光氮互作对闽楠幼苗叶片光合生理特性的影响

以5月龄闽楠幼苗为材料,采用4种光照水平(100%、41.3%、14.3%、3.6%自然光)和4种氮素水平(0、0.5、1、2 mol/L纯氮)的双因素盆栽试验,研究光氮互作下闽楠幼苗的光合生理特性,以探讨其对环境适应性的生理机制。结果表明:(1)遮荫和施氮均能显著提高闽楠叶片光合色素含量;在同一氮素水平下,随光照强度下降,闽楠幼苗叶片可溶性糖(SS)、可溶性蛋白(SP)、净光合速率(P_n)、气孔导度(G_s)、最大净光合速率(P_(max))、暗呼吸速率(R_d)、表观量子系数(AQY)均呈先增后降趋势,并在41.3%自然光照水平时最高;而同期叶片胞间CO_2浓度(C_i)、蒸腾速率(T_r)、光饱和点(LSP)、光补偿点(LCP)均呈下降趋势;闽楠幼苗的叶片PSⅡ最大光化学效率(F_v/F_m)和PSⅡ潜在活性(F_v/F_o)则随光照减弱逐渐增加。(2)同一光照水平下,随着氮素施用量增加,闽楠幼苗叶片SS、SP、光合气体交换参数、光响应曲线特征参数总体呈现先升高后降低的趋势,F_v/F_m和F_v/F_o呈先降后增趋势。(3)不同光照和氮素水平之间存在显著的互作效应,隶属函数分析结果以41.3%自然光照、0.5 mol/L纯N处理的效果最优。研究表明,闽楠幼苗为喜光耐荫植物;适宜遮荫和施氮处理组合可显著改善闽楠渗透调节能力,提高光能利用率,促进光合作用进行,而全光照、过度遮荫、缺氮、或过量施氮均不利于闽楠正常生理代谢。     

基于高通量测序的闽楠幼林根际土壤丛枝菌根真菌群落变化

【背景】闽楠是珍贵用材树种。阐明闽楠根际土壤微生物特征,对科学经营闽楠人工林有指导作用。【目的】明确闽楠人工林恢复过程中根际土壤丛枝菌根群落随林龄的变化特征。【方法】采用高通量Illumina MiSeq测序的方法,评估不同林龄闽楠幼林根际土壤丛枝菌根真菌(Arbuscular Mycorrhiza Fungi,AMF)群落的多样性和组成,揭示造林后闽楠根际土壤真菌群落对时间序列中土壤养分变化的响应特征。【结果】从3个林龄闽楠根际土壤中共得到342 555条有效序列,共得到253个AMF-OTU,分属于1门1纲5目9科14属。α多样性指数表明,丛枝菌根真菌群落的Chao1、Shannon指数随着林龄的增加而增加,但不同林龄间差异不显著。β多样性指数表明,在闽楠幼龄阶段,不同林龄间AMF群落组成差异明显。根据Bray-Curtis相异度分析阐明AMF群落组成的相似性与林龄相关。种水平物种丰度与土壤因子的相关性分析表明,影响AMF群落丰度的主要土壤因子是pH、全钾、硝态氮和铵态氮。铵态氮与优势AMF分子虚拟种Glomus-Franke-A1-VTX00076、Glomus-Franke-A1-VTX00269的丰度呈显著正相关。【结论】随着林龄的增加,闽楠幼龄根际土壤丛枝菌根真菌的种类组成发生了显著变化,影响AMF特性的主要土壤因子是pH、全钾、硝态氮和铵态氮。这些发现将有助于揭示闽楠幼林生态系统和土壤微生物多样性的相互关系和机制,为生物多样性-生态系统功能实验提供理论依据。     

Exogenous Glycine Betaine Reduces Drought Damage by Mediating Osmotic Adjustment and Enhancing Antioxidant Defense in <i>Phoebe hunanensis</i>

Drought stress negatively impacts growth and physiological processes in plants. The foliar application of glycine betaine (GB) is an effective and low-cost approach to improve the drought tolerance of trees. This study examined the effect of exogenously applied GB on the cell membrane permeability, osmotic adjustment, and antioxidant enzyme activities of Phoebe hunanensis Hand.-Mazz under drought stress. Two levels (0 and 800 mL) of water irrigation were tested under different applied GB concentrations (0, 50, 100, and 200 mM). Drought stress decreased the relative water content by 58.5% while increased the electric conductivity, malondialdehyde, proline, soluble proteins, soluble sugars, and antioxidant enzyme activities (superoxide dismutase, catalase, peroxidase) by up to 62.9%, 42.4%, 87.0%, 19.1%, 60.5%, 68.3%, 71.7%, and 83.8%, respectively, on the 25^th day. The foliar application of GB, especially at 100 mM, increased the relative water content of P. hunanensis leaves under drought stress. The concentration of GB from 50 to 100 mM effectively alleviated the improvement of cell membrane permeability and inhibited the accumulation of membrane lipid peroxidation products. Under drought stress, the concentrations of proline, soluble proteins, and soluble sugars in the leaves of P. hunanensis increased as the applied GB concentration was increased and the water stress time was prolonged. Exogenously applied GB decreased oxidative stress and improved antioxidant enzyme activities as compared with treatments without GB application. Furthermore, the physiological and biochemical indexes of P. hunanensis showed a certain dose effect on exogenous GB concentration. These results suggest that GB helps maintain the drought tolerance of P. hunanensis.     

广州闽楠-樟人工混交林物种组成与多样性研究

为了解人工混交林群落结构特征和物种多样性关系,对广州龙眼洞林场内闽楠(Phoebe bournei)-樟(Cinnamomum camphora)人工混交林进行群落结构分析.结果表明,0.37 hm2样地内共有128种植物9563株,隶属于57科99属;其中乔木35种,灌木61种,草本98种.在乔木层中,重要值排名前5...     

浙江楠容器育苗基质的比较和筛选

用泥炭、珍珠岩、蛭石、稻壳和阔叶树木片按不同体积比配成18种基质,以园土为对照,研究了不同基质对1年生浙江楠（Phoebe chekiangensis C．B．Shang）实生苗生长及生理特性的影响并筛选出适宜的浙江楠容器育苗基质。结果表明,以体积比5：3：2的泥炭、蛭石和阔叶树木片为基质培育的浙江楠幼苗的株高、地径、径根比、地上部干质量和鲜质量、根系干质量和鲜质量、根系活力以及叶片可溶性糖和可溶性蛋白质含量等指标均显著高于对照。该基质的持水性和保水性较好,持水量达608．64g·L^-1,可作为浙江楠容器育苗的适宜基质进行推广应用。     

福建罗卜岩闽楠(Phoebe bournei)林中优势树种生态位研究

在福建省三明市罗卜岩自然保护区内选择由落叶阔叶树种为主的常绿落叶阔叶混交林向中亚热带典型常绿阔叶林演替过程中的4个不同演替阶段的代表性群落,以群落组成类型作为一维资源位,以树种的重要值作为资源位上的表现特征,定量分析了闽楠林中优势树种生态位宽度和生态位重叠情况。结果表明,大部分的常绿阔叶树种具有较大的生态位宽度值,而落叶阔叶树种则呈现较小的生态位宽度值;两类树种的;生态位虽有一定程度的重叠,但总体仍然较低。这些结果与两类树种对光等生态因子要求不同直接相关。生态位宽度值较大的常绿阔叶树种之间可产生较高的生态位重叠值。生态位宽度值较大的树种与生态位宽度较小的树种也可产生较大的生态位重叠值,但较小生态位宽度值的树种与较大生态位宽度值的树种往往只有小的生态位重叠值,而较小生态位宽度值的树种之间则可有国产高的生态位重叠值。上述的生态位研究结果有助于理解由落叶阔叶树种为主的常绿落叶阔叶林向中亚热带典型常绿阔叶林演替过程中优势各群的生态适应性变化规律。     

Effects of drought stress on the osmotic adjustment and active oxygen metabolism of Phoebe zhennan seedlings and its alleviation by nitrogen application北大核心CSCD

Aims Two-year-old seedlings of Phoebe zhennan were used in this study to explore the responses of osmotic adjustment and active oxygen metabolism to drought stress and the mitigation effect of nitrogen application. Methods The soil water content was firstly adjusted to four treatment levels, i.e. 80% of field water holding capacity (80% FC), 50% FC, 30% FC and 15% FC, respectively. The physiological variables of plants were measured after one week, and then three nitrogen application rates, control (N0), medium nitrogen (MN) and high nitrogen (HN) were performed at an interval of 7 days for four times (7 d, 14 d, 21 d and 28 d, respectively). The same physiological variables were determined again one month after the accomplishment of nitrogen application. Important findings 1) The free proline (Pro) and soluble sugar (SS) contents in the leaves increased significantly with the aggravation of drought stress after 7 days of drought, but the content of soluble protein (SP) was firstly increased and then declined. The increase of Pro content was especially obvious under severe drought (15% FC). After nitrogen application, the content of Pro raise further, but the values varied in drought treatment. The SS contents under sufficient water supply (80% FC) and mild drought (50% FC) were decreased by MN, but it did not change significantly when supplied with HN despite the soil water content. After nitrogen application, the SP contents under 80% FC and 50% FC were lower than those of no exogenous N, while they were opposite response under 30% FC and 15% FC. 2) Before nitrogen application, with the aggravation of drought stress, the hydrogen peroxide (H2O2) content, superoxide dismutase (SOD) activity, catalase (CAT) activity increased significantly, and the peroxidase (POD) activity showed an up-down trend. After nitrogen application, the content of H2O2 was generally deceased at each water condition, with the maximum decrease at MN, while the HN treatment was not conducive to reduce the content of H2O2. The activities of three kinds of enzymes responded differently to the severity of drought and the level of nitrogen application. 3) Before nitrogen application, the content of malondial-dehyde (MDA) in leaves increased significantly when the soil water content declined to and below 50% FC. The relative electrical conductivity (REC) was decreased at first, and followed by significant increase. Except severe drought (15% FC) stress, the MDA content showed a decreasing trend at MN, but a rebound at HN. As regards severe drought stress, however, the content of MDA increased at both MN and HN, indicating that nitrogen application is not a good choice to alleviate the damage caused by severe drought stress. 4)Two-factor ANOVA revealed an obvious interaction between nitrogen application and drought stress. In conclusion, a proper amount of nitrogen (1.35 g·a–1 for each sapling) could somewhat alleviate drought stress no severer than 15% FC on seedlings of Phoebe zhennan, but excessive nitrogen at rate of or more than 2.70 g·a–1 per sapling is not recommended. © 2018 Editorial Office of Chinese Journal of Plant Ecology. All rights reserved.     

不同施肥水平对桢楠多胚苗生长及光合生理的影响

采用营养袋培育的方法,以苗龄45d(根茎初步木质化)的桢楠幼苗为试验材料,选取单胚苗(D)、双胚大苗(SD)和双胚小苗(SX)3种类型桢楠幼苗栽植于袋中,根据年施复合肥量标准设置对照(CK,每袋0g)、中(M,每袋0.2g)和高(H,每袋0.3g)3个施肥水平,于7月初开始施肥,每20d施1次共分4次(每次25%)施入,分别于8月、10月中旬测定幼苗生长指标和光合生理指标,探讨施肥对桢楠多胚苗生长和光合生理的影响。结果显示:(1)中量施肥(M)对3类幼苗的苗高和地径生长量有明显的促进作用,而高量施肥(H)在整个试验过程中对幼苗生长的影响表现为先促进后抑制的趋势。(2)中量施肥(M)可以促进3类幼苗叶片的叶绿素合成,延长叶片功能周期,增大净光合速率和气孔导度,进而提高幼苗在强光照、高CO_2环境下的光合作用能力。(3)中量施肥可以使幼苗的光补偿点(LCP)、CO_2补偿点(CCP)下降,光饱和点(LSP)、CO_2饱和点(CSP)上升,增强幼苗适应环境的能力,积累更多的有机物;高量施肥对幼苗的光合指标也表现为先促进后抑制的作用。研究表明,适量(每袋0.2g)施肥能促进各类桢楠幼苗光合色素合成、光合作用效率以及对环境的适应能力,从而促进幼苗的生长;适量施肥也使双胚大苗较快缩小与单胚苗生长指标间的差距,同时也对双胚小苗生长表现出一定的促进作用,这对于促进珍贵树种桢楠的种质资源保护、提高苗木出圃率和降低育苗成本有重要意义。     

干旱胁迫对桢楠幼树渗透调节与活性氧代谢的影响及施氮的缓解效应

以二年生桢楠(Phoebe zhennan)幼树为研究对象, 采用盆栽控水的方法, 探讨了桢楠幼树在干旱胁迫下渗透调节和活性氧代谢的变化, 以及施氮对桢楠幼树应对干旱胁迫能力的影响。试验先将土壤含水量调整到4个梯度(田间持水量的80% (80% FC)、50% FC、30% FC和15% FC), 1周后测定受胁迫植株的相关生理指标, 之后进行3个水平的施氮处理(对照N0, 中氮MN, 高氮HN, 各施氮量分4次(即干旱梯度形成后第7、14、21和28天)分别施入)。在施氮结束后30天(即开始施肥处理后51天)再次测定各项生理指标。结果表明: 1)干旱处理7天后, 桢楠叶片中游离脯氨酸(Pro)和可溶性糖(SS)含量均随胁迫强度增大而显著增加, 重度干旱(15% FC)下的Pro含量增加尤为明显, 可溶性蛋白(SP)含量则呈先增加后降低的趋势。施氮后, 各种土壤水分状态下的Pro含量进一步增加。水分充足和轻度干旱MN水平下, SS含量也增加, 而在中度和重度干旱下的SS含量显著降低, HN水平各干旱状态下SS含量变化均不显著。施氮结束后30天时, 80% FC和50% FC下的SP含量表现为施氮组低于对照组, 而30% FC和15% FC下则相反。2)施氮前随着干旱胁迫的增强, 桢楠幼树叶片中过氧化氢(H₂O₂)含量、超氧化物歧化酶(SOD)活性、过氧化氢酶(CAT)活性显著上升, 而过氧化物酶(POD)活性呈先上升后下降的趋势。施氮后, H₂O₂含量总体上表现为减少趋势, 且MN水平下降幅度最大, HN水平反而不利于降低H₂O₂的含量。3种酶活性的变化则因干旱程度和施氮水平的不同而呈现出不同的变化趋势。3)施氮前随着干旱胁迫的增强, 叶片丙二醛(MDA)含量呈显著上升趋势, 相对电导率(REC)先显著下降后显著上升; 施氮后, 除重度干旱胁迫外, 其他各干旱处理植株的MDA含量都表现为在MN水平下有所下降, 而在HN水平下有所回升, 但在重度干旱时, 无论是MN或HN处理, MDA含量均呈上升趋势, 表明在重度干旱胁迫下, 难以通过施氮的方式缓解干旱胁迫产生的伤害。4)双因素方差分析显示, 施氮与干旱胁迫间具有极显著的交互效应。以上结果表明: 施一定量的氮肥有利于缓解桢楠幼树受到的干旱胁迫, 以年施氮量计, 施中氮(N元素质量为1.35 g·株 ^-1)对除重度干旱外的干旱胁迫具有一定的缓解作用, 但施高氮(N元素质量为2.70 g·株 ^-1)时反而会对植株造成不利影响。