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There is general agreement that in many regions additional precipitation with climate change will not be able to balance the increased evaporation rate induced by higher air temperatures, causing periods of intense drought. Although seedlings of Abies balsamea growing in the boreal forest are known for their resistance to harsh environmental conditions, the impact of water stress on their growth still...
We examined the responses of two coniferous species Picea abies and Thuja occidentalis to decreased nitrogen availability. Plants were grown for 2 months in inorganic substrate irrigated by nutrient solution. Nitrogen availability was reduced either by lower N concentration in the nutrient solution or by a patchy supply of a high N concentration to only one side root isolated in a split-root setup...
To investigate the effects of boron (B) on growth, B concentration and distribution of two navel orange cultivars, ‘Newhall’ (Citrus sinensis Osbeck) and ‘Skagg’s Bonanza’ (Citrus sinensis Osbeck) grafted on the rootstock trifoliate orange [Poncirus trifoliata (L.) Raf.], B at five levels was exogenously supplied to 1-year-old grafted plants of both cultivars under greenhouse conditions. Plants were...
Olive growth and productivity are limited by low temperatures mainly during winter, but sometimes also in spring and fall. The most effective way to avoid these damages in areas subjected to these climatic conditions is to select least susceptible varieties, but the choice of the right method to determine cold hardiness is extremely difficult. The aims of the work were (1) to assess LT50 (lethal temperature...
For secondary forests, the major forest resources in China (accounting for more than 50% of the national total), soil respiration (RS) and the relationship between RS and various biotic/abiotic factors are poorly understood. The objectives of the present study were to examine seasonal variations in soil respiration during the growing season, and to explore the factors affecting the variation in...
We developed chronologies based on the width of tree rings, total area of vessels, and the number of vessels per tree ring of the Prosopis flexuosa wood samples from the xerophytic woodlands of central Argentina. We evaluated the influence of climate on these tree-ring characteristics considering the period from 1940 to 2004 (65 years). The width of the rings, the number of vessels, and the total...
Many woody plants show hierarchical shoot growth: annual shoot length decreased with increasing branching order. We hypothesize that plants showing hierarchical shoot growth improve the efficiency in terms of space acquisition and use per invested shoot length. This hypothesis was tested by using a simple geometric simulation model of branch development. In this study, the effective shoot length (EL),...
The oak Em gene, QrEm, was isolated from Quercus robur L. zygotic embryos in RT-PCR using degenerate primers. The full-length cDNA was obtained by RACE. Sequence analyses revealed a high degree of similarity to previously identified Em-like genes from both monocots and dicots. Northern blot analyses showed that QrEm gene is expressed in zygotic embryos during the mid-maturation phase, with a decline...
Using dendroclimatical methods, we compared the growth response to climate fluctuations of three of the main Romanian Carpathian Mountains coniferous species, Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies Karst.) and silver fir (Abies alba Mill.), growing intermixed in a unique stand. Climate and soil conditions were therefore the same for all the trees studied. The experimental site...
A growth ring of an adult Norway spruce (Picea abies [L] Karst.) was analyzed to a high resolution at the single cell level with respect to structural and mechanical changes during the growth period. For this purpose structural characterization was performed by means of light microscopy, scanning electron microscopy and wide angle X-ray diffraction for investigating the geometry of cells, their cell...
Attempts were made to evaluate intrinsic biological units of growth of teak trees, which were identified as age and size at inflection point of diameter at breast height. The observations were further utilized in estimating fractal dimension of the tree crown, which is an important eco-physiological characteristic of the species. A total of 38 teak plantations belonging to different age groups and...
To investigate the potential of Norway spruce (Picea abies L. Karst) as a palaeoclimate archive in the southeastern European Alps, tree ring chronologies were developed from trees growing at two sites in Slovenia which differed in their ecological and climatological characteristics. Ring width, maximum latewood density, annual height increment and latewood cellulose carbon isotope composition were...
Pectinase and cellulase activities are involved in a number of intercellular space-forming processes in plants. In this study, we combined cytochemistry with ultrastructural analysis to investigate the ontogeny of secretory cavity in fruits of Citrus medica L. var. sarcodactylis (Noot.) Swingle, Citrus reticulata Blanco and Citrus limon (L.) Burm. f. Pectinase activity was first detectable at the...
Endogenous variations in the annual growth of trees suggest that similar trends would occur in phyllodes. In comparison to leaves, the characteristics of phyllodes are less well known, hence this study examines the effects of architectural position and age of tree on the phyllodes of Acacia mangium. Phyllodes were investigated on 1-, 2-, and 3-year-old trees from three axis positions within the crown...
The crop species Olea europaea L. (olive tree) is of great economic importance in the Mediterranean region. Hence, many efforts have been done in the last decades to propagate this commercially valuable species by in vitro methods. On the other hand, the lesser known Olea maderensis (Lowe) Rivas Mart. & Del Arco which is a native species of the Madeira Archipelago has only been the subject of...
Sakhalin spruce (Picea glehnii), a native species typically found in northern Japan, has been used in reforestation on hillsides exposed to strong winds. In the reforestation areas, there are south-facing (S-slope) and northwest-facing slopes (NW-slope). Climatic conditions are contrasting between the two slopes, with shallower snow cover on the S-slopes. We compared growth responses of the spruce...
The olive tree (Olea europaea L.), like many other woody plants, has a long juvenile period in which the plant is not able to produce flowers. Knowledge of the moment when the plant is capable of flowering is important for breeding programs and also for determining the physiological basis for sexual reproductive behavior, but currently the only indicator of that moment is the actual flowering. In...
Tree growth is a fundamental indicator for conservation plans of Amazonian floodplain forests. In this study we use dendrochronology to analyze wood growth patterns of Tabebuia barbata and Vatairea guianensis, two tree species occurring in nutrient-rich white-water (várzea, Mamirauá Sustainable Development Reserve, MSDR) and nutrient-poor black-water (igapó, Amanã Sustainable Development Reserve,...
Information on the timing and dynamics of tree ring formation is essential to assess the seasonal behavior of secondary wood growth and its associated environmental influences. Araucaria angustifolia is a dominant species in highland pluvial ecosystems of southeastern South America. Previous investigations indicated that their growth rings are formed annually, but no information exists about the timing...
This study evaluates the relative contributions of leaves and roots to the belowground allelopathic effects of Mikania micrantha. The hypothesis that leaves contribute more to the allelopathic effect than roots was experimentally tested. We assessed the allelopathic effects of aqueous extracts from Mikania leaves and roots on the seed germination and seedling growth of two co-occurring woody plants...
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