温度对大叶桃花心木(Swietenia macrophylla King)幼苗叶片的光合影响

本文研究了大叶桃花心木（Swietenia macrophylla King）一年生幼苗在经过夜温处理后的光响应曲线和在饱和光强下的CO2反应曲线.结果表明:在大气CO2浓度下,叶片的最佳光合作用温度在25-31℃之间,而在饱和CO2浓度下为31-35℃.在25℃以下光合速率开始降低,主要是由于羧化效率的降低,而当温度超过31℃时,光合速率下降,是因为羧化效率的降低和呼吸速率的增加.CO2浓度对光合的促进作用在低温下受到抑制,这意味着未来在CO2浓度增高的情况下,高浓度的CO2对热带常绿植物光合的促进在冬天低温情况下表现不十分明显.图4参23.     

3个与杉木混植木荷种源幼苗对光照响应的差异

目的]探寻不同木荷种源混交林生产力差异的光合机制。[方法]以福建建瓯、江西信丰和浙江龙泉3个木荷代表性种源1年生和2年生幼苗为试验材料,在与杉木混植条件下,设置100%(L0)、50%(L1)和25%(L2)3种光照的光环境,研究3个木荷种源幼苗的生长性状、光合生理及叶绿素荧光特性等对不同光照响应的差异。[结果]1年生和2年生木荷幼苗的苗高、地径和干质量均表现出显著的种源差异,福建建瓯种源幼苗生长优于浙江龙泉种源和江西信丰种源。随着遮阳强度的提高,1年生和2年生2个发育阶段,福建建瓯种源幼苗比叶面积和叶绿素含量等明显增加,叶绿素a/b值、光饱和点、暗呼吸速率和Fo值等均显著降低,表现出较高的形态和生理塑性;相同遮阳处理下福建建瓯种源幼苗总叶面积、叶绿素含量和Fv/Fm值等指标显著高于浙江龙泉种源和江西信丰种源,而叶绿素a/b值、光饱和点、光补偿点和暗呼吸速率则明显低于两种源;长期遮阳和混植状态下福建建瓯种源幼苗可通过较高的生物量分配塑性,增加根系在土壤中分布来响应邻株竞争,进而促进整株干物质的积累;各光环境下,3个木荷种源2年生幼苗Fo、Fm、Fv/Fm和Fv/Fo等叶绿素荧光参数均较1年生幼苗明显升高,但各光环境间差异不显著。[结论]不同木荷种源混交林生产力差异与其对光照的塑性反应能力有关,并随幼苗年龄而变化。     

Effects of osmopriming and hydropriming on vigour and germination of China aster (Callistephus chinensis (L.) Nees.) seeds

The aim of this research was to evaluate the effects of osmopriming and different hydropriming treatments on the vigour and germination of China aster (Callistephus chinensis) seeds. Seed vigour and germination tests were conducted at 10, 20 and 30°C in darkness for untreated, osmoprimed and hydroprimed seeds. The following parameters and categories of seeds and seedlings were evaluated: the mean germination time (MGT), T10, T50, U75–25, U90–10, the percentage of germinating seeds (Gmax), germination capacity, percentage of abnormal seedlings and dead seeds. The results showed that osmopriming accelerated seed germination to the largest extent and improved the uniformity of germination at 10 and 30°C. Among the hydropriming treatments the highest speed of germination was observed for seeds hydrated in 500 μL of water per 1 g of seeds for 48 h at 15°C. This treatment accelerated seed germination at 10°C compared with the control. Osmopriming increased seed germination capacity at 30°C. None of the applied hydropriming treatments improved this parameter.     

Variation in Seed and Seedling Traits of Celtis australis, a Multipurpose Tree, in Central Himalaya, India

Seeds of Celtis australis were collected from 13 different sources, ranging from 550 to 1980 masl, in Central Himalaya, India. Significant (p = 0.05) variations were observed for seed traits among provenances. However, among various characters, seed weight exhibited maximum variation between seed populations compared to other morphological characters. Between provenances, seed weight ranged from 47.8 to 83.1 g/1000 seed, with mean value of 66.9 ± 10.7 g/1000 seed. Significant (p = 0.01) positive correlation was found between morphological characters of seeds including seed weight and elevational range of seed source. For one year old seedlings, average shoot and root growth was 61.1 ± 13.3 and 30.5 ± 5.4 cm, respectively, irrespective of provenance variation. Inter-comparing biomass yield of the seedlings with altitude, average biomass production was 8.4 ± 2.5, 9.4 ± 3.3 and 12.7 ± 1.7 g/plant, respectively, for low (550–1000 masl), middle (1050–1250 masl) and high (1350–1980 masl) altitudinal populations. Significant (p = 0.01) positive correlation between growth performance of seedlings and altitude of the seed source was recorded. Across the provenances, shoots had the highest proportion of total biomass (42.3%), followed by leaves (32.6%) and roots (24.6%). Among various provenances, Badiyargaon, Agroda, Guptakashi, Jakholi, Gajeli, Srinagar and Palampur populations produced heavier seedlings and grew faster compared to seedlings of other sources.     

Differentiation of seed germination and early seedling growth in ten provenances ofEucalyptus microtheca

An investigation of seed germination and early seedling growth ofEucalyptus microtheca was based on seed collection from 10 widely separated provenances in Australia. Genetic variation of seed germination and early seedling growth was observed among a series of provenances whose natural habitats range from different climatic condition. In the ten provenances, both the model of seed relative germination percentage and the model of seed total germination percentage fitted Logistic regression [y=a/(1+exp(-ex+b))]. In comparison with provenances from four high temperature (mean annual maximum temperature >30.0 °C; mean annual minimum temperature >17.0 °C) areas, six low temperature (mean annual maximum temperature <30.0 °C; mean annual minimum temperature <17.0 °C) areas showed the fast germination rate and the high total germination percentage. For each provenance we have 45 seedlings equally divided into three watering levels (100%, 50%, and 25% of field capacity), and studies on relationship between early seedling growth and climatic factors of the natural habitat of provenance. In control treatment, height growth of the seedling has been associated with intrinsically the driest quarter precipitation in the seed collection areas of provenance. In all the treatments, length growth of the biggest leaf of the seedling was related to mean annual maximum temperature and mean annual minimum temperature in origin of provenance. In contrast, basal diameter growth of the seedling was related to mean annual minimum temperature of the seed collection areas in water stress treatment. From an ecological viewpoint, the fast germination rate and the high total germination percentage of the seed and rapid early growth of the seedling appear to be favourable adaptations to the climatic conditions prevailing in the natural habitat of provenance. Responsible Editor: Chai Ruihai     

冷湿层积法对印度冷杉(Abies pindrow)和长叶云杉(Picea smithiana）种子萌发的影响

研究赤霉素(GA3),冷湿和温度 对五个种源的印度冷杉(Abies pindrow)和长叶云杉(Picea smithiana)种子萌发的影响.种子被浸泡在GA3 (10 mg(L-1)中24小时,然后在3(5(C温度的条件下冷藏15天.设计4个温度(10(C, 15(C, 20(C 和 25(C)条件来促进种子的萌发.结果表明,浸泡和冷湿处理明显增加种子的萌发率.在10 (C时种子的萌发率最高.总体结果表明,种子被浸泡在GA3 (10 mg(L-1)中24小时,冷湿藏15天,可以有效地促进印度冷杉和长叶云杉的种子萌发.统计数据表明,浸泡处理、温度和种源以及与温度的相互作用都对种子的萌发有明显的影响.     

Seedling cold hardiness, bud set, and bud break in nine provenances of Pinus greggii Engelm.

Cold hardiness and timing of bud set and bud break are important processes that provide protection of nursery seedlings against low temperatures. Seedlings of 9 provenances of Pinus greggii from two different regions of Mexico were tested to determine cold hardiness, bud set, and bud break timing differences. Needle sections were exposed to freezing temperatures to determine an injury index of each provenance. In addition, bud set and bud break timing were recorded through the fall, winter and spring. There were significant differences in cold hardiness between seedlings from northern and southern provenances. At the maximum cold hardiness, the index of injury (LT₅₀) for northern provenances was LT₅₀ = −18 °C, compared to −12 °C for southern provenances. There was a considerable variation among the provenances in the proportion of seedlings that set terminal buds. Seedlings from northern provenances had greater proportions of seedlings that set a terminal bud than seedlings from southern provenances. There were also significant differences in the bud break timing in the following spring among the 9 provenances. Seedlings from northern provenances broke bud earlier than southern provenances. Cold hardiness, bud set, and bud break timing results may be useful to determine how far a specific seed source can be moved from its natural environment.     

Germination and seedling growth in Abies lasiocarpa (Hook.) Nutt. as affected by provenance,seed pretreatment,and temperature regime

Abies lasiocarpa (Hook.) Nutt. seeds germinated and the seedlings grew on under controlled environments (18 h photoperiod and 16/8 h thermoperiods; 10/10^oC, 20/20°C, 20/10°C, and 25/10°C). The experiment was concluded after 180 days, and the seedlings were scored for stem diameter and length. Four provenances were included: Colorado “high elevation”; (CO), Oregon 1 600 m a.s.l. (OR), British Columbia 1200 m a.s.l. (BC), and Finland (BCF; originally from British Columbia 1800 m a.s.l.). A cold‐moist pretreatment for 30 days improved germination and seedling growth in the BC and BCF seed lots, while the CO and OR seed lots were less affected. Daily fluctuating temperatures improved germination in the BC and BCF seed lots, the widest fluctuation 25/10°C producing the greatest germination. The average length of the seedlings was 34 mm at 20/20°C, 33 mm at 20/10°C, and 37 mm at 25/10°C; differences in hypocotyl length being most important. There were small but significant differences between the provenances in their reaction to temperature regime. The major part of the seedlings produced 2 or 3 flushes of growth in the 180 days period, the CO provenance having the most stabile buds and the OR provenance being the most labile.     

Seedling growth and water relations of three Cedrela species sourced from five provenances: response to simulated rainfall reductions

The effects of different simulated rainfall regimes on water relations, growth, and biomass production and allocation of five provenances of Cedrela fissilis, C. saltensis and C. balansae were assessed in a pot-grown seedling experiment in greenhouse under uncontrolled conditions. Four simulated rainfall regimes were applied: 600 mm year^?1 (severe water deficit), 800 mm year^?1 (mild water deficit), 1,000 mm year^?1 (mild wet), and 1,200 mm year^?1 (well-watered) used as control. Provenances were compared in terms of water relations (midday leaf water potential, Ψ _md and relative water content, RWC), growth (root, shoot and leaf length, neck diameter), growth rate (shoot- and neck growth rate, SGR and NGR), biomass production (root, shoot and leaf dry weight), and biomass allocation (root:shoot ratio, RSR). Multivariate analyses revealed that water relations differed significantly under all simulated rainfall treatments by means of several variables throughout time. Effects of species × treatment, and provenance nested within species × treatment interactions significantly were important. SGR and RSR also were important to explain differences in Ψ _md and RWC between treatments and provenances. Broadly C. balansae and C. saltensis provenances seem to display a better performance than C. fissilis provenances under severe water deficit only. However, despite differences between provenances, it was not possible to clearly separate them according to their origin, based on water relations and growth performance. Even though the results of this study performed on pot-grown seedlings are based on relatively few observations and require additional confirmation, they allow an opportunity for speculation on the factors that are related to intraspecific variations that are likely to occur during the growth of seedlings from different geographical sites in field condition.     

Inter- and intra-provenances variations in seed size and seedling characteristics of Khaya senegalensis A. Juss in Burkina Faso

Within- and between-provenance variations in seed and seedling traits of Khaya senegalensis A. Juss were studied at INERA in Burkina Faso. Nursery grown seedlings from four provenances in Burkina Faso were used for the study. The studies revealed significant variability in all traits evaluated. Seed length and weight significantly varied among provenances and families within provenances, where Bopiel and Koyenga had the highest mean values. Height and root collar diameter of 1 year old seedlings significantly varied among families within provenances. Except leaf biomass ratio and carbon isotope ratio which varied significantly among provenances but not among families within provenances, all other seedling biomass traits—total plant biomass, stem biomass ratio, leaf biomass ratio, root biomass ratio, root shoot ratio, specific leaf area, and leaf area ratio were significantly affected by provenances and families within provenances. The magnitude of variation due to family effect ranged from 65 to 93 % for seed size traits, and from 4.5 to 17.8 % for seedling characters. Estimates of family heritability were moderate to high (0.67–0.95) for seed traits, but low to moderate (0.19–0.59) for seedling characters, indicating that much of the total variation in seed traits is due to the genetic effect. The two most prominent provenances, Koyenga and Bopiel, with higher seed size and greater seedling growth could be considered for an eventual K. senegalensis improvement program in Burkina Faso.     

云杉种和种源生长性状早期评价

[目的]通过对引种的云杉种和种源试验林的适应性和生长变异研究,选育出最适合当地栽培的优良种和种源。[方法]以甘肃省小陇山沙坝试验基地引种的欧洲云杉、黑云杉、白云杉、蓝云杉、红皮云杉和青海云杉6个树种20个种源为研究对象,分别对6、7、9 a幼林龄的生长性状(树高、地径、新梢和冠幅)进行方差分析和相关性分析,以早期评价云杉种和种源。[结果]6、7、9 a生长期内不同云杉种间和种源间的差异多数达到极显著,表明不同种间和种源间存在较大的遗传变异。利用树高兼地径为主要指标筛选出7个优良种源,分别为欧洲云杉加拿大AB01、AB03种源、白云杉加拿大GL01种源;黑云杉加拿大MA05、MA07、MA08和MA10种源,树高、地径现实增益均超过11%。欧洲云杉、白云杉种源树高与经纬度呈极显著的正相关,与海拔呈极显著的负相关;黑云杉种源树高也与经纬度呈极显著的正相关,但与海拔相关不显著。[结论]在原产地纬度49°16'～58°38'N,经度68°13'～118°24'W区域范围内引进欧洲云杉、白云杉、黑云杉种源,是适宜在甘肃小陇山栽培的云杉树种。     

Variation in spring and autumn frost tolerance among provenances of Russian larches (Larix Mill.)

Abstract

Spring and autumn frost tolerance was measured using material from a range-wide (50–67° N, 38–158° E) provenance trial of four Russian larch species (Larix sukaczewii Dyl., L. sibirica Ledeb., L. gmelinii Rupr. and L. cajanderi Mayr.) growing in northern Sweden. Shoots were collected in early May and late September and frozen at ?8, ?12, ?16 and ?20°C. Cambial damage was assessed visually after development under ideal conditions for 2 weeks. Differences in frost damage among provenances were highly significant in both spring and autumn. Autumn frost damage was significantly correlated with provenance latitude and longitude and spring frost damage was significantly correlated with provenance longitude but not latitude. Frost damage was not correlated with provenance elevation. North-western provenances showed the least damage and far-eastern provenances the greatest damage in both spring and autumn. A possible explanation for less spring frost damage to north-western provenances is adaptation to maritime conditions in proximity to the Barents Sea, which is often ice free in late winter. This would counteract early loss of frost tolerance and bud flushing if warm spells occurred in late winter. North-eastern Siberian provenances did not show similar adaptation and may exhibit increased spring frost damage if global warming eventually results in the Arctic Ocean north of Siberia becoming ice free in late winter.     

Tephrosia species and provenances for improved fallows in southern Africa

Seeking an alternative to Sesbania spp. tree fallows, a Tephrosia species and provenance trial was conducted at Msekera Research Station, Chipata (Zambia) to evaluate eleven Tephrosia vogelii and three Tephrosia candida provenances. They were tested for biomass production, quality of biomass, resistance to root-knot nematodes, nitrogen release, and for their effects on soil nitrogen dynamics. At the end of 1.5 years, the T. candida provenances 02970, 02971 and 02972 from Madagascar produced two times greater amount of aboveground biomass than the T. vogelii provenances. There was little variability among the T. vogelii provenances in terms of litter and biomass production. Weed growth was significantly greater under T. vogelii than T. candida provenances. While Tephrosia vogelii provenance 98/02 from Zambia and T. candida 02972 were highly tolerant to the Meloidogyne incognita nematodes, T. vogelii provenances 02977, 98/03, 02973 from Kenya, Zambia and Malawi, respectively, were highly susceptible to the nematodes. The Tephrosia species and provenances showed a wide variability in terms of N, lignin and polyphenol concentration in their foliage. Mineralization of N in the foliage of T. candida provenances 02970 and 02971 and T. vogelii provenances 98/04 and 02974 from Malawi occurred rapidly within 14 weeks of incubation. At the end of the 2-year growth period, there was significantly greater total inorganic N under T. candida provenance 02972 (12.5 mg kg⁻¹) than T. vogelii (5 mg kg⁻¹) provenance Mungwi 98/02. Maize (Zea mays L.) yields after T. candida provenances were greater than those after T. vogelii provenances. Further testing of the most promising provenances is needed for their effects on subsequent maize yields under a range of farm conditions. This revised version was published online in June 2006 with corrections to the Cover Date.     

Two provenances of Quercus ilex ssp. ballota (Desf) Samp. nursery seedlings have different response to frost tolerance and autumn fertilization

Despite evidences that Holm oak has a high plasticity and great adaptability, there is limited or contradictory knowledge of the morphological and physiological variability of this species. Holm oak has been widely used for reforestation projects in Mediterranean areas, but has frequently shown poor field performance. We hypothesized that Holm oak has inter-population differences in physiological responses to abiotic stressors that could affect reforestation success. The influence of nursery culture on the characteristics of Holm oaks from different provenances has not been explored in depth. Thus, we studied the effect of nursery autumn fertilization on morphological traits, frost tolerance, root growth potential, and nutritional status of two Spanish provenances of Holm oak, La Alcarria (a region with inland Mediterranean climate) and Sierra Morena Occidental (a region with a warm coastal Mediterranean climate). There were significant differences between the provenances in frost tolerance, biomass allocation, and leaf nutrient content, suggesting a role of genetic factors. The leaves of seedlings from La Alcarria had less visual damage at ?12°C than seedlings from the warmer provenance (45% vs. 92%). Seedlings from La Alcarria, compared to those from Sierra Morena, had higher leaf P concentration (0.17% vs. 0.15%), greater stem diameter (3.1?mm vs. 2.7?mm), lower shoot-to-root dry mass ratio (0.46 vs. 0.53), and lower slenderness (4.03 vs. 5.31). For both provenances, N autumn fertilization improved growth, root growth potential, cold hardiness, and nutritional status of seedlings. We suggest that forest reforestation programs should consider to a greater extent Holm oak provenances and their tolerances to different abiotic stressors.     

Effects of Previous High N Addition on Nutrient Conditions in Above-ground Biomass of a Picea abies Stand in Sweden

The effect of different thawing procedures on seedling quality in Norway spruce (Picea abies) was evaluated. Freezer-stored seedlings were thawed rapidly for 20 h by immersion in water with an initial water temperature of 8°C or thawed more slowly by gradually increasing the temperature in storage over a period of 8 weeks. Seedlings from these treatments were also compared with seedlings thawed rapidly overnight at 15°C. Frost tolerance, carbohydrate content and the time of bud break were used as indicators of the vitality of the seedlings. Seedlings thawed rapidly in water or air showed significantly better frost tolerance after storage than slowly thawed seedlings. The contents of sucrose and raffinose in seedlings thawed rapidly were also significantly higher than in seedlings thawed more slowly. Bud break occurred later in seedlings thawed rapidly than in slowly thawed seedlings. Rapid thawing in water may be a good method to ensure the delivery of high-quality thawed seedlings throughout the planting season.     

Low light availability affects leaf gas exchange,growth and survival of Euterpe edulis seedlings transplanted into the understory of an anthropic tropical rainforest

Euterpe edulis Mart. (Arecaceae) is a threatened palm tree of the Brazilian Atlantic Rainforest understory with fundamental importance for the restoration of degraded forest environments. We assessed the leaf gas exchange, growth and survival of E. edulis seedlings transplanted at three different forest sites (S1, S2 and S3) in the same area in which cocoa trees had been cultivated in a rustic agroforestry system. Measurement was carried out during the first year after seedling transplantation. The sites were characterised according to canopy openness (CO) and total daily photosynthetic photon flux density (PPFD). Average CO and PPFD values were 13.3%, 8.0% and 6.7%, and 3.34, 2.79 and 0.62 mol m^?2 d^?1 for S1, S2 and S3, respectively. A progressive decline in seedling survival was observed in all sites throughout the experiment. At 387 d after planting, survival at S1, S2 and S3 was 57%, 44% and 37%, respectively. The gross light-saturated photosynthetic rate (A_max), leaf area and plant biomass were significantly higher (P < 0.05) in S1 and S2 when compared with S3. The values of dark respiration rate (R _d) and photosynthetic compensation irradiance (I _c) were sufficiently low for a positive carbon balance. Notwithstanding, the interpretation of results of microclimate variables together with leaf gas exchange and growth variables indicated that seedlings at all sites were in a suboptimal condition to achieve A_max, which is probably the main cause of the dramatic decline in the seedlings’ survival throughout the first year after transplantation. From a practical point of view, if the values of CO and PFD are lower than 10% and 3 mol m^?2 d^?1, respectively, it is suggested that the transplanting of E. edulis seedlings to the understory of abandoned agroforestry systems be accompanied by cultural practices, such as the thinning and pruning of tree tops.     

Are marginal beech (<Emphasis Type="Italic">Fagus sylvatica</Emphasis> L.) provenances a source for drought tolerant ecotypes?

Due to the expected increases of number and intensity of summer droughts in Central Europe the identification of drought tolerant ecotypes becomes more important in future forestry. A common garden experiment with seedlings of Fagus sylvatica provenances from the center (Germany) and eastern margin (Poland) of the species’ distribution range was conducted. Responses of morphological, physiological, chemical and growth parameters to three drought treatments were analyzed. Relative growth rates of the marginal provenance were lower as compared to the central provenance. The marginal seedlings showed a tendency to higher total biomasses because of higher seed masses. In both provenances drought decreased biomass production and root/shoot ratio which was lower in the central provenance. A lower specific root area of the marginal provenance indicated a better adaptation to low xylem water potentials. Under moderate drought, lower leaf δ¹³C signatures may indicate lower stomatal limitation (or a reduced rate of CO₂ assimilation) in the marginal provenance. We conclude that marginal beech provenances may exhibit a better drought adaptation.     

Effects of high temperature kiln drying on the practical performances of Japanese cedar wood (Cryptomeria japonica) II: Changes in mechanical properties due to heating

Japanese cedar wood specimens were steamed at 80°, 100°, and 120°C over 14 days, and their equilibrium moisture content (M) at 20°C and 60% relative humidity, longitudinal dynamic Young’s modulus (E), bending strength (σ _max), and breaking strain (ε _max) were compared with those of unheated specimens. Steaming for a longer duration at a higher temperature resulted in a greater reduction in M, σ _max, and ε _max. The E of wood was slightly enhanced by steaming at 100°C for 1–4 days and 120°C for 1–2 days, and thereafter it decreased. The slight increase in the E of sapwood was attributable to the reduction in hygroscopicity, while sufficient explanation was not given for a greater increase in the heartwood stiffness. Irrespective of the steaming temperature, the correlations between M and the mechanical properties of steamed wood were expressed in terms of simple curves. M values above 8% indicated a slight reduction in E and s max, whereas M values below 8% indicated a marked decrease in the mechanical performances. In addition, the e max decreased almost linearly with a decrease in the value of M. These results suggest that hygroscopicity measurement enables the evaluation of degradation in the mechanical performances of wood caused by steaming at high temperatures.     

Determining thresholds of low soil temperature for ecophysiological traits of black spruce and jack pine seedlings

Many studies have estimated approximately ranges of thresholds of low soil temperature in the growth and ecophysiological traits of trees, but difficultly determined the exact values. To resolve the problem, black spruce (Picea mariana) and jack pine (Pinus banksiana) seedlings were exposed to 5, 10, 15, 20, 25, 30 and 35°C soil temperature in greenhouses. After 90 days of the treatment, net photosynthetic rate (A), stomatal conductance (gs), transpiration rate (E), water use efficiency (WUE) and specific l...