板栗断胚根断茎尖育苗技术的研究

板粟断胚根断茎尖育苗，是将种子催芽后断胚根播种；一年生实生苗和二年生嫁接苗分别长高到３０—４０ｃｍ和７０—８０ｃｍ随即断茎尖，控制主根生长和高生长，促发须根和苗茎加粗生长。结果表明：断胚根苗木比不断胚根苗木根系平均增加２０９．０９％；一年生断茎尖实生苗比不断茎尖实生苗地际径平均增粗２９．９４％；二年生出圃苗地际径平均增粗１４．５１％；断胚根断茎尖苗木比对照（不断胚根不断茎尖）苗木根系平均增加２１１．４８％，一年生实生苗地际径平均增粗３０．３５％，二年生出圃苗地际径平均增粗１９．３７％。断茎尖出圃苗分枝率９８％，每株平均分枝２．５５枝，而不断茎尖的出圃苗有分枝的仅７．３％。造林试验结果证明：断胚根苗木比不断胚根苗木造林成活率提高１２—１５％。     

红松苗木活力与相对电导率关系的研究

本文通过测定不同失水时间的红松苗木的相对电导率，分析相对电导率与红松苗木活力的关系，发现红松苗木活力与水分下降、电解质外渗有密切相关，因此，通过测定苗木相对电导率可预测苗木的活力。     

板栗断胚根断茎尖育技术的研究

板栗断胚根断茎尖育苗，是将种子催芽后断胚根播种；一年生实生苗和二年生嫁接苗分别长高到３０－４０ｃｍ和７０－８０ｃｍ 随即断茎尖，控制主根生长和高生长，促发须根和苗茎和粗生长。结果表明：断胚根苗木比不断胚根苗木根系平均增加２０９．０９％；一年生断茎尖实生苗比不断茎尖实生苗地际径平均增粗２９．９４％；二年生出圃苗地际径平均增粗１４．５１％；断胚根断茎尖苗木比对照苗木根系平均增加２１１．４８％，一年生实     

杨树苗圃冬灌防寒效果研究

本研究用对比实验的方法,测试苗圃地冬灌后的苗木枯梢率、苗木含水率、土壤含水率、苗木相对电导率,以检测杨树苗圃冬灌防寒效果。结果表明:冬灌对一年生沙兰杨苗木越冬含水率变化没有影响;对一年生辽宁杨苗木含水率有所提高;对一年生3016杨苗木含水率没有影响;冬灌能有效提高苗圃地内土壤含水率;冬灌能够明显降低苗圃地内苗木越冬时期的相对电导率,能够在一定程度上提高苗木的抗冻性。     

科技文摘

<正> 断胚根断茎尖培育板栗苗木板栗属深根性树种,苗期以主根和高生长为主,苗木表现为主根粗、长、须根少。因此提高板栗成活率的关键在于控制主根生长,增加须根。湖南省怀化市林业局杨望球于1988—1990年进行了断胚根断茎尖育苗试验和造林对比试验。     

板栗断胚根茎尖育苗法

这里采用当地小板栗育苗的方法:种子催芽后,当胚根3—5cm时,断去1/3-1/2胚根再播种,1年生实生苗和1年生嫁接苗分别长高到30-40cm和70-80cm时随即断茎尖,以控制主根生长和高生长,促发须根和苗茎加粗生长。试验表明:断胚根苗木比不断胚根苗木根系数平均增加209.09％;1年生断茎尖实生苗比不断茎尖实生苗地径平均增粗29.94％,2年     

川楝苗木失水处理对其活力及造林效果的影响

通过对金沙江干热河谷上段乡土树种川楝1年生苗木进行5种晾晒处理试验,测定不同晾晒处理后根系的相对含水率、相对电导率、根系活力和移植后的成活率,分析探讨川楝苗木水分与苗木活力的关系.结果表明:川楝苗木活力与其苗木水分密切相关,在晾晒的过程中苗木失水使相对含水量下降,相对电导率增加,根系活力下降,最终导致苗木成活率降低和影响幼林生长情况.在川楝造林时,要做好起苗后的苗木保护工作,尤其是根系的保护,这对于维持苗木活力,提高造林成活率和保存率有重要的意义.     

垂枝杉茎尖离体培养的研究

<正> 垂枝杉是杉木的一种优良类型,这种杉木的树干通直圆满,枝条纤细,老枝下垂,树冠窄小,不荫田,能耐瘠薄。但由于资源较少,加之营养生长旺盛,结实量不多,致使大面积造林受到一定影响。为了大量生产垂枝杉的优良苗木,湖北省英山县林科所和科学实验站曾于1978年进行了垂枝杉茎尖培养的初步尝试,我们从1980年开始进行了垂枝杉茎尖培养的研究。本试验用茎尖培养方法获得植株,并对影响茎尖培养的有关因素进行了初步     

大叶黄杨盾蚧类害虫的防治

大叶黄杨已成为庭院、公园、道路绿化美化的大众品种，其苗木易繁殖、生长快、抗污染、耐修剪且变种很多，故被大量引种。但由于苗木检疫不严，致使病虫害大有蔓延之势，危害严重，其中盾蚧类害虫危害尤甚。北京周围地区大叶黄杨盾蚧类害虫以卫茅尖盾蚧为主，又名卫茅矢尖盾蚧。１　卫茅尖盾蚧的生活习性卫茅尖盾蚧在北京地区１年２～３代，以３代为主，发生严重时枝条与叶片均呈白色，成若虫群聚于嫩枝、叶片上，吸食液汁，使树叶枯黄早落，生长停滞，危害严重时枝条上介壳密集重叠，造成整株死亡或缺苗断行。雌成虫黄色纺锤形，长约１．５…     

油松、华北落叶松抗旱特性的研究

进行了油松，华北落叶松苗木盆栽试验，在土壤由湿（适宜）到严重干旱的变化过程中，测定了苗木的凋萎系数，叶片水势，根系活力，蒸腾强度，观察了苗木生长的外观反应。对两树种的抗旱性能进行了综合评价，结论是：油松的抗旱性能优于华北落叶松。     

干旱胁迫对美国白蜡幼苗生理指标的影响

以美国白蜡2 a生实生苗为材料,采用盆栽方式进行干旱胁迫试验,测定苗木相对含水量、水分饱和亏、叶绿素含量及细胞质膜透性等生理指标,结果表明:从控水开始至12 d时,其叶片叶绿素含量从4.797 2 mg·g-1下降到3.693 2 mg·g-1,降低了23%;而相对电导率从39.11%上升到58.31%,上升了49.09%,相对电导率变化较大,但叶绿素含量相对稳定,膜系统未受到较严重损伤;胁迫12 d时叶片干鲜比仅比对照增加了9.73%,干旱致死临界点土壤含水量在5%以下,具有较强抗旱性。维持幼苗正常生长的临界土壤含水量为10%。     

Effects of simulated thaw on xylem cavitation,residual embolism,spring dieback and shoot growth in yellow birch

Yellow birch seedlings (Betula alleghaniensis Britt.) that had lost more than 90% of their stem hydraulic conductivity during ambient winter temperatures were exposed to 0 and 20 days of a simulated winter thaw followed by a 48-h freezing treatment at 0, -5, -10, -20 and -30 degrees C. After measuring freezing injury to shoots and roots, the seedlings were placed in a greenhouse where recovery of xylem conductivity and new growth were measured. Shoot xylem cavitation was measured as percent loss of hydraulic conductivity. Shoot freezing injury was assessed by electrolyte leakage (EL) and root freezing injury was assessed by EL and triphenyl tetrazolium chloride reduction. Seedlings pretreated with thaw had higher stem water contents and suffered more freezing damage to roots and shoots (at -20 and -30 degrees C, respectively) than unthawed seedlings. After 3 weeks in a greenhouse, seedlings from the 0, -5 and -10 degrees C freezing treatments showed complete recovery of xylem conductivity, with substantially increased stem water contents. Poor recovery of hydraulic conductivity was observed only in seedlings that were subjected to freezing treatments at -20 and -30 degrees C, regardless of thaw treatment. Of these embolized seedlings, however, only those not previously thawed showed recovery of hydraulic conductivity or regained stem water content after 9 weeks in the greenhouse. Shoot dieback, bud burst and length of new shoots were significantly related to the extent of stem xylem cavitation and freezing injury. We conclude that (1) the simulated winter thaw predisposed yellow birch seedlings to freezing damage in shoots and roots by dehardening tissues and increasing their water content; (2) root freezing damage in turn affected the seedlings' ability to refill embolized stem xylem, resulting in considerable residual xylem embolism after spring refilling; (3) further recovery of stem xylem conductivity was attributable to growth of new vessels; (4) and the permanent residual embolism, together with root and shoot freezing injury, caused increased dieback, bud mortality and reduced growth of new shoots.     

Geographical variation in water relations, hydraulic architecture and terpene composition of Aleppo pine seedlings from Italian provinces

Ecotypic variations in leaf conductance, soil-to-leaf hydraulic conductance, components of tissue water potential, hydraulic architecture parameters and xylem embolism were examined in greenhouse-grown two-year-old Aleppo pine (Pinus halepensis Mill.) seedlings from six origins representing the geographic range of the species in Italy. Cortical resin composition of the seedlings was also determined. Measurements were made on well-watered seedlings and on seedlings subjected to recurring severe drought. Drought-stressed seedlings had lower mean leaf conductances, transpiration rates and soil-to-leaf hydraulic conductances than well-watered seedlings. They also exhibited more negative osmotic potentials, higher relative water deficit at incipient plasmolysis, but a similar maximum modulus of elasticity. Drought-stressed seedlings showed a higher degree of xylem embolism, a lower Huber value, lower leaf specific conductivity and lower specific conductivity than well-watered seedlings. Drought-stressed seedlings of provenances from more xeric habitats (Tremiti, Porto Pino and Mottola) had greater leaf conductances, transpiration rates and soil-to-leaf hydraulic conductances than drought-stressed seedlings of provenances from more mesic habitats (Imperia, Otricoli and Vico del Gargano). They also showed higher osmotic adjustment and a lower degree of xylem embolism. Among provenances, there were no significant differences in hydraulic architecture parameters in response to the drought treatment; however, Tremiti and Porto Pino seedlings displayed smaller drought-induced reductions in specific conductivity and leaf specific conductivity, respectively, than seedlings from other provenances. These differences suggest that seedlings from xeric provenances, especially Tremiti, have greater resistance to desiccation than seedlings from mesic provenances. No clear association was found between terpene variability and the other traits investigated, although terpene composition was related to the geographical distribution of the provenances. We conclude that the drought-tolerance responses of Tremiti make it a more suitable provenance than the others for establishment on sites prone to severe soil water deficits.     

Discussion on Pipe Model through Hydraulic Architecture of Pinus tabulaeformis Seedling

INTRODUCTIONShinozakifirstproposedthepipemodeltheoryin1964(Shinozaki,1964a,1964b).Inthistheory,thewholexylemsoftheplantisassumedasauniformpipe.Hebelievedthatperunitareaofleavesdependedonperunitofareaofthepipetogrowth.Thistheoryisagreedbyresearcherswhofoundthatthesectionareaofthexylemisdirectproportiontotheareaoftheleavesintheendofthexylem.Laterthistheorywasfoundverypracticalinestimatingtheleavesarea,understandingthegrowthandthedistributionofmaterialandenergyintrees(Shinozakig,Yoda,Hozum…     

Vitality characterization of stressed trees based on non-destructive and real-time monitoring of stem water content

The detection of stem water content is necessary as it is an important indicator for measuring woody plant vitality. However, the relationship between stem water content, determined by non-destructive, real-time, and long-term monitoring, and woody plant vitality remains undefined. In this study, the response of woody plant vitality to stem water content under different stress (freeze–thaw, pest, or drought) was analysed by mining the dynamic characteristics of the stem water content in different woody plants at the temporal scales of year, month, and day. Compared with unstressed trees, stressed trees had contrasting diurnal patterns. The stem water content in Populus koreana Rehd. during the freeze period was much lower than that during the thaw period, and opposite diurnal variation trends were observed during the freeze and thaw periods. The stem water content in infected Lagerstroemia indica was lower than that in uninfected L. indica, and the amplitude of the diurnal variation curve was lower in infected than in uninfected L. indica. Under drought stress, the more severe the water shortage, the lower the stem water content in Malus micromalus. When it was below a certain threshold, the diurnal variation trend was opposite to that without water shortage. In conclusion, stem water content dynamics can be used to evaluate the cold, pest, and drought response of trees, which could monitor tree health and guide forest assessment.     

加拿大一枝黄花幼苗生长对土壤水分、光强的响应

设定4个不同水分和光照梯度,测定加拿大一枝黄花的比叶质量、根生物量比、茎生物量比、叶生物量比、叶质量分数、根冠比来评估其对土壤水分、光强的响应.结果显示,土壤相对含水量60％～ 90％,中等光照强度(45％)最适合加拿大一枝黄花的生长.     

干旱胁迫对不同种源沙柳苗木水势和水分利用效率的影响

通过人工模拟方式对5个种源沙柳苗木进行干旱胁迫处理,研究干旱处理不同阶段苗木小枝水势日变化、叶片相对含水量、水分饱和亏缺、保水力及水分利用效率。结果表明:干旱胁迫下5个种源的沙柳苗木小枝水势和叶片相对含水量均下降,而水分利用效率在轻度干旱时呈上升趋势,随干旱胁迫的加剧而下降。干旱处理15天后,民勤种源的沙柳日平均小枝水势下降幅度最大为0.77 MPa,然后依次为达拉特旗0.57 MPa、盐池0.36 MPa、榆林0.25 MPa和乌审旗0.12 MPa,其中民勤种源的苗木在充分供水和干旱胁迫下小枝水势差异达到显著。干旱处理18天后叶片相对含水量分别下降:民勤1.68%、盐池7.03%、达拉特旗7.25%,榆林9.35%和乌审旗11.07%,水分饱和亏缺民勤<盐池<达拉特旗<榆林<乌审旗。结果表明,民勤种源的沙柳抗旱的能力较强,而盐池和达拉特旗沙柳苗木在受到水分胁迫时水分利用效率下降幅度较小,即水分胁迫对苗木干物质的积累影响较小,因此具有更高的经济价值。     

Interacting effects of irradiance and water stress on dry weight and biomass partitioning in Fagus sylvatica seedlings

Abstract

Actual climate models for central Europe predict prolonged summer droughts. Knowledge on how the interaction between light and water availability affects regeneration will hence be of major importance. In an experiment carried out under controlled conditions, newly emerged beech seedlings were grown in pots with sand during 54 days. Three treatments applying three different light levels (2, 9 and 43% relative light intensity) were combined with two soil water treatments (control and drought). At the end of the experiment, seedlings were separated into leaves, stem and root and the seedlings’ dry mass, leaf area and stem length was determined. Low irradiance (2%) had a strong negative effect on dry weights of seedling components, leaf area and specific leaf mass. Drought clearly affected biomass partitioning for seedlings at high irradiance levels (43%). An interaction between irradiance and drought on biomass partitioning in beech seedlings was observed at medium irradiance level (9%). Within a wide range of light levels in the forests, both light and drought may affect biomass partitioning in young seedlings.     

Wood density and anatomy of water-limited eucalypts

We hypothesized that seedlings grown under water-limited conditions would develop denser wood than seedlings grown under well-watered conditions. Three Eucalyptus species (E. grandis Hill (ex Maiden), E. sideroxylon Cunn. (ex Woolls) and E. occidentalis Endl.) were grown in a temperature-controlled greenhouse for 19 weeks with watering treatments (well-watered and water-limited) applied at six weeks. The water-limitation treatment consisted of four drought cycles. Wood density increased by between 4 and 13% in the water-limited seedlings, but this increase was mainly due to extractive compounds embedded in the cell wall matrix. Once these compounds were removed, the increase was 0-9% and was significant for E. grandis only. Water-limitation significantly reduced mean vessel lumen area; however, this was balanced by a trend toward greater vessel frequency in water-limited plants, and consequently there was no difference in the proportion of stem area allocated to vessels. Conduit efficiency value was lowest in the water-limited plants, indicating that there was a cost in terms of stem hydraulic conductivity for decreasing vessel lumen area. Wood density was negatively correlated with vessel lumen fraction in well-watered plants, but this relationship broke down in the water-limited plants, possibly because of the significantly larger proportion of the stem taken up by pith in water-limited seedlings. Diurnal variation in leaf water potential was positively correlated with wood density in well-watered plants. This relationship did not hold in the water-limited plants owing to the collapse of the pressure gradient between soil and leaf. We conclude that drought periods of greater than 1 month are required to increase wood density in these species and that increases in wood density appear to result in diminished capacity to supply water to leaves.     

观赏山楂叶片耐热性生理指标研究初探

在对观赏山楂10个品种高温胁迫下叶片生理指标(相对电导率、叶绿素含量、相对含水量、脯氨酸含量、丙二醛含量和SOD活性)测定的基础上,对其耐热性进行了综合评价。结果表明:高温胁迫下,供试观赏山楂品种叶片的相对电导率上升,脯氨酸、丙二醛含量增加,SOD活性升高,相对含水量下降,叶绿素含量变化不一;且各指标之间存在一定的相关性。结合田间观测,观赏山楂10个品种耐热性大致可聚类为3个级别,即1级(相对耐热):摩登山楂‘托巴’、毛山楂和阿尔泰山楂;2级(中等耐热):华盛顿山楂和英国山楂‘红云;’3级(相对敏感):红蕊山楂、英国山楂‘红保罗’、绿山楂‘冬国王’、鸡矩山楂以及俄罗斯山楂。