Effect of Three Treatment Measures on Harmless Seedling Raising of Pinus sylvestris var. mongolica Litv.

Zhijun WANG，Kaiyan JlN，Rahman·Abdurishid

Institute of Botanical Garden and Afforestation，Xinjiang Academy of Forestry，Urumchi 830000，China

Effect of Three Treatment Measures on Harmless Seedling Raising of Pinus sylvestris var. mongolica Litv.

Zhijun WANG*，Kaiyan JlN，Rahman·Abdurishid

Institute of Botanical Garden and Afforestation，Xinjiang Academy of Forestry，Urumchi 830000，China

Three treatment measures for raising seedlings by sowing，i.e.covering seeds with two layers of forest soil，culturing seedlings under full sunshine and timely sowing in late autumn，were adopted in this study.The results indicated that the three treatments were of good prevention effects on sheath blight or seedling blight，sunscald and rat damage in Pinus sylvestris var.mongolica，could avoid the pollution of agrochemicals to soil and environment as well as decrease cost for raising seedlings，and thus could promote the development of bio-agrochemicals or bio-fungicides with high efficiency and no pollution for resisting the pathogens of sheath blight.

Pinus sylvestris var.mongolica；Harmless；Seedling raising

P inus sylvestris var.mongolica has well-developed root system，good tolerance to cold and drought，fine texture，strong soil adaptability and fast growth in light-e nough places，and is a kind of conifer suitable for wind prevention and sand fixation［1］.Pinus sylvestris var.mongolica was introduced into Xinjiang in 1966，and well cultured［2］.It shows the characteristics of fast growth，good tolerance to barren soil，cold，drought and alkali and alkaline as well as strong adaptability in Xinjiang，and is one of the most abundant evergreen coniferous species used for botanical garden and afforestation in cities and towns of Xinjiang.Though the ecological and economical benefits of Pinus sylvestris var.mongolica have been recognized and its seedling raising has been ofscale and standard，its seedling raising techniques still fall behind［3］.This situation mainly could be seen from following three aspects:（1）the hazard of sheath blight or seedling blight in pine seedlings；（2）the hazard of sunscald in pine seedlings；and（3）rat damage to seeds.For the first aspect，sheath blight，is a worldwide disease common for nurseries of Pinaceae species with severe damage，appears in various regions of China with an incidence of 20%-50%，up to 80%when it is severe and could even cause total loss of yield.Sheath blight could also harm broad-leaved trees including Ananas comosus and Fraxinus mandschurica Rupr.and some crops besides a variety of coniferous trees including Larix gmelinii（Rupr.）Kuzen.，Pinus koraiensis Sieb. et Zucc.，Pinus sylvestris var.mongolica，Pinus densiflora，Pinus thunbergii Parl.，Picea asperata and Abies fabri Craib.Conventional prevention and control methods adopt the comprehensive preventive measures including selecting nursery field，rational fertilization，properirrigation，seed sterilization， soil sterilization and seedling-stage chemical spraying currently，and in a word，agrochemicals are necessary for the prevention andcontrolofsheath blightin pine seedlings［4-7］.For sunscald in pine seedlings，it causes death of tender seedlings easily in 13-15 d from the time when seedlingsgrow outof ground to lignification.In conventional raising methods for pine seedlings，a shade is constructed on a seedbed，to prevent seedlings from dying due to sunscald.The construction of shades in seedling stage could protect seedlings to a certain extent，but the management cost is higher.As to rat damage，which may happen on seeds（pine nuts）of Pinus sylvestris var. mongolica in autumn and winter，the conventional seedling raising usually takes the measure of sowing in spring，which increases the technique links of storage in winter and pregermination in spring，thereby increasing the cost for seedling raising.

The technicians from Xinjiang Academy of Forestry developed three improvement measures for seedling raising of Pinus sylvestris var.mongolica by sowing，which were covering seeds with two layers of forest soil，culturing seedlings under full sunshine and timely sowing in late autumn，which were capable ofpreventing sheath blight，sunscald and rat damage in seedling raising process of Pinus sylvestris var.mongolica fundamentally，achieving the purpose of harmless seedling raising，such that seedling raising of Pinus sylvestris var. mongolica need not to depend on agrochemicals and the cost for seedling raising could be reduced；and meanwhile，this study had certain promotion effect on extraction of high-efficiency biofungicides from the froest soil under Picea schrenkiana forests in China.These three improvement measures are also suitable for seedling raising processes oftree species including Pinaceae Larix gmelinii and Picea asperata.

The Technical Background of The Three lmprovement Measures

The technical background of covering seeds with two layers of forest soil for preventing sheath blight

During 1965-1978，Tree Introduction Department of Xinjiang Institute of Forestry （predecessor of Xinjiang Academy of Forestry）conducted the research of direct seedling forestation on Picea schrenkiana at Tianshan Mountains，during which sheath blight hazard was not observed.Later，the Tree Introduction Department began to conduct regionalized introduction and cultivation tests on 14 foreign Picea species.The experimentfield forintroduction was Tianchi nursery in Fukang of Changji Prefecture （Tianshan Mountains，slightly-acidic fluvial soil，pH=5.8-6.5，with an altitude of 1 900 m），and the introduction tests mainly were conducted seed propagation.Sheath blight occurred in the seedling raising process. The Tree Introduction Department further introduced the bred seedlings of Picea crassifolia，Picea obovata，Picea schrenkiana and Picea meyeri to the arboretum of Xinjiang Academy of Forestry at the plain area of Xinjiang in 1980-1985 （Urumqi，with a soil pH value of 8.5，an altitude of 850 m，an extreme-high temperature of 40.5℃and an extremely-low temperature of 41.5℃）.In the seedling raising by sowing ofPicea crassifolia，Picea obovata，Picea schrenkiana and Picea meyeri，severe sheath blight was observed.

Technicians conducted analysis and comparison on the production conditions in the three test sites，and they paid close attention to different soil conditions of the three sites.It is well known that the pathogens of sheath blight mainly exist in soil，and there might be sheath blight pathogen-antergic substances existing in the soil of Picea schrenkiana forest on Tianshan Mountains.

During the sowing test of Picea crassifolia conducted in the arboretum ofXinjiang Academy ofForestry（Urumqi）later，technicians improved the soil in the arboretum with the forest soil under the Picea schrenkiana forest on Tianshan Mountains，i.e.，the upper soil layer of the seedbeds with a thickness of 30 cm was replaced.Sheath blight was not observed during the sowing experiment of Picea crassifolia carried out on the improved soil.In order to verify whethersheath blight pathogen-antergic substances existed in the soil of the Picea schrenkiana forest on Tianshan Mountains，the technicians from the Pest Control and Prevention Department of the Institute of Forestry performed isolation and culture of mycorrhizal fungi on the forest soil under the Picea schrenkiana forest on Tianshan Mountains with tissue isolation method，and cultured the Fusarium and Rhizoctonia isolated from the seedlings suffering sheath blight together with the mycorrhizal fungi，respectively.It was observed thatthe isolated mycorrhizalfungi gradually surrounded and phagocytosed Fusarium and Rhizoctonia，indicating that the mycorrhizal fungi had a natural antagonistic effect on Fusarium and Rhizoctonia，i.e.，they were natural enemies.This result accorded with the prevention and control efficiency of forest soil on prevention of sheath blight found by technicians.

During the seedling growing test of Pinus sylvestris var.mongolica introduced to Xinjiang，the technicians improved the seedling growing test method of Pinus sylvestris var.mongolica step by step，and found that sheath blight also could be prevented by filling the seed furrows and overlying roots with the forest soil under the Picea schrenkiana forest.This method is simple and convenient and could be mastered easily.

The technicians applied the method of covering seeds with two layers of forest soil to the seedling culture of Picea crassifolia，Picea meyeri and Pinus tabuliformis，which also was successful.

The technical background of culturing seedlings under full sunshine for preventing suncald

In conventional seedling raising methods，a shade is constructed on a nursery by seedling raising staffs to prevent tender seedlings from scalding by strong sunshine at the time of coming up out of the ground in the first year for seedling raising of Pinaceae tree species by sowing.The technicians found during the seedling raising process of Pinus sylvestris var.mongolica that，without constructing shades，until the 14thor 15thday from the time when seedlings grew out of ground to lignification，by spraying seedlings with water twice before the sun came out at an interval of 30 min，the water sprayedon the ground was evaporated after the sun came out and carried partial heat in the upper soil layer away，and then the soil could not scald seedlings.

The technical background of sowing in late autumn for preventing rat damage

The pine nut is one of the food fond by rodents，and，in order to avoid seeds from eating by rats，conventional seedling raising methods usually postpone the sowing time of Pinaceae species to next spring，thereby increasing winter storage and pregermination during seed harvest in autumn to sowing in next spring.If sowing can be conducted in late autumn and avoid eating by rats，then seedling raising links and economic cost could be reduced.In order to find a proper sowing time，from November 1，sowing was performed once every 5 d，and until December 5，and 7 batches of sowing experiments were performed in total.It was found that in northern Xinjiang about November 20 was most suitable for sowing every year at a temperature of-4℃ to-5℃ by three years of continuous experiment.After sowing，forest soil was laid on the bottom of furrows and covered on seeds，which was watered，and then water，soil and seed were slightly frozen together，such that rats could not eat the seeds，without affecting the emergence rate in the second year.The heavy snow falling later on soil could exert certain heat insulation effect.Sowing too early is prone to rat damage，while sowing too late is prone to soil freezing.

Harmless Seedling Raising of Pinus sylvestris var. mongolica

（1）Nursery field selection:Flat fertile field or sandy soil on the lee side against the sun with convenient transportation，good irrigation and drainage conditions and thick soil layer which was loose and neutral or slightly-alkaline could be selected as the nursery field.

（2）Soil preparation:Mature compost 45 000 kg/hm2and ferrous sulfate 6 000 kg/hm2were applied uniformly in late June of the year before，and deep tillage was performed followe by harrowing，levelling and ridging，forming smooth and loose ridges with a length of 10 m and a width of 1.5 m.

（3）Seed treatment:（i）Seed treatment:seeds of Pinus sylvestris var. mongolica were purchased from Gansu or Shanxi in early November and put into air-permeable jute bags which were then put at a dry place on the lee side.（ii）Sowing time:after two times of snowfall in Urumchi，the seeds were sown，generally on November 20 of every year at a temperature of minus 4℃to minus 5℃.And（iii）sowing:before snowing，furrowing was performed on the nursery field to form furrows with a depth of 0.8-1 cm and a row spacing of 20 cm，and a layer of forest soil（0.5 cm）was laid at the bottom of each furrow.After two times of snowfall，snow was swept to two sides of furrows with a broom for later use，seeds were sown on the forest soil in the furrows，watered and covered with a layer of forest soil（with a thickness of 0.5 cm）which was slightly compacted and then covered with the snow at the two sides of furrows.By doing this，sheath blight could be effectively prevented，as well as rat damage could be avoided.

（4）Tending management:（i）Irrigation:irrigation was conducted for the first time when all seedlings came up out of the ground in the second year，and performed once every 15 d afterwards，totally 10 times.（ii）Spraying water:in the period from the time when the seedlings came up out of the ground to the 14thor 15thday，water was sprayed onto seedlings twice before the sun came out at an interval of 30 min，and then，the construction of shades as well as scald of sunshine to seedlings could be avoided.And（iii）Scarification and weeding:in the early stage of seedlings，it was necessary to perform weeding by scarifying soil shallowly in time after irrigation，deep scarification was performed with a depth of 6 cm for properly-decreased times after mid July，and in total，weeding was generally carried out for 7 times in one year by scarification.（iv）Thinning:thinning was conducted when the heights of seedlings reached 1 cm after irrigation while performing weeding，final singling of seedlings was conducted when the seedlings reached a height of 1.5 cm at a density of 20 plants every meter，and irrigation was performed after thinning in time.（v）management and protection in later stage:in the second year，irrigation was performed for 6 times，scarification and weeding were performed for 5 times，0.15%monopotassium phosphate as a leaf fertilizer was applied once or twice after the terminal bud was formed in an amount of 50 kg/667 m2.（vi）Transplanting in the autumn of the second year or in the spring of the third year，seedlings could be transplanted with soil on roots as seedlings with naked roots were prone to death after transplanting.

Discussion

Mycorrhizal fungi in the forest soil of Picea schrenkiana were important to the development of novel biopesticides.

The prevention and control methods for sheath blight mainly are chemical methods in China currently，which would generate certain negative effects in ecological environment pollution，phytotoxicity and soil hardening. Therefore，utilization of antagonism between fungi in soil is very important for biofungicides development.Finding fungicapable ofhighly inhibiting sheath blight in seedling is the tendency in the future study［8-9］.

In the research and application in biological control of sheath blight and application at home and abroad，Trichoderma having inhibition effect on pathogens of sheath blight was screened.There were researches showing that Trichoderma strains had certain antagonism on three kinds of pathogens of sheath blight，but could not effectively kill the pathogens of sheath blight.

In Xinjiang，the pathogens causing sheath blight of pine seedlings are Rhizoctonia and Fusarium.The forest soil under the Picea schrenkiana forest on Tianshan Mountains could prevent the outbreak and hazard of sheath blight，indicating that the forest soil under the Picea schrenkiana forest contained mycorrhizal fungi antagonistic to Rhizoctonia and Fusarium.

Therefore，it is anticipated that the departments for developing biofungicide can isolate fungus strains capableof effectively preventing sheath blight of Pinus seedlings from the forest soil under Picea schrenkiana forests，to finally benefit the society.

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Responsible editor：Yingzhi GUANG

Responsible proofreader：Xiaoyan WU

几种处理措施对樟子松无害化育苗的影响

汪智军*，靳开颜，阿不都热西提·热合曼
（新疆林科院园林绿化研究所，新疆乌鲁木齐830000）

采用双层森林土覆盖种子法、全光照育苗和秋末适时插种3项樟子松播种育苗处理措施，对樟子松立枯病、日灼病和鼠害均有很好的预防作用。这些改进措施，不仅能避免化学药剂对土壤和环境的污染，还能降低樟子松的育苗成本，对我国早日研制出高效无污染的抗立枯病病原菌的生物农药具有一定的促进作用。

樟子松；无害化；育苗

新疆维吾尔自治区公益性科研院所基本科研业务经费资助项目“新疆林科院树木园杨树主要造林树种引种汇集”（2015）。

汪智军（1964-），女，安徽肥西人，硕士，研究员，主要从事林木引种驯化栽培、文冠果良种选育和栽培技术研究，E-mail：wzj4656021@163.com。*通讯作者。

2015-08-02

Supported by Basic Scientific Research Business Expense Project for Public-interest Scientific Institute of the Xinjiang Uyghur Autonomous Region，"Collection of Introduced TreeSpeciesofPopulusfroAfforestationinAroboretumofXinjiangAcademyofForestry".

*Corresponding author.E-mail:wzj4656021@163.com

Received:August 2，2015 Accepted:November 2，2015

修回日期 2015-11-02