Research on Genetic Physiological Ecology of Precious Species:Toona ciliata and Toona ciliata var.pubescens

Bojin ZHAO, Aiguo ZHEN, Runxuan HE, Dehua CHENG, Yang WANG

1. Jianshi Forestry Administration, Jianshi 445300, China;

2. Yingshan Forestry Administration, Yingshan 438700, China;

3. Xiangtan First Middle School, Xiangtan 411100, China;

4. Hubei Vocational College of Ecological Engineering, Wuhan 430200, China

Toona ciliata belongs to genus Toona (Meliaceae family).Toona ciliata is a deciduous or semi-evergreen megaphanerophyte and is a heliophyte with straight trunk,tender and straight tree performance.Toona ciliata var. pubescens belongs to genus Toona (Meliaceae family)as well. Toona ciliata var. pubescens is a deciduous megaphanerophyte with straight trunk and obvious natural training.Toona ciliata and Toona ciliata var. pubescens are precious and fast-growing timber species in tropic and subtropics of China. Toona ciliata and Toona ciliata var. pubescens are key protected wild plants of national levelⅡ,which are called “Chinese mahogany”[1-2], and the timbers of which are superior for furniture. Toona ciliata distributes naturally in India, Burma,Laos, Pakistan, Thailand, Malaysia,Indonesia, Australia, etc. Toona ciliata distribute in low mountains and hills in South China and the geographic coordinate range is 100°16′-119°40′ east longitude and 24°21′-30°31′ north latitude[3]. Toona ciliata is found to be distributed in Nanjiang, Bazhong,Sichuan, which locate at 106°93′ longitude and 32°42′ latitude with the elevation of 620 m[4]. This area is the natural distribution area of Toona ciliata with the highest latitude.In 2013,A well-preserved natural population of Toona ciliata with more than one thousand trees was found in Gucheng County, Hubei Province located at 111° 24′ east longitude and 32° 10′north latitude. Toona ciliata var.pubescens is an endemic tree of China and distributes in Sichuan,Guizhou,Fujian and Anhui with a vertical distribution of 500-2 500 m[5].

The distribution of Toona ciliata and Toona ciliata var. pubescens are not wide in China and they distribute sporadically with small population size but with great development potential[6].The number of Toona ciliata and Toona ciliata var.pubescens decreases gradually because of overexploitation and slow natural regeneration[3].

Germplasm resource, geneticstructure, plant physiology, ecology,breeding, cultivation, afforestation,pharmaceutical, chemical constituent and resource protection of Toona ciliata and Toona ciliata var. pubescens were widely studied by more and more domestic scholars in recent years because they were endangered species with excellent varietal characteristics.The research progresses of Toona ciliata var. pubescens and Toona ciliata were combined in the paper for the supplementation research of Toona ciliata because the biological characteristics of Toona ciliata were the same with as Toona ciliata var. pubescens[5]and the research on Toona ciliata was relative insufficient.

Research on the Genetics Direction of Toona ciliata

The methods for the detection of plant genetic diversity are improved and perfected ceaselessly with the development of biology, especially genetics and molecular biology. The methods have developed from the initial phenotypic variation, subsequent chromosomal polymorphism and protein polymorphism to present DNA polymorphism.

Genetic expressed characters

Using morphology or phenotypic character to detect genetic variation are the most direct, simple and accurate methods. Liu et al. studied the variation patterns of geographic source of seedling period and tanezane growing characters according to the analysis of 11 phenotypic characters such as fruit quality, fruit length and two growth characters including seedling height and ground diameter in 13 provenances in the natural distribution areas of Toona ciliata var. pubescens. Growth characters at seedling period of Toona ciliata var.pubescens were mainly controlled by the level of above or medium on the provenance level; broad-sense heritability and variable coefficient of the height of one-year-old seedlings were the biggest; broad-sense heritability and variable coefficient of ground diameter were the second while the broad-sense heritability and variable coefficient of tanezane were not obvious. Proposing that Toona ciliata var.pubescens could be preliminarily selected in different provenances with the seedling height and ground diameter, and ideal results could be obtained[7].

Zhang et al.used six half-sib families of Toona ciliata in Enshi,Hubei as study materials; significant differences existed in seedling height, ground diameter, leaf length, leaf width, ratio of length to breadth of one-year-old seedlings and elite families were selected. Introduction adaptability in the area with similar latitude and different longitude was tested based on different characters and overall performance[8]. Song et al. used 46 half-sib families of Toona ciliata in Jiangxi,Yunnan, Chongqing, Sichuan etc. as study objects for seedling stage experiment. Six characters including seedling height, ground diameter,crown breadth, main root length, main root width, number of tertiary root of one-year-old seedlings were measured to provide experimental foundation for genetic selection.The research indicated that highly significant differences existed in seedling height,ground diameter and crown breadth among Toona ciliata families and the three characters were controlled by intension inheritance. Biggish genetic improvement effect could be obtained by combined selection of seedling height and ground diameter[9].To some extent, root parameters are important indicators for the evaluation of seedling stage growth and genetic breeding of half-sib families of Toona ciliata.

Selection of superior tree is one of the most effective and reliable methods for elite breeding of forest. Plus selection on progenies of elite trees is the guarantee for sustainable heredity of excellent provenances. The space and potential for genetic improvement and elite breeding are big because of the abundant variations among half-sib families in germplasm families.Wen et al. studied the growth expression of seedling height and ground diameter at seedling stage of progeny seedlings of 20 one-year-old elite Toona ciliata.The results showed that highly significant differences existed in the growth of seedling height and ground diameter among the 20 families of Toona ciliata. Fast-growing families of Toona ciliata with good quality can be screened by selective breeding etc.Twenty percent fast-growing elite families of Toona ciliata during seedling stage were selected based on the analysis results of the growth of seedling height and ground diameter at seedling stage of one-year-old seedlings of Toona ciliata[10]. Liu used progenies of elite Toona ciliata var.pubescens as objects for introduction research and seedling height, ground diameter, dry weight of root, stem mass, ratio of root and stem, total length of root, root surface area, root volume were analyzed at seedling stage.Highly significant differences existed in seedling height, ground diameter,dry weight of root,stem mass and ratio of root and stem, which indicated that there were big differences among various trait heritability of Toona ciliata var. pubescens. The heritability of seedling height was the highest, and the heritabilities of ground diameter,dry weight of root,stem mass and ratio of root and stem were medium while the heritabilities of total length of root,root surface area, root volume were relative low[11].

Modern digital technology has the advantages of high efficiency and convenience for the plus selection of Toona ciliata at seedling stage. Ferreira et al. used best linear unbiased prediction(BLUP)at the individual level with multiplicating and combined traditional prediction technology with digital image software (Image-j) to estimate genetic parameter and genetic value of Toona ciliata by the processing of complex and unstable data,which had practicability,speediness and high efficiency for genetic breeding[12].

Molecular marker technique

Morphological marker, a simple method, can be easily affected by environmental conditions and dominance or recessive of genes, and the genetic expression of which is not stable sometimes. DNA molecular marker technique can fast and accurately analyze plant genetic diversity for more genetic information, which overcomes the long period and unstabilizing factors of traditional analysis method.

In the area of molecular marker technique, traditional magnetic beadsenrichment (a method for the isolation of microsatellite DNA in genome) had been improved and microsatellite DNA had been isolated from the genome of Toona ciliata var. pubescens, and the microsatellite DNA had been sequenced; SSR primers were designed and synthesized, and SSR reaction system was optimized to provide technical support for further research of genetic structure and genetic variation of Toona ciliata var. pubescens populations[13]. SSR molecular marker had been applied to the analysis of genetic diversity of Toona ciliata var.pubescens populations. The genetic differentiation coefficient of Toona ciliata var. pubescens populations was 0.185 4 and the gene flow(Nm)among populations was 1.098 3,which illustrated that the genetic variations among Toona ciliata var. pubescens populations were low; the genetic distances among populations were significantly correlated with geographical distances[14]. The research of genetic structures of three natural populations of Toona ciliata var. pubescens with microsatellite marker indicated that the genetic diversities among the natural populations of Toona ciliata var.pubescens were low; the gene flow was higher than the average level of contrastive perennial plant while the genetic differentiation coefficient was lower than the average level; one of the three natural populations had spatial genetic structure while the genetic variation of alleles of the other two natural populations lacked spatial genetic structures[15]. Genetic diversity research of central populations and peripheral populations indicated that the genetic diversities of peripheral populations of Toona ciliata var.pubescens were higher than the central populations; the genetic differentiation degrees of central populations were obviously smaller than the peripheral populations; the genetic distances of populations were not significantly related with geographical distances and the genetic differentiations among populations might resulted from terrain[16].

The conservation of biological diversity namely to protect the genetic diversity because the genetic diversity of a species is closely related with its viability and competitiveness . The plant population sizes of natural reserved Toona are very small with scattered distribution and the characteristics of the populations include very little seedlings, low genetic diversities,small variations among natural plants and bad renewal ability, which implies serious recession of inbreeding[18].The low level of genetic diversities of natural populations of Toona ciliata var.pubescens might be related with frequent human activities on the populations and the severe human intervention resulted in decreased genetic diversity[14]. Therefore, the conservation of natural populations of Toona ciliata var.pubescens should be enhanced.

Research on Physiology and Ecology

Plant physiology is a science for the research of laws governing life activities of plants including plant growth and development, morphogenesis,conversion of matter and energy,information transfer, signal transduction and the influence of environment conditions in vivo and in vitro on plant vital activity.Physiological studies of Toona ciliata are mainly focused on the area of stress,photosynthesis and nutrient.

Physiological study

Great progress has been achieved for physiological study of Toona ciliata in recent years. Drought stress is mainly studied in the area of stress resistance research. Wu et al.performed drought stress experiment with different periods on one-year-old potted seedlings of five clones of Toona ciliata in April; the leaf relative water content of young clone seedlings of Toona ciliata was the lowest under the severe stress(waterbreak for 17 d after normal water apply); the differences of relative watering content among different clones were not significant; leaf chlorophyll content of young seedlings was the highest and the differences of leaf chlorophyll content of seedlings among different clones were not significant;leaf chlorophyll content of full period clone seedlings of Toona ciliata showed an increasing tendency[19].Research on leaf net photosynthetic rate, stomatal conductance, intercellular CO2concentration, chlorophyll content and leaf area of Toona ciliata var. pubescens seedlings under the treatments of three soil moistures(high,medium,low)with full exposure,60% shading and 80% shading revealed that daily photosynthetic progress of Toona ciliata var.pubescens under full exposure and moderate shading in summer at seedling stage were “two peaks”;high luminous intensity and high temperature at noon contributed to obvious phenomenon of photosynthesis “noon break”; soil moisture content was proportional to leaf area under the same light condition;seedlings of Toona ciliata var.pubescens increased leaf area and improved chlorophyll content to effectively use light radiation and to form ecology survival countermeasure for the adaption to shading condition[20].

Water stress experiment with the clones of Toona ciliata seedlings indicated that clones with strong resistant ability to drought could be screened by the variation tendency of chlorophyll content,MDA content,proline content,SOD activity and POD activity of clone seedlings[21]. Plus selection of promotion lines with the combination of survival rate of cuttage, rooting percentage during summer and autumn and amount of growth of one-year-old seedlings was a feasible method for Toona ciliata breeding[21]. Foliar SOD and POD were significantly different among different clones with different drought stress treatment. Foliar SOD contents of clone seedlings of Toona ciliata were the highest (606.83 U/g)under medium stress (water-break for 12 d after normal water apply)and foliar SOD contents of different clone seedlings were not significantly different under various periods; foliar POD contents of seedlings were the highest under severe stress (water-break for 17 d after normal watering apply) and foliar POD contents of clone seedlings were not significantly different,and foliar POD content decreased following the test period[22].

Shortage of microelement was against the growth of height and diameter, dry matter accumulation of Toona ciliata M. Roem var. australis and the most direct effect was resulted from the boron deficiency. Boron deficiency resulted in withered tenderleaves and morphological change of shoot and root. Manganese deficiency resulted in foliar roll-up and slight yellows; copper deficiency resulted in blue point on leaves and wilted leaves;zinc deficiency resulted in shortened internode and decrescent lanceolate leaves; iron deficiency resulted in slow growth of plants and yellows of tender leaves[23].Leaf length,leaf area,biomass, content and accumulation of Pb in each organ were different when potted seedlings of one-year-old Toona ciliata grew on acid purple soil,calcareous purple soil and atteration in the Southwest exposed to Pb stress with different concentrations (0, 200,450 mg/kg and 2 000 mg/kg), and the resistances and transfer efficiencies of Pb contamination by Toona ciliata were different. As a fast-growing timber species with resistance to Pb,Toona ciliata could be used as a pioneer species for the remediation of Pb contaminated soil in the Southwest because of the ability of Pb absorption and Pb accumulation[24].

Ecological study

Ecology is a science to analyze and solve environmental problems faced by species and adaptability of plants under different environments.

Toona ciliata is a deciduous species and new shoot has not sprouted on leafless culm top in early March; it lasts 260 d from germination to leaf fall. Toona ciliata seedling is shade tolerant and updated well under crown canopy, and root sprouting ability of Toona ciliata is strong.Toona ciliata sprouts in late March,blooms in June to July, matures in mid to late October,falls leaves in late November and it takes 260 d in all. Toona ciliata often mixes plant with Machilus leptophylla, Quercus dentata, Lisea coreana,Liquidambar formosana,Maackia amurensis, Pteroceltis tatarinowii[25]and also mixes with Toona ciliata var.pubescens. Toona ciliata grow well on fertile, moist, well drained open forest land, forest edge and ravined valley with deep soil layer[26].

The size of plant population affects its life potential and small population size is one of the characteristics of endangered populations[27]. Toona plants distribute dispersedly with bad update ability and the natural reserved population sizes are very small. In order to reveal interrelationships among populations in Toona ciliata var.pubescens community, to reveal the structures and functions of populations, to understand the development laws of populations, typical sample plots of different geographic positions,of different soil conditions and different community compositions were selected to measure various ecological factors and to set quadrat for the analysis of inter specific associations of main species in Toona ciliata var. pubescens community; Fu et al. found that the overall association of multiple species in Toona ciliata var. pubescens community was significant positive correlation but the inter specific association between Toona ciliata var.pubescens and plants of tree layer was not significant, and the populations were facing interspecific competition, selection and succession of environment[28].

The threatening factors of Toona ciliata are shown as follows:low germination rate of seed, slow growth at seedling stage, small population size,serious inbreeding depression, serious human disturbance, disruptive biotope[18].Shen investigated Toona ciliata resources,especially Toona ciliata var. pubescens in Huaping, Yunnan.Quadrat points were randomly selected and quadrats were extracted in each quadrat points based on different elevations (locations); quantity, age group, ecological regime of Toona ciliata in quadrats were recorded. The relative density d(d=n/s)of Toona ciliata was calculated within quadrats to acquire total distribution[29]. Endangering factors were proposed based on the species characteristics and distribution characteristics. In situ conservation was proposed as the main safeguard procedure and ex situ conservation was proposed as the assistant safeguard procedure while scientific research monitoring and protection publicity should be strengthened[18,29].

Suggestions and Prospects

Toona ciliata is a national secondclass protective wild plant, a precious fast-growing timber species and is one of the preferred species for tree species structure adjustment of mixed coniferous broad leaved forests. Currently, molecular markers are only used for the research of genetic structure of Toona ciliata var. pubescens but not used for Toona ciliata var.pubescens breeding.Research on genetic characters of Toona ciliata has still been restricted to phenotypic variation and genetic research on molecular level has not been reported. More abundant genetic information can be obtained by genetic diversity analysis of Toona ciliata with DNA molecular marker technique to study geographical provenance variation. Molecular genetic structure and molecular genetic breeding of Toona ciliata are urgent to be researched on.

Ecology research on population dynamics, on population structure and spatial pattern,on geographical provenance variation and selection of superior trees of Toona ciliata has rarely been reported. The development and utilization of Toona ciliata and Toona ciliata var. pubescens, especially utilization research on chemical and pharmacological have an extensive foreground.

Reference

[1]China Editorial Board of sylva(中国树木志编委会). Afforestation technology of main tree species in China (中国主要树种造林技术)[M]. Beijing (北京): China Forestry Publishing (中国林业出版社),1981.

[2]ZHEN WJ(郑万钧).China sylva(中国树木志):The first volume(第1 卷)[M].Beijing(北京):China Forestry Publishing(中国林业出版社),1983:797.

[3]WU JY (吴际友),CHEN Y (程勇).Softwood cutting propagation of Toona ciliata clones (红椿无性系嫩枝扦插繁殖试验) [J]. Anhui Forestry Science and Technology(安徽林业科技),2011,38(4)5-8.

[4]LONG HL(龙汉利),FENG Y(冯毅),XIANG Q (向青), et al. A study of the growth characteristics of Toona ciliata in mountainous areas around the Sichuan basin(四川盆周山地红椿生长特性研究)[J].Journal of Sichuan Forestry Science and Technology (四川林业科技),2011,32(3):37-41.

[5]ZOU GS(邹高顺).Research of introduction cultivation of precious Toona ciliata and Toona ciliata var.pubescens (珍贵树种红椿与毛红椿引种栽培研究)[J].Journal of Fujian College of Forestry(福建林学院学报),1994,14(3):271-276．

[6]MA XL (马献良). Primary studies on seedling of Toona ciliata(红椿播种育苗初步研究)[J]. Anhui Forestry Science and Technology (安徽林业科技),2005,127(4)7-8.

[7]LIU J (刘军), ZHANG HY (张海燕),JIANG JM (姜景民), et al. Geographic variation of seed/fruit and seedling growing traits in Toona ciliata var.pubescens(毛红椿种实和苗期生长性状地理种源变异)[J]. Journal of Nanjing Forestry University (Natural Science Edition)(南京林业大学学报(自然科学版)),2011,35(3):55-59.

[8]ZHANG YD(张亚东), ZHONG Y(钟艺),ZHAO H (赵虎),et al.Primary study on seedlings of Toona ciliata different families of enshi Hubei provenance(湖北恩施种源红椿不同家系育苗试验初报)[J].Hubei Forestry Science and Technology(湖北林业科技),2013,3:17-20.

[9]SONG P(宋鹏),ZHANG YL(张懿琳),GU YJ (辜云杰), et al. Seedling Traits of Toona ciliata from different half-sib families (红椿半同胞家系苗期特性分析)[J].Journal of Zhejiang Forest Science and Technology (浙江林业科技), 2013, 33(3):74-78

[10]WEN WH (文卫华),WU JY (吴际友),CHEN MG (陈明皋), et al. Seedling growth performance of Toona ciliata elite trees progeny(红椿优树子代苗期生长表现) [J]. Chinese Agricultural Science Bulletin(中国农学通报),2012,28(34):36-39.

[11]LIU J(刘军),CHEN YT(陈益泰),HE FP(何费平), et al. A study on genetic variations of seedling traits of plus tree of Toona ciliata var. pubescens (毛红椿优树子代苗期性状遗传变异研究)[J].Acta Agriculturae Universitatis Jiangxiensis (江西农业大学学报), 2008, 30(1):64-67.

[12]FERREIRA RT, VIANA AP, BARROSO DG, et al. Toona ciliata genotype selection with the use of individual BLUP with repeated measures[J].Scientia Agricola,2012,69(3):210-216.

[13]LIU J(刘军), SUN ZX(孙宗修), CHEN YT (陈益泰), et al. Isolation of microsatellite DNA from endangered tree species Toona ciliata var. pubescens and optimization of SSR reaction system(珍稀濒危树种毛红椿微卫星DNA分离及SSR 反应体系优化)[J].China Biotechnology (中国生物工程杂志),2006,26(12):50-55.

[14]LIU J(刘军),CHEN YT(陈益泰),JIANG JM(姜景民),et al.Study on population genetic structure in Toona ciliata var.pubescens with SSR(毛红椿群体遗传结构的SSR 分析)[J].Forest Research(林业科学研究),2009,22(1):37-41.

[15]LIU J(刘军), CHEN YT(陈益泰), SUN ZX (孙宗修), et al. Spatial genetic structure of Toona ciliata var. pubescens populations in terms of spatial autocorrelation analysis(基于空间自相关分析研究毛红椿天然居群的空间遗传结构)[J].Scientia Silvae Sinicae (林业科学),2008,44(6):45-51.

[16]LIU J(刘军),JIANG JM(姜景民), ZOU J(邹军),et al.Genetic diversity of central and peripheral populations of Toona ciliata var. pubescens, an endangered tree species endemic to China(中国特有濒危树种毛红椿核心和边缘居群的遗传多样性)[J].Chinese Journal of Plant Ecology (植物生态学报),2013,37(1):52-60.

[17]DONG YC(董玉琛).Detection of biodiversity and crop genetic diversity(生物多样性及作物遗传多样性检测)[J].Crop Germplasm Resources(作物品种资源),1995,(3):125.

[18]LIANG RL(梁瑞龙),LIAO RY(廖仁雅),DAI J (戴俊).Analysis of endangering factors of Toona ciliata and protection strategies(红椿濒危原因分析及保护策略)[J].Guangxi Forestry Science(广西林业科学),2011,40(3):201-203．

[19]WU JY(吴际友),LI ZH(李志辉),LIU Q(刘球), et al. Responses of drought stress on relative water content of leaf and chlorophyll content of young Toona ciliata Roem. clone seedlings(干旱胁迫对红椿无性系幼苗叶片相对含水量和叶绿素含量的影响)[J]. Chinese Agricultural Science Bulletin(中国农学通报),2013,29(04):19-22.

[20]ZHANG L(张露),GUO LH(郭联华),DU TZ(杜天真),et al.The effects of shading and soil water content on photosynthesis of Toona ciliata var.pubescens seedlings(遮荫和土壤水分对毛红椿幼苗光合特性的影响)[J].Journal of Nanjing Forestry University(Natural Sciences Edition)(南京林业大学学报(自然科学版)),2006,30(5):63-66.

[21]CHEN CX (陈彩霞),WANG RH (王瑞辉),WU JY (吴际友),et al.Physiological response of Toona ciliata clone sedlings under continuous drought conditions(持续干旱条件下红椿无性系幼苗的生理响应)[J].Journal of Central South University of Forestry &Technology(中南林业科技大学学报),2013,33(9):46-49.

[22]LIU Q(刘 球),CHEN CX(陈彩霞), WU JY(吴际友),et al.Response of drought stress on anti-oxydant enzyme in leaves of young Toona ciliata clone seedlings(红椿无性系幼苗叶片抗氧化酶指标对干旱胁迫的响应)[J]. Journal of Central South University of Forestry&Technology(中南林业科技大学学报),2013,33(11):73-76.

[23]MORETTI BS, FURTINI NETO AE,PERES BENATTI B,et al.Characterization of Micronutrient Deficiency in Australian Red Cedar(Toona ciliata M.Roem var. australis)[J]. International Journal of Forestry Research, 2012,Article ID 587094,1-9.

[24]HU FJ (胡方洁), ZHANG J (张健),YANG WQ (杨万勤). Effects of Pb stress on the growth,development and Pb enrichment properties of Toona ciliata(Pb 胁迫对红椿 (Toona ciliata Roem) 生长发育及Pb 富集特性的影响)[J]. Journal of Agro-Environment Science(农业环境科学学报),2012,31(2):284-291.

[25]WU LL (吴莉莉),WANG MF (王鸣凤),CHEN BL (陈柏林). Research of biological characteristics and artificial cultivation experiment of Toona ciliate(红椿树的生物学特性和人工栽培实验研究)[J]. Anhui Agricultural Science Bulletin(安徽农学通报),2006,12(7):168-169．

[26]HUANG HL(黄红兰), LIANG YL(梁跃龙),ZHANG L(张露).Research status and strategies on resources conservation and breeding of Toona ciliata var.pubescens (毛红椿资源保护和培育的研究现状与对策) [J]. China Forestry Science and Technology (林业科技开发),2010,24(1):10-14.

[27]CHEN XY (陈小勇). Effects of habitat fragmentation on genetic structure of plant populations and implications for the biodiversity conservation(生境片段化对植物种群遗传结构的影响及植物遗传多样性保护)[J]. Acta Ecologica Sinica (生态学报),2000,20 (5):884-892.

[28]FU FL (付方林), ZHANG L (张露),YANG QP (杨清培), et al. A study on the interspecific association of dominant species in Toona ciliata var.pubescens natural forests communities(毛红椿天然林优势种群的种间联结性研究)[J]. Acta Agriculturae Universitatis Jiangxiensis (江西农业大学学报),2008,29(6):982-987.

[29]SHEN XH (沈新华). Resource status and protection countermeasures on Toona ciliata in Shilongba township Huaping County(华坪县石龙坝乡红椿资源状况及保护对策)[J].Qinghai Science and Technology of Agriculture and forestry (青海农林科技),2010,2:72-74.

[30]ZOU J (邹军). Germination test and seedling raising technique of Toona ciliata (红椿发芽试验与育苗技术)[J].Yunnan Agricultural Science and Technology (云南农业科技), 2012, 6:47-48.