合。     

固氮粪产碱菌（Alcaligenes faecalis）表面基团与水稻根系粘质…

应用荧光探针ＦＭＡ和荧光胺，证明ＥＰＳ中多肽的一些基因如ＳＨ基和ＮＨ基参予了与 系粘质的相互作用。ＮＨ４＾＋浓度可诱导ＥＰＳ中ＳＨ基和ＮＨ基数量的变化，并导致ＥＰＳ中多肽的构象改变，ＥＰＳ中的这些基因在粪产碱菌与水稻根系的结合过程起了重要作用。     

固氮粪产碱菌ntrC基因的表达及固氮调节功能研究

采用双亲结合方法，将粪产碱菌Ａ１１５０ｌｎｔｒＣ和ｎｔｒＣ－ｌａｃＺ融合基因转入Ａ１５０１中，获得携带双拷贝ｎｔｒＣ的结合子Ａ１５０１（ｐＬＡＣ１）和ｎｔｒＣ－ｌａｃＺ融合基因的结合子Ａ１５０１（ｐＬＡＣ２）。在微好氧条件下，当铵为６ｍｍｏｌ时结合子Ａ１５０１（ｐＬＡＣ１）仍保持３４．８％的固氮活性，表明在粪产碱菌中ｎｔｒＣ具有固氮正调节功能。在不同铵、氧、ｐＨ和盐浓度等条件下测定结合子Ａ１５０１     

盐胁迫下粪产碱菌在水稻根表的定殖(英文)

粪产碱菌A1 5 0 1能在氯化钠浓度高达 4%的固体和液体介质中良好生长 ,合成IAA和固定空气中的氮素。当氯化钠浓度超过 3 %时 ,A1 5 0 1丧失运动和趋化能力。一定盐浓度胁迫下A1 5 0 1能定殖在水稻根表和根毛区和侧根伸出部位 ,表现出较高的联合固氮活性。0 5 %的氯化钠能促进A1 5 0 1在水稻根表的定殖能力。A1 5 0 1能通过侧根伸出部位侵入根内。     

水稻根际固氮粪产碱菌的研究（综述）

粪产碱菌分离自我国南方水稻田中，根据系统发育分类法属变形细菌中β亚类。粪产碱菌不仅能附着于水稻根表，部分细菌还能进入稻根细胞内，有较高的固氮能力，在高铵下它仍能合成固氮酶，并具有明显的ＰＧＰＲ作用。本文系统地论述了粪产碱菌的生物学特性及其联合固氮研究的进展。     

A SYSTEM FOR MEASURING THE RATES OF EVOLUTION OF NITROUS OXIDE AND NITROGEN FROM INCUBATED SOILS DURING DENITRIFICATION

An incubation system is described for studying denitrification rates in incubated soil by measuring the gaseous products removed in a stream of helium flowing across the soil. The system has been used to demonstrate the effect on denitrification of air-drying a soil. A constant rate of denitrification occurs in soil pre-incubated aerobically at 50% water holding capacity for a period of 3 weeks prior to the denitrification assay. By contrast, air-dry soil wetted immediately prior to denitrification measurement showed a rapid increase in denitrification rate to a maximum at 1–3 days and a decline thereafter until a steady state is reached about 2–4 weeks after rewetting. Nitrous oxide was the dominant product from both soils studied: the ratio of N₂O to N, in the gases evolved changed little with time for the pre-incubated soil, but diminished with time of incubation for the air-dried soil.     

BIOMASS ALLOCATION AND NITROGEN DISTRIBUTION IN RYEGRASS UNDER WATER AND NITROGEN SUPPLIES

Ryegrass (Lolium perenne L.) in grassland is known to sustain with water and nitrogen (N). This study investigates biomass and N partitioning in plant organs (roots, main and the youngest tillers) under water-nitrogen interactions. Nitrogen was applied at the rates of 50 and 100 mg N kg^?1 as N₁ (low N) and N₂ (high N) treatments, respectively, with uniform irrigation until 440 growing degree-days (GDD). Thereafter, the water supply was restricted to 50 mL on a weekly basis (W₁) against 50 mL on a daily basis (W₂) and concurrently, N enriched with 1 atom% ¹⁵N isotopes. Cumulative tillers’ biomass increased linearly from 1st to 8th order, but thereafter reached a plateau with further increases in number of negligible weights. Initially tiller mass and number per plan did not differ (P < 0.05) with water and/or N applications but changed at 788 GDD with clear differences at 911 GDD with the highest under N₂W₂ and lowest under N₁W₁. Nitrogen concentration sharply decreased from 530 to 700 GDD and then levelled off with age. The decline was more pronounced in tillers than roots. The high N treatment showed elevated N-concentration under both water treatments. Watering on a daily basis promoted vegetative growth. High water and N levels significantly (P < 0.05) influenced concentration of N absorbed during ¹⁵N labeling (N_L) in all organs with relatively pronounced N_L under N₂. The additive positive effect of W₂ and N₂ was obvious on N_L as compared to N_T, which showed that plants discriminate N-uptake on mass basis. Nitrogen (mobile) was higher in young and ¹⁵N (heavier) was low in young tillers and vice versa. Accumulation of N absorbed during ¹⁵N labeling (¹⁵N_A) was significant knowing that water is a strong determining factor of N concentration in ryegrass organs.     

稻田土壤氮矿化类型与氮肥效应

近年来许多研究工作指出:水稻一生所需的氮素主要来自土壤。一些研究还注意到,土壤有机氮的矿化强度、容量及矿化类型与水稻生长有密切的关系^[3,4]。只有弄清土壤的供氮特征,才能通过施肥技术,协调土壤供氮和水稻需氮之间的供求关系,达到合理施肥和稳产高产的目的。本工作希望用实验室培养方法,测定土壤氮素矿化量及其累积曲线类型,研究其与田间试验中水稻产量、吸氮量及氮肥效应的关系,为预测土壤供氮水平和因土施肥技术提供依据。     

水稻对有机、无机态肥料氮和土壤氮的吸收利用探讨

为了研究我国有机、无机肥配合施用的供肥特点,培土效果和增产作用,我们从1978年春以来,以¹⁵N示踪法进行有机、无机态肥料氮转化问题研究,在江苏四种代表性士壤上,即太湖地区黄泥土(代号A),丘陵地区板浆白土(代号B),苏北里下河地区鸭屎土(代号C),淮北地区花碱土(代号D)上进行。以¹⁵N标记的怪麻和硫酸按分别作有机和无机态氮源,全部作基肥,供试作物为水稻南粳34号,盆淋试验重复三次,另在板浆白土上增加重复次数,以分期测定土壤、植株中氮素动态。详细的试验材料及方法已另文登载^[1]。试验中的不同肥料处理列于表1。     

施氮水平对大豆氮素积累与产量影响的研究

以绥农14为材料,利用砂培和15N标记的方法研究了施氮水平对大豆氮素积累及产量的影响。结果表明:随着施氮水平的提高,大豆全株氮素积累量及叶柄、荚皮、籽粒中氮素积累量呈现先增加后下降的趋势;高氮水平增加了叶片和茎中氮素积累量,N150较N0处理叶片的氮素积累量增加了3倍,而茎增加了5倍,但减少了根中氮素积累,降低了大豆全株和籽粒中根瘤固氮量及其所占比例,降低了肥料氮和根瘤氮的收获指数,其中根中氮素积累N150较N50处理降低了60.3%,全株根瘤氮和籽粒中根瘤氮N150较N0分别降低了74.9%、85.7%,肥料氮的收获指数N150较N50降低19.8%,根瘤氮的收获指数N150较N0降低25.5%。随着施氮水平的增加,大豆产量也呈现先增加后下降的趋势,施氮水平的增加促进了大豆植株株高、结荚高度和始荚节位的显著增加,但对节数没有明显影响,N150和N0比较株高增加了55.2%,结荚高度增加了199.7%,始荚节位增加了142.9%。     

旱作水稻与花生间作系统中的氮素固定与转移及其对土壤肥力的影响

以花生和旱作水稻为材料 ,采用分隔方法和15N同位素示踪法 ,在不同氮素水平下研究了水稻与花生间作复合体的氮素营养优势、间作花生的生物固氮效率、花生体内氮素向水稻的转移。并在田间条件下研究了花生单作、水稻单作、水稻 /花生间作 3种栽培方式下对土壤氮素肥力的影响。结果表明 :( 1 )水稻和花生间作有产量优势和氮素营养优势 ,在N 0kghm- 2 、N 2 2 5kghm- 2 和N 3 0 0kghm- 2 三个氮素水平下 ,根系不分隔的水稻生物量分别比分隔处理的高 3 0 0 3 %、1 0 1 %和 2 2 % ;水稻氮素吸收量分别比分隔处理的高 74 0 3 %、1 6 93 %和 2 3 2 % ;( 2 )花生在N 2 2 5kghm- 2 和N 3 0 0kghm- 2 氮素水平下 ,分隔处理和不分隔花生固氮量分别为 3 8 1 1 %、40 97%和 1 4 81 %、2 0 49% ,间作能提高花生固氮效率 ;( 3 )花生体内氮素在共生期内可以转移到水稻体内 ,花生固氮量和氮素转移没有相关 ;( 4 )与水稻单作比较 ,花生 /水稻间作可以改善土壤的氮素营养。     

SOIL PARTICLE-SIZE FRACTIONS AND NITROGEN MINERALIZATION

Fractionation of East African arable soil samples into size groups < 2 mm has significantly influenced mineralizable N values. There was no evidence to suggest that refined soil fractions of < 2 mm would be an advantage for the determination, by incubation methods, of mineralizable N. Differences were more nearly related to simple physical fractionation of the soil. Organic C, total N, and silt contents of the different particle-size fractions were positively and significantly correlated with mineralizable N; coarse plus fine sand content of the different soil fractions was negatively and significantly correlated with mineralizable N.     

氮在紫色土中的移动和水稻氮素利用率的研究

利用养分渗漏池研究了紫色土中氮肥品种、用量对氮素移动、淋失和水稻氮肥利用率的影响。结果表明:淹水期间淋失的氮素基本形态是NH4+-N,主要分布在土壤表层,并随时间而下移;NH4+-N 淋失量与降雨量呈显著正相关;氯化铵促进了NH4+-N 的淋失,但其氮肥利用率比尿素高8 个百分点,说明水稻上可酌施含氯化肥;增施氮肥增加了NH4+-N 的淋失量,减少了氮肥利用率,建议水稻施氮控制在150kg/hm2。     

农田氮素的气态损失与大气氮湿沉降及其环境效应

本文总结了近年来有关农田N素气态损失与湿沉降研究的成果,讨论了农田N素气态损失的主要途径、排放量、影响因素及其环境危害。同时结合对太湖地区农田N素气态损失与大气N湿沉降的试验结果,阐述了化肥N的气态损失对大气和水体环境的影响,以及酸雨由硫酸型向硫酸和硝酸混合型变化的驱动因素。