Effect of different pre-sowing treatments on seed germination percentage and growth performance of Acacia auriculiformis

Seed morphology,germination and seedlings growth of Acacia auriculiformis were studied.The experiment was conducted in the nursery of Forestry and Wood Technology Discipline,Khulna University,Bangladesh.Matured seeds of the species were collected from healthy trees of road side plantation from different areas of Khulna District,Bangladesh and treated with five pre-sowing treatments（control,immersion in cold water,immersion in hot water,scarification with sand paper and immersion in concentrated H2SO4）.The average length,breadth and thickness were found to be（0.58±0.017） cm,（0.44±0.007） cm and（0.20±0.089） cm,respectively.Germination was conducted in polybags with a mixture of top soil,coconut husk,coarse sand,and fine sand in a ratio of 3：4：1：1.Results reveal that pre-sowing treatments influences the germination rates of seeds that significantly increase the percentage germination compared with those in control（43%） and cold water treatment（52%）.The highest germination success rate was found 83% in hot water treatment followed by 78% in scarification with sand paper,and 75% with immersion in H2SO4.Germination started from 7 to 12 days and completed between 28 and 35 days period in all treatments.ANOVA showed the significant difference（p0.05） among the treatments in seed germination,but no significant difference among treatment with regard to starting day,closing day and total germination period.In case of height and diameter growth,seedlings originated from the seeds with hot water treatment shows significantly higher in wet season（from May to July）.Hot water treatment can be recommended on seed germination of the species in rural Bangladesh.

Effects of industrial and residential sludge on seed germination and growth parameters of Acacia auriculiformis seedlings

A study was conducted to evaluate the effects of sludge （industrial and residential） on seed germination and growth performance of Acacia auriculiformis seedlings at the nursery of Institute of Forestry and Environmental Sciences, Chittagong University （IFESCU）, Bangladesh. Before sowing of the seeds, different combinations of sludge were incorporated with the nutrient-deficient natural forest soils. Seed germination and growth parameters of the seedlings （shoot and root length, collar diameter, fresh and dry weight of shoot, and root and total dry biomass） were recorded after one, two and three months of seed sowing. Physio-chemical parameters （pH, organic carbon, nitrogen, phosphorus, and potassium） and heavy metals （chromium, nickel, manganese, cadmium and zinc） of each treatment were also analyzed before sowing of seeds and after harvesting of seedlings. Results show that the seed germination percentage and the seedling growth parameters varied significantly in the soil added with sludge in comparison to control. The highest germination percentage （90%） was observed in the treatment of soil with residential sludge of 2：1 compared to control. The highest growth and biomass of the seedlings as well as the maximum percentage of organic carbon and nutrients （N, P and K） were also recorded in the same combination. Soil added with industrial sludge had a higher concentration of heavy metal than that of residential sludge. The highest concentrations of heavy metals were found in soil added with industrial sludge of 1：1. It is recommended that soil added with residential sludge of 2：1 provide good condition for better seed germination and growth ofA. auriculiformis seedlings in degraded forest soil.

Pulpwood Quality of the Second Generation Acacia auriculiformis

The physical,chemical and fibre characteristics of the 6,8 and 10 years old akashmoni(Acacia auriculiformis)wood from the second generation seed and their suitability for pulping were assessed and compared with the wood of 10 years old from the first generation seed.The A.auriculiformis of 8 years old had the highestα-cellulose and lower lignin than those of 6 and 10 years old,which are similar to the first generation wood.This study also evaluated the effect of cooking time,temperature and active alkali on kraft pulping.The most important influence factors for pulp yield and kappa number were active alkali charge and time.The highest screened rejects were observed for young tree.Delignification degree of the 1st generation was faster than that of the 2nd generation A.auriculiformis.

Characterization of mean stem density,fibre length and lignin from two Acacia species and their hybrid

The objective of this study was to compare the wood properties related to wood pulp quality of two widely planted Acacia species viz.Acacia mangium Willd.and Acacia auriculiformis A.Cunn.Ex Benth.and their hybrid.Acid insoluble lignin content(Klason),mean stem density and fibre length differed considerably among the species and hybrids.A.mangium possessed a high percent of lignin content compared to A.auriculiformis and the Acacia hybrid.However,mean stem density of A.auriculiformis was higher than A.mangium and the hybrid.Fibre length of heartwood tissues was generally shorter than that of sapwood tissues.The hybrid had longer fibres than the parent species.Lignin was negatively correlated with mean stem density.Generally,the wood properties of the hybrid were superior to its parent species.The significant intraspecific variation observed for wood properties of Acacia species could be used in breeding superior hybrids combining desirable traits of the two species.Considering thedifficulty involved in accurately measuring the lignin content compared to mean stem density,selection for plants with low lignin content can be achieved by indirect selection of high mean stem density.

大叶相思开放式组培体系的建立

通过筛选开放式组培中适合大叶相思腋芽诱导、不定芽增殖和生根的培养基,探究建立大叶相思(Acacia auriculiformis)开放式组培体系。以大叶相思含饱满腋芽的茎段为外植体,选择0.8 g/L多菌灵作为消毒剂,0.2 g/L百菌清作为抑菌剂,MS培养基为基本培养基,探究适合芽诱导培养的MS培养基比例和6-BA浓度组合;采用L9(3~4)正交试验设计,优化增殖培养基中6-BA、IBA和IAA的浓度配比;同时,探究IBA和NAA在生根培养中的影响及最佳浓度组合。结果表明:MS培养基的比例显著影响芽诱导率、褐化率和叶片数,高浓度6-BA对芽诱导有促进作用,大叶相思最佳芽诱导培养基为1/8 MS+1.5 mg/L 6-BA,芽诱导率达94.07%;6-BA、IBA、IAA浓度对增殖影响的显著性逐渐降低,适合不定芽增殖的细胞分裂素和生长素配比为2.0 mg/L 6-BA+0.5 mg/L IBA+0.5 mg/L IAA,45 d培养后增殖倍数为2.73;IBA、IAA浓度以及两者的交互效应对大叶相思的生根影响显著,适合生根的生长素组合为1.5 mg/L IBA+0.1 mg/L NAA,最高生根率为90.03%,组培苗根系生长健壮。本研究构建了大叶相思开放式组培体系,为其他树种的开放式组培的研究提供了重要参考。

修枝措施和造林密度对杂交相思人工幼林生长的影响

设计了2个试验因素:3种造林密度和2种修枝措施,研究其对杂交相思(Acacia mangium×A.auriculiformis)人工幼林生长的影响。对修枝措施进行单因素方差分析,修枝对高密度(1 667株/hm~2)杂交相思幼林的生长有一定的促进作用;对中密度(1 600株/hm~2)的无显著影响;而对低密度(1 111株/hm~2)的则有一定的抑制作用。对造林密度和修枝措施进行双因素方差分析,2个因素间存在交互作用,高密度+修枝为最佳处理组合,即为杂交相思人工幼林最佳的初期栽培模式。

相思良种‘中研10号’

相思良种‘中研10号’是从越南引种经区域化试验后选出的优良无性系,其母本为马占相思(Acacia mangium),父本为大叶相思(A.auriculiformis)。‘中研10号’速生性突出,其4年生平均单株材积超过对照母本马占相思84.5%。‘中研10号’干形通直,尖削度小,冠幅紧凑。‘中研10号’马大相思可采用组培和扦插方式繁殖,造林成活率高。其木材基本密度0.427g/m^3,木质素含量21.11%,综纤维素含量70.35%,α-纤维素含量39.89%,适用于建筑材、板材、纸浆材等工业用原材料。

不同造林密度对杂交相思无性系人工林早期生长的影响

为了找出杂交相思(Acacia mangium×A.auriculiformis)人工林最佳造林密度,以达到最佳经济收益,本试验选用3种造林密度,采用单因素、随机区组设计进行杂交相思无性系人工林的密度试验。对1.7年生和2.5年生的观测资料进行分析,可得:不同造林密度对杂交相思人工幼林的树高、胸径和材积均有显著的影响。随着密度的增加,树高、胸径和材积均表现出与密度间的正相关关系,且随着林龄的增大,密度的调控效应越显著。2.5年生的杂交相思人工林,其树高、胸径和单位面积上的立木材积量均在1 667株/hm^2造林密度时达到最大值,分别为7.16 m、7.63 cm和32.36 m^3/hm^2。

氮素对马大杂种相思芽诱导的影响

以马大杂种相思(Acacia mangium×A.auriculiformis)为试验材料,研究培养基中缺少氮素(即缺少硝酸钾和硝酸铵)对其芽诱导的影响,为今后组培技术的可持续发展提供重要参考。结果显示:培养基中缺少氮素,马大杂种相思的芽诱导率、污染率、褐化率、诱导芽的茎长和叶片数因培养基不同而存在差异;最佳的芽诱导培养基为:1/2 MS(缺氮)(缺氮,是指MS培养基中的大量元素缺少硝酸铵和硝酸钾)+0.2 g/L百菌清+1.0 mg/L 6-BA+5 g/L琼脂,芽诱导率可达94.8%,其诱导芽的生根率为83.0%,与对照处理诱导芽的生根率(90.4%)无显著差异。我们发现:缺氮处理诱导的芽未表现明显的缺氮症状,其生长状态与全素处理诱导的芽没有多大差别,这说明氮素在马大杂种相思芽诱导中并非必不可少。研究结果为其他植物开展相关研究提供重要参考。