氮对苹果幼树水分利用效率的影响

以２年生盆栽新红星／平邑甜茶苹果树为试材,初步探讨了土壤不同水分状况下氮肥对植株水分利用效率（ＷＵＥ）及有关参数的影响,结果表明,充足供水时,随施Ｎ量的增加,植株ＷＵＥ降低,施Ｎ导致气孔导率（Ｇｓ）增大,对蒸腾（Ｔｒ）的提高幅度大于光合（Ｐｎ）;供水不足时,施Ｎ植株的ＷＵＥ明显高于对照,不同施Ｎ水平的ＷＵＥ表现为：高Ｎ〉中Ｎ〉低Ｎ,ＷＵＥ改善是由于叶肉羧化能力提高,导致光合增强。     

常规灌溉条件下嫁接和增施氮肥对温室黄瓜耗水量及水分利用效率的影响

在日光温室内研究了常规灌溉条件下,嫁接和3种施氮水平（0、110和331 kg·hm^-2）对日光温室黄瓜耗水量和水分利用效率的影响.结果表明：在嫁接和追施氮肥331 kg·hm^-时,黄瓜耗水量最高,冬春茬和秋冬茬分别为3 350和2 181 m³·hm^-2,水分利用效率也最高,两茬口分别为27.2和36.9 kg·m^-3.在施氮量相同的情况下,嫁接黄瓜的耗水量比自根黄瓜提高3%～6%,经济产量和水分利用效率则分别提高28%和209%;随着施氮量的增加,嫁接黄瓜耗水量和水分利用效率均显著增加,自根黄瓜耗水量也随施氮量的增加而增加,但水分利用效率却在施氮110 kg·hm^-2时最高.因此,嫁接栽培可显著提高黄瓜耗水量及水分利用效率,且随着施氮量的增加而显著增加;增施氮肥也可显著提高自根黄瓜的耗水量,但氮肥增施过多则将降低自根黄瓜的水分利用效率.     

不同水分和氮素处理对寒地水稻生育及产量的影响

为了探讨不同水分和氮素处理对寒地水稻生长发育及产量的影响,以水稻品种空育131、龙粳21为试验材料,于2010—2011年度在黑龙江建三江进行水分、氮素处理大田试验,水分为雨养、间歇灌溉、水层灌溉3个水平,氮素为不施氮、常规施氮(112—135 kg/hm2)、高氮(142—173 kg/hm2)3个水平。结果表明:与水层灌溉相比,雨养水稻生育期缩短1—5 d,生长指标明显降低,产量显著降低,间歇灌溉水稻生育期、生长指标与其相似,产量差异不显著。与常规施氮相比,不施氮生育期缩短2—5 d,高氮条件下延长2—4 d;施氮量增加,生长指标增大,产量显著增加;低氮条件下,水分不足的限制作用明显,高氮能一定程度弥补水分的限制,促进水稻生长。增加施氮量及灌溉水平可以显著地提高有效穗数、每穗粒数。在试验条件下,水氮互作效应不显著。间歇灌溉及高氮管理具有较好的增产效应及资源利用率,研究可为寒地水稻生产进行水氮科学管理、实现高产高效提供理论依据。     

氮磷营养对夏玉米水分敏感性及生理参数的影响

依据盆栽试验数据,采用Jenson模式,研究了黄土区夏玉米的水分模型。结果表明,玉米在拔节—抽穗期和抽穗—灌浆期对缺水最敏感,拔节前和灌浆—成熟期敏感性小;较高肥力水平使需水关键期水分敏感性指数增加相对较多,而在非水分关键期增加较少。较高的N、P水平增大了玉米叶片的光合速率,中度干旱条件下,N、P肥对Pn的增加幅度大于充分供水时的增加幅度;施用N、P增加了玉米叶片的蒸腾速率,但土壤水分条件影响了N、P对蒸腾速率的作用;施用N、P肥可以提高玉米的单叶WUE,随水分条件的改善而增加。高N处理的玉米根重均低于相应的低N处理,施P对玉米根系生长有明显的促进作用,中度干旱条件下的增幅大于充分供水时的增幅;不同施P处理玉米地上生物量的增幅明显大于不同施N处理的增幅;随水分条件的改善,玉米的根冠比增加,不同水分条件下施N均降低了根冠比,而施P增加了根冠比。     

施用氮、磷肥对作物体内养分含量的影响

２年四季盆栽试验结果表明：（１）施用磷肥能改善作物地上部生物学产量向籽粒分配．在Ｎ、Ｐ胁迫条件下,施Ｎ增加非经济产量与经济产量比值．（２）对于谷子,在Ｎ、Ｐ亏缺条件下,施Ｎ能增加茎叶含Ｎ量,降低Ｎ向籽粒中转移;施磷能改善Ｎ在茎叶与籽粒之间的分配。（３）对于小麦,在Ｎ或Ｐ胁迫条件下,补施Ｐ或Ｎ均能增加冠根吸Ｎ量之比,对于谷子,其对冠根吸Ｎ量之比影响与小麦完全不同．（４）谷子在Ｎ、Ｐ胁迫条件下,施Ｎ能降低Ｐ在籽粒中积累,施Ｐ却能显著地改善磷向籽粒中转移,小麦在Ｎ、Ｐ胁迫条件下,增施Ｐ或Ｎ均能显著改善磷向籽粒中转移。     

农田生态系统N、P营养平衡及其肥料效应

９年的农田生态系统Ｎ、Ｐ营养平衡定位试验研究表明,Ｎ、Ｐ肥配合施用,实行秸秆还田,可提高土壤有机质和全Ｎ含量,使土壤速效和迟效Ｐ库容量得到补充．最后几年的Ｐ肥利用率达２１．１—６５．１％,Ｎ肥为４９—７５％．储备性施Ｐ第１年的利用率只有６．５－７．３％,而前３年之和达到２４—２８．５％,９年３个时段平均利用率２７．９—４２．８％,补偿性施Ｐ的１９．５—４２．９％．施Ｐ６５．５ｋｇ·ｈａ－１·ｙｒ－１时,既能满足作物对Ｐ的需求又能补充土壤速效Ｐ库容量．     

施氮量对不同肥力水平下夏玉米碳氮代谢及氮素利用率的影响

以郑单958为材料,在高产田和中产田两种地力水平下,利用15N标记法研究了施氮量对夏玉米氮素分配率、利用率和碳氮代谢的影响.结果表明:高产田适量施氮可以提高玉米产量,过量施氮没有表现出进一步增产效果,其氮肥利用率较低(29 04%).中产田随施氮量的增加产量提高,但氮素利用率却降低.各个器官15N积累量依次为籽粒>叶片>茎>根>叶鞘>穗轴.在高产田,当施氮量超过300kg·hm-2时,玉米籽粒和叶片中积累15N有所下降,而茎和根中积累15N的量随施N量的增加而增加;在中产田,随着施N量的增加,籽粒和穗轴积累15N量均相应增加.高产田叶片的硝酸还原酶活性、谷氨酰胺合成酶活性和蔗糖磷酸合成酶活性以及籽粒中蔗糖合成酶活性和酸性转化酶活性均是施氮300kg·hm-2时最大,施氮450 kg·hm-2则抑制了其活性的增强,而中产田的各个酶活性则随着施氮量的增加而增加.     

控释氮钾肥对海棠氮、磷、钾利用率的影响

采用盆栽试验,研究了控释氮钾肥对海棠实生苗生长、磷钾利用率及土壤-作物系统中氮素平衡的影响.结果表明:控释肥的释放与海棠苗对养分的需求一致;控释氮肥显著提高了植株钾素的利用率;控释钾肥显著提高了植株氮素的利用率.施钾量相同情况下,控释氮肥(CN)和控释氮钾肥(NK)的株高、茎粗无显著差异,但均高于普通肥料(SF).植株干物质量、磷的利用率、钾的吸收量和利用率大小顺序均为:NKCNSF.施钾量对株高、茎粗无明显影响,但对NK处理的干物质量有显著影响.磷素利用率随控释钾肥施用量增加而显著提高,而普通钾肥施用量对其无明显影响.钾素利用率随施钾量提高而降低.氮素利用率大小顺序为NKCNSF,损失率顺序则相反,NK和CN的残留率无显著差异,但均高于SF.控释钾肥施用量对氮素利用率、损失率有显著影响,对残留率无明显影响.     

太湖地区氮肥减量对水稻氮素吸收利用的影响

为了明确太湖地区高产稻田适宜施氮量,以提高水稻氮素利用效率,减少稻田氮素流失对农业生态环境的影响,本研究在调查当地农户稻田氮肥施用量的基础上,通过秸秆还田和基肥机械深施,设置不施氮肥(N0)为空白对照,当地习惯施氮水平360 kg·hm-2(N1),以及在此基础上减少氮肥施用量的10%(N2)、20%(N3)、30%(N4)等5个处理,研究其对水稻氮素利用率的影响。结果表明:氮肥减量使水稻不同生育时期稻田土壤速效氮含量明显下降;在当地习惯施氮量水平的基础上,减少10%的氮肥施用量,使水稻产量增加1.9%;与当地习惯施氮量水平相比较,N2处理水稻氮素累积量差异不明显,N3和N4处理则表现为显著下降;随着氮肥减量幅度的增加,水稻氮素籽粒生产效率逐渐增高;在当地习惯施氮量水平的基础上,通过基肥机械深施和秸秆还田等技术的应用,减少10%的氮肥施用量,能够保证水稻高产稳产,并使水稻氮肥农学利用率、氮肥吸收利用率、生理利用率以及氮肥偏生产力均得到明显提高。     

农田水氮关系及其协同管理

作物施氮反应及其氮肥利用率不仅取决于氮肥管理,还与水资源管理有关,并且受到地区气候因素的影响。针对中国灌溉农区氮肥环境污染问题日益突出,协调农田水氮管理,如通过改善水资源管理,发挥水氮协同效应,以提高水分利用效率来改善氮肥利用率,实现水氮利用率双赢,是当前农业水氮管理中亟待探讨和回答的问题。通过对农田水氮协同相关研究文献资料的综述,以华北平原集约种植体系水氮管理为例,根据历年统计数据,分析了该区年水热条件下粮食产量与水、氮及水氮利用效率之间的关系。研究表明,水和氮与作物产量在一定范围表现为水氮的协同效应。水分利用效率一般随灌溉水量减少及氮肥用量增加而提高;氮肥利用效率随氮用量增加而下降。适量节水和减氮分别有助水分利用效率和氮肥利用效率的改善。在气候变暖、变干条件下,适量施氮成为改善水氮利用效率的关键对策。     

Photosynthetic performance along a light gradient as related to leaf characteristics of a naturally occurring <Emphasis Type="Italic">Cypripedium flavum</Emphasis>

Photosynthesis, leaf structure, nitrogen content and nitrogen allocation in photosynthetic functions of Cypripedium flavum were studied in a naturally varying light regime. Light-saturated leaf net photosynthetic rate (A (max)) was strongly correlated with leaf dry mass per area (LMA), mesophyll conductance (g (m)) and area-based leaf nitrogen content (N(area)), with all variables increasing with increasing irradiance. Such coordinate variation of all these parameters illustrates the plastic response of leaf structure to high light (HL). Leaf N(area) was greater under HL than in low light (LL). The fractions of leaf nitrogen partitioning in carboxylation (P (R)) and bioenergetics (P (B)) were positively related to LMA. In contrast, P (R) and P (B) decreased with increasing mass-based leaf nitrogen content (N(mass)). However, no correlation was found between leaf nitrogen investment in light harvesting (P (L)) and either LMA or N(mass). Like maximum rate of carboxylation (V (cmax)) and electron transport (J (max)), the J (max)/V (cmax) ratio, which was strongly correlated to LMA, also increased significantly with irradiance. Under HL, leaf maximum photosynthetic nitrogen efficiency (ANUE) and intrinsic water use efficiency (WUE) were greater than in LL conditions, despite a small difference in WUE. This suggests that a functional balance in the photosynthetic machinery favors leaf photosynthetic plasticity of C. flavum in response to different light conditions. Given an ample soil nitrogen supply, C. flavum may offset its susceptibility to HL by efficient nitrogen use and higher stomatal and mesophyll conductance against photoinhibition so as to keep leaf photosynthesis positive.     

干旱胁迫对不同施氮水平麻疯树幼苗光合特性及生长的影响

采用盆栽控水的方法,研究了干旱胁迫（连续干旱0 d,5 d,10 d,…,45 d）对不同施氮水平(对照 0 kg N·hm^-2、低氮 96 kg N·hm^-2、中氮 288 kg N·hm^-2、高氮 480 kg N·hm^-2)麻疯树幼苗光合特性及其生长的影响.结果表明: 随干旱胁迫强度的增加,各施氮水平麻疯树幼苗叶片相对含水量、苗高生长量、地径生长量、叶面积、净光合速率、蒸腾速率和气孔导度均降低,且各水分处理间差异极显著(P<0.01);随干旱时间的延长,叶绿素含量和水分利用效率表现出先升高后降低的趋势,而胞间CO₂浓度呈先降低后升高的趋势.正常供水时,施氮处理均不同程度提高了麻疯树幼苗的光合能力,促进了麻疯树幼苗的生长,且施氮量越高效果越好;干旱条件下,氮素营养对植株光合能力和生长的影响与干旱程度和施氮水平有关.轻度干旱时,提高施氮水平对植株光合能力和生长具有明显的促进作用;中度干旱时,中氮的促进作用明显高于其他施氮水平;严重干旱时,低氮的促进效果最好,高氮的促进作用减弱并逐渐转向抑制.     

Arbuscular Mycorrhizal Fungi Alter Fractal Dimension Characteristics of Robinia pseudoacacia L. Seedlings Through Regulating Plant Growth,Leaf Water Status,Photosynthesis, and Nutrient Concentration Under Drought Stress

The influence of arbuscular mycorrhizal fungi (AMF), Funneliformis mosseae and Rhizophagus intraradices, on plant growth, leaf water status, chlorophyll concentration, photosynthesis, nutrient concentration, and fractal dimension (FD) characteristics of black locust (Robinia pseudoacacia L.) seedlings was studied in pot culture under well-watered, moderate drought stress, and severe drought stress treatments. Mycorrhizal seedlings had higher dry biomass, leaf relative water content (RWC), and water use efficiency (WUE) compared with non-mycorrhizal seedlings. Under all treatments, AMF colonization notably enhanced net photosynthetic rate, stomatal conductance, and transpiration rate, but decreased intercellular CO₂ concentration. Leaf chlorophyll a and total chlorophyll concentrations were higher in AM seedlings than those in non-AM seedlings although there was no significant difference between AMF species. AMF colonization improved leaf C, N, and P concentrations, but decreased C:N, C:P, and N:P ratios. Mycorrhizal seedlings had a larger FD value than non-mycorrhizal seedlings. The FD value was positively and significantly correlated to the plant growth parameters, photosynthesis, RWC, WUE, and nutrient concentration but negatively correlated to leaf/stem ratio, C:N and C:P ratios, and intercellular CO₂ concentration. We conclude that AMF lead to an improvement of growth performance of black locust seedlings under all growth conditions, including drought stress via improving leaf water status, chlorophyll concentration, photosynthesis, and nutrient uptake. Moreover, FD technology proved to be a powerful non-destructive method to characterize the effect of AMF on the physiology of host plants during drought stress.     

The effects of light and nitrogen on photosynthesis,leaf characteristics,and dry matter allocation in the chaparral shrub,Diplacus aurantiacus

Summary Plants of Diplacus aurantiacus, a successional shrub common in California chaparral, were grown under controlled conditions in which either quantum flux density or nitrogen availability was varied. Photosynthesis and leaf nitrogen content were determined on a leaf area and a leaf weight basis, and whole plant growth was monitored.There was a direct relationship between photosynthesis and leaf nitrogen content on both area and weight bases. Reduced light intensity of the growth environment resulted in reductions in light-saturated photosynthesis and nitrogen content on an area basis, but not on a weight basis. With reduced nitrogen availability, photosynthesis and leaf nitrogen content per unit leaf weight decreased.Resource use efficiency increased as the resource became more limiting. The results are consistent with a model of plant growth in which net carbon gain of the leaf is maximized. Abbreviations. For brevity, the following set of abbreviations is used in presenting and discussing the results. P/area and N/area are, respectively, photosynthesis and leaf nitrogen content per unit leaf area. P/wt and N/wt are the same quantities per unit leaf dry weight. SLW (specific leaf weight) is dry weight per unit leaf area. RGR (relative growth rate) is the relative rate of increase in shoot dry matter per day     

环境因子对小麦叶片水分利用效率影响的实验研究和数值模拟

根据现有的光合作用和蒸腾作用的模型,利用Ｂａｌｌ－Ｂｅｒｒｙ 的气孔导度模型,将叶片的光合作用模型和蒸腾作用模型结合起来,建立了光强（Ｉ）、叶片－大气水汽饱和差（ＶＰＤ）和大气ＣＯ２ 浓度（Ｃａ）等环境因子对小麦叶片水分利用效率（ＷＵＥ）影响的模型。由于这３ 种环境因子对光合、蒸腾的影响方式上的差异,作为两者之比的叶片ＷＵＥ随各环境因子的变化出现复杂的图景,同时,在人工气候箱内分别于这３ 个因子变化时对光合、蒸腾的变化作了测定,计算了叶片的Ｗ ＵＥ。测定结果与模拟结果的对比表明,在多数情况下两者符合程度良好,但在高Ｃａ下有较大的偏离     

Relationships between photosynthetic activity and silica accumulation with ages of leaf in Sasa veitchii (Poaceae, Bambusoideae)

BACKGROUND AND AIMS: Bamboos have long-lived, evergreen leaves that continue to accumulate silica throughout their life. Silica accumulation has been suggested to suppress their photosynthetic activity. However, nitrogen content per unit leaf area (N(area)), an important determinant of maximum photosynthetic capacity per unit leaf area (P(max)), decreases as leaves age and senescence. In many species, P(max) decreases in parallel with the leaf nitrogen content. It is hypothesized that if silica accumulation affects photosynthesis, then P(max) would decrease faster than N(area), leading to a decrease in photosynthetic rate per unit leaf nitrogen (photosynthetic nitrogen use efficiency, PNUE) with increasing silica content in leaves. METHODS: The hypothesis was tested in leaves of Sasa veitchii, which have a life span of 2 years and accumulate silica up to 41 % of dry mass. Seasonal changes in P(max), stomatal conductance, N(area) and silica content were measured for leaves of different ages. KEY RESULTS: Although P(max) and PNUE were negatively related with silica content across leaves of different ages, the relationship between PNUE and silica differed depending on leaf age. In second-year leaves, PNUE was almost constant although there was a large increase in silica content, suggesting that leaf nitrogen was a primary factor determining the variation in P(max) and that silica accumulation did not affect photosynthesis. PNUE was strongly and negatively correlated with silica content in third-year leaves, suggesting that silica accumulation affected photosynthesis of older leaves. CONCLUSIONS: Silica accumulation in long-lived leaves of bamboo did not affect photosynthesis when the silica concentration of a leaf was less than 25 % of dry mass. Silica may be actively transported to epidermal cells rather than chlorenchyma cells, avoiding inhibition of CO2 diffusion from the intercellular space to chloroplasts. However, in older leaves with a larger silica content, silica was also deposited in chlorenchyma cells, which may relate to the decrease in PNUE.     

氮、磷、钾营养对冬小麦光合作用及水分利用的影响

在中国科学院封丘农业生态实验站长期肥料实验的基础上,选择氮磷(T1)、氮钾(T2)、磷钾(T3)和氮磷钾(T4)4个肥料处理,以不施肥为对照(CK),研究了长期施用氮、磷、钾肥对小麦抽穗期和灌浆期净光合速率(Pn)、蒸腾速率(Tr)和水分利用效率(WUE)日变化的影响.结果表明:小麦抽穗期和灌浆期T4处理的Pn日变化值显著高于CK,其他处理与CK未达到显著性差异,各处理Pn日积累量大小为T4＞T1＞T2＞T3＞CK;缺氮、缺磷和缺钾均降低了叶片Pn,影响大小依次为缺氮＞缺磷＞缺钾;小麦抽穗期和灌浆期Tr日变化曲线呈单峰型,处理间日变化值差异不显著;缺氮、缺磷和缺钾均降低了叶片WUE,抽穗期,T1、T4处理的WUE日变化值显著高于CK,而T3、T2与CK差异不显著,说明缺氮、缺磷对WUE的影响最大,灌浆期,T4处理的WUE日变化值显著高于CK;不同肥料处理仅改变了小麦光合日变化的幅度,而未改变其变化规律,氮、磷、钾复合施肥有效地提高了小麦的光合生产和水分利用效率.     

Experimental Study and Mathematical Simulation of Water Use Efficiency in Wheat Leaves Affected by Some Environmental Factors

By incorporating Ball-Berry model of stomatal conductance into the models of photosynthesis and transpiration, a model of leaf water use efficiency (WUE) as affected by several environmental variables [irradiance (Ⅰ), vapor pressure deficit (VPD) and atmospheric CO2 concentration (Ca) ] was constructed. Because the environmental variables influenced the photosynthetic rate and transpiration rate in different ways, the changes of leaf WUE with these factors were quite complicated. The rates of photosynthesis and transpiration of wheat leaves were also measured in the phytotron where the environmental variables were kept within certain ranges, and leaf WUE was calculated therefrom. The results of simulation fit quite well with the measurements except at high Ca.     

冬小麦对有限水分高效利用的生理机制

通过对不同土壤供水条件下的孕穗开花期的冬小麦叶片CO₂/H₂O气体交换参数的系统测定,研究了光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、细胞间隙CO₂浓度(Ci)、叶温(Tl)与水分利用效率(WUE)间的关系。结果表明,WUE并不随Pn的增长直线增长,而是呈现出二次曲线的变化趋势;只有当蒸腾达到一定程度时,Tr才对WUE产生影响,而Tr过大时WUE则有下降的趋势;WUE与Ci呈负相关,随Ci的增加WUE呈递减趋势;叶温升高对光合和蒸腾都有促进作用,当超过了某种限度则表现为抑制作用,表明在一定温度范围内,Tl升高对水分利用不利;随Gs的增大,WUE增大到一定程度则不再增加,甚至出现一种回落趋势.     

夏玉米苗期有限水分胁迫拔节期复水的补偿效应

以作物调亏灌溉原理为基础 ,对夏玉米苗期水分胁迫拔节期复水进行了试验研究。结果表明 ,复水增加了夏玉米叶片气孔导度和光合速率 ,提高叶片水平上的水分利用效率(WUE)。复水 2天后 ,叶片气孔导度和光合速率即恢复到对照水平 ,部分时段 ,特别在下午 ,复水处理表现出高于对照的“反冲”现象。复水使苗期受旱的夏玉米株高、叶面积、地上 (下 )部分干物重和根系生长发育都恢复到或接近充分供水的植株生长水平。使其产量及构成因子与对照接近 ,水分利用效率显著地提高了 2 4 7%。这为玉米中后期的水分管理 ,提高玉米水分利用效率 ,提供了一定的理论依据 ;也提供了一种便于广大农民掌握的简单易行的灌溉方式