Decreased morphogenetic potential in peach palm stem-like cells in long-term in vitro conditions

Peach palm(Bactris gasipaes Kunth)has been micropropagated from pre-procambial cells that provide stem-like cell niches,(i.e.,pre-procambial cells),multipotent,pluripotent and totipotent for direct vascularization,adventitious buds and somatic embryogenesis,respectively.The direct induction of adventitious buds and somatic embryogenesis reduces the frequency of mutations when compared to indirect morphogenesis.Long-term in vitro cultivation of perennial species such as peach palm cause the clones to age and deteriorate;however,the consequences for morphogenesis potential are not fully clear.The morphogenic potential of peach palm clones established and in vitro cultivated for 8 years(regeneration of adventitious buds without callus formation)was investigated in leaves,roots and stem bases using histological and histochemical analyses.Data from long-term cultures(8-years-old)was compared to data from short-term cultures(1-year-old).Morphogenic pathways monitoring for direct induction of somatic embryos and adventitious buds revealed a strong morphogenic reduction potential in the pre-procambial cells,parenchyma cells in the proximal region of stem bases,and external cells of leaf sheaths.Initial cells of shoot apical meristems and pre-procambial cells commit cell reprogramming to the undifferentiated state and subsequent acquisition of cellular competence.These results are applicable in the micropropagation of peach palm,with consideration to obtaining clones and their long-term in vitro culture.     

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Let seabuckthorn serve construction of ecological environment in west China better.............................. QIAN zheng-ying Ⅲ(1)· Special Article·Seizing opportunities and pioneering a cause laboriusly to open up a new prospect of seabuckthorn workin new century ... Center of Development and magement for seabuckthorn, Ministry of W. R. Ⅰ(1～3)Construction of ecological economy system of seabuckthorn in west China ................. LU Wen Ⅲ(2～5)·Column on Arenaceous Land Con…     

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Phll卜r Seabu吨比orn如ye卜pine血。Eyel卜w RIver加slrl,1996～2000… ’··、…·’…”、……。……、·’·’…·。·“””·”’·。·’·。…”…·’…··’…‘’……·’…·。··HlppophO6 offl(?,仁otnlllisslorL of wzttei conservancy In the YellowRlver①(1～3)。SPecial Article·卜tr0ng山el川fig巾e leadership,Increasll〕g ti〕e门mut to push Lhlnese scLbuckthorrl industry t<) a new stage·、、··、…、·、”、·’·。·、,·,、…··、………、·Nltl Maosheng(1～3〕”化tlonal programme f…     

Variations in fine root dynamics and turnover rates in five forest types in northeastern China

Quantifying fi ne root(≤ 2.0 mm in diameter) distribution and turnover is essential for accurately estimating forest carbon budgets. However, fi ne root dynamics are poorly understood, possibly because of their inaccessibility. This study quantifi es fi ne root distribution and turnover rates for fi ve representative Chinese temperate forests types. Fine root number, diameter, biomass, necromass, production, mortality, and turnover rates were measured using a minirhizotron over a 12-month period. More than 90% of the fi ne roots were < 0.5 mm in diameter, with thin fi ne roots at shallow layers, and thicker ones in deeper soil layers. The fi ne root dynamics were signifi cantly diff erent among the forest types. Coniferous plantations had fewer fi ne roots, less biomass, necromass, production and mortality but greater average diameters than fi ne roots of broadleaved forests. All traits, except for diameter, decreased along the soil profi le. Fine root numbers and production exhibited a unimodal seasonal pattern with peaks occurring in summer, whereas biomass, necromass and mortality progressivelyincreased over the growing season. The turnover rates of roots < 0.5 mm varied from 0.4 to 1.0 a-1 for the fi ve forest types, 0.5–1.0 a-1 for the soil layers and 0.2–1.1 a-1 for the seasons, with the largest turnover rate at the 0–10 cm depth in summer. The patterns of fi ne root numbers, biomass, necromass, production, mortality, and turnover rates varied with forest types, soil depths, growing season and diameter classes. This study highlights the importance of forest types and diameters in quantifying fi ne root turnover rates.     

Will changes in root-zone temperature in boreal spring affect recovery of photosynthesis in Picea mariana and Populus tremuloides in a future climate?

Future climate will alter the soil cover of mosses and snow depths in the boreal forests of eastern Canada. In field manipulation experiments, we assessed the effects of varying moss and snow depths on the physiology of black spruce (Picea -mariana (Mill.) B.S.P.) and trembling aspen (Populus tremuloides Michx.) in the boreal black spruce forest of western Québec. For 1 year, naturally regenerated 10-year-old spruce and aspen were grown with one of the following treatments: additional N fertilization, addition of sphagnum moss cover, removal of mosses, delayed soil thawing through snow and hay addition, or accelerated soil thawing through springtime snow removal. Treatments that involved the addition of insulating moss or snow in the spring caused lower soil temperature, while removing moss and snow in the spring caused elevated soil temperature and thus had a warming effect. Soil warming treatments were associated with greater temperature variability. Additional soil cover, whether moss or snow, increased the rate of photosynthetic recovery in the spring. Moss and snow removal, on the other hand, had the opposite effect and lowered photosynthetic activity, especially in spruce. Maximal electron transport rate (ETR(max)) was, for spruce, 39.5% lower after moss removal than with moss addition, and 16.3% lower with accelerated thawing than with delayed thawing. Impaired photosynthetic recovery in the absence of insulating moss or snow covers was associated with lower foliar N concentrations. Both species were affected in that way, but trembling aspen generally reacted less strongly to all treatments. Our results indicate that a clear negative response of black spruce to changes in root-zone temperature should be anticipated in a future climate. Reduced moss cover and snow depth could adversely affect the photosynthetic capacities of black spruce, while having only minor effects on trembling aspen.     

Developing Agroforestry in Slopelands to Combat Non-point Pollution in China

The status of agricultural non-point source （NPS） pollution in China is quite austere owing to lots of factors, the characteristics of which include severe N, P eutrophications in water bodies, unsuitable structure of agriculture and the lack of reasonable management. It was well known that forest could play an important role to control soil ＆ water erosion, uptake extra soil nutrients as well. However forest coverage is rather low in the headwaters region. The research on the causes of NSP pollution and the significance by developing agroforestry to deal with the problem is presented in the paper, as well as the function of agroforestry and the related measures of pollution controlling, e.g., riparian forest buffer zones building. As a conclusion, controlling the loss of soil and water is regarded as an important crucial action and major research direction in the field. Thereby the benefits of pushing up agroforestry in slops to combat water eutrophication and prevent NSP pollution from worsening are significant.     

Model of Cost-benefit Flow in Six Green Projects in China

From the point of cost-benefit flow and with the Six Green Projects in China as the case and background, it iscriticized that the cun~nt natural resource and environmental management and the policies in China have some problems unsolvedsince the model of cost-benefit flow is still centralized and mainly in an administrative way in spite of many efforts madetheoretically and practically. It is suggested that a new model based on market-oriented economy from the point of cost-benefit flowwith Six Green Projects Management and Policies System consist of complete natural reserve (NR). Management system includedenvironmental nature reserves in addition to biodiversity nature reserve, paid using nature resources, an environmental conservationand construction industry and renewable resource production incentive system that turn the direct administration and operation tomanagement and services. The detail figure of the new model of cost-benefit flow is provided and the main points related arediscussed in this paper.     

Principles and Practice of Forestation in Saline Soil in China

China is the most populated country in the world, andits land area is not the largest, especially its cultivatedland is gradually declining with socio-economicdevelopment. In order to meet the demand to grain,vegetable and so on, wasteland must be reclaimed(Zhang Jianfeng, 2004). In China there is a large scaleof salt-affected land, e.g. in Lop Nur 5 000 km2, inTurfan almost the same, in Quidam Basen 20000 km2 (Gong Hongzhu, et al, 1984). Owing toadverse conditions crops growing in salty s…     

Progress and Trend in Forest Scientific Researches in the World

Editor's note The 9th session of the general assembly of IUFRO was held atMontreal, Canada on August 5-11, 1990. The Chinese delegationpresent at this conference was headed by Liu Yuhe, the president     

Genotypic Variation in Nutrient Selectivity in Populus under NaCl Stress

We used a salt-resistant poplar genotype Populus euphratica and two salt-sensitive genotypes, Populus 'popularis 35-44' (P. popularis) and the hybrid P. talassica Kom x (P. euphratica + Salix alba L.) to examine genotypic differences in nutrient selectivity under NaCl stress. One-year-old seedlings of P. euphratica and one-year-old hardwood cuttings of P. popularis were used in a short-term study (24 hours), while in a long-term study, up to 4 weeks, two-year-old seedlings of P. euphratica and the hybrid P. talassica Kom x (P. euphratica + Salix alba L.) were compared. In the short-term study, K+ concentration in the xylem sap ([K+]xylem) of P. euphratica significantly increased after salt stress was initiated, and maintained 1-2 fold higher than control levels during the period of salt stress (24 hours). Xylem Ca2+ and Mg2+ concentrations ([Ca2+]xylem, [Mg2+]xylem) in P. euphratica resembled the pattern of K+ despite a lesser magnitude in elevation. However, [K+]xylem, [Ca2+]xylem and [Mg2+]xylem in P.     

Public cost-sharing in private forest investments in Finland 1983–2000

A model of public cost-sharing in private forest investment is proposed to describe the substitution between the private financing of investments and public investment assistance. The substitution depends on the curvature conditions of the forest investment function on forest stock. When the second-order investment effects are close to zero or when they do not exist, the funding substitution will not take place. A simultaneous econometric model for private and public funding employing forest incomes, forest income taxes, interest rates, investment scale and market wood price expectations as exogenous variables is estimated. The model estimation based on Finnish regional data in 1983–2000 rejects the substitution alternative. A 10% increase in private investment funding increases the demand for public funding at the same rate, but a 10% increase in public funds will increase the private funds supply by 2.5%. Significant income effects are found only in the case of private funding. In northern Finland, the scale effects are large for public financial assistance. The effects of the income tax reform on the private supply of funds are positive, especially for the new wood-sales profit taxation, whereas the interest rate and price expectation effects are negative.

Advances in the Triploid Breeding Program of Populus tomentosa in China

本文报道了毛白杨三倍体育种的研究进展．应用染色体加倍、种间杂交和花粉辐射技术，成功选育出了２０个回交杂种异源三倍体无性系，最优三倍体无性系８年生单株材积达到了０．３６ｍ３，超过一般二倍体的２．５５倍．由此表明，育种材料的遗传组成和育种方法是获得较高遗传增益的基础．二倍体选种增益一般为４５％，回交杂种增益为１５５％，而异源三倍体最优无性系的增益为２５５％．     

Are neighboring trees in tune? Wood formation in Pinus pinaster

Neighboring trees growing under identical environmental conditions can exhibit different dynamics and periods of growth. Despite the recent advances in cambial biology, the exogenous and endogenous factors generating asynchronous xylem growths still remain undetermined. This study investigated timings and duration of xylem formation in maritime pine (Pinus pinaster Ait.) from an even-aged plantation in Portugal growing under Mediterranean climate. Cambial phenology and stem diameter were monitored weekly, from March to December 2010, on two classes of trees divided according to the tree ring widths of the last 15 years, but similar age and size: fast- and slow-growing trees. We tested the hypothesis that differences in tree ring widths result from cell production which in turn affects timings of xylogenesis and that the bimodal growth pattern, typical of the Mediterranean, originates from a double reactivation of the cambium: in spring and autumn. Cambial activity started earlier and ended later in fast-growing trees, confirming that cell production is a key factor determining the duration of xylogenesis. Intra-annual variations in stem diameter recorded by band dendrometers revealed two peaks of increment occurring in spring and late summer. However, the number of cambial cells did not increase in late summer, which suggested that the second peak of increment was caused by stem rehydration, rather than by a reactivation of cell division. These results demonstrated that the variability in the timings of xylem phenology observed among trees of the same age and size and growing under similar environmental conditions was closely related to cell production and not to age or size per se.     

The Spring Change in Hydraulic Architecture Characteristics in Some Woody Plants

Ten healthy tree species with regular management were selected on the campus of Beijing Forestry University, and they belong to tall tree, shrub and liana, respectively. Water potential and hydraulic architecture parameters of one-year-old twigs were measured in sunny day in the last ten days of March to the middle ten days of May in 2002. The results show that the daily change in water potential of tree species examined appears convex, i.e. the water potential is higher in the morning and evening, and lower in the midday. The change trend of water potential is consistent among different months. The seasonal change trend of water potential appears lower in March than that in April and May. There is a similar relationship between the daily change trend of water potential and special conductivity in spring, i.e. the higher the water potential, the higher the special conductivity, but this trend of change is not entirely synchronic. The seasonal change of special conductivity of conifer species is not obvi     

Practice and Use of Tree Species in Urban Forestry in Thailand

1 INTRODUCTIONUrban forestry can be viewed as a specialized branchof forestry, which deals with the science and art ofplanting, implementing the greenery in and around urbanand populated area. It includes tree planting in temples,offices, schools, hospitals, homesteads, highways orroads between towns or cities as well as public parksand recreational parks so that it contributes directlyand indirectly to the physical, physiological, sociologicaland economic well being of the communitiesconc…     

Cupressaceae Plants in China

This paper examed the Cupressaceae taxa in China. It is identifled that 30 species and 16 varieties in 7 genera in thefamily are indigenous, and estimated that about 25 species and 4 varieties have been introduced into this country since the beginning of this century. It is urgent that more furthur studies need to be carried out in the country on the taxonomy especially of junipers and cypresses, on the re-classification ofexisting cultivars, and on the development of new cultivars for future needs.     

The Application of GIS in Small Watershed Classification in Loess Plateau

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Changes in and evaluation of surface soil quality in Populus × xiaohei shelterbelts in midwestern Heilongjiang province,China

To examine changes in surface soil quality over time in Populus × xiaohei shelterbelts, we collected soil samples from five shelterbelts of different ages and also from former cropland left fallow for 25 years. Twenty-one surface soil(0–20 cm) properties were measured, and variation in soil quality was assessed using one-way ANOVAs and multiple comparison tests. Based on this analysis, 16 soil indexes were used in a model evaluating soil quality, with each index given weight as determined by the correlation coefficient. Compared with the control, the postmature forest had greater soil moisture content but lower bulk density( P 0.05). The mature forest also had higher soil pH, total organic carbon, alkali-hydrolyzed nitrogen, available phosphorus, and biomass nitrogen content, but reduced nitrate-nitrogen and total phosphorus content than the control( P 0.05). Total porosity was highly positively correlated with aeration, nitrate-nitrogen, alkali-hydrolyzed nitrogen, available phosphorus, microbial biomass carbon and microbial biomass nitrogen. Soil total organic carbon, ammonium nitrogen, nitrate-nitrogen, alkali-hydrolyzed nitrogen, total nitrogen, available phosphorus, microbial biomass carbon and microbial biomass nitrogen were all strongly correlated. In the soil quality evaluation model, total organic carbon was assigned the highest weight and total potassium content the lowest. The soil quality index was lowest in the near-mature forest and greatest in the postmature forest. Generally, soil quality in P opulus × xiaohei shelterbelts varied with age and was higher in the 10–20 cm versus 0–10 cm soil layer. After a single forest generation, surface soil quality was significantly improved.