桤木采穗圃无性系管理技术研究

研究表明:桤木无性系植株嫩枝总芽数主要取决于树龄和无性系遗传特性,同时与无性系植株定干高度、修枝、施肥等密切相关。在桤木无性系采穗圃中,无性系植株定干高度以90 cm为宜,无性系植株枝条宜进行轻短截,并加强施肥管理,既可提高嫩枝总芽数,又能扩大树冠,增强树势,提高采穗圃穗条的产量和质量。     

桤木群体遗传分化研究I.DNA提取和PCR条件的建立

桤木(ＡｌｎｕｓｃｒｅｍａｓｔｏｇｙｎｅＢｕｒｋ)为桦木科(Ｂｅｔｕｌａｃｅａｅ)植物,主要分布于四川盆地及其周边地区。桤木喜光、喜湿,根系发达,对土壤要求不严,适应性强,在长江中下游地区防护林建设中具有重要作用。国外对桤木属(Ａｌｎｕｓ)植物的研究起步较早,主要集中于生理生化方面包括生长、固Ｎ、抗涝性以及种间杂交研究等[1　3]。虽有学者利用ＲＦＬＰ研究其核糖体ＤＮＡ的基因结构、以同工酶技术研究桤木属的群体遗传变异[4　6],但未见应用ＲＡＰＤ技术的研究报道。随着现代生物技术的发展,生物多样性的检测技术日趋成熟和多…     

中亚热带四川桤木与台湾桤木幼林的光合生态特性

四川桤木与台湾桤木是湖南乃至亚热带地区极具发展前景的阔叶纸浆原料林树种.为了系统研究四川桤木与台湾桤木在湖南的适应性,对四川桤木、台湾桤木4年生幼林的主要光合特性进行了研究.结果表明:(1)两种桤木的光合作用日变化有单峰与双峰曲线两种类型,四川桤木光合作用日变化在6月、9月净光合速率呈双峰曲线型,4月和10月、11月净光合速率呈单峰曲线型;台湾桤木净光合速率日变化在4月、6月、10月和11月呈双峰曲线型,而9月份净光合速率日变化呈单峰曲线型.一年中以6月份的净光合速率峰值最高,分别达18.68和23.51μmol/m2.s,10月或11月最低.(2)两种桤木光照强度日变化始终成单峰曲线,只是峰值出现的时间不同,在4月、6月和9月,光照强度峰值在中午12:00~13:00出现,10月光照强度以中午12:00最高,11月13:00最高;一年中,光照强度峰值6月份最高(1 800μmol/m2.s),11月份的最小,仅1 260μmol/m2.s.(3)气孔导度、蒸腾速率和叶面水气压亏缺的日变化与季节变化趋势规律和净光合速率一致,两种桤木的蒸腾速率和叶面水气压亏缺的日变化有单峰与双峰曲线两种类型;一年中两种桤木蒸腾速率峰值均以6月份的的峰值最高为8.10 mol/m2.s(台湾桤木)和6.38 mol/m2.s(四川桤木),其次是4月份,在11月份的蒸腾速率的峰值最小;两种桤木的叶面水气压亏缺峰值均以6月最高,其次是9月、10月,生长初期的4月份和末期的11月份较小.(4)四川桤木光饱和点为262~468μmol/m2.s,光补偿点介于11~104μmol/m2.s,不同部位的叶片和不同季节的光饱和点和光补偿点均有差异;台湾桤木的光饱和点介于288~409μmol/m2.s,光补偿点为14~102μmol/m2.s,二种桤木具有较低的光补偿点,即利用弱光的能力较强.     

四川桤木人工林不同年龄段生物量的研究

对湖南湘西北地区3个立地条件相近的5年生、8年生和14年生四川桤木人工林的生物量进行了研究.结果表明:3个年龄段桤木林分的生产力分别为14.40、13.30、16.67 t·hm-2,均表现出较大的生产力.     

四川桤木优株扦插繁育技术初报

引种栽培四川桤木4年后进行优株选择,在此基础上取优株1年生健壮穗条,采用不同浓度的GGR生根剂处理,在相同立地条件和培管措施下,分2、3、5、9月四个季节进行扦插育苗对比试验,结果表明:扦插季节对育苗成苗率有较大影响,运用200×10-6浓度的GGR处理穗条30 m in,成活率为91.33%,成苗效果最佳。     

西南桤木木塑复合材料的研究

采用乙烯基类系列单体——丙烯腈(AN)、甲基丙烯酸甲酯(MMA)、丙烯酸(AA)三元共聚单体注入西南桤木木材中，制成新型的高分子复合材料(AMA—WPC)。单体的注入用满细胞法，聚合用热引发法，并采用添加氯化锌对木材细胞壁进行活化等工艺对木塑复合材进行了研究和分析。实验样品按照国标GBl927—1943有关规定进行测试，并结合傅立叶红外光谱和扫描电镜探讨了各因素对AMA—WPC材料接枝率及性能的影响。结果表明：改性后西南桤木木塑复合材料具有优异的物理、力学性能。与素材相比较，AMA—WPC的密度提高了59．8％，顺纹抗压强度提高了76．7％，抗弯强度提高了90．4％，抗弯弹性模量提高22．2％，端面硬度提高102．3％，径面硬度提高153．6％，弦面硬度提高152．2％，吸水率降低56．7％，湿膨胀率降低19．0％。     

Genetic variation ofAlnus trabeculosa populations in Japan

Alnus trabeculosa Hand.-Mazz. is classed as “near threatened,” and efforts should be made to conserve the species, but effective action would require understanding of its genetic variation and structure. Therefore, the genetic variation at 12 isozyme loci was examined in seven populations of the species in Japan. The expected heterozygosity within species (H _es=0.222) and the expected heterozygosity within populations (H _ep=0.199) were found to be slightly higher than in most other woody species. The coefficient of genetic differentiation (G _ST=0.146) was also high. The northernmost population had the lowest values for almost all measures of genetic variation, and populations in southern Japan tended to show greater within-population variation than those in northern Japan. The level and distribution of genetic variation in this species might be related to its life history and ecological traits, and distribution history.     

Effect of seed coverings and seed pretreatments on the germination response of <Emphasis Type="Italic">Alnus glutinosa</Emphasis> and <Emphasis Type="Italic">Betula pubescens</Emphasis> seeds

The germination of common alder (Alnus glutinosa (L.) Gaertn.) and downey birch (Betula pubescens Ehrh.) seeds is often poor in bare-root nurseries. The effect of a variety of seed coverings and a few seed pretreatments on seedling emergence was examined in this study in an attempt to address this problem. Seeds of each species were sown in trays containing nursery soil, covered with grit, gravel, sand, combinations of these coverings, a hydromulch or a sealed plastic cloche and then incubated for 6 weeks at 17–20°C. The grit combined with sand or gravel, the hydromulch and the cloche increased seedling emergence when compared with the standard grit. In another experiment, seeds of each species were fully imbibed (FI) (>50% moisture content, MC), as per standard practice, or adjusted to target MC (TMC) (30–35% MC) levels, and then chilled to release dormancy. Some seeds of each MC treatment were primed at 20°C for 2 days following chilling, after which all seeds were evaluated in laboratory tests and a nursery trial. Germination potential of the FI seeds declined in the lab tests by the second test date, which was reflected in low seedling emergence in the nursery in birch. The primed FI seeds of alder germinated most rapidly in the nursery, but other effects were not significant. Seedling emergence was better in the nursery in response to the TMC than the FI pretreatment in birch.

我国旱冬瓜的研究动态及方向

通过对旱冬瓜在良种选择、育苗技术、群落特征及应用等方面的研究结果进行总结,提出了旱冬瓜分布区自然条件差异悬殊,遗传分化极为明显,种源、个体差异很大等特点。针对目前存在着选育不充分、速生丰产栽培技术体系不完善、病虫害防治缺乏等问题,提出了加快良种选育、开展区域化栽培试验及速生丰产林培育技术的研究方向。     

江南桤木育苗技术的研究

本文研究了江南桤木不同播种量和不同水分管理方法的育苗效果。结果表明，播种量以45kg／hm2量为宜，苗木高生长、地径生长和优质苗产量均优于其他几种处理方法；水分管理以“湿管法”育苗效果最好，苗木的高生长、地径生长和优质苗产量与“水管法”、常规育苗方法间均存在显著差异。