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1.
硝态氮对不同品种水稻硝酸还原酶、谷氨酰胺合成酶活性及表达量的影响 总被引：6，自引：1，他引：5
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Rapid nitrogen（N） transformations and losses occur in the rice rhizosphere through root uptake and microbial activities. However,the relationships between rice roots and rhizosphere microbes for N utilization are still unclear. We analyzed different N forms（NH＋4,NO-3, and dissolved organic N）, microbial biomass N and C, dissolved organic C, CH4 and N2O emissions, and abundance of microbial functional genes in both rhizosphere and bulk soils after 37-d rice growth in a greenhouse pot experiment. Results showed that the dissolved organic C was significantly higher in the rhizosphere soil than in the non-rhizosphere bulk soil, but microbial biomass C showed no significant difference. The concentrations of NH＋4, dissolved organic N, and microbial biomass N in the rhizosphere soil were significantly lower than those of the bulk soil, whereas NO-3in the rhizosphere soil was comparable to that in the bulk soil. The CH4 and N2O fluxes from the rhizosphere soil were much higher than those from the bulk soil. Real-time polymerase chain reaction analysis showed that the abundance of seven selected genes, bacterial and archaeal 16 S rRNA genes, amoA genes of ammonia-oxidizing archaea and ammonia-oxidizing bacteria, nosZ gene, mcrA gene, and pmoA gene, was lower in the rhizosphere soil than in the bulk soil, which is contrary to the results of previous studies. The lower concentration of N in the rhizosphere soil indicated that the competition for N in the rhizosphere soil was very strong, thus having a negative effect on the numbers of microbes. We concluded that when N was limiting, the growth of rhizosphere microorganisms depended on their competitive abilities with rice roots for N. 相似文献
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根区氮钾水平对杂交和常规水稻品种光合作用及根系生长的影响 总被引：1，自引：0，他引：1
Root box experiments were conducted to evaluate the effects of N and NK levels in the root zone on shoot photosynthesis and root growth of hybrid an cultivar of rice (Oryza sativa L.) on two paddy soils (clayey and silty).The results showed that dry matter yields in the hybrid and the cultivar were considerably increased by NK supply,bu the effect was greater for the hybrid.Supply of NK in the root zone significantly increased photosynthetic rate of the lower position leaf and the active green leaf area per plant,in which the effects were much more obvious in the hybrid rice than in the cultivar.High NK supply in the root zone stimulated the root growth,and decreased pH and increased the oxidation zone in the rhizosphere in both entries,but to a greater extent in the hybrid .The results indicated that higher NK levels were needed to maintain higher root activity and shoot photosynthetic capacity in rice,particularly in hybrid rice. 相似文献
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A rhizobox experiment with two phosphorus （P） treatments, zero-P （0 mg P kg^-1） and plus-P （100 mg P kg^-1） as Ca（H2PO4）2.H2O, was conducted to study the chemical and biochemical properties in the rhizosphere of two rice genotypes （cv. Zhongbu 51 and Pembe） different in P uptake ability and their relationship with the depletion of soil P fractions. Plant P uptake, pH, phosphatase activity, and soil P fractions in the rhizosphere were measured. Both total dry weight and total P uptake of Pembe were significantly （P 〈 0.05） higher than those of Zhongbu 51 in the zero-P and plus-P treatments. Significant depletions of resin-Pi, NaHCO3-Pi, NaHCO3-Po, and NaOH-Pi, where Pi stands for inorganic P and Po for organic P, were observed in the rhizosphere of both Zhongbu 51 and Pembe under both P treatments. Pembe showed a greater ability than Zhongbu 51 in depleting resin-Pi, NaHCO3-Pi, NaHCO3-Po, NaOH-Pi, and NaOH- Po in the rhizosphere. HCl-Pi and residual-P were not depleted in the rhizosphere of both genotypes, regardless of P treatments despite significant acidification in the rhizosphere of Pembe under zero-P treatment. Higher acid phosphatase （AcPME） activity and alkaline phosphatase （AlPME） activity were observed in the rhizosphere of both Zhongbu 51 and Pembe compared to the corresponding controls without plant. AcPME activity was negatively （P 〈 0.01） correlated to NaHCO3-Po concentration in the rhizosphere of both Zhongbu 51 and Pembe, suggesting that AcPME was associated with the mineralization of soil organic P. 相似文献
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增硝营养对水稻不同生育时期生长及氮素吸收同化的影响 总被引：14，自引：0，他引：14
The effect of nitrate （NO3^-） on rice （Oryza sativa L.） growth as well as N absorption and assimilation during different growth stages was examined using three typical rice cultivars. Dry weight, yield, N uptake, nitrate reductase activity （NRA） in leaves, and glutamine synthetase activity （GSA） in roots and leaves during their entire growth periods, as well as the kinetic parameters of ammonium （NH4^＋） uptake at the seedling stage, were measured with solution culture experiments. Results indicated that addition of NH4^＋-N and NO3^-N at a ratio of 75：25 （NH4^＋＋NO3^- treatment） when compared with that of NH4^＋-N alone （NH4^＋ treatment） increased the dry weight of ‘Nanguang＇ cultivar by 30% and ‘Yunjing 38＇ cultivar by 31%, and also increased their grain yield by 21% and 17%, respectively. For the four growth stages, the total N accumulation in plants increased by an average of 36% for ‘Nanguang＇ and 31% for ‘Yunjing 38＇, whereas the increasing effect of NO3^- in the ‘4007＇ cultivar was only found at the seedling stage, in the NH4^＋＋NO3^- treatment compared to the NH4^＋ treatment, NRA in the leaves increased by 2.09 folds, and GSA increased by 92% in the roots and 52% in the leaves of the three cultivars. NO3^- supply increased the maximum uptake rate （Vmax） in the ‘Nanguang＇ and ‘Yunjing 38＇ cultivars, reflecting that the NO3^- itself, not the increasing N concentration, increased the uptake rate of NH4^＋ by rice. There was no effect on the apparent Michaelis-Menten constant （Kin） of the three cultivars. Thus, some replacement of NH4^＋ with NO3^-could greatly improve the growth of rice plants, mainly on account of the increased uptake of NH4^＋ promoted by NO3^-, and future studies should focus on the molecular mechanism of the increased uptake of NH4^＋ by NO3^-. 相似文献
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集约水稻系统下施肥对土壤有机氮形态及供氮的影响 总被引：6，自引：0，他引：6
Changes of soil organic nitrogen forms and soil nitrogen supply under continuous rice cropping system were investigated in a long-term fertilization experiment in Jinhua, Zhejiang Province, China. The fertilizer treatments included combination of P-K, N-K, N-P, and N-P-K as well as the control. After six years of continuous double-rice cropping, total soil N and hydrolysable N contents remained stable in plots with N treatments, while the hydrolysable N contents were substantially reduced in those plots without N application. Compared to the unbalanced fertilization treatments, P and K increased the percentage of hydrolysable ammonium N in the total soil N with the balanced application of N, and also maintained higher rice grain yields and nitrogen uptake. Grain yield was positively correlated with total N uptake （r = 0.875^＊＊）, hydrolysable N （r = 0.608^＊＊）, hydrolysable ammonium N （r = 0.560^＊＊） and the hydrolysable unknown N （r = 0.417^＊＊）. Total N uptake was positively correlated with hydrolysable N （r = 0.608^＊＊）, hydrolysable ammonium N （r = 0.440^＊＊） and hydro, lysable unknown N （r = 0.431^＊＊）. Soil nutrient depletion and/or unbalanced fertilization to rice crop reduced N content in soil microbial biomass, and therefore increased C/N ratio, suggesting a negative effect on the total microbial biomass in the soil. 相似文献
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长期施用无机肥对稻田红壤生化特性的影响 总被引：7，自引：0，他引：7
A long-term experiment was set up in Yingtan of Jiangxi Province to investigate the effects of long-term application of inorganic fertilizers on the biochemical properties of a rice-planting soil derived from Quaternary red earth. Noncultivated soils are extremely eroded and characterized by a low pH and deficiencies in available nutrients, in particular P and N. After 13 years of inorganic fertilization in cultivation for double-cropped rice, the biochemical properties of the soil were changed. The nitrification potential and urease activity were higher in the treatments with N application than those without N application. Acid phosphatase activity and dehydrogenase activity were also higher in the treatments with P application than in those without P application. The dehydrogenase activity correlated well with the concentrations of both total P and hydrolysable N and with rice crop yield, suggesting that dehydrogenase activity might be a suitable indicator for improvement in soil fertility. 相似文献
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缺铁水稻根表铁膜对硒的转运和吸收的影响 总被引：2，自引：0，他引：2
Under anaerobic conditions, ferric hydroxide deposits on the surface of rice roots and affects uptake and translocation of certain nutrients. In the present study, rice plants were cultured in Fe-deficient or sufficient solutions and placed in a medium containing selenium （Se） for 2 h. Then, FeSO4 was added at the various concentrations of 0, 10, 40, or 70 mg L-1 to induce varying levels of iron plaque on the root surfaces and subsequent uptake of Se was monitored. The uptake of Se was inhibited by the iron plaque, with the effect proportional to the amount of plaque induced. The activity of cysteine synthase was decreased with increasing amounts of iron plaque on the roots. This may be the important reason for iron plaque inhibition of Se translocation. At each level of iron plaque, Fe-deficient rice had more Se than Fe-sufficient rice. Furthermore, with plaque induced by 20 mg Fe L-1, plants from Fe-deficient media accumulated more Se than those from Fe-sufficient media, as the Se concentration was increased from 10 to 30 or 50 mg L^-1. We found that phytosiderophores, highly effective iron chelating agents, could desorb selenite from ferrihydrite. Root exudates of the Fe-deficient rice, especially phytosiderophores in the exudates, could enhance Se uptake by rice plants with iron plaque. 相似文献
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To-date, assessments of nitrogen use efficiency (NUE) of sugarcane have not included the contribution of its components, nitrogen uptake efficiency (NUpE) and nitrogen utilization efficiency (NUtE). This study determined these values, based on biomass and plant nitrogen (N) content, in two four-month-old pot-grown genotypes. The treatments included six N regimes, with nitrate (NO3—N) or ammonium (NH4+-N) supplied alone, or as NO3?-N for the first 6 weeks and then NH4+-N until harvest, each as 4 or 20 mM. Regardless of the N form, NUE was higher at four than at 20 mM due to significantly higher NUpE at low N supply. The results indicated that there was luxury N uptake and preference for NH4+-N nutrition, which resulted in the highest determined NUE. There were significant differences between genotypes in biomass, morphological growth parameters, N uptake, total plant N and NUE, the latter matching previously established sucrose yield-based NUE field rankings. 相似文献
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NH_4~+和NO_3~–是对植物有效的两种主要无机氮源。水稻一般被认为是偏好NH_4~+的植物,但是在NO_3~–条件下,水稻也能良好地生长。大多数关于水稻铵硝营养的报道是在pH 6.0左右的水培条件下开展的,但是对于酸性条件下水稻铵硝营养研究很少。随着土壤酸化的加重及一些边际酸性土壤被用作水稻种植,研究酸性条件下水稻的铵硝营养具有重要意义。本文采用水培试验,在pH 5.0的条件下,通过添加和不添加pH缓冲剂MES(2-(N-吗啡啉)乙磺酸),研究了NH_4~+和NO_3~–对水稻生长、氮效率和矿质养分(N、P、K、Ca、Mg、Fe、Zn、Cu、Mn)吸收的影响。结果表明,在不添加MES的条件下,水稻地上部生长(株高、叶绿素含量、干重)在NH_4~+和NO_3~–之间没有显著差异,而添加MES后,NH_4~+处理的水稻地上部生长优于NO_3~–。不管是否添加MES,NO_3~–处理的水稻地下部生长(根长、根表面积和根物质量)优于NH_4~+。水稻含氮量和氮利用效率在不同NH_4~+和NO_3~–处理之间没有显著差异,但是NH_4~+处理的水稻氮吸收效率高于NO_3~–。与NO_3~–相比,NH_4~+增加了水稻地上部P和Fe含量,而降低了水稻地上部Ca、Mg、Zn、Cu和Mn含量,对K含量影响较小。上述结果表明,NH_4~+有利于改善水稻地上部生长,提高氮吸收效率、地上部P和Fe含量,而NO_3~–则有利于水稻发根,提高地上部Ca、Mg、Zn、Cu和Mn含量。 相似文献
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增硝营养对不同基因型水稻苗期氮素吸收同化的影响 总被引：21，自引：7，他引：21
利用控制条件下的溶液培养方法,研究了增硝营养(NH4+∶NO3-比例为100∶0和50∶50)对4种不同的基因型水稻(常规籼稻、常规粳稻、杂交籼稻、杂交粳稻)苗期生长和氮素吸收同化的影响。结果表明,增NO3-营养可以增加水稻叶片的光合速率,促进水稻对氮素的吸收,提高氮素利用率,进而促进水稻生长;不同基因型水稻在增NO3-营养下氮积累量增幅不同主要是由于其生物量增幅不同,而整株氮素含量增幅差异不大;NO3-的存在可增强谷氨酰胺合成酶和硝酸还原酶的活力,促进水稻对NH4+和NO3-的同化利用,从而增加了氮素在植株地上部的积累同化;籼稻与粳稻相比,杂交粳稻与杂交籼稻相比,前者在氮素吸收利用上均表现出更为明显的优势。 相似文献
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Nitrogen (N), ammonium (NH4+) and nitrate (NO3?), is one of the key determinants for plant growth. The interaction of both ions displays a significant effect on their uptake in some species. In the current study, net fluxes of NH4+ and NO3? along the roots of Picea asperata were determined using a Non-invasive Micro-test Technology (NMT). Besides, we examined the interaction of NH4+ and NO3? on the fluxes of both ions, and the plasma membrane (PM) H+-ATPases and nitrate reductase (NR) were taken into account as well. The results demonstrated that the maximal net NH4+ and NO3? influxes were detected at 13–15?mm and 8–10.5?mm from the root apex, respectively. Net NH4+ influx was significantly stimulated with the presence of NO3?, whereas NH4+ exhibited a markedly negative effect on NO3? uptake in the roots of P. asperata. Also, our results indicated that PM H+-ATPases and NR play a key role in the control of N uptake. 相似文献
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采用田间小区试验,监测夏玉米不同生长期土壤水分和硝态氮剖面含量变化,研究不同施氮量对其时空变化及籽粒产量、水肥利用效率的影响,探讨氮肥对水肥资源高效利用的调节作用。结果表明：不同施氮处理,土壤剖面水分和硝态氮随土壤深度的变化趋势基本一致,即表层50 cm土壤水分和硝态氮含量较高且呈降低态,50-110 cm相对较低且波动较小,灌浆期二者均达到最低值;各生长期表层50 cm土壤含水量呈不施氮处理均高于施氮处理,50-110 cm土层则相反;施氮能提高土壤硝态氮含量,土壤硝态氮运移受土壤水分状况和含量的影响,含量越高,向下移动越深;施氮能显著提高水分利用效率及籽粒产量,增产效果明显（增产28.52%-37.86%）,二者均以施氮240 kg/hm^2处理最高;随施氮量的增加籽粒产量及籽粒吸氮量和水分利用效率增幅均表现为先升高后降低之趋势,当施氮量超过240 kg/hm^2后,籽粒产量和水分利用效率提高并不显著;不施氮与施氮处理氮素生产力、氮肥利用率之间均存在极显著差异。在本试验条件下,从控制土壤硝态氮积累及取得较高的产量和氮素利用率综合考虑,夏玉米的适宜施氮量范围应控制在120-240 kg/hm^2较好。 相似文献
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Many bryophytes rely to a large extent on atmospheric deposition for their nutrient uptake.However, increasing levels of atmospheric ammonium NH 4 + and nitrate NO 3 - attract concern as to the possible harmful effects onbryophytes from these two nutrient sources. Changes in nitrate reductase (NR) activities, cation(Ca, K and Mg), total nitrogen (N) and organic acid concentrations were investigated for themosses, Racomitrium lanuginosum, Rytidiadelphus loreus and Philonotis fontana, in response to asingle field misting with 3 mol m-3 NH 4 + and NO 3 - . Increases of 20% were recordedfor tissue N content, 48 hr after misting with N containing solutions. When labelled NH 4 + or NO 3 - were applied to R. Lanuginosum at 1, 3 and 6mol m-3 concentrations, partitioning ofincorporated 15N between different tissueregions occured, with the highest N uptake in the upper stem and leaves. High concentrations ofapplied N resulted in reduced efficiency of N uptake. NH 4 + applications caused declines in NR activities, organic acidsand cations, whereas, NO 3 - treatments causedthe reverse response. Changes in cation contents, organic acids and NR activity reflect short-termregulation of N metabolism in the presence of defined N sources, as well as potential mechanismsof regulating cell pH homoeostasis. The consistency of physiological responses, especially NRactivities, over short-term pollution episodes, provides evidence for their use as indicators of both NH 4 + and NO 3 - pollution. 相似文献
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Uptake and assimilation of inorganic N in young rice plants has been studied with labelled N (N-15). Depletion of the plants' carbohydrate content, obtained by a preceding dark period, resulted in a drastic reduction of NH4 +-N uptake. Plants exposed to low light intensity showed diminishing NH4 +-N uptake rates as compared with plants exposed to full light intensity, the latter showing constant NH4 +-N uptake rates during the whole experimental period. The percentage of labelled insoluble N in total labelled N was not significantly affected by a preceding dark period, whereas the low light intensity resulted in a lower proportion of insoluble N in roots and shoots. The incorporation of labelled N into the insoluble fraction (proteins, nucleic acids) was higher in plants fed with NH4 +-N than in those fed with NO3 -. The uptake of NH4 +-N was not significantly affected by NO3 -, whereas the NO3- uptake rate was considerably reduced in the presence of NH4 +-N. Low energy status of plants affected the nitrate uptake more than the uptake of NH4 +-N. The results show that uptake and assimilation of inorganic N depend much on the energetic status of plants. Nitrate uptake and assimilation is more sensitive to low energy conditions than NH4 +-N. 相似文献
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Although to date individual gross N transformations could be quantified by ~(15)N tracing method and models,studies are still limited in paddy soil.An incubation experiment was conducted using topsoil(0-20 cm) and subsoil(20-60 cm) of two paddy soils,alkaline and clay(AC) soil and neutral and silt loam(NSL) soil,to investigate gross N transformation rates.Soil samples were labeled with either ~(15)NH4_NO_3 or NH_4~(15)NO_3,and then incubated at 25 °C for 168 h at 60%water-holding capacity.The gross N mineralization(recalcitrant and labile organic N mineralization) rates in AC soil were 1.6 to 3.3 times higher than that in NSL soil,and the gross N nitrification(autotrophic and heterotrophic nitrification) rates in AC soil were 2.4 to 4.4 times higher than those in NSL soil.Although gross NO_3~- consumption(i.e.,NO_3~- immobilization and dissimilatory NO_3~- reduction to NH_4~+ rates increased with increasing gross nitrification rates,the measured net nitrification rate in AC soil was approximately 2.0 to 5.1 times higher than that in NSL soil.These showed that high NO_3~- production capacity of alkaline paddy soil should be a cause for concern because an accumulation of NO_3~- can increase the risk of NO_3~- loss through leaching and denitrification. 相似文献
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不同铵硝配比对弱光下白菜氮素吸收及相关酶的影响 总被引：2，自引：0，他引：2
以黑色遮阳网覆盖模仿弱光环境, 使光照强度为自然光的20%左右, 以自然光照为对照, 采用精确控制水培溶液氮素营养, 研究NH4+-N/NO3--N 比例分别为0/100、25/75、50/50、75/25、100/0 对弱光下白菜氮代谢及硝酸还原酶和谷氨酰胺合成酶活性的影响。结果表明, 弱光下, 白菜的鲜重及叶片总氮量以NH4+-N/NO3--N 比为25/75 时最大, NH4+-N/NO3--N 比为100/0 时最低。随弱光处理的进行, 白菜叶片中硝酸还原酶活性及谷氨酰胺合成酶活性均呈下降趋势, 但NH4+-N/NO3--N 比为25/75 时, 可维持叶片内较高的硝酸还原酶活性及谷氨酰胺合成酶活性。试验表明, NH4+-N/NO3--N 比25/75 是白菜在弱光下生长的较适宜氮素形态配比。 相似文献