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1.
【目的】进一步探讨枳橙对氮素吸收利用机制,为柑橘生产上提高氮素利用效率和科学施肥提供科学依据。【方法】以枳橙为材料,采用水培方法,在Hoagland配方的基础上进行调节,研究了不同形态氮素配比对枳橙幼苗硝酸还原酶(NR)活性变化及相关基因表达量的影响。【结果】幼苗叶片及根系NR活性均随着培养时间的延长而增加,且叶片NR活性高于根系。其中2号(NO_3~-∶NH_4~+=7∶3)和3号(NO_3~-∶NH_4~+=5∶5)处理的叶片酶活最高;1号(NO_3~-∶NH_4~+=10∶0)和2号(NO_3~-∶NH_4~+=7∶3)处理根系的NR活性显著高于其他处理;进一步研究NR相关基因表达情况表明:3个基因(CitNia1、CitNia2、CitNia OA)在不同处理的枳橙幼苗体内均有表达,其中CitNia1和CitNia2分别是根系和叶片NR相关主效基因,2者均受到NO_3~-、NH_4~+配比诱导,且3号处理(NO_3~-∶NH_4~+=5∶5)下表达量最高。【结论】枳橙幼苗硝态氮代谢的主要部位为叶片,且CitNia2是主效基因,通过调节铵硝比例可以促进其表达。  相似文献   

2.
汤丹丹  刘美雅  范凯  阮建云 《园艺学报》2017,44(9):1759-1771
铵态氮(NH4~+)和硝态氮(NO_3~-)是茶树吸收利用的两种主要氮素形态,且茶树具有对NH4~+偏性利用的特点,其对NH4~+的吸收利用效率明显高于NO_3~-,造成这种差异的原因可能在于茶树对NH4~+、NO_3~-吸收、同化机制的差异。从代谢途径来看,茶树对NH4~+、NO_3~-的吸收利用均首先需要通过对氮素的转运,然后再参与谷氨酰胺合成酶/谷酰胺–α–酮戊二酸氨基转移酶(GS/GOGAT)同化过程。系统地综述了茶树氮素利用的营养特性及对参与氮素吸收、同化过程所涉及关键基因的研究现状;同时重点关注氮素同化中限速酶——谷氨酰胺合成酶(GS)编码基因家族成员的相关研究,为解析茶树氮素偏性利用机制提供新的研究点。  相似文献   

3.
本试验采用溶液培养和正交设计,比较了氮素形态(NO_3~--N和NH_4~+-N)、溶液pH值(pH5.5和pH7.5)和氮素浓度(240ppm和120ppm)对红桔和枳根系生长的影响。结果表明,氮素形态对根系生长具有十分显著的影响。NH_4~+-N营养植株的根系生长较NO_3~--N营养植株的差,表现根最少,吸收根数量较少,较细。本文还对NH_4~+-N抑制柑桔根系生长的可能原因进行了讨论。  相似文献   

4.
以平邑甜茶实生苗为试材,采用~(15)N同位素示踪法、气压过程分离法(BaPS)和磷酸甘油双层海绵通气法,研究酰胺态有机氮[CO(NH_2)_2-N]、铵态氮(NH_4~+-N)及硝态氮(NO_3~--N)对平邑甜茶~(15)N利用、分配和损失的影响。结果表明:5月17日施无机氮肥对植株生物量积累效果显著,铵态氮和硝态氮~(15)N利用率分别为13.68%和13.25%,显著高于有机氮肥的5.25%;早施氮肥还可有效抑制氮素的土壤损失,其中施NO_3~--N处理植株的氨挥发损失仅占施氮量的1.83%;晚施(7月15日)处理中,无机氮肥利用率较早期施用显著减少时对酰胺态有机氮利用率和氨挥发损失影响不大。所以早期施用NH_4~+-N或NO_3~--N是确保植株生长量和氮肥利用率的有效措施,后期合理配施酰胺态有机氮则是减少氮肥损失的有效途径。  相似文献   

5.
以冬樱花（Cerasus cerasoides[D. Don]Sok）扦插苗和实生苗为试材,研究其在水培条件下对外源铵态N（氮）和硝态N比例（5︰0、4︰1、3︰2、2︰3、1︰4）处理中铵态N、硝态N和总无机N素在24 h后的吸收动力学响应。结果表明：随着外源铵：硝比例的降低,铵态N的净流速逐渐下降,硝态N的净流速逐渐上升,扦插苗吸收的总无机N素净流速在外源铵︰硝比为3︰2时达到最大（6.70 ± 0.34）μmol ? h-1后下降,而实生苗在外源铵︰硝比为1︰4时达到最大（14.88 ± 1.99）μmol ? h-1;总体上,总无机N素进入扦插苗的平均净流速[（4.76 ± 1.29）μmol ? h-1]低于实生苗[（12.95 ± 1.35）μmol ? h-1]（P < 0.05）,但两种苗木间净吸收速率差异不显著（32 ~ 34 μmol ? h-1 ? g-1）。养分吸收动力学参数拟合结果显示,扦插苗更加偏好于吸收硝态N,实生苗则更加偏好于吸收铵态N,但当外源铵硝比小于4︰1时,两种苗木同时偏向于对硝态N的吸收。控制外源铵硝比例在3︰2可以促进冬樱花扦插苗对无机N素的吸收,而控制外源铵硝比例在2︰3以下则更有利于实生苗对无机N素的吸收。  相似文献   

6.
糖和氮对山楂组织培养新梢生根的影响   总被引：1，自引：0，他引：1  
采用敞口山楂组培新梢研究糖和无机氮源对不定根形成的影响,含有高水平蔗糖的培养基比低水平蔗糖的培养基新梢生根率高。新梢对糖的这种反应与糖代谢和物理渗透都有关,用甘露醇作为渗透代替剂在低浓度蔗糖存在下无作用,当蔗糖浓度达到一定程度时(86.64mmol·1~(-1))能影响新梢的生根率。在培养基中分别加入NO_3~(-)-N或NH_4~(+)-N作为唯一氮源,或是在MS培养基中加入NO_3~-/NH_4~+比率为标准的混合氮源,在测试范围(0～120mmol·1~(-1))内均降低新梢的生根率,三者对生根的抑制作用大小顺序依次为NH_4~+>NO_3~(-)-NH_4~(+)-N>NO_3~(-)-N.NO_3~-/NH_4~+的比率影响生根。NO_3~-/NH_4~+比率与生根之间呈直线正相关。糖/氮比值高有利于生根。插穗中碳、氮的绝对量及碳/氮比率可作为山楂新梢生根的指标。  相似文献   

7.
以贵农5号刺梨品种为材料,研究了不同氮素形态供氮条件、营养元素缺素胁迫和不同土壤水分状况下刺梨植株根、茎、叶的硝酸还原酶活性(NRA)及其与总氮及硝态氮含量的关系。结果表明,供应的氮源为30%NO3--NH4+70%NH4+-N时,能够促进刺梨对氮素的吸收,根和叶中总氮含量最高,而NRA并不最强。单纯供应NO3--N时,根和叶中的NRA最强,但总氮含量显著低于同时供应NO3--N和NH4+-N的处理。单纯供应NO3--N和同时供应NO3--N和NH4+-N时,刺梨根和叶中NRA与总氮含量、硝态氮含量呈显著的负相关;同时供应NO3--N和NH4+-N时,刺梨对氮素的吸收并不完全受NR的支配。在缺氮、缺钼条件下,根和叶中都没有检测出NRA;在缺铁、缺硼条件下,根中的NRA很低,叶中没有检测出NRA;其他营养元素缺素胁迫对根和叶中NRA抑制程度的强弱顺序为缺Zn>缺P>缺Mg>缺Ca。根、叶、茎中的NRA与土壤含水量呈极显著正相关,而NO3--N含量则与土壤含水量呈极显著负相关。  相似文献   

8.
【目的】明确不同温度和氮形态营养条件下荔枝根系吸收K~+、Ca~(2+)和Mg~(2+)能力的差异。【方法】以黑叶荔枝实生苗为材料,进行水培实验。设置6个温度处理(10、15、20、25、30和35℃)和3种氮营养形态处理(硝态氮、1/2硝态氮+1/2铵态氮和铵态氮)。研究荔枝吸收K~+、Ca~(2+)和Mg~(2+)养分离子的动力学参数(最大吸收速率I_(max)、亲和力A_m和离子补偿点C_(min))变化,比较根系吸收营养能力的差异。【结果】除温度与氮营养的交互作用对荔枝吸收Ca~(2+)的A_m无显著影响外,温度、氮营养及两者的交互作用对荔枝吸收K~+、Ca~(2+)和Mg~(2+)均有显著影响(p 0.05)。硝态氮和1/2硝+1/2铵处理下荔枝吸收K~+的3个动力学参数随温度升高而波动变化,而铵态氮处理下动力学参数随温度升高变化不大。硝态氮处理下荔枝吸收Ca~(2+)的I_(max)随温度升高而提高,其他营养下随温度升高而波动变化;荔枝吸收Ca~(2+)的A_m均随温度升高而先降低后提高,而C_(min)随温度及氮营养变化的趋势与A_m的相反。不同氮营养下荔枝对Mg~(2+)的动力学参数随温度的升高而波动变化。【结论】在秋梢生长和果实膨大期,硝铵混合氮源比单一形态氮源更有利于荔枝对钾、钙和镁营养的吸收。在秋梢老熟期至开花前可以叶面喷施钙肥和镁肥为荔枝补充钙和镁营养。  相似文献   

9.
<正> 本试验旨在研究苹果、杏和油桃幼树及结果树在不同生长期对铵态氮(NH_4—N)和硝态氮(NO_3—N)的吸收;供试品种苹果为Topred(顶红),杏为Peeka(皮卡)、油桃为Nectared—9(油桃9号);施入的氮素均为同位素~(15)N。结果表明,对于幼树,三个树种在整个生长季节内都更易吸收NH_4—N;对于结果树,苹果树仍更易吸收NH_4—N,而油桃特别是杏树则更易吸收NO_3—N,并且主要在生长季节的后期吸收。在果实生长期,叶片、根、枝条和果实中的N的吸收总量下降,这可能是树体  相似文献   

10.
为探讨不同形态及配比氮肥(NH4+-N、NO3--N)对番茄幼苗根系形态、生理特征的影响,以盆栽番茄幼苗为供试材料,设置不同浓度配比的铵态氮与硝态氮处理,测定番茄幼苗根系的鲜重、干重、根粗、根长、根数、比根长及根冠比.结果显示,在75％铵态氮+25％硝态氮的氮肥比例下,番茄幼苗根系生物量最大;空白对照的根冠比值最大;2...  相似文献   

11.
Summary

A major cause of uncertainty in predicting the demand of nitrogen (N) fertilizer by means of mathematical models is the treatment of apparent net N mineralization (ANM) and apparent recovery rate (REC) of mineral N supply (N fertilizer plus soil mineral N at planting). REC and ANM were analysed in 29 multi-level N fertilizer trials conducted with a range of vegetable crops over a period of 11 years. REC differed substantially between experiments (0.29 to 1.24). ANM ranged from 13;110 to 140 kg N ha–1; it decreased with an increasing N supply, and increased with the time between planting and harvest. A simple regression model was used to predict ANM. The model consisted of both a N supply-dependent and supply-independent term, and used N supply and growing time as input parameters. Whereas the model significantly reduced the variance in measured ANM (r2 = 0.45, n = 129), the residuals showed a considerable variation (standard deviation (SD) = 37 kg N ha–1). It is not feasible to predict N fertilizer demand without predicting net N mineralization and fertilizer recovery. Therefore, the regression model is recommended despite its inaccuracy, which is taken into account by adding a security margin to the fertilizer recommendation.  相似文献   

12.
不同氮素形态和施氮量对‘鸭梨’果实品质的影响   总被引：1，自引：0，他引：1  
【目的】探讨不同氮素形态和施氮量对梨果实香气品质的影响。【方法】以‘鸭梨’为研究对象,不同氮素形态试验设置了6个处理T1~T6:100%尿素(酰胺态),100%硝态氮,硝铵比为70∶30,硝铵比为50∶50,硝铵比为30∶70,100%氨态氮,以喷清水为对照,于生长季节进行果面喷施试验;不同施氮量以酰胺态尿素进行试验,设置了高氮、中氮、低氮3个处理。【结果】不同处理均提高了果实的营养品质,T1处理的总糖量最高,不同氮素形态处理对‘鸭梨’果实香气品质的影响不同,100%氨态氮香气物质含量最高,100%硝铵香气物质含量最低,其余介于2者之间。不同氮素施用量试验结果表明,中氮处理‘鸭梨’果实香气物质总量最高,为684 ng·g-1,低氮处理香气物质种类最多为40种,高氮处理香气物质总量较中氮处理减少了43.36%。【结论】铵态氮处理果实香气最高,全硝态最低,高氮处理不利于‘鸭梨’果实香气提升。  相似文献   

13.
The National Aeronautics and Space Administration (NASA) has been conducting controlled environment research with potatoes (Solanum tuberosum L.) in recirculating nutrient film technique (NFT)-hydroponic systems as a human life support component during long-duration spaceflight. Standard nutrient solution management approaches include constant pH regulation with nitric acid (HNO3) and daily adjustment of electrical conductivity (EC) equivalent to half-strength modified Hoagland's solution, where nitrate (NO3-) is the sole nitrogen (N) source. Although tuber yields have been excellent with such an approach, N use efficiency indices are expected to be low relative to tuber biomass production. Furthermore, the high amount of N used in NFT-hydroponics, typically results in high inedible biomass, which conflicts with the need to minimize system mass, volume, and expenditure of resources for long-duration missions. More effective strategies of N fertilization need to be developed to more closely match N supply with demand of the crop. Hence, the primary objective of this study was to identify the optimal N management regime and plant N requirement to achieve high yields and to avoid inefficient use of N and excess inedible biomass production. In separate 84-day cropping experiments, three N management protocols were tested. Treatments which decreased NO3(-)-N supply indirectly through lowering nutrient solution EC (Expt. I), or disabling pH control, and/or supplying NH4(+)-N (Expt. III) did not significantly benefit tuber yield, but did influence N use efficiency indices. When supplied with an external 7.5 mM NO3(-)-N for the first 42 days after planting (DAP), lowered to 1.0 mM NO3(-)-N during the final 42 days (Expt. II), plants were able to achieve yields on par with plants which received constant 7.5 mM NO3(-)-N (control). By abruptly decreasing N supply at tuber initiation in Expt. II, less N was taken up and accumulated by plants compared to those which received high constant N (control). However, proportionately more plant accumulated N was used (N use efficiency) to produce tuber biomass when N supply was abruptly lowered at tuber initiation in Expt. II. Hence, a hydroponic nutrient solution N management system may be modified to elicit greater plant N-use while maintaining overall high tuber yield as opposed to achieving high tuber yields through excess N supply and shoot growth.  相似文献   

14.
Mobile nitrogen (N) forms may be better N indicators of the N status of trees than total nitrogen (TN) due to their higher sensitivity to increasing N supply. A field experiment was carried out over a 3-year period to compare foliar concentrations of total N (TN), soluble N (SN), chlorophyll (Minolta SPAD readings), NH4–N and NO3–N as indicators of soil N availability in nectarine, Prunus persica L. Batsch, cv. ‘Fantasia’ (grafted on ‘Nemaguard’ peach, P. persica × P. davidiana) trees. Young trees were exposed to a range of fertilizer-N application rates. Based on correlation analysis, the best association between leaf N compounds with soil N supply and trunk diameter and/or fruit yield was obtained with TN and chlorophyll SPAD readings. Leaf concentrations of mobile N compounds (NH4–N and NO3–N) increased more than any other N compound under high N supply; however, their inconsistency among years and low leaf concentration difficult their use as N indicators. The optimum foliar TN for growth decreased with tree age, 4.4%, 3.6% and 3.3% in non-bearing 1-year-old trees, non-bearing 2-year-old trees and 3.3 fruit-bearing 3-year-old trees. The optimum SPAD readings were 40 in 2-year-old trees and 42 in 3-year-old trees. Stable N compounds (TN and chlorophyll SPAD) could be used to N diagnosis in the zone of N deficiency, and soluble N compounds (NH4–N and NO3–N) to diagnoses N excess.  相似文献   

15.
Summary

Single and combined effects of three planting dates and three plant densities on nitrogen uptake and nitrogen harvest by Brussels sprouts (Brassica olerácea var. gemmifera) were studied in field experiments. The total amount of nitrogen taken up by the crop at harvest ranged between 220 and 325 kg ha–1. Although final crop dry matter decreased, total nitrogen uptake was not lower when planting was delayed. This resulted in increased nitrogen concentrations both in the total crop and in the harvested product. Forty to fifty per cent of the nitrogen taken up by the harvest was removed from the field with the product. Within the range of 2.7 to 4.4 plants per m2, plant density had no effect on final nitrogen uptake nor on the amount of nitrogen harvested with the product. The results indicate that nitrogen fertilizer recommendations should take planting date into account, because with delayed planting less dry matter will be accumulated with a corresponding lower nitrogen requirement. There was no interaction of effects of planting date and plant density on nitrogen uptake.  相似文献   

16.
Managed turf areas are both a source and a sink for greenhouse gases (GHGs). Management practices, including turfgrass selection and mowing, influence the amount of carbon (C) and nitrogen (N) stored in the soil, as well as the associated GHG emissions. The objective of this research was to determine the net C and N balance (i.e. the amount of C and N stored less the amount emitted) of managed turfgrass systems with different grasses (species and cultivars) and management practices (mowing frequency and grass clippings management). Data explicitly quantified in this experiment include annual mowing requirements and accompanying GHG emissions, annual dry matter yield, soil C and N accumulation, and GHG flux of tall fescue (Schedonorus arundinaceus) and Kentucky bluegrass (Poa pratensis) cultivars with varying growth rates. Leaf, verdure, and root tissue C and N were also determined, along with the corresponding biomass. Estimations of emissions from fertilization, irrigation, and pesticide applications were also included in the net balance calculations.All of the turfgrasses and management practices in this experiment resulted in a system-wide net C sink, though the magnitude of the sink varied by turfgrass selection and management strategy. In general, higher-yielding grasses and management practices increased soil C but also increased mowing requirements and thus emissions. Returning grass clippings was found to increase yield, soil and leaf tissue N, and soil C, but it also marginally increased mowing requirements. The results of this experiment support the assertion that managed turfgrass areas can act as a net C sink to help curb the increasing atmospheric GHG concentrations. The C sequestration potential of managed turfgrass is another of the numerous functional benefits of urban grasslands.  相似文献   

17.
Summary

Liquid organic fertilisers made from extracts of plant residues can provide a sustainable alternative for vegetable production, since they are not produced using fossil fuels and are easy to apply as side-dressing fertilisers. The aims of this study were: (i) to evaluate the influence of extraction time and the addition of papain on the composition of aqueous extracts of cauliflower, tomato leaf, or whole tomato plant residues; and (ii) to explore the fertigation potential of such extracts for lettuce cultivation. After 10 d of extraction, approx. 30% of all plant residue nitrogen (N) was transferred to the liquid fraction, of which 8 – 15% was in mineral form. Ammonium was the main mineral form of N in all extracts. Nitrate concentrations were higher in whole tomato plant residues than in tomato leaves or cauliflower residues. The addition of papain increased the amount of total N in solution when used at concentrations ≥ 400 mg l–1.

Compared to the mineral nutrient solution (control), plant extracts were comparable in mineral N, lower in phosphate, and higher in all other nutrients examined, as well as in Na+ and Cl– ions. The application of each extract to lettuce seedlings resulted in reduced plant growth in all treatments compared to the control, probably due to their higher electrical conductivity and, possibly, ammonium toxicity. Further research is needed in order to balance the nutrient composition and to increase the transfer of plant residue nutrients into the extracts.  相似文献   

18.
Summary

The effect of rate and date of application of nitrogen fertilizer on the partitioning of biomass and nitrogen in Brussels sprouts was studied in field experiments. Growth of Brussels sprouts was in two phases: during the first phase mainly leaves and stem were produced and during the second phase mainly bud growth occurred. At the onset of bud growth, 60–80% of the total biomass was produced and an equal proportion of nitrogen had been taken up. Final bud weight and bud nitrogen content correlated positively with the total biomass and nitrogen content at the onset of bud growth. Partitioning of biomass and nitrogen among the different above-ground plant organs was hardly affected by the nitrogen availability and the time of the fertilizer application. Harvest index at the final harvest was 0.25 for the biomass and 0.45 for nitrogen. During bud growth, leaf senesced at a high rate. Biomass and, especially, nitrogen was remobilized from the leaves before shedding. During bud growth the decrease in nitrogen content of the leaves was up to 50% of the nitrogen increase of the buds. When additional N was applied at the onset of bud growth, N remobilization decreased. An N application at the onset of bud growth increased bud growth due to a delay of leaf shedding. Nitrogen concentration in the buds increased due to a N application at the onset of bud growth, which resulted in a greener appearance. When a certain amount or nitrogen was split into two portions (half at transplanting and half at the onset of bud growth) the nitrogen concentration of the buds was higher than when applied completely at transplanting only, but the partitioning of biomass and the bud yield was not affected.  相似文献   

19.
A field trial conducted to determine the response of pineapple cultivar ‘Kew’ to varying levels of N with constant P and K under both irrigated and rainfed conditions, was utilised for studying the relationships between base and leaf N content of “D” leaf (first fully developed leaf) and yields. The soil was high in available N and medium in available P and K. Samplings were done in the 5th, 8th and 11th months. Application of N was clearly reflected in both base and leaf N content at all stages. Differences in base N and leaf N due to irrigation or no irrigation were observed only in the 8th-month sampling. Critical levels of base and leaf N were worked out utilising the statistical procedure of Cates and Nelson (1971).  相似文献   

20.
菜地土壤氮素迁移转化研究进展   总被引：1，自引：0，他引：1  
《中国瓜菜》2017,(8):1-6
农业面源污染已成为我国环境污染的重要组成部分,对我国农业生产和生态环境安全带来了较大风险。农田氮素随地表径流流失和地下淋溶是引起日益突出的农业面源污染的主要因素之一。氮素养分是影响蔬菜产量的重要因子,为追求经济效益,菜地氮肥投入量大,过量施肥造成的氮素污染问题日趋严重。笔者综述了菜地氮素迁移转化研究现状,探讨了菜地施肥、地表径流、地下淋溶、氨挥发等菜地土壤氮素迁移和转化途径,分析了土壤中氮素矿化、硝化和反硝化过程,并对今后研究方向进行了展望。  相似文献   

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