In this study we investigated the dynamics of growth and quality features of 1+0 Austrian Pine (AP; Pinus nigra Arn.), Scots Pine (SP; Pinus sylvestris L.) and Maritime Pine (MP; Pinus pinaster Aiton) seedlings in containers Yukosad (YS; hard plastic, 75cm³, 610 seedlings m^-2) and Siset (SS; gray cardboard with white coating, 128 cm³, 589 seedlings m^-2). The experiment, for all Pine species, was conducted in randomized blocks in four replications. Each replication contained 10 multipots of each container type. After the seed germination, every 15 days, i.e. 10 times during the vegetation season, 10 seedlings of each of 4 replications, i.e. 40 seedlings of each container and Pine species, were analyzed. The following morphological characteristics were measured: shoot height (SH), root collar diameter (RCD), shoot dry weight (SDW), number, length and dry weight (RDW) of I, II and III order lateral roots (FOLR, SOLR and TOLR) and of the central root. Quality ratios and indexes were calculated. The dynamics of growth of selected features during the vegetation season was expressed as trend lines. AP and SP seedlings, grown in containers YS had higher values of almost all measured traits (SH, RCD, SDW, number, length and dry weight of FOLR, SOLR and TOLR). However, in AP, the SS seedlings had better values of quality indexes and ratios (SQ, DQI, SDW/RDW and RDW/SDW ratio), than YS seedlings. SP seedlings, except for SQ, had better quality indexes in YS container. MP seedlings, with some exceptions, have better above ground quality features in SS containers, while root systems don’t differ significantly in both containers. Root quality indicators (root intensity and root bound indexes) are more favorable in SS containers in all Pine species. The polynomial trend lines in AP and SP grow in similar way and intensity in both containers, gradually increasing during the vegetation season. MP seedlings differ in much more intensive growth of above ground features, especially in the half of the vegetative period in both containers, while during this period root quantity and length stagnates. Generally, the quality of AP and SP seedlings is more or less equal and satisfactory in both containers, while MP seedlings show slightly better results in SS container.

The genus Callistemon belongs to the family Myrtaceae and comprises 34 species. They are woody aromatic trees or shrubs that are widely distributed in the wet tropics. According to the scientific literature, research on seed germination of this genus was rarely carried out. The germination requirements of Callistemon citrinus and Callistemon linearis were studied under controlled conditions in the laboratory. Seeds of both species were tested for germination at constant temperatures of 25°C, 30°C, 40°C, and at room temperature (23 ± 2°C) coupled with total darkness. Seeds were sown in Petri dishes (0.8% agar water) for 25 days of incubation. The kinetics of germination was determined according to four closely related parameters viz. final germination percentage (FGP), mean germination time (MGT), coefficient of velocity of germination (CVG) and time to 50% germination (T50). The room temperature of 23 ± 2 °C was found optimally suitable for both species, with 80% FGP and 11.1 days MGT for C. citrinus, and only 21.7% FGP and 12.4 days MGT were recorded for C. linearis. Furthermore, significant decrease in FGP was observed in both species at 25°C, 30°C and 40°C of temperature. The analysis also revealed that day 12-15 after seed sowing is suitable for final counts. Due of its very low FGP, seeds of C. linearis need an additional study to determine their viability. 

Seeds of many tree-species possess a hard seed coat which is impervious to water. These seeds often take a long time to germinate, resulting in heterogeneity and a delay in seedlings development which is an inconvenience for reforestation success. The aim of the present work was to determine the possibilities to improve the germination of five leguminous trees of the genus Acacia that have been recorded in the arid and the desert region of Algeria using sulphuric acid. A duration of 30 min of immersion in sulphuric acid improved the seed germination up to 97.5% and 99% for A. albida and A. laeta, respectively. Increasing the time of immersion (from 30 to 90 min) improved the germination percentages for A. ehrenbergiana and A. seyal seeds to 92.5% and 93.7%, respectively. Increasing this duration to 120 min had a positive effect on A. tortilis seed germination, improving the final germination rate up to 97%. Understanding of seed Germination Requirements is very important for regeneration and successful tree establishment in forest nurseries as well as for direct plantation in arid and semi-arid lands.

Drought and salinity act simultaneously in tolerance and acclimatization under saline conditions. Therefore, plants subjected to these types of stress should have developed specific structural adaptations at the early stages of development. The solution to these environmental problems is to look for species that are relatively water-efficient and resistant to recurrent episodes of various abiotic stresses such as salt stress. In this study, the salinity tolerance index, ionic homeostasis and osmoprotection were evaluated in A. karroo and A. saligna plants of 90 days old and cultured at various concentrations of NaCl for 21 days. Results showed that salt caused remarkable changes in some growth-related parameters (dry biomass) represented by the salinity tolerance index (STI). Na⁺, Ca2⁺, and Ratio_Na⁺/K⁺ content in the leaves increased with salinity levels, while K⁺ contents were significantly reduced compared to the control in both acacia species. Levels of proline, total free amino acids and reducing sugars have been accumulated considerably in the leaves. A. karroo was more salt-tolerant than A. saligna. Our results showed that the adaptability of a species to salinity is closely related to ion selectivity and biomass production. The seedlings also accumulated significantly a set of important osmolytes in leaves under salt stress, showing a marked increase in secondary metabolite accumulation. This adaptation proved very specific to each species for better survival in saline environments.  

Temperature can directly and indirectly impact the livelihood of inhabitants of a country and the natural environment as a whole. The surface temperature trend approximations for South Africa (SA) were calculated using a linear-regression fitting model. The model was adapted at The University of Reunion Island and was referred to as the Trend-Run model. The geophysical signal of the model was split into a sum of oscillations, which was used to clarify most of its variability. The trend values were calculated from the residual terms as a linear function. The model used atmospheric oscillations, which included Annual (AO), Semi-Annual (SAO), Quasi-Biennial Oscillations (QBO), El Niño-Southern Oscillation (ENSO), the 11-years solar cycle-Sun Spot Number (SSN) and Indian Ocean Dipole (IOD). The South African Weather Service (SAWS) data were used for the study. Data sets over a 31-year period, from March 1980 to December 2011, were used to measure the validity of the Trend-Run model, to determine the contribution and effect of this particular oscillation, and the validity of the model. The Trend-Run model showed very high applicability to the surface temperatures in all provinces across the SA region under investigation. High coefficient of determination values between (0.70-0.91) were recorded for surface temperatures across all provinces in the country with minor variations. The AO, ENSO and SAO were the highest contributing forcings in the model, thereby showing their high relevance to the success of this model in the study area. The temperature increases are expected to negatively impact on the biomes of SA, including the forest biome. Selected tree species of Acacia, Eucalyptus and Pinus could be impacted negatively with rising temperatures, which would negatively impact on the forestry industry in SA. As expected, the model did obtain a high success rate that ranged from 70% to 91% in the areas under study, however, there was still room for improvement by the possible inclusion of additional atmospheric forcings to the model that maybe be applicable to the weather and forestry distribution in SA.

This review covers most of the published literature on potassium (K) fertilization in bareroot seedbeds with the intent to concentrate on the southern United States. The timing and rates of K fertilization for bareroot seedlings are often based on logic and myths and, as a result, K recommendations vary considerably. Some recommend bareroot pine seedlings be fertilized with twice as much K as nitrogen (N) while others apply less than 100 kg ha^-1. It was determined that several long-held claims about K fertilization are invalid. Nursery seedbeds do not need to contain four times as much available K as N and the belief that extra K fertilization will increase freeze tolerance or drought resistance of non-deficient seedlings is invalid. There are no data to support the claim that K fertilization increases root growth or assists in the formation of terminal buds. For sandy seedbeds, there is no need to apply K before sowing. Adding extra K during the fall does not increase seedling morphology or seedling performance when loblolly pine seedlings, at lifting, have more than 0.5% K in needles. A reduction of K fertilization can be achieved by reviewing foliar tests prior to K top-dressings.

The location of the Bolivarian Republic of Venezuela in the tropical region of northern South America, in the Northern Hemisphere, with a total area of 91.64 million ha, of which 49.6 million correspond to natural forests (54.12 % of the national territory). Venezuela shows a series of geographic advantages that allow a rapid growth and development of the trees in comparison with the temperate zones where the growth is extremely slow. However, the occurrence of deforestation processes has intensified in a sustained way in the recent history of the country.

In the period from 1920 to 2008, the loss of 26.43% of the forested area has been recorded. Likewise, in the period 1975-1988, deforestation was estimated at 216,000 ha year^-1, equivalent to 2.9 million ha in 13 years (Catalan 1992). Deforestation has now increased to worrying levels and according to FAO estimates (2010), in Venezuela, a forested area of more than 288.000 ha year^-1 is deforested.

In the middle of the 20^th century several public and private institutions began an important effort to reforest areas of sandy soils of scarce depth on a bed of highly impermeable clay. With erosion processes generated as a result of strong winds that causes severe damage to the little existing vegetation. It was expected that with the passage of time this region could become a desert in the oriental plains of Venezuela. This is how the Maderas del Orinoco Companies (CVG - PROFORCA), the Venezuelan Corporation of Guayana (CVG), Smurfit Kappa Cartón of Venezuela, San Carlos Forestry Development, Masisa. Propulso, among others, started in different regions of the country the establishment of plantations for various purposes. For this they have used fast growing forest species such as: Pinus caribaea var hondurensis, Eucalyptus Urophylla, Acacia magnium, Caraipa llanorum, Tectonia grandis, Hebea brasiliens, Gmelina arborea, Erisma uncinatum, among others. At present, a reforested area of 650.000 ha has been reached. This has favored the protection of natural habitats by reducing the pressure for exploitation and use of the forests.

The legal framework established in the new National Constitution, approved in 1998, is based on decrees of 1825-1829 of the Liberator Simón Bolívar and classifies the territory in diverse forest areas establishing a modern environmental conservation policy. A historical summary and the current legislation with the classification that promises a rational management of the national territory is presented.

Two schools of thought address the optimum soil pH (measured in water) for growing hardwood seedlings in bareroot nurseries. One school uses nutrient surveys in non-fertilized forests to determine the best pH range for growing seedlings in fertilized nurseries. Some students of this school believe hardwood seedlings grow best at pH 6.0 to 7.5. In contrast, another school relies on research from pH trials to conclude that fertilized hardwoods can grow well in soils that range from pH 4.5 to 6.0. This article compiles some of the findings from seedbed and greenhouse trials and attempts to use data to dispel a few myths about the “optimum pH” for growing hardwood seedlings. Greenhouse trials suggest many fertilized hardwoods grow better in acid soils (pH 4-6) than in nearly neutral soils (pH 6.0-7.5). The optimal pH for growth differs among species and, therefore, it is a myth that all hardwood seedlings grow best at pH 6 to 7.5. Most nursery managers in the southern United States grow bareroot hardwoods between pH 4.8 and 6.0.

This study applied a total energy approach to model seedling growth for container-grown loblolly pine (Pinus taeda L.). Seedlings were grown in three container stocktypes representing a range of cavity volume and density patterns. These seedlings were grown under both controlled greenhouse and outside compound environmental conditions under well-defined cultural conditions. Models for temperature and light ranges were created from work on the ecophysiological performance and morphological development of loblolly pine to these atmospheric conditions. A PhotoThermal data set was created by generating hourly averages of these two environmental variables during the growing season. Light and temperature data were integrated, each weighted equally, into PhotoThermal hours (PT_H) to assess the crop growth response. Loblolly pine seedling growth in both the greenhouse and outside compound was directly related to PT_H. Seedling growth was also related to the container type with the largest cavity volume and lowest cavity density having the greatest growth per PT_H. Application of the PhotoThermal model is discussed for growing seedlings in an operational program having multiple production steps, delivery dates and nursery locations.

The present work demonstrates the effects of moist cold stratification on seed dormancy breaking in Hawthorn (Crataegus monogyna Jacq.). We also examined the fruit and seed morphology. Mature and ripe fruits were collected, the pulp removed and the seeds (stones) left in the sun to dry for three days. Four temperature regimes viz. 4°C, 6.5°C (natural conditions where the fruits were harvested), 10°C and 20°C were used for stimulating seed germination under total darkness. For each treatment, there were four replicates with 50 seeds incubated in a plastic container between two layers of moist sand at 15%. At the end of the experiment, non-germinating seeds were tested for viability using Tetrazolium chloride (TZ).  After 4 months, the final germination (FGP) was expressed as a percentage of the total number of seeds in each treatment. The fruits of Hawthorn were 14.9 ± 0.73 mm long and 15.1 ± 0.84 mm in diameter and weigh 2.05 ± 0.28 g. The seeds were 8.29 ± 0.43 mm long and 6.75 ± 0.39 mm in diameter and weigh (0.25 ± 0.04) g. The thousand-fruit weight was 2,000 g and of the thousand-seeds weight was 280 g. The statistical analysis indicated significant effect (p < 0.0001) of treatment on seed germination. Dormancy in this species was broken most effectively by cold stratification at 4°C and under natural conditions with 76% and 67.5% of FGP, respectively. Most of the nongerminated seeds of C. monogyna were viable (dormant) as judged by TZ.