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Interrelationships Between Nitrogen Supply and Photosynthetic Parameters in Vicia faba L. 总被引:2,自引:2,他引:0
We determined for Vicia faba L the influence of nitrogen uptake and accumulation on the values of photon saturated net photosynthetic rate (P
Nmax), quantum yield efficiency (), intercellular CO2 concentration (C
i), and carboxylation efficiency (C
e). As leaf nitrogen content (NL) increased, the converged onto a maximum asymptotic value of 0.0664±0.0049 mol(CO2) mol(quantum)–1. Also, as NL increased the C
i value fell to an asymptotic minimum of 115.80±1.59 mol mol–1, and C
e converged onto a maximum asymptotic value of 1.645±0.054 mol(CO2) m–2 s–1 Pa–1 and declined to zero at a NL-intercept equal to 0.596±0.096 g(N) m–2. fell to zero for an NL-intercept of 0.660±0.052 g(N) m–2. As NL increased, the value of P
Nmax converged onto a maximum asymptotic value of 33.400±2.563 mol(CO2) m–2 s–1. P
N fell to zero for an NL-intercept of 0.710±0.035 g(N) m–2. Under variable daily meteorological conditions the values for NL, specific leaf area (L), root mass fraction (Rf), P
Nmax, and remained constant for a given N supply. A monotonic decline in the steady-state value of Rf occurred with increasing N supply. L increased with increasing N supply or with increasing NL. 相似文献
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Expression of a Cloned Cyclopropane Fatty Acid Synthase Gene Reduces Solvent Formation in Clostridium acetobutylicum ATCC 824 下载免费PDF全文
Yinsuo Zhao Lucia A. Hindorff Amy Chuang Melanie Monroe-Augustus Michael Lyristis Mary L. Harrison Frederick B. Rudolph George N. Bennett 《Applied microbiology》2003,69(5):2831-2841
The cyclopropane fatty acid synthase gene (cfa) of Clostridium acetobutylicum ATCC 824 was cloned and overexpressed under the control of the clostridial ptb promoter. The function of the cfa gene was confirmed by complementation of an Escherichia coli cfa-deficient strain in terms of fatty acid composition and growth rate under solvent stress. Constructs expressing cfa were introduced into C. acetobutylicum hosts and cultured in rich glucose broth in static flasks without pH control. Overexpression of the cfa gene in the wild type and in a butyrate kinase-deficient strain increased the cyclopropane fatty acid content of early-log-phase cells as well as initial acid and butanol resistance. However, solvent production in the cfa-overexpressing strain was considerably decreased, while acetate and butyrate levels remained high. The findings suggest that overexpression of cfa results in changes in membrane properties that dampen the full induction of solventogenesis. The overexpression of a marR homologous gene preceding the cfa gene in the clostridial genome resulted in reduced cyclopropane fatty acid accumulation. 相似文献
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夏玉米植株及叶片生长发育热量需求的试验与模拟研究 总被引:19,自引:1,他引:18
通过比较国内多种积温计算方法造成的结果差异,推荐一种有较强生物学意义和普适性的职温计算方法,并以此计算了不同播期,不同品种,不同密度以及不同水肥管理条件下夏玉米各生育阶段,从出苗到各叶片完全展开以及各叶片生期的积温,讨论了影响植株及叶片生长发育期积温稳定性的主要因子,并模拟了单株出速度与出苗后温度累积及叶片生活期积温需求与叶龄的定量关系。 相似文献
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固氮螺菌的固氮分子调控研究进展 总被引:3,自引:0,他引:3
本文对巴西固氮螺菌周氨基因的结构和调控进行综述。其固氮基因的调控可分为两种水平:通过DRAT-DRAG系统的翻译后水平和通过NifA蛋白的转录水平。通过NifA活性进行调控的机理目前尚不明了。 相似文献
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Zhao Y Hindorff LA Chuang A Monroe-Augustus M Lyristis M Harrison ML Rudolph FB Bennett GN 《Applied and environmental microbiology》2003,69(5):2831-2841
The cyclopropane fatty acid synthase gene (cfa) of Clostridium acetobutylicum ATCC 824 was cloned and overexpressed under the control of the clostridial ptb promoter. The function of the cfa gene was confirmed by complementation of an Escherichia coli cfa-deficient strain in terms of fatty acid composition and growth rate under solvent stress. Constructs expressing cfa were introduced into C. acetobutylicum hosts and cultured in rich glucose broth in static flasks without pH control. Overexpression of the cfa gene in the wild type and in a butyrate kinase-deficient strain increased the cyclopropane fatty acid content of early-log-phase cells as well as initial acid and butanol resistance. However, solvent production in the cfa-overexpressing strain was considerably decreased, while acetate and butyrate levels remained high. The findings suggest that overexpression of cfa results in changes in membrane properties that dampen the full induction of solventogenesis. The overexpression of a marR homologous gene preceding the cfa gene in the clostridial genome resulted in reduced cyclopropane fatty acid accumulation. 相似文献
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BACKGROUND AND AIMS: The aim of this study was to investigate the effects of the interactions between the microbial symbionts, Rhizobium and arbuscular mycorrhizal fungi (AMF) on N and P accumulation by broad bean (Vicia faba) and how increased N and P content influence biomass production, leaf area and net photosynthetic rate. METHODS: A multi-factorial experiment consisting of four different legume-microbial symbiotic associations and two nitrogen treatments was used to investigate the influence of the different microbial symbiotic associations on P accumulation, total N accumulation, biomass, leaf area and net photosynthesis in broad bean grown under low P conditions. KEY RESULTS: AMF promoted biomass production and photosynthetic rates by increasing the ratio of P to N accumulation. An increase in P was consistently associated with an increase in N accumulation and N productivity, expressed in terms of biomass and leaf area. Photosynthetic N use efficiency, irrespective of the inorganic source of N (e.g. NO3- or N2), was enhanced by increased P supply due to AMF. The presence of Rhizobium resulted in a significant decline in AMF colonization levels irrespective of N supply. Without Rhizobium, AMF colonization levels were higher in low N treatments. Presence or absence of AMF did not have a significant effect on nodule mass but high N with or without AMF led to a significant decline in nodule biomass. Plants with the Rhizobium and AMF symbiotic associations had higher photosynthetic rates per unit leaf area. CONCLUSIONS: The results indicated that the synergistic or additive interactions among the components of the tripartite symbiotic association (Rhizobium-AMF-broad bean) increased plant productivity. 相似文献
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