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坡度与施肥密度对毛竹林氮素流失的影响 总被引：1，自引：0，他引：1
《广西林业科学》2021,50(3)
为研究坡度与施肥密度对笋用毛竹(Phyllostachys edulis)林氮素流失的影响,在典型的笋用毛竹林内建立径流场,收集并检测不同类型毛竹林径流水中的NH4+-N、NO3--N、TN和TP含量。结果表明,施肥后短期内,毛竹林径流水中的NH4+-N、NO3--N和TN含量升高,之后缓慢下降。坡度对NH4+-N、NO3--N和TN含量的影响较大;随着坡度的增加,NH4+-N、NO3--N和TN在径流水中的含量及年流失总量均增加;30°坡毛竹林中的NH4+-N、NO3--N和TN年流失总量均最高,分别为69.72、136.13和413.50 g·hm-2·a-1。施肥密度对养分流失也有较大影响;随着施肥密度的增加,NH4+-N、NO3--N和TN在径流水中的含量及年流失总量均增加,最高年流失总量分别为64.47、132.74和364.94 g·hm-2·a-1。在整个试验周期内,TP在径流水中的含量和年流失总量均无显著变化。施肥是毛竹林径流水中NH4+-N、NO3--N和TN含量升高的原因之一。 相似文献
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不同形态氮素配比对马大杂种相思无性系幼苗生长的影响 总被引：1，自引：0，他引：1
在温室内采用不同氮形态配比的营养液,水培研究9个马大杂种相思（Acacia mangium×A.au-riculiformis Cunn.ex Bench）无性系幼苗的生长状况,结果表明,NO3^-∶NH4＋值对马大相思生长及生物量的影响均达到极显著水平。当NO3^-∶NH4^＋为25∶75时,马大相思幼苗的苗高、生物量干质量及生物量鲜重积累均达到最大。而NO3^-∶NH4^＋为75∶25时,根长净生长量最大,但抑制了苗高的生长;在供氮总量不变的条件下,NO3^-∶NH4^＋为25∶75时最有利于马大杂种相思幼苗的生长。 相似文献
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二氧化氮对樟树幼苗硝酸还原酶活力和氮元素积累的影响 总被引：1，自引：0，他引：1
采用开顶式人工熏气装置,对1年生樟树幼苗进行了为期2个月不同体积分数NO2(0.1、0.5和4.0μL/L)熏气试验,研究其对幼苗叶片硝酸还原酶活力(NR)和氮元素积累的影响.结果表明:在整个熏气过程中,0.1和0.5μL/L NO2均增强了樟树幼苗叶片的NR活力,其中0.5μL/L NO2处理的NR活力为各处理中最强,且显著强于对照,4.0μL/L NO2则抑制了NR活力;3种处理均不同程度提高了樟树幼苗叶片N元素的积累,其中0.1和0.5μL/L NO2均使樟树幼苗叶片N元素含量显著提高,4.0μL/L NO2的影响则因熏气时段而不同. 相似文献
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为进一步明确毛竹幼苗无土栽培的最佳条件,阐明毛竹N形态响应差异的影响因素,加快毛竹实生苗的培育.研究超纯水、砂和蛭石3种栽培介质,2 mM不同N形态(NH4+-N、NO3--N)以及3种pH值(3.8、5.8、7.8)处理对毛竹幼苗地上部的苗高、叶片数、叶绿素相对含量(SPAD)及地上部生物量的影响.结果表明:在蛭石和水培时,毛竹生长表现出明显的喜铵性,并且在pH为3.8时生长最好;而砂培时,毛竹幼苗生长对NH4+-N和NO3--N以及pH的响应差异都不明显.相关性分析结果表明,对地上部生长的影响为:栽培介质>pH值>N形态.毛竹幼苗生长及对不同N形态的响应受外界环境条件影响,在蛭石中栽培,供应NH4+-N为主、pH值为3.8的营养液,其生长最好.研究结果可为毛竹幼苗的无土栽培和繁育提供理论参考. 相似文献
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摘要：在温室内采用水培的方法研究了不同氮形态配比下,9个马大杂种相思（Acacia mangium×A. auriculiformis Cunn．ex Bench）无性系幼苗的生长状况发现,NO3- ：NH4+ 比例对马大相思生长及生物量的影响均达到极显著水平。在马大相思幼苗生长方面,当NO3- ：NH4+ 比例为25：75时,苗高净生长量最大,而NO3- ：NH4+ 比例为75：25时,根长净生长量最大,但抑制了苗高的生长;在生物量方面,当NO3- ：NH4+ 比例为25：75时,马大相思幼苗的生物量干重及生物量鲜重积累均达到最大。因此,在供氮总量不变的条件下,NO3- ：NH4+ 比例为25：75时最有利于马大杂种相思幼苗的生长。 相似文献
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氮素形态及配比对铁核桃苗生长及营养吸收的影响 总被引：3，自引：0，他引：3
采用盆栽试验方法,以铵态氮、硝态氮和尿素[CO(NH2)2]为氮源,研究氮素形态及配比对铁核桃苗植株大小、生物量、根系形态特征和苗木元素含量及积累量的影响。结果表明:氮素形态及配比对铁核桃苗木的高度、基径、根冠比值、地上部和根系的生物量、根系形态特性、苗木中元素含量及积累量有明显的影响。以50%NH+4-N+50%NO-3-N为氮源的苗高、基径、根冠比值、整株及地上部和根系的生物量、根系的总表面积及平均直径、根尖数、苗木中元素含量及积累量都最大;单一供应CO(NH2)2的苗木根系总长度和总体积最大,苗木整株和地上部及根系的生物量、苗木中的元素含量及积累量仅低于50%NH+4-N+50%NO-3-N的处理;单一供应NO-3-N的苗木矮小,整株、地上部及根系的生物量和根系的形态及生长指标都最低,各种元素的含量及积累量也最少;单一供应NH+4-N时,在夏季叶片出现大量灼烧状坏死,其症状随NH+4-N的比例增加而加重,苗木也纤细,组织不充实,须根短,坏死较多,植株的生物量和根冠比及根系总长度、表面积、体积、平均直径和根尖数都较小,营养元素的积累量也较低。铁核桃对NH+4-N或NO-3-N没有明显的偏好。在NH+4-N与NO-3-N的比例各占50%时能够更好地促进铁核桃苗木的生长及营养的吸收,尿素也有较好的效果。 相似文献
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《中国林副特产》2016,(5)
以1年生白桦苗木为试验材料,在全自动温室内进行砂培试验,探讨了4种不同磷素浓度(0.125、0.5、1.0、2.0mmol/L)处理对白桦幼苗生物量、叶绿素含量、可溶性蛋白含量以及根、茎、叶氮磷分配的影响。结果表明:(1)不同磷处理对白桦幼苗总生物量的影响显著,在正常供磷水平下达最大;(2)P_(2.0)水平下叶绿素a、b、a+b及类胡萝卜素含量比P_(0.125)增加了43.1%、46.0%、44.7%和42.4%,可溶性蛋白含量在供磷水平为1.0mmol/L时最高;(3)不同磷处理对幼苗各器官全磷含量影响差异显著,吸收的磷素主要分配到了幼苗的叶片部分,但对全氮含量影响不显著。 相似文献
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通过测定CO2浓度倍增条件下肋果沙棘幼苗气体交换特征、水分利用效率、叶片性状和生长特性,研究青藏高原特有种肋果沙棘对大气CO2浓度升高的生理生态响应.结果表明:CO2浓度倍增可显著提高肋果沙棘幼苗的净光合速率、水分利用效率,促进幼苗营养器官(根、茎、叶)生物量和总生物量的积累,且肋果沙棘趋于向地上部分(尤其是茎)分配更多的干物质.CO2浓度倍增使肋果沙棘幼苗比叶面积、平均单叶面积、叶片氮含量分别降低27％,33％和41％,碳氮比增加73％,而叶片碳含量无显著影响.CO2浓度升高条件下肋果沙棘幼苗不仅通过增加光合能力、水分利用效率和生物量累积产生明显的“施肥效应”,而且通过降低比叶面积、平均单叶面积和叶片氮含量表现出较强的下调适应能力,进而有利于其应对更为复杂的生存环境. 相似文献
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对长沙市樟树人工林生态系统的大气降水、主要树种叶片和土壤中的N含量进行定位观测,探讨大气氮湿沉降对城市森林生态系统各分室N含量的影响。结果表明:大气降水中NH4+-N含量具有明显的月动态特征,3、4和11月份较高,其中3月份为全年最高值,达6.7 mg.L-1,8月份为全年最低值,仅为2.7 mg.L-1,大气降水中NO3--N含量月变化相对平稳,3、8、10和11月份含量均高于1.2 mg.L-1,11月份为全年最高值,高达1.9 mg.L-1,7月份为全年最低值,仅为0.4 mg.L-1。樟树、红叶树、木莲叶片全N含量的平均值呈现出明显的月动态变化特征,4月份为全年最高值,达17.48 g.kg-1,10月份为全年最低值,仅为10.78 g.kg-1。土壤层(0～15 cm)全N、速效N含量的月动态变化趋势基本一致,3、8、9和10月份含量较高,并同时在10月份达到全年最高值,但全N和速效N最低值出现在不同月份,分别为6月和4月。大气降水NH4+-N和NO3--N含量与植物全N、土壤全N和速效N含量存在一定的相关性,其中大气降水NH4+-N、NO3--N含量与植物全N含量相关系数分别为0.414 3、0.531 3,表明大气降水NH4+-N、NO3--N含量对植物叶片全N含量有明显的影响。 相似文献
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We examined changes in root system architecture and physiology and whole-plant patterns of nitrate reductase (NR) activity in response to atmospheric CO2 enrichment and N source to determine how changes in the form of N supplied to plants interact with rising CO2 concentration ([CO2]). Seedlings of Betula alleghaniensis Britt. and Pinus strobus L., which differ in growth rate, root architecture, and the partitioning of NR activity between leaves (Betula) and roots (Pinus), were grown in ambient (400 microl l(-1)) and elevated (800 microl l(-1)) [CO2] and supplied with either nitrate (NO3-) or ammonium (NH4+) as their sole N source. After 15 weeks of growth, plants were harvested and root system architecture, N uptake kinetics, and NR activity measured. Betula alleghaniensis responded to elevated [CO2] with significant increases in growth, regardless of the source of N. Pinus strobus showed no significant response in biomass production or allocation to elevated [CO2]. Both species exhibited significantly greater growth with NH4+ than with NO3-, along with lower root:shoot biomass ratios. Betula showed significant increases in total root length in response to elevated [CO2]. However, root N uptake rates in Betula (for both NO3- and NH4+) were either reduced or unchanged by elevated [CO2]. Pinus showed the opposite response to elevated [CO2], with no change in root architecture, but an increase in maximal uptake rates in response to elevated [CO2]. Nitrate reductase activity (on a mass basis) was reduced in leaves of Betula in elevated [CO2], but did not change in other tissues. Nitrate reductase activity was unaffected by elevated [CO2] in Pinus. Scaling this response to the whole-plant, NR activity was reduced in elevated [CO2] in Betula but not in Pinus. However, because Betula plants were larger in elevated [CO2], total whole-plant NR activity was unaffected. 相似文献
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不同氮源对黑松幼苗根-土界面无机磷形态转化及有效性的影响 总被引：1，自引：0，他引：1
用根垫-冰冻切片法研究不同氮源对石灰性潮土中黑松幼苗根-土界面无机磷形态转化及有效性的影响。结果表明:铵态氮(NH4+-N)处理后幼苗根-土界面pH值较对照处理明显降低,而硝态氮(NO3--N)处理后幼苗根-土界面pH值较对照处理升高,不同氮源引起的幼苗根-土界面pH值变动的幅度取决于氮源的质量分数。铵态氮处理明显降低了幼苗根-土界面Ca2-P,Fe-P和Al-P质量分数,100,200和400mg·kg-1的铵态氮处理后,距根表0～1mm处Ca2-P较土体亏缺率分别为37.1%,45.9%和57.7%,Fe-P较土体亏缺率分别为23.4%,29.1%和38.2%,Al-P较土体亏缺率分别为25.1%,28.0%和33.2%;硝态氮处理增加了幼苗根-土界面Ca2-P,Fe-P和Al-P质量分数,但不显著。铵态氮与硝态氮处理后幼苗根-土界面Ca8-P的亏缺程度较对照分别加大或降低,但不明显。铵态氮与硝态氮处理后幼苗根-土界面Ca10-P和O-P质量分数较对照处理变化很小。铵态氮引起的黑松幼苗根-土界面pH值的降低,促进了幼苗根-土界面处无机磷的形态转化,提高了根-土界面无机磷的生物有效性,显著增加了根系对磷的吸收。 相似文献
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We measured fine root N concentration, root in vivo nitrate reductase activity (NRA) and root uptake capacity for (15)NH(4) (+) and (15)NO(3) (-) along an N-deposition gradient from northern Sweden to central Europe, encompassing a variation in N deposition rates of < 5 to about 40 kg N ha(-1) year(-1). The focus was on Picea abies (L.) Karst., but Fagus sylvatica L. in central Europe and Pinus sylvestris L. and Betula spp. in northern Sweden were also studied. We assumed that, with an increased supply of N, root N concentration would increase, activity of the inducible enzyme nitrate reductase (NR) in roots would increase, particularly with an increasing supply of NO(3) (-), and root uptake capacity for inorganic N would decline, reflecting a lower demand for N. As expected, fine root N concentration in P. abies increased along the gradient from 1.1% (d.w. basis) at the northern site to 2.1% at central European sites. This variation compared with an amplitude of 0.7-1.5% for foliage. Root in vivo NRA was low in northern Sweden, and higher in central Europe. Picea abies and broad-leaved species had similar root NRA. At one location in Denmark and one in France, however, root NRA in the spring was very high in F. sylvatica. Root uptake capacity for NO(3) (-), as measured in excised roots, was low throughout the transect, but in P. abies, it was high for NH(4) (+) in northern Sweden and decreased by a factor of 4 with increasing N deposition. A similar pattern was found in the broad-leaved species. Unless the higher availability of NO(3) (-) and lower specific root uptake capacity per unit root mass for inorganic N in central Europe (compared with northern Sweden) is balanced by a higher root biomass, the central European forests will be a weaker sink for N. 相似文献
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以马尾松人工林及林下灌木短柱茶为研究对象,采用根系分泌物原位收集法,分析凋落物处理[对照(保持原状凋落物不变,CK)、去除凋落物(LR)、添加凋落物(LA)]对两树种根系分泌物碳输入速率、根际土壤氮含量和氮转化相关酶活性的影响,并分析其相关关系。结果表明:凋落物输入量变化对马尾松和短柱茶根系分泌物碳输入速率无显著影响。同一凋落物处理下,马尾松和短柱茶根系分泌物碳输入速率无显著差异。凋落物输入量变化不显著影响根际土壤氮含量及马尾松根际土壤脲酶、羟胺还原酶、硝酸还原酶和亚硝酸还原酶活性,短柱茶根际土壤硝酸还原酶活性表现为去除凋落物处理显著大于对照,其余氮转化相关酶活性未表现出显著差异。可能是凋落物处理时间较短,凋落物未完全分解或者是林分年龄较大有关。相关关系结果表明,单位根长根系分泌物碳输入速率与根际土壤全氮(TN)含量呈显著负相关关系,单位根表面积根系分泌物碳输入速率与根际土壤硝态氮含量(NO-3-N)含量呈显著负相关关系。表明根系分泌物碳输入与根际土壤氮素相互影响。 相似文献
15.
An understanding of root system capacity to acquire nitrogen (N) is critical in assessing the long-term growth impact of rising atmospheric CO2 concentration ([CO2]) on trees and forest ecosystems. We examined the effects of mycorrhizal inoculation and elevated [CO2] on root ammonium (NH4+) and nitrate (NO3-) uptake capacity in sweetgum (Liquidambar styraciflua L.) and loblolly pine (Pinus taeda L.). Mycorrhizal treatments included inoculation of seedlings with the arbuscular mycorrhizal (AM) fungus Glomus intraradices Schenck & Smith in sweetgum and the ectomycorrhizal (EM) fungus Laccaria bicolor (Maire) Orton in loblolly pine. These plants were then equally divided between ambient and elevated [CO2] treatments. After 6 months of treatment, root systems of both species exhibited a greater uptake capacity for NH4+ than for NO3-. In both species, mycorrhizal inoculation significantly increased uptake capacity for NO3-, but not for NH4+. In sweetgum, the mycorrhizal effect on NO3- and NH4+ uptake capacity depended on growth [C02]. Similarly, in loblolly pine, the mycorrhizal effect on NO3- uptake capacity depended on growth [CO2], but the effect on NH4+ uptake capacity did not. Mycorrhizal inoculation significantly enhanced root nitrate reductase activity (NRA) in both species, but elevated [CO2] increased root NRA only in sweetgum. Leaf NRA in sweetgum did not change significantly with mycorrhizal inoculation, but increased in response to [CO2]. Leaf NRA in loblolly pine was unaffected by either treatment. The results indicate that the mycorrhizal effect on specific root N uptake in these species depends on both the form of inorganic N and the mycorrhizal type. However, our data show that in addressing N status of plants under high [CO2], reliable prediction is possible only when information about other root system adjustments (e.g., biomass allocation to fine roots) is simultaneously considered. 相似文献
16.
Acidic deposition in high-elevation forests in the Appalachian Mountains of the eastern United States has been implicated in the decline of red spruce (Picea rubens Sarg.). Elevated soil acidity may increase soil Al availability and toxicity to roots. Enhanced soil solution NO(3) (-) concentrations, resulting from precipitation inputs and enhanced soil organic matter mineralization, may exacerbate Al toxicity by increasing root Al uptake. We exposed red spruce seedlings to 350, 500, 800 or 1400 micro M NO(3) (-) and 0 or 200 micro M Al in a factorial design in sand-nutrient solution culture to test if increased NO(3) (-) concentrations enhance Al uptake and toxicity. In addition to significant reductions in seedling growth parameters resulting from Al exposure, we found significant interactions between NO(3) (-) and Al for seedling height growth rate, needle weight, shoot weight and root weight. Differences in these parameters between Al treatments became more pronounced as solution NO(3) (-) concentration increased and reflected an Al-mediated inhibition of seedling response to increasing NO(3) (-) concentration. Solution NO(3) (-) concentrations above 500 micro M induced root nitrate reductase (NR) activity, whereas shoot NR activity increased in response to NO(3) (-) up to 500 micro M and declined above that concentration. In contrast, exposure to Al depressed NR activity of roots but tended to stimulate needle NR activity. Foliar N concentrations increased in seedlings grown in cultures containing between 350 and 500 micro M NO(3) (-), with no change above 500 micro M. Increasing concentrations of NO(3) (-) depressed foliar P concentrations, with reductions being greatest in seedlings exposed to 1400 micro M NO(3) (-). Exposure to Al increased foliar Ca, K and Al concentrations, decreased foliar P concentrations, and inhibited increases in foliar Mg concentration in response to increasing NO(3) (-). The consistent interactions between NO(3) (-) and Al for growth, root NR activity and foliar Mg concentration were the result of an inhibition of seedling response to NO(3) (-) mediated by Al in solution, rather than enhanced Al toxicity resulting from growth in the presence of elevated NO(3) (-) concentrations. 相似文献
17.
Foliage, fine-root, woody-tissue and stand respiration in Pinus radiata in relation to nitrogen status 总被引：1，自引：0，他引：1
We measured respiration of 20-year-old Pinus radiata D. Don trees growing in control (C), irrigated (I), and irrigated + fertilized (IL) stands in the Biology of Forest Growth experimental plantation near Canberra, Australia. Respiration was measured on fully expanded foliage, live branches, boles, and fine and coarse roots to determine the relationship between CO(2) efflux, tissue temperature, and biomass or nitrogen (N) content of individual tissues. Efflux of CO(2) from foliage (dark respiration at night) and fine roots was linearly related to biomass and N content, but N was a better predictor of CO(2) efflux than biomass. Respiration (assumed to be maintenance) per unit N at 15 degrees C and a CO(2) concentration of 400 micro mol mol(-1) was 1.71 micro mol s(-1) mol(-1) N for foliage and 11.2 micro mol s(-1) mol(-1) N for fine roots. Efflux of CO(2) from stems, coarse roots and branches was linearly related to sapwood volume (stems) or total volume (branches + coarse roots) and growth, with rates for maintenance respiration at 15 degrees C ranging from 18 to 104 micro mol m(-3) s(-1). Among woody components, branches in the upper canopy and small diameter coarse roots had the highest respiration rates. Stem maintenance respiration per unit sapwood volume did not differ among treatments. Annual C flux was estimated by summing (1) dry matter production and respiration of aboveground components, (2) annual soil CO(2) efflux minus aboveground litterfall, and (3) the annual increment in coarse root biomass. Annual C flux was 24.4, 25.3 and 34.4 Mg ha(-1) year(-1) for the C, I and IL treatments, respectively. Total belowground C allocation, estimated as the sum of (2) and (3) above, was equal to the sum of root respiration and estimated root production in the IL treatment, whereas in the nutrient-limited C and I treatments, total belowground C allocation was greater than the sum of root respiration and estimated root production, suggesting higher fine root turnover or increased allocation to mycorrhizae and root exudation. Carbon use efficiency, the ratio of net primary production to assimilation, was similar among treatments for aboveground tissues (0.43-0.50). Therefore, the proportion of assimilation used for construction and maintenance respiration on an annual basis was also similar among treatments. 相似文献
18.
Branches of nine-year-old loblolly pine trees grown in a 2 x 2 factorial combination of fertilization and irrigation were exposed for 11 months to ambient, ambient + 175, or ambient + 350 micro mol mol(-1) CO(2). Rates of light-saturated net photosynthesis (A(max)), maximum stomatal conductance to water vapor (g(max)), and foliar nitrogen concentration (% dry mass) were assessed monthly from April 1993 until September 1993 on 1992 foliage (one-year-old) and from July 1993 to March 1994 on 1993 foliage (current-year). Rates of A(max) of foliage in the ambient + 175 CO(2) treatment and ambient + 350 were 32-47 and 83-91% greater, respectively, than that of foliage in the ambient CO(2) treatment. There was a statistically significant interaction between CO(2) treatment and fertilization or irrigation treatment on A(max) on only one measurement date for each age class of foliage. Light-saturated stomatal conductance to water vapor (g(max)) was significantly affected by CO(2) treatment on only four measurement dates. Light-saturated g(max) in winter was only 42% of summer g(max) even though soil water during winter was near field capacity and evaporative demand was low. Fertilization increased foliar N concentration by 30% over the study period when averaged across CO(2) treatments. During the study period, the ambient + 350 CO(2) treatment decreased average foliar N concentration of one-year-old foliage in the control, irrigated, fertilized and irrigated + fertilized plots by 5, 6.4, 9.6 and 11%, respectively, compared with one-year-old foliage in the corresponding ambient CO(2) treatments. The percent increase in A(max) due to CO(2) enrichment was similar in all irrigation and fertilization treatments and the effect persisted throughout the 11-month study period for both one-year-old and current-year foliage. 相似文献
19.
The growth and mineral nutrition of Gmelina arborea Roxb. seedlings were investigated in response to four nitrogen-based fertilizers applied at 0, 2.5, 5.0 or 7.5 g N per plant. Nitrogen sources included NH(4)-N as ammonium sulfate, NO(3)-N as potassium nitrate, NH(4)NO(3)-N as calcium ammonium nitrate, and urea-N as urea. Seedlings fertilized with NH(4)NO(3)-N or urea-N had greater height, collar diameter, dry weight, net assimilation rate, and relative growth rate than seedlings fertilized with NH(4)-N or NO(3)-N. For all sources of nitrogen, increasing the amount of exogenously supplied N per plant promoted shoot growth more than root development, hence the root to shoot ratios of all fertilized seedlings were smaller than those of the unfertilized controls. Applications of NO(3)-N increased the nitrogen, potassium, and phosphorus concentrations of fertilized seedlings. Regardless of source, a nitrogen application of 2.5 g N per plant was apparently optimal for the growth of Gmelina seedlings on a latosolic soil. 相似文献
20.
空心莲子草是世界性恶性杂草。研究用使它隆乳油2g/L和Round up 15mL/L喷施空心莲子草进行防除效果比较试验。结果表明:喷药后7d,空心莲子草受害的形态和防除快速效果看,Round up防除效果优于使它隆乳油的,药后30天,从根系生理指标测定看,除Round up处理的根系硝酸还原酶活性明显高于使它隆乳油处理的外,二者对根系其他生理指标的影响无明显差异;从第二年空心莲子草复发情况看,Round up处理的区域空心莲子草无复发,而使它隆乳油处理的杂草有3%～5%左右的复发。Round up防除空心莲子草的效果优于使它隆乳油。 相似文献