Effects of pre- and post-planting shading on growth of container Norway spruce seedlings

Norway spruce (Picea abies (L.) Karst.) is shade-tolerant and sensitive to high irradiance, summer frosts and winter desiccation, which can impair its reforestation success. In this study, artificial pre- and post-planting shading was examined to determine their effects on post-planting shoot and root growth as well as the vigor of one- and two-year-old Norway spruce seedlings. Three planting experiments were carried out on open nursery fields (Exp. 1, 2) and on a mounded forest clearcut in central Finland (Exp. 3). Before planting, the seedlings were stored over winter either in a freezer or on open fields under snow cover. For two weeks prior to planting, half of the seedlings were placed in the open and the other half under a horizontal shade netting (light transmittance 56 %) (Exp. 1, 2). All seedlings were planted with or without a vertical post-planting shade, which was located on the southern side. Post-planting shading enhanced shoot growth and reduced damage (better visual vigor and needle color and less pine-weevil damage) on Norway spruce seedlings for at least two years after planting (Exp. 2, 3). Those seedlings, that had been stored over winter in the open and kept in shade prior to planting seemed to benefit most from post-planting shading (Exp. 2). However, post-planting shading may give variable results, depending on the seedling quality and weather conditions after planting, and may even reduce shoot growth if no pre-planting shading is used (Exp. 1). Shoot growth may also be improved at the expense of root growth (Exp. 3). The costs of manufacturing and installing post-planting shades may limit their use in practice, for example, to selected regeneration sites where there is high risk of frost damage but where no alternative silvicultural procedure (shelterwood or nurse crop) has been used.     

Plantlet regeneration from leaf protoplasts ofPopulus euphratica

Protoplasts were isolated from the leaves of sterile plants ofPopulus euphratica Oliv. by using 1% Cellulase “Onozuka” RS and 0.25% Pectolyase Y-23 in 0.6m of mannitol solution. Protoplasts were cultured in modified Murashige and Skoog's (MS) medium which contained no ammonium ions but was supplemented with BAP (6-benzylaminopurine), 2,4-D (2,4- dichlorophenoxy-acetic acid), and 1% sucrose at the cell density of 9×10⁴/ml. Cell divisions occurred in every culture medium, especially in the medium containing 0.5 mg/l of BAP and 0.1 mg/l of 2,4-D, in which callus was successfully induced by successive culture through cell cluster formation. Shoots were regenerated from the callus, and their growth was enhanced on 1/2 MS medium containing 0.8 mg/l of BAP. Finally, shoots were rooted and plantlets were regenerated on 1/2 MS medium without a hormone. A part of this paper was presented at the 106th Annual Meeting of the Jpn. For. Soc. (1995).     

沙地云杉林天然更新格局及其影响因子的灰关联分析

为了揭示沙地云杉种群发生、发展的内在机制,寻找影响沙地云杉林天然更新的瓶颈因子,应用格局分析和灰关联分析的方法对内蒙古白音敖包国家级自然保护区沙地云杉林的天然更新格局及其主要影响因子进行了研究。结果表明:沙地云杉林天然更新幼苗、幼树呈聚集分布,且死亡率高;枯枝落叶层厚度、下木盖度以及腐殖质层厚度对沙地云杉林天然更新影响最大,其关联度分别达到了0.749,0.746和0.678;海拔高度和坡度的关联度分别为0.615,0.621,与天然更新的关联度最小,对天然更新影响较小。     

合江方竹地下茎生长规律研究

合江方竹地下茎的生长特性直接影响到发笋质量.研究结果表明合江方竹鞭、根在土壤中主要分布于在0～25 cm范围以内,尤以5～10 cm分布量最多;鞭角、1/2鞭长处鞭径、鞭节间长度在不同丛间的存在显著或极显著差异;竹鞭具有先行一定长度生长,再在该段的上部集中发鞭的规律性.同时,6～9月温度和降雨是竹鞭长生长的限制因子.     

水稻原生质体愈伤组织再生植株培养程序的比较

在4种不同的培养程序中应用了几种处理方法, 并对其在诱导水稻原生质体起源的愈伤组织 再生植株中的效果进行了比较。 直接将愈伤组织从含有2,4-D的增殖培养基转移到含有BA 和NAA的植株再生培养基上培养, 只能得到少量的弱苗(第1种程序)。 在增殖培养基中添加 ABA诱导了结节状的愈伤组织形成, 使愈伤组织的植株再生能力明     

Comparison of fertility between the F1, F2 and anther derived lines in the crosses of indica/japonica and japonica/indica in rice (Oryza sativa L.)

Summary Response of anthers in in vitro culture was examined in the indica-japonica hybrids of rice (Oryza sativa L.). Significant genotypic differences were observed for callus induction and regeneration among the different interracial hybrids of indica-japonica races. Induction frequency of haploids ranged from 57.7 to 72.9 per cent and doubled haploid androgenic lines ranged from 27.1 to 42.3 per cent in the anther culture of the different hybrids. The indica-japonica hybrids recorded partial pollen grain and spikelet fertility in F1 (29.9 to 41.5% and 19.4 to 48.7% respectively) as well as in F2 (42.7 to 50.6% and 37.1 to 54.4% respectively). In contrast, the androgenic doubled haploid lines recorded significant increase and the pollen grain and spikelet fertility was 76.3 and 78.6 per cent respecitively. The results suggested that the sterility barriers for realising genetic recombinants and fixation of fertile homozygous lines in indica-japonica hybridization programme could be overcome through F1 anther culture technique.Abbreviations BAP Benzyl Amino Purine - 2,4-D 2,4-Dichlorophenoxy acetic acid - MS Murashige & Skoog medium - IAA Indole Acetic Acid     

Effect of stand density and humus removal on regeneration of Pinus densiflora seedlings in a mixed conifer and broad-leaved forest

We studied the impact of stand density and forest floor humus removal on regeneration of Pinus densiflora in a mixed conifer and broad-leaved forest on the Daimonji-Yama Mountain,Kyoto,Japan.Three levels of stand density were set,i.e.,a clear-cut site,a heavily thinned site and a lightly thinned site.In each density treatment,comparisons were carried out between humus removal (A 0 -free)and humus intact(A 0 -intact)subplots.We counted the emergence of sown pine seeds and measured survival and growth of pine seedlings over the next four years.In addition,light conditions and the recovery of understory were monitored.Results show that thinning intensity and humus removal promoted the establishment and growth of seedlings.One exception,however,was that seedling growth was minimal in the heavily thinned A 0 -intact subplots.This was due to a strong response of understory vegetation growth on the treatment combination,which hindered the pine seedling growth.Furthermore,we found that the canopy openness measured at 1.3-m height remained at least 35%for the heavily thinned site in 2008.The results suggest that the removal of the A 0 layer after heavy thinning is the most effective and labor-saving operation for P.densiflora regeneration.     

矮牵牛茎段植株再生体系的建立

将矮牵牛Petunia hybrida Vilm的茎段接种在MS附加不同激素的培养基上进行愈伤组织诱导.结果表明:在MS BA1.0 mol.L-1 NAA1.0 mol.L-1的培养基上可以形成愈伤组织,而且经过继代培养仍可形成愈伤组织;茎段或愈伤组织接种在MS BA1.0 mol.L-1 NAA0.1 mol.L-1的培养基上可以形成不定芽,且诱导率达100%;健壮的高1.5~2.0 cm的不定芽接种在1/2MS IBA0.5 mol.L-1 AC1.0 g.L-1的培养基上,其生长根状况良好,生根率达100%.     

Wildfire Effects on Understory Vegetation,Natural Regeneration,and Forest Floor Fuels in a Sierran Mixed Conifer Stand

Wildfire effects on understory shrubs and herbs, regeneration of the seedling and sapling size classes, and downed and dead fuels were assessed in a mixed conifer stand located in the Lake Tahoe Basin in which California white fir (Abies concolor var. lowiana [Gord.] Lemm.) was most abundant but with Jeffrey pine (Pinus jeffreyi Grev. & Balf.) also prevalent. In burned and unburned stand portions, prefire measurements served as a basis of comparison for the postfire measurements pertinent to each study component. Fire severely suppressed the understory vegetation, which was dominated by shrubs such as bush chinquapin (Chrysolepis sempervirens [Kellogg] Hjelmqvist) and antelope bitterbrush (Purshia tridentata [Pursh] DC.), while a tepid postfire recovery of most of the preexisting species in the burned stand portion was augmented by new ones, including shrubs such as snowbrush (Ceanothus velutinus Douglas ex Hook.) and whitethorn (Ceanothus cordulatus Kellogg) ceanothus and herbs such as Holboell's rockcress (Arabis holboellii Hornem.). Tree seedling abundance was also substantially reduced in the burned portion, but the postfire population was dominated by Jeffrey pine whereas white fir had been most prevalent originally. Sapling regeneration was eliminated from the burned stand portion regardless of species. Downed and dead fuel loading was severely diminished by the fire, especially regarding fine fuels, permitting subsequent sheet erosion to imperil new seedling regeneration. These results contribute to an understanding of the direction and pace of postwildfire succession on sites occupied by Sierra Nevada mixed conifer and similar forest cover types, which is critical in decisions concerning the need for, and extent of, postfire site rehabilitation measures.     

高山红景天愈伤组织的超低温保存

高山红景天叶片在附加6-BA 2 mg·L-1和NAA 0.5 mg·L-1的改良MS培养基中诱导出愈伤组织,将愈伤组织放入10%DMSO 0.5 mol·L-1山梨醇的冰冻保护剂中,4℃冰箱中放置8 h,然后以1℃·min-1的降温速度降至-40℃,停留2 h后投入液氮保存,在40℃水浴中化冻.冻存后的愈伤组织用液体培养基MS 6-BA 2 mg·L-1 NAA 0.5 mg·L-1反复冲洗后,转入固体培养基中进行暗培养,2周后转入光照(2 000 1x)培养.5周后观察到高山红景天愈伤组织呈鲜绿色,长势较为旺盛,愈伤组织存活率达到75.64%.冻存后的愈伤组织可诱导成苗.