研究植物生态化学计量特征，有助于了解植物体内 C 、 N 和 P 的分配规律及确定限制植物生长的元素。以广东云浮 3 年生米老排人工林为研究对象，分析了叶 C 、 N 、 P 含量及其化学计量季节特征，探讨了元素间的异速生长关系。结果表明： C 、 N 和 P 含量的年平均值分别为 497.82 g / kg 、 21.95 g / kg 和 0.98 g / kg ； C:N ， C:P ， N:P 的年平均值分别为： 22.98 ， 527.64 ， 23.06 ；叶的 C 含量及 C:N 、 C:P 、 N:P 比的变化趋势为先降低后升高再降低，而 N 、 P 含量的变化趋势相反。叶片的年平均 N:P 高于中国年平均水平 (16.3) 。叶 C 、 N 和 P 具有显著的异速生长关系 (N-C 1.839 , p = 0.000; N-P 0.708 , p = 0.000; C-P 2.865 , p = 0.021) 。研究表明， 3 年生米老排生长主要受 P 元素限制，对本研究区及时补充 P 肥有助于米老排的生长。本研究为米老排的生产实践和经营管理具有现实指导意义。

为更好地发掘和利用现有闽楠种质资源,本研究利用7个SSR位点对江西和福建16个闽楠群体的237份材料进行基因型分析,采用逐步聚类(随机取样策略,位点优先取样策略)和模拟退火算法(等位基因数目最大化策略,遗传距离最大化策略)4种取样方法构建闽楠核心种质,并将各遗传多样性指标进行分析.结果 表明:7个SSR位点共检测到50个等位基因,平均为7.143,平均有效等位基因为2.115,Shannon信息指数为0.778,观测杂合度为0.302,期望杂合度为0.442.基于逐步聚类方法构建的核心种质相较于基于模拟退火算法构建的核心种质各遗传参数指标都相对较高.对其进行t检验后,选择以基于逐步聚类位点优先取样策略在25％的取样比例下选取的种质为核心种质,其等位基因数、平均有效等位基因数、多态性位点百分率、Shannon多样性指数的保留率分别为初始种质的98％、104.92％、90.09％、97.94％.筛选出的59份核心种质材料能够较好地代表闽楠种质资源的遗传多样性,为闽楠的种质资源保存提供科学依据.

为筛选米老排容器苗最佳施肥组合,采用L16 (45)正交试验设计和等量施肥法,研究N、P和K肥3因素对米老排容器苗苗高、地径、生物量以及养分利用的影响.研究结果表明:不同施肥组合处理对米老排容器苗苗高、地径、总生物量等指标均有着显著影响,配方施肥对米老排容器苗的生长发育具有明显促进作用;3种肥料对米老排容器苗苗高生长的影响效应均是N＞P＞K,其施肥最优组合是N1P3K2(每株施N、P和K分别为50、50、60 mg),对地径生长和生物量积累影响效应均为N＞K＞P,施肥最优组合分别是N1P4K2(每株施N、P和K分别为50、60、60 mg)和N1P4K1(每株施N、P和K分别为50、60、45 mg);合理的配方施肥能有效提高米老排苗木的养分利用效率.综合苗木各指标看,米老排容器苗最优施肥配方是:N1P4K1(每株施N、P和K分别为50、60、45 mg).

Background SPL (SQUAMOSA-promoter binding protein-like) proteins form a large family of plant-specific transcription factors that play essential roles in various aspects of plant growth and development. They are potentially important candidates for genetic improvement of agronomic traits. However, there were limited information about the SPL genes in Jatropha curcas , an important biofuel plant. Results In Jatropha, 15 JcSPL genes were identified. Phylogenetic analysis revealed that most of the JcSPLs were closely related to SPLs from woody plant rather than herbaceous plant and distantly related to monocotyledon SPLs. Gene structure, conserved motif and repetitive sequence analysis indicated diverse and specific functions of some JcSPL genes. By combination of target prediction and degradome sequencing analysis, 10 of the 15 JcSPLs were shown to be targets of JcmiR156. Quantitative PCR analysis showed diversified spatial-temporal expression patterns of JcSPLs . It is interesting that the expression levels of JcSPL3 were the highest in all tissues examined in 7- or 10-year-old plants and exhibited increasing trend with plant age, suggesting its important role in the regulation of age development in Jatropha. Overexpression of JcSPL3 in Arabidopsis resulted in earlier flowering time, shorter silique length and reduced biomass of roots. Conclusions Through comprehensive and systematic analysis of phylogenetic relationships, conserved motifs, gene structures, chromosomal locations, repetitive sequence and expression patterns, 15 JcSPL genes were identified in Jatropha and characterized in great detail. These results provide deep insight into the evolutionary origin and biological significance of plant SPLs and lay the foundation for further functional characterization of JcSPLs with the purpose of genetic improvement in Jatropha.

If the additivity of the biomass allometric equation is not taken into account, it can result in erroneous estimation of forest biomass. The aim of this study was to evaluate biomass allocation patterns within separate tree parts, and to develop additive allometric equations for Mytilaria laosensis in southeast China. For this study, 42 destructive sampled trees were used to develop allometric equations for total biomass. We estimated biomass allocation by calculating the biomass fraction of each component (stem, branches, roots and leaves). We examined the relationships between each biomass fraction and diameter at breast height, tree height and crown diameter as independent variables. The seemingly unrelated regressions method was used to fit the biomass into additive allometric equations. The stem had the largest proportion of biomass (70.44%), followed by roots (20.35%), and branches (7.17%), with the smallest proportion of biomass being in the leaves (2.04%). Stem, leaf, and branch Seite 86 G. Qin, R. Li, W. Zou, N. Yu, J. Yang, G. Yin, Z. Wang, Z. Chen biomass ratios increased with diameter at breast height, while a reverse trend was found for belowground biomass ratios. The additive biomass models showed a good model fit explaining 94–98% of variance. This study contributes to species-specific allometric equations and the knowledge of crown, aboveground, and total biomass, which is lacking for most subtropical forests. The allometric biomass model constructed in our study can be used to estimate the biomass and carbon pool of Mytilaria laosensis plantations in Southeast China.

If the additivity of the biomass allometric equation is not taken into account, it can result in erroneous estimation of forest biomass. The aim of this study was to evaluate biomass allocation patterns within separate tree parts, and to develop additive allometric equations for Mytilaria laosensis in southeast China. For this study, 42 destructive sampled trees were used to develop allometric equations for total biomass. We estimated biomass allocation by calculating the biomass fraction of each component (stem, branches, roots and leaves). We examined the relationships between each biomass fraction and diameter at breast height, tree height and crown diameter as independent variables. The seemingly unrelated regressions method was used to fit the biomass into additive allometric equations. The stem had the largest proportion of biomass (70.44%), followed by roots (20.35%), and branches (7.17%), with the smallest proportion of biomass being in the leaves (2.04%). Stem, leaf, and branch biomass ratios increased with diameter at breast height, while a reverse trend was found for belowground biomass ratios. The additive biomass models showed a good model fit explaining 94-98% of variance. This study contributes to species-specific allometric equations and the knowledge of crown, aboveground, and total biomass, which is lacking for most subtropical forests. The allometric biomass model constructed in our study can be used to estimate the biomass and carbon pool of Mytilaria laosensis plantations in Southeast China.

文中从枝下高、枝条数量、分枝特征和枝条空间分布对林分密度的响应规律等方面评述国内外的枝条发育研究进展,并对今后的枝条发育研究进行了展望.

Branch development is related to the formation of wood knots and affects timber quality and future market value of plantations and native forests alike. This study provides a theoretical basis and reference for knot-free timber production in a Mytilaria laosensis plantation. The branch diameter, length, angle, status (alive or dead), azimuth, and branch height under 12 m were measured for 60 dominant or co-dominant trees in response to five planting density treatments (625, 833, 1111, 1667, and 2500 stems ha(-1)). With increasing planting density from 625 to 2500 stems ha(-1), the mean branch diameter and branch length decreased by 7.09% and 8.70% respectively. Dead and live branch angle decreased by 10.54% and 9.66% respectively, while number of living branches increased by 31.67% from 625 to 2500 stems ha(-1). Analyzing the spatial distribution using branch azimuth, we discovered that branches pointing north were more abundant and had larger diameter, larger branch length, and higher branch angle than branches pointing south. Branch diameter, length, and number were positively related to the relative branch height. Our results underline that increasing the planting density from 625 to 2500 stems ha(-1) considerably affect branch growth. Thus, optimizing planting density when establishing Mytilaria laosensis plantations according to the forest management targets and future pruning can improve the timber quality and future value.

Key message Geography and tree diameter were the major factors in determining oleoresin yield in Sindora glabra. The tangential diameter and area of secretory canals are reliable indicators of the oleoresin amount. Abstract Sindora glabra is a native tropical plant of China that exudes copious amounts of oleoresin from wounds on the stem. Elucidation of the mechanism affecting the oleoresin yield is of particular importance for development and selection of superior germplasm. In this study, the variation in oleoresin yield and anatomical traits of the stem of S. glabra were investigated in four main natural populations in Hainan. The results showed that annual oleoresin yield varied considerably among populations. The oleoresin yield exhibited an increasing trend with the increment of tree stem diameter until the diameter was over 80 cm. Moreover, oleoresin production in the wet season was higher than in dry season. The analysis of oleoresin chemical composition indicated that the four populations belong to the same chemotype despite the amount of four types of sesquiterpenes varying greatly among areas. Anatomical analysis revealed that quantitative traits of secretory canals including tangential diameter, area, density and frequency were significantly different among populations and tree diameters. Furthermore, the tangential diameter and area of secretory canals were positively correlated with oleoresin yield. These results suggested that the tangential diameter and area of secretory canals are reliable indicators of the oleoresin amount and can be used for selection purposes in S. glabra.

利用百度试验法研究树龄及树高对米老排木材干燥特性的影响,确定米老排木材干燥工艺.结果 表明:随着树龄的增长,木材的短表裂数量增多,长表裂长度增大,截面变形程度逐渐减缓,扭曲度不断变大;在同一树龄中,上端木材的扭曲程度较下端木材更严重,下端木材的翘曲度较上段木材更严重;米老排木材的干燥初期开裂综合等级为5级,内部开裂为2级,截面变形为3级,扭曲为5级,翘曲变形为2级,干燥速度为2级;采用本研究干燥工艺,30 mm厚米老排木材从初含水率76.78％降至6.02％,干燥周期为16.12 d.干燥缺陷综合质量等级为2级,可满足实木制品质量要求.

为指导苗期养分科学管理,本研究以温室盆栽的米老排(Mytilaria laosensis)幼苗为材料,采用等量施肥(C)、阶段递增施肥(A)和修正指数施肥(ME)3种方法,每种方法设置50、100、200、400、600 mg/株5个氮素水平,并以不施肥为对照,共设置16个处理,分析不同供氮方式对米老排苗木生长的影响.结果表明:米老排叶片净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)均随供氮水平的增加呈现出先增后减的趋势,改善其光合气体交换作用效果最佳的处理是200C>100ME>100A;而胞间CO2浓度(Ci)则随施氮量的增加而总体上表现下降趋势;所有施肥处理中,米老排幼苗叶片叶绿素a含量、叶绿素总量、类胡萝卜素含量和叶绿素a/叶绿素b值均有不同程度的增加;施肥处理显著降低苗期米老排叶片的丙二醛含量和超氧化物歧化酶活性,此外低剂量施肥能够降低叶片中游离脯氨酸含量.等量施肥200 mg/株的供氮方式总体上最有利于改善光合气体交换作用、提高光合作用和降低丙二醛含量.

报道了同年同批种源的闽楠(Phoebe bournei)幼林在由湖南省的郴州、广东的乐昌和肇庆组成的区域栽培试验结果,发现郴州、乐昌、肇庆3地闽楠幼林的树高、胸径2个生长指标间存在差异,且与依据林木生长量的一般栽培区的生长量值一致.由此可见,2种栽培区划均有科学性,做闽楠产业发展规划时应参考2个区划进行规划.

[目的]探究不同造林密度对米老排枝条发育的影响规律,为米老排修枝培育无节良材提供理论依据.[方法]本研究以8年生米老排密度试验林为研究对象,通过调查一级枝条的数量、基径、长度、分枝角、分枝高和方位角等观测数据,分析5种造林密度对米老排林分9 m以下枝条发育以及空间分布的影响.[结果]表明:米老排枯枝层的高度随密度的增大而增高,枝条总量和枯枝数量受密度影响不显著,林分枯枝率随密度的增大而增大,活枝量与密度呈负相关;米老排树干9 m以下枝条基径、枝长和分枝角均随密度的增大而减小;水平方向上,同一密度,不同方位的枝条基径、枝长、分枝角和数量均随方位角的增大先减小后增大,在光照条件较好的方位区间(0～90°或316～360°)内达到最大值;垂直方向上,枝条基径、长度、数量随相对位置的升高先逐渐增大,之后无显著变化.[结论]造林密度对米老排枝条大小的影响显著,高密度(2 500株hm-2)可以抑制枝条的生长;建议根据培育目的选择合适的造林密度,并采用目标材种培育技术,在幼龄期对优势木及亚优势木进行人工修枝,提高木材质量.

The production of knot-free and high-quality wood can be a vital issue in silviculture and forest management. In this study, knot properties, branch occlusion, and wood discoloration were investigated in an 11-year-old Mytilaria laosensis plantation in Guangxi, China, to examine the effectiveness of natural pruning in reducing knot-related defects. A total of 1513 occluded branches from 20 trees were sampled and dissected. Occluded branches were most common at heights of 2–6 m, and the mean diameter of the occluded branches gradually increased with height from the base to 6 m. Linear and generalized linear mixed-effect models were developed to reveal the relationship between branch occlusion and discoloration. The mortality of branches was highest in the third and fourth year and it took roughly three to six years to occlude. The mixed-models indicated that the branch occlusion time was positively correlated with the occluded branch diameter and dead branch stub length, and negatively correlated with the stem radial increment during branch occlusion. Branch discoloration was positively correlated with the occluded branch diameter and branch occlusion time, and was negatively correlated with the branch angle. The probability of wood discoloration also increased with the branch occlusion time. Our findings contribute to a better understanding of the spatiotemporal allocation and internal characteristics of occluded branches, and provide a reference for growing high-quality M. laosensis wood.

以广西凭祥立地条件一致树龄为7、14、21、28 a的米老排为研究对象,采用加权积分对其解析木单项加工性能进行评价,比较不同树龄、树高对木材综合加工性能的影响.结果表明:随着树龄的增长,米老排木材的机械加工性能有所改善,刨切、铣削、开榫性能1级比例逐渐改善,砂光性能1级比例呈现先上升后回落的趋势,钻孔性能基本无差异基本无差异;同一株木材,上端的刨切性能优于下端,砂光性能、铣削性能差于下端;根据机械加工性能综合评分,米老排木材生长至21～28a时各项机械加工性能最优.

In order to understand the growth adaptability of Phoebe bournei provenance from Fujian and select suitable germplasm for popularization and cultivation in the north of Guangdong, the tree height, DBH, single plant volume, crown width and crown rate of 125 families from 18 different Phoebe bournei provenances of8-year-old Phoebe bournei families test forest in Lechang City, Guangdong Province were evaluated and selected by methods of variance analysis, correlation analysis, principal component analysis and cluster analysis. The results showed that there were significant differences both among provenances and among families. The 5 traits of Phoebe bournei were highly significantly difference (p＜0.01). The tree height, DBH, single volume and canopyhad significant positive correlation with each other (p＜0.01). The height of the tree was positively correlated with the crownrate (p＜0.05), and negatively correlated with the latitude of provenance (p＜0.05). The results of principal component analysis indicated that the comprehensive ranking top 5 provenances were Fujian Qingliu (FJQL), Fujian Pingnan (FJPN), Fujian Yongan (FJYA), Fujian Youxi (FJYX) and Fujian Zhangping (FJZP), respectively.The cluster analysis of 5 traits of Phoebe bournei divided the 18 provenances into 3 categories: the best performance was FJQL only, the second type were FJYA, FJPN, FJZH, FJSW, FJZP and FJYX. The third category included the remaining 11 provenances with poor comprehensive characters. The top 20 pedigrees were selected as excellent families by taking the volume of single plant as the selection criterion. Based on the principal component analysis, cluster analysis and selection of excellent pedigree, 3 provenances, namely FJYA, FJZH and FJQL, were selected as germplasms for Phoebe bournei cultivation in northern Guangdong.

[目的]探讨不同造林密度对米老排人工林生长的影响规律,为米老排人工林定向培育过程中的密度控制提供参考。[方法]以广东省云浮市造林后6年生米老排人工林为研究对象,对不同造林密度(625、833、1 111、1 667、2 500株·hm -2 )林分平均树高、优势木高、胸径、保留率和枝下高等生长指标进行连续4年调查。[结果]表明:随着造林密度的增大,米老排林分平均胸径、胸径连年生长量、保留率、单株材积和材积连年生长量均显著减小,而枝下高、林分蓄积量和蓄积连年生长量显著增加。在一定密度范围内,造林密度对林分高生长的影响比较小。造林后第6年,密度1 667株·hm -2 林分的平均树高最大（11.4 m）,优势木高以密度1 111株·hm -2 林分的最大（13.3m）,树高连年生长量以密度625株·hm -2 林分的最大(1.5 m·a -1 );密度625株·hm -2 林分的平均胸径、胸径连年生长量、单株材积和材积连年生长量均最大,分别为14.3 cm、2.5 cm·a -1 、0.097 3 m~3和0.038 2 m~3·a -1 ,比密度2 500株·hm -2 林分的分别增加27.7%、81.0%、49.0%和82.4%;密度2 500株·hm -2 林分的枝下高、蓄积量和蓄积连年生长量均最大,分别为6.0 m、149.4 m~3·hm -2 和44.8 m~3·hm -2 ·a -1 ,分别是密度625株·hm -2 林分的2.61、2.52、1.95倍。[结论]分析了造林密度对米老排初期生长的影响,对米老排人工林的培育具有理论指导意义。

Terpenes serve important physiological and ecological functions in plants. Sindora glabra trees accumulate copious amounts of sesquiterpene-rich oleoresin in the stem. A transcriptome approach was used to determine the unique terpene biosynthesis pathway and to explore the different regulatory mechanisms responsible for the variation of terpene content among individuals. Analysis of de novo-assembled contigs revealed a complete set of genes for terpene biosynthesis. A total of 23,261 differentially expressed unigenes (DEGs) were discovered between high and low oil-yielding plants. DEG enrichment analysis suggested that the terpene biosynthesis process and the plant hormone signal transduction pathway may exert a major role in determining terpene variation in S. glabra. The expression patterns of candidate genes were further verified by quantitative RT-PCR experiments. Key genes involved in the terpene biosynthesis pathway were predominantly expressed in phloem and root tissues. Phylogenetic analysis and subcellular localization implied that S. glabra terpene synthases may evolve from a common ancestor. Furthermore, two sesquiterpene synthase genes, SgSTPS1 and SgSTPS2, were functionally characterized. SgSTPS1 mainly generated β-caryophyllene from farnesyl pyrophosphate. SgSTPS2 is a versatile enzyme that catalyzes the formation of 12 sequiterpenes from farnesyl pyrophosphate and synthesis of three monoterpenes using geranyl pyrophosphate. Together, these results provide large reservoir for elucidating the molecular mechanism of terpene biosynthesis and for exploring the ecological function of sesquiterpenes in S. glabra.

A novel esterase gene TLip was identified from the strain Thauera sp. and expressed at high levels in Escherichia coli. The TLip protein shared the highest identity (48%) to esterase TesA from Pseudomonas aeruginosa when compared to enzymes with reported properties. Phylogenetic analysis showed that TLip belongs to the GDSL family of bacterial lipolytic enzymes. TLip was an alkaline esterase with a broad optimal temperature range 37-50 °C and an optimal pH of 8.0. Substrate specificity assays showed that TLip preferred medium chain p-nitrophenyl esters (C6 -C12 ). Besides, the activity of TLip was strongly inhibited by Cu2+ but greatly enhanced by Triton X-100 and Tween 80. Thermostability assay revealed that TLip was stable without loss of activity at 37 °C and still retained 69% activity at 50 °C after 2 H of incubation. Together, these provided a good candidate for further exploration of TLip as a promising biocatalyst in industry.

为筛选米老排容器苗生长的最佳基质配方,研究了黄心土和轻基质不同配比对容器苗生长和叶绿素荧光特性的影响.结果表明,米老排苗高、地径和总生物量随轻基质比例的增加呈先增加后降低的趋势,且以T5处理(黄心土:轻基质=5:5)达最大值,分别是对照的3.60、1.97和13.5倍.除主根长外,各处理的根系指标均大于对照.随轻基质比例的增加,米老排幼苗总根长、总根表面积、总根体积等均表现为先增加后减少的趋势,以T5处理达到峰值;而根系平均直径则随轻基质的增加呈增大的趋势.T5处理的初始荧光Fo最小、最大荧光Fm和PSII最大光化学效率(Fv/Fm)最大,其光化学能力最强.因此,米老排容器苗在黄心土:轻基质=5:5中生长最优,建议推广轻基质比例为50％～60％的混合基质作为米老排容器育苗基质.