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地木耳对蕃茄生长的影响 总被引:4,自引:0,他引:4
地木耳是蓝藻门植物,具有生物固氮作用,分别以地表施加、土中施加、浸泡材料与酶提取液的方式在番茄的营养生长期和花蕾期施加,均有增肥效应。地表施加效果最好,且营养生长期施加的作用大于花蕾期;地木耳的用量随每一植株生活的环境不同而异。只要使地木耳保持活力,白天进行光合作用,夜间便可进行固氮作用,它可以持续地进行生物固氮,且具有累加效应。 相似文献
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THE BIOLOGY OF MYCORRHIZA IN THE ERICACEAE 总被引:4,自引:4,他引:0
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荚膜红细菌的分离鉴定及其协同固氮作用 总被引:3,自引:0,他引:3
从上海南汇县的水稻根系中分离得到一株光合固氮菌SDH2,经形态、细胞膜结构、生理生化等特征的分析鉴定,以伯杰细菌鉴定手册第九版和JFImhoff的光合硫细菌和绿硫细菌的生理学和分类[1]一文为依据,确定该菌为荚膜红细菌Rhodobactercapsulatus。同时,发现该菌与水稻根表的其它固氮菌之间具有协同生长和协同固氮效应。 相似文献
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本文对从中国东北地区土壤中分离到的8株弗氏中华根瘤菌(Sinorhizobiumfredit)进行了血清学和氢代谢研究。交叉凝集试验结果表明其中存在3种血清型,而Sj5与国内外目前发现的14种S.fredii接种的大豆依赖共生固氮作用,在其株木质部汁液中,含有大量的酰脲(尿囊酸+尿囊素),它是共生固氮氮素贮存和运输的主要形式,与接种B.japonicum的值株木质部汁液中的氮运输特征基本相同。而施以无机氮源的大豆植株,其木质部汁液中酰脲含量相对较低,但却含有相对多的氮基酸[1]。 相似文献
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THE ECOLOGY OF NOSTOC 总被引:1,自引:0,他引:1
Nostoc is a genus of filamentous cyanobacteria that can form macroscopic or microscopic colonies and is common in both terrestrial and aquatic habitats. Much of the success of Nostoc in terrestrial habitats is related to its ability to remain desiccated for months or years and fully recover metabolic activity within hours to days after re-hydration with liquid water . Nostoc can also withstand repeated cycles of freezing and thawing and, thus, is an important component of extreme terrestrial habitats in the Arctic and Antarctic. The ability to fix atmospheric N 2 can provide an advantage in nitrogen-poor environments . Nostoc also has the ability to screen damaging ultraviolet light in terrestrial and shallow benthic habitats. The genus potentially could be important in paddy rice culture because it fixes nitrogen that may later be released and used by plants; it also may play a role in soil formation and may increase nitrogen input to natural aquatic and terrestrial ecosystems. The abilities to survive in terrestrial habitats and fix N 2 are important in symbiotic interactions with fungi (lichens), liverworts, hornworts, mosses, ferns, cycads, and the angiosperm Gunnera. Nostoc is somewhat resistant to predation; this probably is related to production of large amounts of sheath material, synthesis of microcystin-like toxins by some strains, and formation of colonies that are too large for many algivores to consume. Some organisms can subsist on Nostoc, although it may not be a preferred food source. Lytic cyanophages also infect Nostoc, but little is known about population control of Nostoc in its natural environment, Late Precambrian fossils resembling Nostoc have been described, and Nostoc possibly has been an important component of many terrestrial and aquatic communities since that time . 相似文献
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在缺钾培养条件下,高粱苗地上部单位鲜重含钾量由于地上部鲜重的增加而下降。从高梁苗钾缺乏症出现的时间、频率和程度来看,Pro培养似乎有利于缓和或减轻缺钾对植物造成的伤害。在同样含钾量情况下,以Ca(NO_3)_2为氮源的苗受到缺钾伤害要重于以Pro为氮源的苗受到的伤害,其钾缺乏症植株的百分数增加值与含钾量降低值之比为0.26,以Pro为氮源的缺钾营养液培养的苗为0.09,即下降同样量的钾前者苗的钾缺乏症的增加要大大地超过后者。Pro并不减轻在缺钾情况下叶绿素含量的下降。 相似文献
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杉木人工林生态系统中氮素的动态特征 总被引:13,自引:2,他引:11
本文介绍会同县18年生杉木人工林生态系统中氮素的分布、转化、消长和循环方面的初步研究。结果表明,该系统总氮量为12287.6公斤/公顷,其中约有97%存在土壤库中,植物固定的氮仅占总氮量的2.5%。杉木枝叶中的氮含量因受“稀释效应”的影响,表现为随时间的推移而降低,尤其是在当年生枝叶的萌发初期。该生态系统每年经水文学途径获得7.35公斤N/公顷,径流输出0.98公斤N/公顷,即该系统每年以6.37公斤/公顷的速率净积累氮,表明杉木林生态系统对氮素的保存和利用的能力较高。文章还建立了氮素动态数学模型并进行初步模拟。 相似文献
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Diazotrophic cyanobacteria can take up combined nitrogen (nitrate, ammonium, amino acids, dissolved organic nitrogen) from solution, but the interaction between N2 fixation and uptake of combined nitrogen is not well understood. We studied the effects of combined nitrogen ) additions on N2 fixation rates in the cyanobacterium Trichodesmium erythraeum (IMS‐101) maintained in continuous culture in an N‐free medium (YBCII) and a 12:12‐h light:dark cycle. We measured acetylene reduction rates, nutrient concentrations, and biomass throughout the 12 h of illumination after the addition of nitrate (0.5–20 μM) at the start of the light period. Compared with unamended controls, Trichodesmium showed strong inhibition of acetylene reduction (up to 70%) in the presence of , with apparent saturation of the inhibition effect at an initial concentration of approximately 10 μM. The inhibition of acetylene reduction persisted through much of the light period as concentration in the culture vessel decreased. Recovery of N2 fixation was observed late in the light period in cultures amended with low concentrations of (<5 μM) when ambient concentrations had decreased to 0.3–0.4 μM in the culture vessel. Nitrate uptake accounted for as much as 86% of total N uptake and, at the higher treatment concentrations, more than made up for the observed decrease in N2 fixation rates. We conclude that Trichodesmium can obtain significant quantities of N through uptake of nitrate and does so in preference to N2 fixation when sufficient is available. 相似文献
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We tested whether experimentally enhancing nutrients around the kelp Hedophyllum sessile would increase growth, tissue nitrogen, or allocation to phenolic compounds. Packets of time‐released fertilizer were anchored adjacent to fronds in the field, and algae were monitored for several months. Although fertilizer packets increased the concentration of ammonium, nitrate, and phosphorus adjacent to treatment algae by an order of magnitude, there was little evidence that this increased frond growth or size. Hedophyllum individuals showed no tendency to alter allocation patterns in response to nutrient addition. Tissue carbon and nitrogen was unchanged by the nutrient manipulation; most H. sessile had tissue nitrogen concentrations in excess of 2.0% of dry mass. Additionally, the concentration of phloroglucinol equivalents was also unaffected by the presence of increased water column nutrients. Although nutrient concentrations in the water column surrounding the study site show relatively high mean values for ammonium, nitrate, and phosphorus, they are characterized by high spatial and temporal variation. Nonetheless, these data suggest that this intertidal kelp is not limited by nitrogen or phosphorus in wave‐exposed areas in the northeast Pacific Ocean. 相似文献
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采用原位(In situ)模拟实验方法研究了外加N源对杉木叶凋落物分解及土壤养分淋失的影响,结果表明,施加NH^+4-N时,杉木叶凋落物的失重率与对照(未加任何N的处理)相比,没有差异:而施加NO^-1-N时,使杉木叶凋落物分解速率显著提高(p=0.05,达10%以上,与施加NH^+4-N相比,施加NO^-3-N明显促进了杉木叶凋落物的分解(p=0.05)。施加NH^+4-N和NO3^--N会产生 相似文献
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不同抗旱品种高粱苗中脯氨酸累积的差异 总被引:3,自引:0,他引:3
高粱抗旱品种“3197 B”比不抗旱品种“三尺三”在同样渗透胁迫条件下,要累积更多的游离脯氨酸。未受渗透胁迫前,两品种地上部的总氨基氮和游离氨基氮水平相似。氨基酸组成也相同。六种主要氨基酸分别占总的量和游离氨基酸量的50%和65%左右。受渗透胁迫24h后,总氨基氮水平未变,游离氨基氮增加,两品种的变化相似。因而,品种间脯氨酸累积的差异,似乎不因蛋白质或游离氨基酸的氨基酸组分的不同和蛋白质水解或合成受促进或抑制程度的不同而异。受渗透胁迫后,3197B植株内不但脯氨酸绝对量,而且相对量都超过“三尺三”。脯氨酸合成的潜在能力在3197B和“三尺三”之间有差别。 相似文献
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A planktonic alga similar in general morphology and pigments to Aureococcus anophagefferens Hargraves and Sieburth has caused persistent and ecologically damaging blooms along the south Texas coast. Experiments using 100 μM NO3?, NO2?, and NH4+ demonstrated that the alga could not use NO3? for growth but could use NO2? and NH4+. Doubling iron or trace metal concentrations did not permit growth on NO3?. Chemical composition data for cultures grown in excess NO3? or NH4+, respectively, were as follows: N·cell?1 (0.88 vs. 1.3 pg), C:N ratio (25:1 vs. 6.4:1), C:chlorophyll a (chl a) (560:1 vs. 44:1), and chl a·cell?1 (0.033 vs. 0.16 pg). These data imply that cells supplied with NO3? were N-starved. Culture addition of 10 mM final concentration chlorate (a nitrate analog) did not affect the Texas isolate while NO3? utilizing A. anophagefferens was lysed, suggesting that the NO3? reductase of the Texas isolate is nonfunctional. Rates of primary productivity determined during a dense bloom indicated that light-saturated growth rates were ca. 0.45 d?1, which is similar to maximum rates determined in laboratory experiments (0.58 d?1± 0.16). However, chemical composition data were consistent with the growth rate of these cells being limited by N availability (C:N 28, C:chl a 176, chl a·cell?1 0.019). Calculations based on a mass balance for nitrogen suggest that the bloom was triggered by an input of ca. 69 μM NH4+ that resulted from an extensive die-off of benthos and fish. 相似文献
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本文报告了以蒸馏水、10%甘油和5%二甲基亚砜(DMSO)为保护剂,用液氮冻结法保存5种8株曲霉的效果,并检测了这些菌分别产生的亚甲基丁二酸、柠檬酸、蛋白酶和糖化酶的生理活性。这些菌在液氮气相(接近-150℃)中保存180天全部保持着生活能力,它们的培养特征和形态特征保留原来的形状。所测定的液氮保存8株菌种的生理活性,除两株糖化酶活力稍有降低外,其它菌株没有明显的变化。 相似文献