RE-ESTABLISHMENT OF SYMBIOSIS TO Anabaena-FREE Azolla

Symbiosis to Anabaena-free Azolla has been re-established by placing indusium containing Anabaena onto the Anabaena-free megasporocarps. Anabaena-free megasporocarps were obtained by removing the indusium and the apical membrane of the megaspore apparatus of normal Azolla. The recovery of symbiosis in artificially reconstituted Azolla-Anabaena association was confirmed using the scanning electron microscope, monoclonal antibody test (McAb-C_(16)), and nitrogen fixation capacity (ARA).Laboratory-grown Anabaena azollae cells inoculated subsequently to the decapitated megaspore apparatus were observed to have entered the leaf cavities of sporophyte, although some portions of Anabaena filaments were found outside the leaf cavity. Plants invaded by artificially inoculated Anabaena did not have sufficient N_2-fixing activity to allow the growth in the N-free medium.

秸秆还田联合稻田养萍对水稻产量、品质及氮素利用率的影响

秸秆还田在提高水稻产量和土壤肥力方面具有巨大潜力。然而,在水稻生长初期,秸秆的掺入可能会导致微生物的氮固定,从而抑制水稻的生长和对氮素的吸收。具有高效固氮能力的红萍可以作为优质绿肥放养于稻田,能提供氮素来满足水稻生长的需要,可以缓解秸秆还田造成的氮缺乏。为明确秸秆还田联合稻田养萍对水稻谷物产量、氮肥利用效率和谷物品质的影响,田间试验设置了5个处理[不施肥(CK)、常规施用化肥(F)、常规施用化肥+秸秆还田(FS)、常规施用化肥+稻田养萍(FA)、常规施用化肥+秸秆还田+稻田养萍(FSA)]。结果表明:FS处理水稻产量、氮素吸收量、氮肥利用率、糙米率、精米率、垩白粒率、垩白度、直链淀粉含量、蛋白质含量及镁、铁和锌含量均与F处理差异不显著,钙含量显著低于F处理(P<0.05);FA处理糙米率、精米率、蛋白质含量、镁和铁含量与F处理差异不显著,水稻产量、氮素吸收量、氮肥表观利用率、垩白粒率、垩白度显著高于F处理(P<0.05),直链淀粉含量、钙含量和锌含量显著低于F处理(P<0.05);FSA处理蛋白质、钙、镁、铁和锌含量与F处理差异不显著,水稻产量、氮素吸收量、氮肥农学利用率、氮肥表观利用率、垩白粒率、垩白度显著高于F处理(P<0.05),直链淀粉含量、糙米率和精米率显著低于F处理(P<0.05)。综上所述,秸秆还田联合套养红萍共作能显著提高水稻产量和氮肥利用效率,且未降低稻米的营养品质,是一项有潜力的南方稻田耕作措施。

稻萍共生对水稻磷素吸收和磷肥利用效率的影响

稻萍共生是我国传统的稻作方式,能提高水稻产量和氮肥利用效率,然而目前还鲜有研究关注稻萍共生对水稻磷肥利用效率的影响。通过田间试验,探讨稻萍共生处理对稻田土壤理化性质、水稻产量和磷肥利用效率的影响。结果表明:稻萍共生处理未显著改变土壤有机质、总氮、总磷和有效磷含量,但显著提高土壤硝态氮含量(P<0.05)。稻萍共生促进了水稻的磷吸收,显著增加了籽粒磷吸收量(P<0.05)和地上部总磷吸收量(P<0.05)。此外,稻萍共生还提高了水稻的磷肥回收利用率(P<0.05),说明稻萍共生处理能有效提高水稻磷肥利用效率,为水稻磷肥的高效利用提供了参考途径。

Physiology and Ultrastructure of Azolla imbricata as Affected by Hg 2+ and Cd 2+ Toxicity

The toxic effects of different gradient concentrations of Hg2+ and Cd2+ on chlorophyll content, chlorophyll a/b value, photosynthetic O-2 evolution, respiration rate, anti-oxidase system (superoxide dismulase (SOD), catalase (CAT), peroxidase (POD)) and ultrastructure of the cells of Azolla imbricata (Roxb.) Nakai were studied. The results showed that with Hg2+ and Cd2+ increase, chlorophyll content and chlorophyll a/b value, photosynthetic O-2 evolution decreased drastically; respiration rate peaked at 2 mg/L pollutant and declined afterwards. The activities of SOD, CAT and POD increased first and decreased afterwards except the activity of POD, which decreased with the increasing of Cd2+ concentration. Ultrastructural observation showed that the extent of ultrastructural damage was much more serious with higher pollutant concentration and longer time of stress. This resulted in swelling of chloroplast, disruption and disappearance of chloroplast membrane and disintegration of chloroplasts; swelling of cristae of mitochondria, deformation and vacuolization of mitochondria; condensation of chromatin in nucleus, dispersion of nucleolus and disruption of nuclear membrane. The experimental results showed: (1) Hg2+ and Cd2+ pollution not only destroyed physiological activities, but also caused irreversible damage to its ultrastructure, thus leading the cells to death; (2) With increase in the stress of Hg2+ and Cd2+, ultrastructural damage was related to the changes of plant physiology; (3) The toxic symptoms of plant showed an evident correlation between dose and effect; (4) The toxicity of Cd2+ on A. imbricata is heavier than that of Hg2+ under the same treatment time and concentration. The lethal concentration of Hg2+ to A. imbricata ranged from 3.5 to 4 mg/L, and that of Cd2+ ranged from 3 to 3.5 mg/L. The damage of cell ultrastructure on Anabaena azollae Strasburger was observed. The results indicated that tolerance of Azolla imbricata for Hg2+ and Cd2+ was higher than that of A. imbricata.

镉对满江红(Azolla imbricata)-鱼腥藻(Anabaena azollae)共生体氮代谢的影响

在实验室条件下,研究了不同浓度(0、0.01、0.05、0.1、0.5mg/L)的Cd对满江红-鱼腥藻共生体异型胞频率,固氮酶、谷氨酰氨合成酶活性以及铵态氮、游离氨基酸、可溶性蛋白、总氮含量的影响。结果表明,在整个实验期间,0.01mg/LCd处理对上述指标均没产生显著影响,说明满江红-鱼腥藻共生体对Cd具有较强的耐性。当培养液中Cd浓度≥0.05mg/L时,随溶液中Cd浓度的增加和处理时间的推移,异型胞频率、固氮酶活性、谷氨酰氨合成酶活性、可溶性蛋白含量和总氮含量逐渐下降,而铵态氮含量在处理初期显著降低,随后迅速增加,游离氨基酸含量则逐渐增加。研究结果表明高浓度的Cd处理导致满江红-鱼腥藻共生体氮代谢的紊乱,最终造成氮素积累量的下降。

从“Azolla Event”论满江红在生态农业中的应用

从分析始新世满江红在地球气候从"温室效应"向"冰室效应"转变的过程所起的作用入手,指出满江红具有在未来生态农业应用的潜力,包括作为优质农产品的生产原料、作为控制农业生态环境和重金属污染的植物、作为外太空开发的先行植物等。并提出要加强满江红在节能、环保和有机肥源、外源基因导入和满江红孢子果生产技术的研究以充分发挥满江红在未来生态农业中的作用。

小叶满江红(Azolla microphylla)内生细菌多样性的T-RFLP分析

[目的]应用T-RFLP技术揭示小叶满江红内生细菌的多样性。[方法]将分离自实验室无菌培养的小叶满江红内生细菌进行16SrDNA-PCR扩增,产物用MspI、HhaI、HaeIII、HinfI 4种内切酶进行酶切,通过检测带荧光标记的片段,将所获得的数据用相关的软件工具Phylogenetic Assignment Tool(PAT)进行比对分析。[结果]通过比对获得10个科42个属的细菌菌种。[结论]T-RFLP技术配合生物信息学软件能较有效地揭示小叶满江红内生细菌的多样性。

满江红Azolla imbricata(Roxb.)Nak的生物学特征及其渔业利用

满江红(Azollaimbricata)天然资源丰富,产量高,渔业利用价值比较大。论文综述了近年来满江红的部分研究工作,介绍了满江红的生物学特征及其渔业利用,在前人的基础上,提出利用“鱼类—满江红”走生态养殖的模式。

高产高蛋白饲草满江红 (Azolla imbricata)放养技术研究初报

满江红属蕨类植物 ,以营养体的侧枝断离无性繁殖方式为主 ,粗蛋白、赖氨酸、磷、粗脂肪含量均高于紫花苜蓿。研究结果表明 ,群体延续时间为 7d时 ,繁殖系数最高 ,在西北地区 4～ 9月份的适宜生长季节 ,采用薄膜微水放养技术 ,每公顷水面生产鲜草约 450 t,折合干重 45t,粗蛋白 1 1 .2 5t。

不同光照条件下4种满江红(Azolla)品系体内多酚氧化酶活性的变化

在生物学观察测定基础上，引入生化测定方法探讨不同光照条件下卡洲满江红３００１ 、小叶满江红４０１８ 、杂交萍９０４６ 和回交萍ＭＨ３１ 四个红萍品系体内多酚氧化酶（ＰＰＯ） 活性变化趋势。结果表明，光照影响各满江红品系的生长速率与抗霉腐病能力，随着光照强度减弱，各品系的生长速率和抗霉腐病能力都下降。在低光下，供试的满江红品系生物量与体内ＰＰＯ 活性的相关性显著（ｒ＝ ０ ．９５６０） 。低光下满江红各品系生长速率、抗霉腐病能力和体内ＰＰＯ 活性的从高到低依次为卡洲满江红３００１ 、杂交萍９０４６ 、小叶满江红４０１８ 和回交萍ＭＨ３１ 。从生理、生化角度讨论了满江红耐荫性与体内多酚氧化酶活性的关系。

Evaluation of Nitrogen and Phosphorus Wastes Produced by Nile Tilapia (<i>Oreochromis niloticus</i>L.) Fed <i>Azolla</i>-Diets in Earthen Ponds

Nitrogen (N) and phosphorus (P) wastes produced by Nile tilapia Oreochromis niloticus L. fed Azolla, an aquatic atmospheric nitrogen fixing fern, was evaluated for 90 days in pond experiment. Six isonitrogenous (29.2% crude protein) and isoenergetic (16.9 Kj·g–1) diets A0, A10, A20, A30, A40 and A50, containing 0%, 10%, 20%, 30%, 40% and 50% of Azolla meal (AM) respectively, as partial fishmeal (FM) substitutes, was provided to experimental fish. The Azolla-free diet A0 served as a control. Fish specific growth rate (SGR) was higher with the control diet, the lower values being obtained in A50-fed fish (P Azolla could be used in diet to sustain Nile tilapia growth and as “environmentally-friendly” ingredient to limit P loss, while providing N to the field, beneficially in tropical marshland pond where this nutrient is already limiting.

Eocene Cooling Through Sustained Growth of Azolla?

Through analyses of unique microlaminated sediments recovered from the Lomonosov Ridge during Integrated Ocean Drilling Program(IODP) Expedition 302,it became evident that enormous blooms of the free floating freshwater fern Azolla occurred within the Arctic Basin during an extended period of～1.2 Ma in the Eocene.The timing of the Azolla

Approximate Compositional Values and Tissue Fatty Acid Profiles of Nile Tilapia (<i>Oreochromis niloticus</i>L.) Fed <i>Azolla</i>-Diets in Earthen Ponds

The approximate general composition and the fatty acid profile of Nile tilapia fed Azolla-diets in ponds were studied for 90 days. Six isonitrogenous (29.2% CP) and isoenergetic (16.9 kJ·g>sup>-1) diets were formulated to contain 0% (A0), 10% (A10), 20% (A>sub>20), 30% (A30), 40% (A40) and 50% (A50) of Azolla meal (AM), as partial fish meal (FM) substitutes. Diet A0 without AM served as a control. Fish growth decreased as AM level exceeded 20% in diets (P 0.05). Crude lipid was significantly lower in fish fed A50 and significant differences were also found in crude ash (P 20, A30 and A50. High level of the fern reduces growth without negatively affecting fatty acid in fish. Fish PUFA, especially the (n - 3) fatty acids, are affected positively, even when fed 50% AM, which is good for the quality of the fish produced in regard to the benefits for the health of consumers.

Growth and fatty acid composition of Nile tilapia <i>Oreochromis niloticus</i>L. fed Azolla-diets, in tanks and in earthen ponds: A comparative study

Two 90-day experiments were conducted in the same period in tanks and in earthen ponds to study the effects of culture systems on growth and fatty acid (FA) of Nile tilapia (Oreochromis niloticus L.) fingerlings (mean weight: 16.3 g) fed Azolla, as partial replacement for fish meal (FM). Diets were isonitrogenous (29.2% CP) and isoenergetic (16.9 kJ·g-1) containing 0% (A0), 10% (A10), 20% (A20), 30% (A30), 40% (A40) and 50% (A50) of Azolla meal (AM) respectively. Diet A0, without AM, acted as a control. In both experiments, fish growth decreased as AM level increased in diets (P P 30-A50). Interestingly, those fish were rich in eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). Consequently, the n-3/n-6 values decreased in tanks, whereas an increasing trend was found in ponds, and values were significantly higher in ponds than in tanks (0.35 - 0.53 vs. 0.08 - 0.17). The results suggest raising Nile tilapia with Azolladiets in ponds to improve growth and produce fish with a better FA composition, for the wellbeing of consumers.

Effects of Various Environmental Factors on Biological Characteristics of Azolla

This study was conducted to screen and breed Azolla varieties with strong resistance.Four Azolla samples( CD,XT,HY,YZ) were collected from Hunan Province,and the growth characteristics such as propagation coefficient,temperature,light intensity,pH value and humidity were analyzed using artificial culture method.The results showed the four Azolla varieties all had the largest reproduction coefficients after cultured for 21 d,and the optimum culture conditions were temperature at 24-28 ℃,illumination intensity of 15 000-20 000 lx,pH 6.0,and humidity of 60%-80%.Among the four Azolla varieties,YZ has strong reproductive performance and high temperature resistance,and XT has strong acid resistance.

2,4-D Hyper Accumulation Induced Cellular Responses of Azolla pinnata R. Br. to Sustain Herbicidal Stress

In the present experiment with ongoing concentration(0µM,100µM,250µM,500µM and 1000µM)of 2,4-D,the responses of Azolla pinnata R.Br.was evaluated based on cellular functions.Initially,plants were significantly tolerated up to 1000µM of 2,4-D with its survival.This was accompanied by a steady decline of indole acetic acid(IAA)concentration in tissues with 78.8%over the control.Membrane bound H^(+)-ATPase activity was over expressed within a range of 1.14 to 1.25 folds with activator(KCl)and decreased within a range of 57.3 to 74.6%in response to inhibitor(Vanadate)application.With regards to IAA metabolism,plants recorded a linear increase with wall bound oxidase activity up to maximum concentration of 2,4-D.The variations were more moderated when wall bound IAA-oxidase recorded a linear increase proportionate to the 2,4-D concentrations.This was more extended with the presence of different isoforms of IAA-oxidase which was much more pronounced with distinct polymorphisms of expressed proteins,however,not independent to the 2,4-D concentrations.Polyamines like spermine,spermidine and putrescine(spm,spd and put)were not consistent in concentration with the dosages of 2,4-D.Besides these,plants were induced to apoplastic NAD(P)H oxidase activity maximally by 1.6 folds under 500µM 2,4-D over control.Still,putrescine responded more or less consistently and recorded maximally 11.9 folds at 500µM 2,4-D as compared to the control.NAD(P)H oxidase activity recorded maximally 1.6 folds against control and remain consistent throughout the concentrations of 2,4-D.GPX along with APX were more linear in responses through the concentration of 2,4-D except CAT as compared to control.On enzymatic antioxidative activity,peroxidases(GPX and APX)were overexpresed in a similar manner except for catalase with a non-significant rise.In stabilization of cellular redox,glutathione reductase attended maximum value by 2.45 folds at 1000µM evidenced with significant variations in protein polymorphism.The sensitivity of 2,4-D also appeared in Azolla with a maximum loss of nucleic acids as documented by the comet assay.Moreover,the Azolla might have some DNA damage protective activity as evident using frond extract with plasmid nick assay.Therefore,Azolla plants with its cellular responses is evident to sustain against the 2,4-D herbicidal stress and may be granted in bio remediation process for the contaminated soil.

Mineralization and Availability of Azolla and Cyanobacteria Biomass Nutrients in Rice Soil

Two sets of experiments were conducted to study the chemical composition, mineralization and availability of nutrients （particularly N） of Azolla biomass and cyanohacteria blooms in submerged rice soil. One set of experiment was conducted with Azolla without soil and the other with both Azolla and cyaobacteria with soil, in laboratory condition. Large samples were collected from the rice fields. The study shows that Azolla and cyanobacterial biomass contain good amounts of C, N, P and Ca. The chemical analysis of oxidizable C, total N, P and Ca showed that Azolla biomass contain 20.7% oxidizable C, which is higher than the cyanobacterial biomass （9.18%）. The N content in Azolla biomass was found to be 4.32%, than that of cyanobacterial biomass, i.e., 2.57%, however, P and Ca contents were also found to be higher in Azolla averaging to 124.83 ppm and 345.3 mg/100 g, respectively than cyanobacteria. The leachate analysis revealed that Azolla biomass release about 39.18% to 64.48% oxidizable C and about 19.23% to 33% N after 45 days of incorporation of soil dilution. Incorporation of Azolla and cyanobacterial biomass N@ 100 kg/ha significantly improved the oxidizable organic C, total as well as available N content in soil up to 75 days of incubation. Due to the incorporation of Azolla in soil, oxidizable organic C increased 25.51%, total N 4.10% and available N 47.65%. Almost similar trend of increase was also observed with the incorporation of cyanobacterial blooms.

The Growth of Rice(Oryza sativa L.)on Non Tidal Lowland Soil through Enrichment of Azolla and Different Level Fertilization Dosage(N and P)

Rice can grow in the non tidal lowland despite its limited soil fertility.One of the biofertilizers that can be used to improve fertility is azolla.This research aims to evaluate the growth of rice in non tidal lowlands using azolla to enrich the soil and different dosage of N(Nitrogen)and P(Phosphate)fertilization.A FCRD(Factorial Completely Randomized Design)was adopted consisting of 3 treatment factors,namely concentrations of N with doses of N1:46 kg/ha;N2:69 kg/ha;N3:92 kg/ha;P with P1:34 kg/ha;P2:68 kg/ha;and the application of azolla(A0:without azolla and A1:with 100 g/m2 azolla).The result showed that enriching the soil with azolla,fertilization dosage N and P,has a significant effect on plant height in the 4th WAP(Week After Planting).Furthermore,the interaction between azolla and N significantly influences panicle number,grain weight,and plant height at 2nd,4th,and 8th WAP.Conclusively,the application of azolla,N,and P fertilization supplied nutrients to rice crops in the non tidal lowland.

满江红金属元素含量的种间差异及其富集特性研究

为揭示满江红属(Azolla Lam.)植物资源材料对金属元素吸收积累特性差异,该研究采用ICP-MS的方法,对8种21个满江红品系的12种金属元素含量进行测定分析,比较不同种类满江红中金属元素含量的差异及富集特性,通过主成分分析确定满江红属品系的特征金属,并采用聚类法对供试材料进行分类。结果表明:(1)满江红属植物中金属元素含量变异系数大于30%的有8种,其中Mo含量在品系间差异最大(127.73%),Ca含量在品系间差异最小(18.94%)。(2)满江红属植物对土壤中不同金属元素的富集能力不同,富集系数大小依次为Mn>Mg>Mo>K>Cd>Ca>1。(3)不同种满江红对金属元素K、Mg、Mn、Zn、Mo的富集能力存在显著差异(P<0.05)。(4)满江红的特征金属元素为Cd、Hg、Ca、Mn、Cu、Zn、K和Cr。(5)基于特征金属元素含量的聚类结果显示,当遗传距离为15时,可将21份满江红资源分为3类,与传统分类基本吻合,其中品系‘3006’和‘MH3-1’对重金属Cd、Cr和Hg的富集能力较强,聚为一类。研究认为,满江红对金属元素的富集存在种间差异,且这种差异可以作为满江红品种分类的参考依据。

水生植物满江红及其农业产业化应用研究进展

满江红(Azolla pinnata subsp.Asiatica)是一种萍-藻共生的小型水生蕨类植物,具有固氮能力强、粗蛋白含量高和富钾的功能,农业应用价值较高,一直受到关注。红萍在农业生产应用上历史悠久,传统上红萍多用于绿肥利用、淡水鱼饲料,也有用于猪、鸡、鸭等饲料,降本节支的成效显著。近年来也逐步应用于污水治理,其具有去除富营养化水体中氮、磷的作用,显示出较好的水体环境治理效果。通过总结红萍育种、抗逆性、肥料化、饲料化、污水净化利用等方面的研究进展,分析了红萍综合利用中的优势及潜力,并提出红萍在农业产业化中的应用对策,以期为乡村资源高效利用与农业绿色发展提供参考及借鉴。