伞房属4个树种/亚种在广东乐昌的早期生长表现

分析引自澳大利亚东部的桃金娘科（Myrtaceae）伞房属(Corymbia) 4个树种/亚种在广东省乐昌试验点的早期生长表现,结果表明：10 a生时,4个树种/亚种生长量最大的是大叶斑皮桉（Corymbia henryi）,其次是斑皮柠檬桉（Corymbia citriodora ssp. variegata）、柠檬桉（Corymbia citriodora ssp. citriodora）和斑皮桉（Corymbia maculata）,平均单株材积分别为0067 4、0059 0、0054 1和0034 1 m3;与8 a生时比较,4个树种/亚种在10 a生时仍保持较快的增长速度,材积增长均在67%以上,其中斑皮桉的材积增长率高达1450%。方差分析结果表明：在试验组Ⅰ,柠檬桉和大叶斑皮桉3个生长性状在家系间差异极显著（P＜001）,种源间胸径差异达极显著水平（P＜001）,树高差异达显著水平（P＜005）,单株材积差异不显著;在试验组Ⅱ,斑皮柠檬桉和斑皮桉3个生长性状在种源、家系间差异极显著（P＜001）。以单株材积高于对照为选择目标,选出大叶斑皮桉2个种源2个家系,斑皮柠檬桉5个种源11个家系,共计7个种源13个家系,分别占参试种源和家系总数的389%和140%。     

不同预处理方法对柠檬桉染色体制片技术的影响

以柠檬桉种子的根尖为研究材料,通过比较了3种浓度的秋水仙素、2 mmol·L-1的8-羟基喹啉、冰水混合物及以不同比例冰水混合物和0.1%的秋水仙素的混合液等预处理,在多个时间梯度对柠檬桉根尖染色体制片的影响进行了研究,结果发现：3种浓度秋水仙素预处理中,0.1%秋水仙素预处理1.5 h的染色体浓缩适中,分散性好,有较多的分裂相;2 mmol·L-1的8-羟基喹啉预处理的染色体均分散性较差,且分裂相较少;冰水混合物预处理12 h 的染色体浓缩适中且分裂相较多,分散程度较好。其余处理时间的染色体浓缩程度不理想,不易进行染色体分析;混合液中2：3比例下的染色体分散性较好,且浓缩程度适中,有较多的分裂相,综合比较结果由优到劣的处理方法为：0.1%秋水仙素预处理1.5 h＞2：3混合液＞冰水混合物处理12 h＞2 mmol·L-1的8-羟基喹啉,其中在上午11：30—12：30取材,0.1%的秋水仙素处理根尖1.5 h,效果最佳。     

托里桉组培快繁技术初步研究

以2 a托里桉超级苗不同株系的茎段为外植体进行组培快繁研究,结果表明：适合诱导的培养基为MS改良+6-BA 0.5mg·L-1+NAA 0.1 mg·L-1;适合6号株系增殖培养基为MS改良+6-BA 0.2 mg·L-1+NAA 0.1 mg·L-1,适合7号、10号株系的增殖培养基为MS改良+6-BA 0.3 mg·L-1+NAA 0.2 mg·L-1;适当缩短继代周期是解决桉苗顶稍枯萎、上部叶片脱落等症状简单、有效的方法;适合的生根培养基为1/2MS改良+ IBA 0.2 mg·L-1+ ABT 0.6 mg·L-1,生根苗移栽成活率可达90%。     

班皮桉及其近邻树种CCR基因分子变异分析

选取伞房属班皮桉及其近邻树种共5部类16个样本提取基因组DNA,用2对引物进行PCR扩增,采用凝胶直接纯化,改进测序反应后测序.以Eucalyptus gunniiCCR作对照,通过ClustalW进行比对分析序列变异和MEGA 3进行系统进化分析.结果显示:在所得到的伞房属16个样本CCR序列中,A,C,G和T 4种核苷酸所占比例分别为24.92%,23.18%,23.22%和28.67%,A T含量明显高于G C.共发现292个变异位点,占分析位点总数的9.71%,变异除118个转换和97个颠换外,有93个位点的插入/缺失,其中简约信息位点185个,占63.36%.部分变异位点重叠.转换与颠换比值为1.22∶1.00.CCR系统发育树显示:E.gunnii是一个单独分枝,5部类亲缘可以分辨开来,Rufaria尤其明显.Rufaria最早产生分歧,其次是Ochraria和Cadagaria,Blakearia分歧属最迟进化.     

Impacts of increased fire frequency and aridity on eucalypt forest structure,biomass and composition in southwest Australia

Water stress and fire disturbance can directly impact stand structure, biomass and composition by causing mortality and influencing competitive interactions among trees. However, open eucalypt forests of southwest Australia are highly resilient to fire and drought and may respond differently to increased fire frequency and aridity than forests dominated by non-eucalypt species. We measured the variation in stem density, basal area, stand biomass, sapwood area, leaf area and litterfall across 16 mixed jarrah (Eucalyptus marginata) and marri (Corymbia calophylla) forest stands along an aridity gradient in southwest Australia that had variable fire histories. Fire frequency was defined as the total number of fires over a ∼30-year period and aridity as the ratio of potential evapotranspiration to annual precipitation. Total stand biomass and sapwood area were predicted from diameter at breast height of individual jarrah and marri trees using allometric equations. Leaf area was estimated using digital cover photography. More arid and frequently burnt stands had higher stem density, especially of smaller trees, which were mainly jarrah. Overall, both standing biomass and leaf area decreased at more arid sites, while sapwood area was largely unaffected by aridity, suggesting that these stands respond to increased water limitation by decreasing their leaf area relative to their sapwood area. Biomass of marri was reduced at more arid and, to a lesser extent, at more frequently burnt stands. However, total stand biomass (jarrah and marri) and leaf area index did not vary with fire frequency, suggesting that less marri biomass (due to slower growth rates, higher mortality or less recruitment) was compensated by an increase in the density of jarrah trees (regeneration). We conclude that increased fire and drought shift tree species composition towards more fire-resistant species and result in denser stands of smaller trees. In contrast, total stand biomass declines with increasing aridity, but has no association with fire frequency.     

3个澳大利亚伞房花属树种在华南地区的观赏价值分析

柠檬桉、皱果桉、托里桉作为伞房花属树种,在我国已经成功引种,在木材生产、园林观赏等领域不同程度应用,作为具有重要观赏价值的树种,对其观赏性状的特点缺乏深入分析.本文根据园林景观植物的观赏要求,从整体树形、树皮、花色、花期、叶形、叶色、枝干特点入手,结合生态特性,探讨这3个树种的观赏价值及其应用形式,以为这些树种能在我国,尤其是华南地区园林中的应用提供参考依据.     

伞房属4个树种在广东德庆的引种试验

本文分析了引自澳大利亚东部的伞房属(Corymbia)桉树4个树种16个种源85个家系及6份混合种子,以来自广东省的2份柠檬桉混合种子作为对照,共计93个家系,在广东省德庆试验点近3 a的生长表现。试验家系的平均成活率为77.71%,平均保存率73.23%。成活率和保存率较高的树种是柠檬桉,为78.85%和75.51%,其次为斑皮柠檬桉,为77.71%和73.23%。树种、种源和家系间的树高、胸径和单株材积生长均在0.000 1水平上差异显著。初步选出柠檬桉2个种源的5个家系,斑皮柠檬桉3个种源的9个家系,大叶斑皮桉2个种源3个家系,共计7个种源17个家系,分别占参试种源和家系的38.9%和18.3%。     

Infection and disease development of Quambalaria spp. on Corymbia and Eucalyptus species

Quambalaria spp. are eucalypt leaf and shoot pathogens of growing global importance, yet virtually nothing is known regarding the manner in which they infect and colonize their hosts. A study of the infection process of Q. pitereka and Q. eucalypti on Corymbia and Eucalyptus species was thus undertaken using light, scanning and transmission electron microscopy after artificial inoculation. Conidial germination was triggered when relative humidity levels exceeded 90% and commenced within 2 h in the presence of free water. Light reduced germination but did not prevent germination from occurring. Conidial germination and hyphal growth occurred on the upper and lower leaf surfaces with penetration occurring via the stomata or wounds on the leaf surface or juvenile stems. There was no evidence of direct penetration of the host. Following penetration through the stomata, Q. pitereka and Q. eucalypti hyphae grew only intercellularly without the formation of haustoria or interaction apparatus, which is characteristic of the order Microstromatales. Instead, the presence of an interaction zone is demonstrated in this paper. Conidiophores arose through stomatal openings producing conidia 7 days after infection.     

Genetic variation in growth and wood-quality traits of Corymbia citriodora subsp. variegata across three sites in south-east Queensland,Australia

Ten growth or wood-quality traits were assessed in three nearby Corymbia citriodora subsp. variegata (CCV) open-pollinated family-within-provenance trials (18 provenances represented by a total of 374 families) to provide information for the development of a breeding program targeting both pulp and solid-wood products. Growth traits (diameter at breast high over bark [DBH], height and conical volume) were assessed at 3 and 7 years of age. Wood-quality traits (density [DEN], Kraft pulp yield [KPY], modulus of elasticity [MoE] and microfibril angle [MfA]) were predicted using near-infrared spectroscopy on wood samples collected from these trials when aged between 10 and 12 years. The high average KPY, DEN and MoE, and low average MfA observed indicates CCV is very suitable for both pulp and timber products. All traits were under moderate to strong genetic control. In across- trials analyses, high (>0.4) heritability estimates were observed for height, DEN, MoE and MfA, while moderate heritability estimates (0.24 to 0.34) were observed for DBH, volume and KPY. Most traits showed very low levels of genotype × site interaction. Estimated age–age genetic correlations for growth traits were strong at both the family (0.97) and provenance (0.99) levels. Relationships among traits (additive genetic correlation estimates) were favourable, with strong and positive estimates between growth traits (0.84 to 0.98), moderate and positive values between growth and wood-quality traits (0.32 to 0.68), moderate and positive between KPY and MoE (0.64), and high and positive between DEN and MoE (0.82). However, negative (but favourable) correlations were detected between MfA and all other evaluated traits (?0.31 to ?0.96). The genetic correlation between the same trait expressed on two different sites, at family level, ranged from 0.24 to 0.42 for growth traits, and from 0.29 to 0.53 for wood traits. Therefore simultaneous genetic improvement of growth and wood property traits in CCV for the target environment in south-east Queensland should be possible, given the moderate to high estimates of heritability and favourable correlations amongst all traits studied, unless genotype × site interactions are greater than was evident.