Response of five tree species to salinity and waterlogging: shoot and root biomass and relationships with leaf and root ion concentrations

Unproductive saline and waterlogged (WT) wastelands could be beneficially transformed into agroforestry systems using trees tolerant to these stresses. We studied the salinity and waterlogging tolerance of five Australian tree species (Acacia salicina, Casuarina glauca, Casuarina obesa, Eucalyptus camaldulensis and Eucalyptus occidentalis) during seedling stage and their relationships with root and leaf ion concentrations. 8-month old plants were exposed for 5 months to five irrigation water salinity treatments (EC values between 2 and 22 dS m^?1) and two waterlogging treatments (drained or WT). The salinity tolerance of the five species was high, although decreased in WT conditions. Irrespective of salinity, the two Casuarina species were more tolerant and the other three species were less tolerant to WT than drained conditions. In all species, salinity and waterlogging increased leaf Cl^? and Na⁺ and decreased leaf Ca²⁺, but not leaf K⁺. Root Cl^? and Na⁺ increased with salinity but not with waterlogging. Salinity tolerance was negatively correlated with Cl^? and Na⁺ leaf accumulation rates per unit increase in salinity. Waterlogging reduced the ability of the seedlings to exclude Cl^? and Na⁺ from the leaves. The two most salt tolerant Casuarina species under both drained and WT conditions showed the highest leaf Cl^? and Na⁺ exclusion and the highest root Cl^? and Na⁺ accumulation, suggesting that sequestration of these toxic ions in their roots was a significant salt-tolerant mechanism. Revegetation of saline and WT wastelands with these tolerant Casuarina species could be profitably used for biomass, biofuel and renewable energy production.     

Calcium mineral nutrition increases the tolerance of Quercus ilex to Phytophthora root disease affecting oak rangeland ecosystems in Spain

Root rot caused by the soil-borne pathogen Phytophthora cinnamomi is leading to significant oak tree mortality in rangeland ecosystems in south western Spain. Susceptibility to P. cinnamomi infections of Q. ilex seedlings with a standard nutrition, deficient in K⁺, and deficient in Ca²⁺, was tested. Oaks deficient in K⁺ showed high values in Ca²⁺ content and were tolerant to the disease. Nutritional deficiency in Ca²⁺, however, did not lead to a higher K⁺ level in plants and induced poorer root development. In addition, K⁺ plant content does not appear to have any effect on pathogen tolerance. Based on these results, we conclude that satisfactory calcium nutrition may confer Holm oaks with a greater tolerance to root disease caused by P. cinnamomi. For this reason, limestone supplements are recommended as a measure against root rot caused by P. cinnamomi in rangelands in southern Spain, as a good option for control of oak root disease.     

Proton translocating ATPase mediated fungicidal activity of eugenol and thymol

Eugenol (1) and thymol (2) exhibit excellent fungicidal activity against pathogenic yeasts, including isolates resistant to azoles. The rapid irreversible action of compound-1 and compound 2 on fungal cells suggested a membrane-located target for their action. We investigated their effect on H⁺-ATPase mediated H⁺-pumping by various Candida species. Both compounds inhibit H⁺-ATPase activity at their respective MIC values — 500 and 100 μg/ml. Glucose stimulated H⁺-extrusion was also inhibited significantly by compound 1 and compound 2. Inhibition of H⁺-ATPase leads to intracellular acidification and cell death. Inhibition of cell growth and H⁺-efflux by test compounds suggests that their antifungal properties are related to their inhibitory effects on H⁺-ATPase.     

宽叶杜香叶柄再生体系建立及种质离体保存研究

The tender leafstalks of Ledum palustre var.dilatatum were used as explants for the experiment.Uniform design for the most suitable media for shoots regeneration immediately at base of tender leafstalks,rooting and germplasm conservation in vitro was screened.The results showed that N6+ZT 2.65 mg·L-1+IAA 0.05 mg·L-1 was fits for shoots regeneration,the frequency of shoots induction was higher than 92.5%;MS(modified)+IAA 0.1 mg·L-1+Kt 0.75 mg·L-1 for rooting,the rate of rooting was 98%;N-68+B9 2.5 mg·L-1+ Ph...     

盐胁迫对16种幼苗渗透调节物质的影响

采用盆栽的方法,对16种2年生幼苗盐(NaCl)胁迫40 d,并进行耐盐性研究。结果表明:随盐浓度的升高,各树种的脯氨酸、可溶性糖和甜菜碱含量均呈上升趋势,在400 mmol·L-1盐浓度下,沙枣和水蜡的脯氨酸含量比对照分别增加了662.0%和562.8%,而可溶性蛋白含量在各树种间差异较大;Na+和Cl-含量在不同部位(根、茎和叶)均随盐浓度增加而增加,鞑靼忍冬、药鼠李、风箱树和醉鱼草叶片中Na+含量增加了5 20倍。K+和Ca2+含量随树种不同表现各异。综合各树种盐害症状和渗透调节物质变化特性,认为柽柳、唐古特白刺、西伯利亚白刺、卫矛和沙柳具有高度耐盐性,水蜡、沙枣、糖朴、美国皂荚和药鼠李具有中高度耐盐性,杜梨、竹柳、鞑靼忍冬、醉鱼草、风箱树和美国白蜡具有中度耐盐性。脯氨酸、可溶性糖和矿质元素含量(尤其是Na+、K+和Cl-)的变化对植物耐盐能力的影响较普遍也较大。     

Verbascoside isolated from Tectona grandis mediates gastric protection in rats via inhibiting proton pump activity

Evidences have suggested that Tectona grandis (TG) attenuates gastric mucosal injury; however its mechanism has not yet been established. The aim of present study was to evaluate the gastroprotective mechanism of ethanolic extract of TG (E-EtOH), butanolic fraction (Fr-Bu) and to identify its active constituents. Anti-ulcer activities were evaluated against cold restraint (CRU) and pyloric ligation (PL) induced gastric ulcer models and further confirmed through H⁺ K⁺-ATPase inhibitory activity. Cytoprotective activity was evaluated in alcohol (AL) induced gastric ulcer model and further through PGE₂ level. E-EtOH and Fr-Bu attenuated ulcer formation in CRU. Moreover E-EtOH and Fr-Bu displayed potent anti-secretory activity as evident through reduced free acidity and pepsin activity in PL, confirmed further by in vitro inhibition of H⁺ K⁺-ATPase activity. In addition cytoprotective potential of E-EtOH and Fr-Bu were apparent with protection in AL model, increased PGE₂ content and enhanced mucin level in PL. Phytochemical investigations of Fr-Bu yielded terpenoides and a phenolic glycoside, verbascoside. The anti-secretory mechanism of verbascoside mediated apparently through inhibition of H⁺ K⁺-ATPase with corresponding decrease in plasma gastrin level, is novel to our finding. Gastroprotection elicited by TG might be through proton pump inhibition and consequent augmentation of the defensive mechanism.     

盐胁迫对红楠幼苗生长及Na+、K+吸收和分布的影响

In order to explore the salt tolerance mechanism of Machilus thunbergii, the effects of salt stress on seedling biomass, root morphology, sodium and potassium absorption and distribution were studied. The results showed that the above-ground biomass increased slightly under lower salt stress conditions, while the below-ground biomass, root length and root surface area showed a downtrend. The above-ground growth was limited under high concentration salt stress, while the under-ground growth was not subject to significant restrictions. The absorption of Na⁺ in root increased under salt stress, but that of K⁺ decreased. The ability of Na⁺ transporting from root to leaf and stem was weakened. The accumulation of Na⁺ in stem and leaves was less. With the decreased absorption of K⁺, the ratio of Na⁺/K⁺ also continuously increased. With the increased concentration of salt stress, the ability of K⁺ absorption in roots increased. The ability of K⁺ transporting from root to leaf and stem was enhanced, which resulted in significant increase of K⁺ in the leaves and stem. The accumulation of Na⁺ in the under-ground was significantly greater than that in above-ground, while the K⁺ content in above-ground increased significantly, which played a key role in maintaining normal growth and metabolism of M. thunbergii.     

3种白刺耐盐性的对比分析

以2年生西伯利亚白刺、齿叶白刺和唐古特白刺苗为材料,设置0、100、200、300、400 mmol.L-1NaCl 5种盐浓度开展胁迫试验,测定并对比分析其对盐胁迫的生长及生理生化响应。结果表明:低盐浓度处理促使白刺生长速度和生物量增加、叶绿素含量增高,高盐浓度处理下这种促进作用降低;在100 mmol.L-1的盐处理下,唐古特白刺、西伯利亚白刺、齿叶白刺叶绿素含量均达最高,分别为0.72、0.78、0.61 mg.g-1;在400 mmol.L-1的盐处理下,唐古特白刺、西伯利亚白刺、齿叶白刺生物量为最低,分别为10.49、12.42、10.19 g.株-1,仅为对照的75%79%;3种白刺中,唐古特白刺的Na+/K+最高,施盐处理下西伯利亚白刺的Na+/K+均高于对照,而齿叶白刺则低于对照;随着盐浓度的增加,3种白刺叶片中可溶性蛋白的含量递增,可溶性糖含量则先增后减;低盐浓度处理的唐古特和西伯利亚白刺叶片中MDA含量比对照低,齿叶白刺却比对照高;3种白刺的POD和SOD活性在盐处理下高于对照,其中唐古特白刺叶片中POD活性最低,齿叶白刺中SOD活性最高;3种白刺在盐胁迫下均能正常生长。     

Anti-ulcer constituents of Annona squamosa twigs

Phytochemical investigation of Annona squamosa twigs, resulted in isolation and identification of twelve known (1-12) compounds among them one 1-(4-β-D-glucopyranosyloxyphenyl)-2-(β-D-glucopyranosyloxy)-ethane (11) is synthetically known but first time isolated from natural sources. Their structures were elucidated using 1D and 2D NMR spectroscopic analysis. The isolated compounds (2-8, 11) were evaluated for H⁺ K⁺-ATPase activity. Three of these compounds (+)-O-methylarmepavine (2), N-methylcorydaldine (3), isocorydine (6) showed promising anti-secretory activity. Activity of these compounds, comparable to the standard drug omeprazole is novel to our finding. Moreover, there is no information accessible regarding the pharmacological effect of A. squamosa on the gastrointestinal system. This study is the first of its kind to show the significant anti-ulcer effect of A. squamosa. The present study aimed to evaluate the gastroprotective effect of A. squamosa (AS) and to identify its active constituents. Anti-ulcer activity was evaluated against cold restraint (CRU), pyloric ligation (PL), aspirin (ASP), alcohol (AL) induced gastric ulcer and histamine (HA) induced duodenal ulcer model and further confirmed through in vitro assay of H⁺ K⁺-ATPase activity and plasma gastrin level. AS and its chloroform and hexane fraction attenuated ulcer formation in CRU, PL, HA model and displayed anti-secretory activity in vivo through reduced free, total acidity and pepsin in PL, confirmed by in vitro inhibition of H⁺ K⁺-ATPase activity with corresponding decrease in plasma gastrin level. Cytoprotection of AS was apparent with protection in AL, ASP models and enhanced mucin level in PL.     

Does soil organic matter variation affect the retention of NH4 and NO3 in forest ecosystems?

Human activities have fundamentally changed global nitrogen (N) cycling, leading to elevated N deposition in most parts of the world. The fate of deposited N, whether being retained to sustain plant growth or causing ecosystem N saturation, is critical to the global carbon (C) cycling and local environment. In a short-term laboratory experiment, we used ¹⁵N-labeled NH₄⁺ and NO₃⁻ to study the fate of N inputs in forest soils and what regulates N retention. Soils with a wide range of organic matter content and other attributes were collected from a 70-year-old plantation containing monotypic stands of Norway spruce (Picea abies), red pine (Pinus resinosa), sugar maple (Acer saccharum), and red oak (Quercus rubra), and separated into 0-5 cm and 5-15 cm layers. Nitrogen added to the soil was either immediately extracted (Time 0: T0) with K₂SO₄ solution, or incubated for 7 d (T7) and then extracted. Retention of ¹⁵N into the non-extractable soil pool at T0 was limited; but after the 7-d incubation, between 20 and 70% of the ¹⁵NH₄⁺ was retained. Nitrification transformed on average 50% of the ¹⁵NH₄⁺ into ¹⁵NO₃⁻ during the incubation while retention of ¹⁵NO₃⁻ at T7 remained low (7.40 ± 1.08%). Retention of ¹⁵NH₄⁺ into non-extractable soil at T7 was positively correlated to the percentage of soil organic matter (SOM) (r² = 0.323, P < 0.001), and was significantly higher (P < 0.001) in the high-SOM 0-5 cm layer than in the low-SOM 5-15 cm layer. Conversion of ¹⁵NH₄⁺ to ¹⁵NO₃⁻ during incubation significantly reduced the ¹⁵NH₄⁺ retention (P < 0.001). Our results suggest that the variations of SOM and other soil attributes play strong roles in the retention of newly deposited inorganic N and could affect forest ecosystem responses to chronic N deposition.     

Cytochemical localization of H+-ATPase and sub-cellular variation in mesophyll cells of salt-treated Cyclocarya paliurus seedlings

Cyclocarya paliurus seedlings of three provenances were treated with three levels of salt (0, 51.0 and 85.0 mmol/L NaCl) in a hydroponic system of a phytotron. The ultrastructural distribution of H⁺-ATPase activity and ultrastructural variation were investigated in mesophyll cells of C. paliurus seedlings after 12 or 20 days of salt treatment. The results showed that under normal growing conditions, H⁺-ATPase activity was low and localized mainly in the nucleus. After 12 days of salt treatment and an increase in salinity, we found that the greater the H⁺-ATPase activity, the lighter the damage suffered by mesophyll subcells after 20 days of salt treatment and the stronger the salt-adaptation ability of seedlings. The location of H⁺-ATPase, largely in the nucleus, indicated that salt-damage suffered by the seedlings was light, whereas its presence, mainly in the vacuoles, showed that salt-damage was more serious. Our preliminary conclusion is that the salt-tolerance level of C. paliurus seedlings for the three kinds of provenances was in the following order, from high to low: Huangshan seedlings from Anhui Province > Kunming seedlings from Yunnan Province > Jiujiang seedlings from Jiangxi Province.     

Afforestation method affects the isotopic composition of planted Pinus halepensis in a semiarid region of Spain

We used an isotopic approach to evaluate the effects of three afforestation methods on the ecophysiology of an Aleppo pine plantation in semiarid Spain. The site preparation methods tested were excavation of planting holes (H), subsoiling (S), and subsoiling with addition of urban solid refuse to soil (S + USR). Five years after plantation establishment, trees in the S + USR treatment were over three times larger than those in the S treatment, and nearly five-fold larger than those planted in holes. Differences in tree biomass per hectare were even greater due to disparities in initial planting density and pine tree mortality among treatments. Pine trees in the S + USR treatment showed higher foliar P concentration, δ¹³C and δ¹⁵N than those in the S or H treatments. Foliar δ¹⁵N data proved that trees in the S + USR treatment utilized USR as a source of nitrogen. Foliar δ¹³C and δ¹⁸O data suggest that improved nutrient status differentially stimulated photosynthesis over stomatal conductance in the pine trees of the S + USR treatment, thus enhancing water use efficiency and growth. In the spring of 2002, trees in the S + USR treatment exhibited the most negative predawn water potentials of all the treatments, indicating that the rapid early growth induced by USR accelerated the onset of intense intra-specific competition for water. The results of this study have implications for the establishment and management of Aleppo pine plantations on semiarid soils. Planting seedlings at low density and/or early thinning of pine stands are strongly recommended if fast tree growth is to be maintained beyond the first few years after USR addition to soil. Foliar C, O and N isotope measurements can provide much insight into how resource acquisition by trees is affected by afforestation techniques in pine plantations under dry climatic conditions.     

An assessment of rainfall modification in mountainous ecosystems dominated by Fagus sylvatica L. and Picea abies (L.) Karst. (Western Balkans,Bulgaria) by multivariate analyses

Bulk precipitation, throughfall, and stemflow samples were collected in Petrohan site (Western Balkan, Bulgaria), operating in the framework of the Long-Term Ecological Research network, during a 6-year period (1995–2000). This mountain area is characterized by the presence of beech and spruce forests (Fagus sylvatica L. and Picea abies (L.) Karst.) and is utilized for drinking water supply. All samples were analyzed for pH and major inorganic anions (Cl^?, NO₃ ^?, and SO₄ ^2?) and cations (Ca²⁺, K⁺, Mg²⁺, Na⁺, and NH₄ ⁺). Results show that bulk precipitation in this region is mainly acidic (pH = 5.1), and the dominant neutralization components in the rainwater are Ca²⁺ and NH₄ ⁺. As for Ca²⁺, K⁺, Mg²⁺, Cl^?, and SO₄ ^2?, they are not originated by marine source. Cluster analysis and principal component analysis were used for investigating the possible sources contributing to the chemical composition of the bulk precipitation and its possible modifications during the passing through beech and spruce stands. Results highlight that local and long-range transport-related anthropogenic sources and natural sources contribute to the anion and cation content of the bulk precipitation. The enrichment of the solution through the foliage made up of dry depositions is significant in both stands, but canopy leaching processes are much greater in the spruce forest, especially for Ca²⁺. As for the stemflow, it follows the same pattern as the throughfall, but N uptake and a strong K⁺ and Mg²⁺ leaching are observed mainly in the spruce stand.     

Current uptake of 15N-labeled ammonium and nitrate in flooded and non-flooded black spruce and tamarack seedlings

? We investigated the effects of flooding for three weeks on physiological responses and uptake of NH ₄ ⁺ and NO ₃ ^? by black spruce (Picea mariana (Mill.) BSP.) and tamarack (Larix laricina (Du Roi) K. Koch) seedlings fertilized with labeled (¹⁵NH₄)₂SO₄ or K¹⁵NO₃ in a growth chamber experiment.

? Flooding reduced photosynthesis (A), transpiration (E), water use efficiency (WUE), and current uptake of NH ₄ ⁺ and NO ₃ ^? in both species.

? Under flooding, there were no significant differences between the two species in uptake of either NH ₄ ⁺ or NO ₃ ^? at the whole-plant level but black spruce had higher translocation of NH ₄ ⁺ to the shoots than did tamarack.

? Under non-flooded conditions, black spruce seedlings exhibited higher uptake of both NH ₄ ⁺ and NO ₃ ^? than did tamarack and demonstrated preferential uptake of NH ₄ ⁺ (19. 7 mg g^?1dw) over NO ₃ ^? (12.3 mg g^?1dw after three weeks). In contrast, non-flooded tamarack seedlings had equal uptake of NH ₄ ⁺ (4.96 mg g^?1dw) and NO ₃ ^? (4.97 mg g^?1dw).

? We hypothesize that the ability of tamarack to equally exploit both ¹⁵NH ₄ ⁺ and ¹⁵NO ₃ ^? would confer an advantage over black spruce, when faced with limitations in the availability of different forms of soil nitrogen.

     

Comparison of neuroprotective effects of five major lipophilic diterpenoids from Danshen extract against experimentally induced transient cerebral ischemic damage

We observed neuroprotective effects of five major lipophilic diterpenes derived from Danshen (Radix Salvia miltiorrhiza) extract, such as cryptotanshinone (CTs), dihydrotanshinone I (DTsI), tanshinone I (TsI), tanshinone IIA (TsIIA) and tanshinone IIB (TsIIB), in the hippocampal CA1 region (CA1) against transient ischemic damage in gerbils. These diterpenes were administered 30 min before ischemia–reperfusion and the animals were sacrificed 4 days after ischemia–reperfusion. In the vehicle-treated-group, cresyl violet positive (CV⁺) cells and neuronal nuclei (NeuN)⁺ neurons were significantly decreased in the CA1. However, in the TsI- and CTs-treated-ischemia-groups, CV⁺ and NeuN⁺ neurons were abundant in the CA1. In the other groups, the number of CV⁺ and NeuN⁺ neurons was less than the TsI- and CTs-treated-ischemia-groups. In addition, gliosis induced by ischemic damage was apparently blocked in the TsI- and CTs-treated-ischemia-groups. These results suggest that TsI and CTs among five major lipophilic diterpenes have strong potentials for neuroprotection against ischemic damage.     

卷荚相思组培快繁技术研究

[目的]建立16年生卷荚相思优树组培快繁技术体系。[方法]以16年生卷荚相思优树的当年新生枝条带腋芽茎段为材料,对卷荚相思外植体进行消毒、初代培养、增殖培养、生根培养和移植等。[结果]表明:通过对16年生卷荚相思成年优树采条进行扦插,以扦插苗建立采穗圃,选取采穗圃中当年生健康无病虫害枝条的中段为外植体,最佳消毒方式为75%的酒精处理0.5 min和0.1%的升汞处理18 min,其存活率达69.33%,芽诱导率达86.67%;最佳初代培养基为改良MS+蔗糖40 g·L-1,出芽率为91.33%。最佳增殖培养基为MS+6-BA 0.5 mg·L-1+NAA 0.1 mg·L-1+蔗糖30 g·L-1,35 d增殖倍数可达3.50倍;最佳生根培养基为1/2 MS+IBA 0.25 mg·L-1+NAA 0.5 mg·L-1+蔗糖40 g·L-1,15 d生根率为96.11%;将生根苗移植至以沙为基质的营养杯中,存活率为71.11%。[结论]研究解决了16年生卷荚相思成年优树外植体污染率高和芽诱导率低等问题,建立的组培快繁技术体系对今后加快卷荚相思良种选育及优质苗木大量扩繁具有重要作用。     

Development of an efficient protocol for plant regeneration from nodal explants of recalcitrant bamboo (Bambusa arundinacea Retz. Willd) and assessment of genetic fidelity by DNA markers

The present study describes an efficient method for in vitro plant regeneration in B. arundinacea through axillary shoot bud proliferation. Nodal explants were excised, cultured on MS medium containing different concentrations of 6-benzylaminopurine (BAP), kinetin (KIN) (0.5–5.0 mg l^?1) alone and/or in combinations with KIN/BAP (0.5 mg l^?1). The highest frequency (91.5 %) of multiple shoot bud induction with maximum number of shoots (85 shoots/explant) was noticed on MS medium + 3.0 mg l^?1 BAP + 0.5 mg l^?1 KIN. The regenerated multiple shoots were elongated on MS medium + 4.0 mg l^?1 KIN + 2.0 mg l^?1 gibberellic acid (GA₃) with maximum shoot length (4.9 cm). The elongated shoots were transferred to MS medium containing indole-3 butyric acid (IBA; 0.5–5.0 mg l^?1) alone and/or in combination with 0.5 mg l^?1 KIN and BAP. Highest frequency of rooting (75 %) was obtained on half-strength MS medium + 2.0 mg l^?1 IBA + 0.5 mg l^?1 KIN. After hardening, the plantlets were shifted to the green house and subsequently established in the field conditions with 90 % survival rate. random amplified polymorphic DNA (RAPD) markers were used to evaluate the genetic stability of the regenerants. RAPD profiles generated from the regenerated plants were found to be monomorphic, similar to the control. Results confirmed that the regenerated plants were true-to-type in nature and the developed micropropagation protocol could be used for large scale plant production of B. arundinacea.     

白花泡桐优树试管嫁接幼化及组培快繁技术研究

以白花泡桐优树‘白优2号’为试验材料,通过组织培养和试管嫁接方法,对白花泡桐优树材料的幼化技术进行了研究.结果表明:外植体初代培养萌发的嫩芽为最适合的接穗;‘建始桐3号’为试管嫁接较合适的砧木;采用劈接进行;MS+ NAA0.3 mg·L-1+蔗糖30 g·L-1为试管嫁接培养基;继代增殖和生根培养基分别为1/2MS ...     

Nitrogen form and concentration interact to affect the performance of two ecologically distinct Mediterranean forest trees

Most studies examining inorganic N form effects on growth and nutrition of forest trees have been conducted on single species from boreal or temperate environments, while comparative studies with species from other biomes are scarce. We evaluated the response of two Mediterranean trees of contrasting ecology, Quercus ilex L. and Pinus halepensis Mill., to cultivation with distinct inorganic N forms. Seedlings were fertilized with different NH₄ ⁺/NO₃ ^? proportion at either 1 or 10 mM N. In both species, N forms had small effects at low N concentration, but at high N concentration they markedly affected the plant performance. A greater proportion of NH₄ ⁺ in the fertilizer at high N caused toxicity as it reduced growth and caused seedling death, with the effect being greater in Q. ilex than in P. halepensis. An increase in the proportion of NO₃ ^? at high N strongly enhanced growth relative to low N plants in P. halepensis but had minor effects in Q. ilex. Relatively more NH₄ ⁺ in the fertilizer enhanced plant P concentration but reduced K concentration in both species, while the opposite effect occurred with NO₃ ^?, and these effects were enhanced under high N concentration. We conclude that species responses to inorganic N forms were related to their ecology. P. halepensis, a pioneer tree, had improved performance with NO₃ ^? at high N concentration and showed strong plasticity to changes in N supply. Q. ilex, a late successional tree, had low responsiveness to N form or concentration.     

Improvement of the tissue culture technique for <Emphasis Type="Italic">Melaleuca alternifolia</Emphasis>

Tea tree oil is extracted from the leaves and twigs of Melaleuca alternifolia (Maiden & Betche) Cheel, and it is widely used in medicines, food preservatives, cosmetics and health care products. Traditional propagation of M. alternifolia from seeds does not necessarily transfer the desired characteristics from their mother trees, the seedlings are not uniform, and the multiplication rate from cuttings is relatively low. For these reasons, it is necessary to develop tissue culture techniques for this species. This study showed that an efficient explant initiation medium for M. alternifolia was MS 1/2 + BA 0.6 mg L^?1 + NAA 0.1 mg L^?1 + sucrose 30 g L^?1, which yielded a 75.9 % initiation rate. An efficient multiplication medium was MS + BA 0.3 mg L^?1 + NAA 0.15 mg L^?1 + sucrose 30 g L^?1, which yielded a 4.3 multiplication rate and 3.2 cm shoot length. The rooting medium was MS 1/2 + IBA 0.1–0.25 mg L^?1 + sucrose 15 g L^?1, which yielded a 100 % rooting rate, 2.94–3.32 roots per individual and 1.36–1.44 cm root length. Local red-core soil was suitable as a transplant medium, and yielded 98 % survival. This study improved the tissue culture technique for mass-propagation of M. alternifolia, enabling the production of high quality plants for market.