切除薹苞处理对蒜薹货架期品质的影响

以苍山大田蒜薹为试材,采后在常温下进行切除薹苞处理,以不作任何处理为对照,于25℃下放置,定期测定其品质指标,研究切除薹苞处理对蒜薹货架期品质的影响。结果表明,切除薹苞处理能够较好地抑制薹条的老化,减缓可溶性固形物含量、水分、叶绿素和VC含量的降低速率,延长蒜薹的货架期。     

绵羊类胚胎干细胞的分离与克隆

从胚胎发育阶段、饲养层和培养体系等方面对影响绵羊类ES细胞分离、克隆效率的因素进行探讨。结果显示：致密桑葚胚和囊胚的ICM增殖率高于囊胚和孵化囊胚。绵羊类ES细胞在同源绵羊胎儿成纤维细胞（SEF）上生长比较缓慢,最终传代次数也低于小鼠胎儿成纤维细胞（MEF）组。培养液中同时添加胎牛血清（FBS）和Knock-out血清替代品（KSR）,绵羊类ES传至7代,添加了碱性成纤维细胞生长因子（bFGF）后,最高可传至8代,而单纯添加KSR或FBS,分别传至4代和5代。对类ES细胞进行AKP染色、核型分析、体外分化试验,证实分离的类ES细胞符合ES细胞的主要特征,而且表达多潜能性细胞因子Nanog。由此认为,致密桑葚胚和囊胚更适合绵羊类ES细胞的体外分离和培养,而且MEF更适合于绵羊类ES细胞的分离传代,培养液中添加5%FBS和15%KSR,比较适合类ES细胞的分离传代,bFGF对绵羊类ES细胞的增殖具有促进作用。     

Estimating the frequency of stem rot in Picea abies using an increment borer

The likelihood of detecting decay present in Norway spruce trees when taking bore core samples at breast height or at stump height was analyzed in two stands. The actual numbers of decayed trees were obtained after the trees were felled. More than 80% of the decay extending to breast height level was detected by taking core samples at that level. However, these core samples revealed only 40–70% of the actual amount of decay present at stump height. At stump height a higher portion of the total amount of decay present was revealed. Heterobasidion annosum was detected in 69 and 77% of the decayed trees in the two stands.

Misjudgements occurred mainly where either (i) decay was present at stump height but not at breast height or (ii) when the decay column had a lateral position. At breast height the probability of finding lateral rot columns was higher than at stump height.     

红松木倾斜角度对其木材形成组织的影响

为研究树干倾斜角度对应压木木材细胞壁形成过程的影响,以7年生红松苗木为研究对象,对其茎干进行不同角度的倾斜处理.先后测定苗木的树高和胸径、木材形成组织中的木质素和纤维素含量、傅里叶红外变化光谱和极性代谢产物.结果表明:倾斜角度对高生长的抑制作用非常显著,对直径生长无显著影响.倾斜后木质素含量增加,纤维素含量降低;倾斜角度对木质素和纤维素含量均有显著影响.不同倾斜角度FTIR吸收峰强度也有明显差异.糖类、脂类、氨基酸、含氮化合物、有机酸等代谢物随倾斜角度呈现不同的变化规律.因此,红松苗木50°倾斜处理形成典型的应压木结构.代谢物相对含量的变化规律与形成的木材宏观性质相吻合.代谢物的变化也反映了树木对应力刺激的响应机制.     

昙花盆栽技术措施

本文简要介绍了昙花的植物学特征、生态学特性,阐述了昙花的繁殖、移栽、光照、肥水管理、整形修剪、病虫害防治以及花期调控等技术措施,为今后人们盆栽和养护昙花提供技术指导和帮助。     

Crookedness of pedunculate oak (Quercus robur L.) growing under a canopy of Scots pine (Pinus sylvestris L.)

Natural regeneration of pedunculate oak growing under a canopy of Scots may be used for conversion into a mixed or predominantly broadleaved forest. From an economic perspective it is desirable that the oaks have straight stems. In this paper we present a case study for analysing oak stem curvature and its causes. The study was conducted in a mature pine stand with understorey oaks of age ca. 60 years in Poland. The oaks were classified into two main groups as either straight or crooked. The following variables were measured or assessed for the oaks: (1) stem curvature (crookedness), total tree height, diameter at breast height (DBH) and some tree crown characteristics, (2) the growth of DBH and height in each year of the life of each tree and (3) the competitive pressure of surrounding trees. Durable stem curvatures were formed at the culmination of the height increment. The first 20 years of the life of the oak were crucial in terms of stem quality. The annual height increment was larger in the years when the curvature was formed than in adjacent years. The factors that caused crooked stems were the same for straight and crooked oaks, but the magnitude of the response was different. When planning the conversion of Scots pine into oak, full overhead light should be provided as early as possible, but not later than 20 years since the establishment of the regeneration.     

Seedling shoot,needle and bud development in three provenances of Pinus sylvestris and Pinus contorta cultivated in northern Sweden

The patterns of current‐year shoot, needle and terminal bud elongation in seedlings of three Scots pine (Pinus sylvestris L.) and three lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) provenances were compared during the third and fourth growing seasons after planting. Lodgepole pine produced longer shoots and buds than did Scots pine, mainly because lodgepole pine formed more stem units and elongated at a faster rate. Stem unit length and the duration of shoot and bud elongation differed relatively little between species and provenances. Lammas or polycyclic growth occurred in some lodgepole pine provenances, but not in any Scots pine provenance, and was associated with enhanced shoot elongation. Needle elongation commenced earlier, proceeded at a faster rate, and was greater in lodgepole pine than in Scots pine, but ceased about the same time in all species and provenances. The heat sum required to attain 50% of final length was lower for shoots and needles in lodgepole pine than in Scots pine, and for shoots in northern provenances than in southern ones. Mitotic activity in the apical meristem of the terminal bud, which occurred less than one week after the seedlings were free from snow, started and ceased about the same time in each species, but was higher in lodgepole pine than in Scots pine early in the shoot elongation period.     

Distribution and frequency of Cronartium flaccidum on Melampyrum spp. in permanent sample plots in Finland

Abstract

In 2006, the distribution and frequency of pine stem rust Cronartium flaccidum was studied on Melampyrum spp. in permanent sample plots of an EU forest health monitoring program and of a BioSoil program in Finland. The frequency of Melampyrum spp. infected with C. flaccidum was low, but the rust was recorded in new locations of eastern Finland. No uredinia of C. flaccidum were observed in samples collected from over 700 plots. Telia were common on Melampyrum sylvaticum but were occasionally also found on Melampyrum pratense and Melampyrum nemorosum. Melampyrum pratense was the most common species growing in plots on mainly dry sites. Melampyrum sylvaticum was seldom detected, suggesting that alternate hosts are absent from northern Finland or that the current sample plot network is too sparse for effective disease monitoring in the north. No relationship between C. flaccidum, Melampyrum spp. and rust incidence in host trees was observed, which implies that the autoecious Peridermium pini is a more likely pathogen than C. flaccidum locally. Because plots containing M. sylvaticum occur almost solely in southern Finland, the plots with M. sylvaticum reflect the best changes in rust epidemics in that area. In the future, nutrient-rich sites containing M. sylvaticum may serve as a source of rust epidemics. It is unlikely that C. flaccidum will spread to dry sites via M. pratense.     

The effect of release cutting on the growth and external quality of the dominant trees in a Pinus sylvestris stand established by spot sowing

The effect of the number of Pinus sylvestris trees in seed spots on the growth and external quality of the dominant trees was studied. The trees were monitored during the period between release cutting and the first commercial thinning. The treatments were one, two and four of the tallest seedlings retained per seed spot, and a control. The mean height of the dominant trees was highest in the one‐tree and two‐tree treatments. Diameter at breast height (DBH) increased with increasing spacing. On average, the stump diameter was 1.5–4.7 cm greater in the one‐tree treatment than in the control. Slenderness (height/DBH) was highest in the control treatments. The average living crown limit of the dominant trees was 4.6 m, and was at its highest in the two‐tree treatment. The results indicate that the competition in seed spots decreases the height growth of the dominant trees.