Forest Seeds Research Articles

Effects of chronic oral exposure to insecticide teflubenzuron on the midgut of the honey bee Apis mellifera workers: histopathological insights into pesticide toxicity.

The honey bee Apis mellifera plays a significant role as a pollinator of native and cultivated plants, by increasing the productivity of several cultures, preserving the flora, and producing forest seeds. However, bee populations are declining worldwide, including A. mellifera, due to Colony Collapse Disorder, mainly resulting from the constant use of pesticides in the crops. Teflubenzuron is a physiological insecticide that belongs to the benzoylurea group, which inhibits chitin synthesis, the main component of the insect integument classified as safe for non-target insects, including bees. However, its effect on non-target organs of insects remains unknown. The midgut is the main organ of the digestive tract, which works in digestion and absorption and may be exposed to pesticides that contaminate food resources. The present work aimed to verify if the insecticide teflubenzuron is toxic and has histopathological effects on the midgut of A. mellifera adult workers. Workers exposed orally and chronically to the field-realistic concentration of teflubenzuron present 81.54% mortality. The epithelium of the midgut of these bees presents high vacuolization, spherocrystals, cell fragments released to the organ lumen, apocrine secretion, nuclear pyknosis, loss of cell-cell contact, and damage to regenerative cell nests and to the peritrophic matrix. These results indicate that the chitin synthesis-inhibiting insecticide teflubenzuron is toxic to A. mellifera after chronic oral exposure, at realistic field concentration, although it is classified as non-toxic to adult and non-target insects.

Chemical and Mechanical Scarification as Techniques for Overcoming Dormance in Red Tent Seeds (Adenanthera pavonina L.)

Purpose: Evaluate chemical and mechanical scarification techniques, as methods for overcoming dormancy in red vine seeds. Theoretical Framework: Based on scientific articles found on search engines and books in the field of seeds, types of forest seeds, types of dormancy in forest seeds and techniques for overcoming dormancy. In order to support the explanation of how techniques for overcoming dormancy are related to the rate and time of germination of red seed seeds, and how germination time can subsequently affect the quantity of seedlings produced, as well as their initial growth. Method: The experiment was installed to test the following treatments: T0 – without scarification; T1 – mechanical scarification; T2 chemical scarification with 80% H2SO4 for half an hour; T3 – chemical scarification with 80% H2SO4 for one hour; T4 – chemical scarification with 0.4% KNO3 for half an hour; T5 – chemical scarification with 0.4% KNO3 for one hour. The design used was completely randomized, with six treatments, five replications and 20 seeds in each replication. At the end of 30 days, counting from the beginning of germination, the following variables were evaluated: germination speed index (IVG), average germination time (TMG), germination percentage (G) and germination speed index (IVG). Results and Conclusion: The most efficient methods for germinating the red tent seeds were mechanical scarification with sandpaper and immersion in 0.4% KNO3 for half an hour. However, mechanical scarification would be the most easily used and least expensive method for producing seedlings in nurseries. Research Implications: These results indicate that the mechanical scarification technique is an efficient method for overcoming the dormancy of the red tent, which is integumentary. Understanding the most efficient and effective techniques for overcoming dormancy in seeds of species that present this characteristic is important to allow, within the nursery, germination to occur quickly and uniformly. Consequently, making it possible to obtain seedlings with more uniform sizes, even though these are produced from seeds. Originality/Value: A high germination rate and uniform initial growth are important factors within the nursery, especially if it is of a commercial nature, but also for the restoration of areas, because it allows seedlings to be obtained in less time.

The efficiency of pre-sowing application of humic preparations when applied to European spruce (Picea abies) seeds

ABSTRACT The article discusses the relevance of increasing the sowing qualities of forest seeds. The results of studies on the influence of humic preparations on the sowing qualities of the European spruce (Picea abies) are presented. The positive effect of the studied humic preparations on the germinative energy and germinating ability of seeds was noted. The best effect is obtained when processing seeds which have reduced sowing qualities. The dependence of germinating ability of seeds on duration of soaking in the working solution of humic preparations and the content of the active substance in them has been established. The best indicators of germinating ability and germinative energy were noted when the seeds were soaked for 20 hours in a humic preparation with a humic acid content of 9.9 g/l.

Изучение спектрометрических особенностей лесных семян для улучшения посевных качеств: ретроспективный кластерный анализ направлений научного ландшафта

Forest seeds spectral data in the visible and infrared regions of electromagnetic radiation lengths quite effectively
 differentiate the origin, viability, types of seeds, their infestation with pests and diseases, the ability to absorb and lose
 water. The search for a method of seed testing that is both experimentally simple, fast and effective for predicting germination is necessary to increase the energy efficiency of forest nurseries in the production of planting material. The retrospective references systematization (N = 55, 1998-2023, terms [Scholar Query = seeds* AND (spectr* OR optic*) (properties OR features) AND analysis]) into clusters was carried out on the basis of eight performance criteria represented by
 rank variables. The level of similarity and difference between clusters is determined by the method of the most distant
 neighbors with the grouping of data by the square of the Euclidean distance. The most distant criterion from other criteria
 is the level of invasiveness of testing (the square of the Euclidean distance is 25, p < 0.05). Correlation analysis of nonparametric criteria indicates a direct strong interaction between the level of financial and organizational costs (Spearman
 coefficient ρ = 0.77; p = 0.0008), time costs and low machine learning capability (ρ = 0.725; p = 0.0008). In the future, it
 is planned to periodically supplement the set of systematic data to obtain an objective assessment of seed testing methods,
 as well as using a seed passport to evaluate the relationship of RGB spectral data of more than 1 000 individual seeds
 with early growth of seedlings in a post-pyrogenic experimental site of the forest landscape of the Voronezh region by
 example (Pinus sylvestris L. var. Negorelskaya).

Reforestation pipeline: case for quality management of NIR-region grading of Scots pine seeds and FLR-algorithm for information processing

When controlling the process of improving the quality of seeds by separating on a spectrometric basis, the primary information about the state of Scots pine seeds is carried by the wavelengths of optical fluxes and their amplitudes. The algorithm for analyzing the required characteristics of small forest seeds in the infrared range is a corresponding sequence of logical terms that provide the ability to determine the specified seed parameters by a combination of spectral frequencies and light flux amplitudes taken from the corresponding photodetectors. At ΔС = 0.5, the efficiency of the algorithm was 77.6 %, and at ΔС = 0.9, respectively, 99.5 %. In this regard, the choice of ΔС is the result of a compromise between the cost of rejection of high-quality seeds and losses when using unrecognized low-quality seeds and it is made according to the results of relevant experiments.

Studying of the Amount of Energy Required to Operate the Nursery Tray Planting Machine

A study was conducted at the University of Baghdad-College of Agricultural Engineering Sciences - Department of Agricultural Machinery and Equipment for the agricultural season 2023 with the aim of designing, manufacturing and testing a machine used to planting agricultural nursery tray with different types of vegetable or horticultural seeds or forest seeds of various forms, and using different agricultural media where they are conducted The planting process is by pulling the seeds with a negative pressure vacuum system, and then they are feding to the dishes in their right place to complete the planting process. The study included three factors: The speed of the main belt in three levels: 0.43, 0.66 and 0.90 m.sec−1 and three types of agricultural media: Petmus, mix of Petmos and silt 1:1 and silt, and three types of seeds that were planted. A factorial experiment was carried out using a design (CRD) with three replications using the least significant difference and a probability level (LSD = 0.05) to compare the mean of the coefficients. Some performance indicators of the machine were studied, including: Consumed electrical power, electric power, the productivity of the machine, and the efficiency of the machine in picking seeds. The results indicated The peat moss medium excelled in recording the least consumed electric power, which amounted to 2075.8 watts, and the lowest electric power, which amounted to 0.007751 kWh. And the third speed of the conveyor belt excelled in achieving the highest productivity of dishes per hour, amounting to 105.08 dishes.hour−1, and the first speed achieved the least consumed power, amounting to 2047.3 watts, and the least consumed electrical energy at the third speed, which amounted to 0.007703 kWh.

Сибсовое потомство карельской березы на Заонежской лесосеменной плантации

The article reports the results of studies on the growth and development of curly birch sibs progeny (produced through controlled pollination) aged 35 and 15 years growing in the Zaonezhye forest seed orchard (sites 1 and 2, respectively) in south-eastern Karelia, Medvezhyegorsky District. The number of trees with signs of wood figure in the seed progeny of curly birch in site 1 was 67 % by the age of 20 years, and by the age of 35 years – almost 80 %. This can probably be attributed to the genetic characteristics of the parent (plus) trees on one hand and to the favorable conditions in the forest seed orchard during the first years of the sibs progeny development on the other. Four of the 36 hybrid families (selected to include forward- and backcrossing products) were used for the case study of the growth and development patterns in stands of different age. The sibs progeny of these hybrid families was dominated by high-stemmed plants, but the main trunk shape in the 15-year-old stand was one with necks and muffs, while in the 35-year-old stand – with small protuberances. The rate of height growth in the trees decreased notably with age, whereas radial (stem diameter) growth, on the contrary, accelerated. As the bark grew thicker, however, the formerly bulgy surface “smoothed down”. We have also identified specific features of the ground vegetation formed under the effect of curly birch plantations of different age (15- and 35 years old). A conclusion drawn from the study is that good results from targeted cultivation of curly birch with figured grain (e.g., for sliced veneer) can be achieved already by the age of 20–35 years. Furthermore, considering the number of trees and their origin, this forest seed orchard constitutes an essential part of the valuable gene pool of curly birch, which may turn into a source for expanded reproduction of the resources of this unique member of the European forest tree flora. For citation: Vetchinnikova L.V., Titov A.F., Kostina E.E., Zhigunov A.V. Sibs Progeny of Curly Birch at the Zaonezhye Forest Seed Orchard. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 5, pp. 9–26. (In Russ.). https://doi.org/10.37482/0536-1036-2023-5-9-26

Assessing the Amount of Force Necessary to Pick off Cones from Siberian Larch, Scots Pine and Siberian Pine Trees

The article presents the results of studies conducted in Eastern Siberia, dedicated to determining the amount of force required for detachment of Siberian larch, Scots pine and Siberian pine cones, which is one of the main indicators that determines the parameters of cone collecting machines and mechanisms for coniferous species. The pick-off force for the cones was measured at different collection times in the upper, middle, and lower parts of the crown and at different angles of pull-off force direction. The limits of these forces variability are: for the Scots pine – 23.5–48.1 N, for the Siberian larch – 27.5–42.2 N; for the Siberian pine – 3.9–7.8 N. The data obtained can serve as a basis for calculating the parameters of cone collecting mechanisation tools for the aforementioned species. When designing machines and mechanisms for collecting the coniferous trees’ cones, it is necessary to have initial data that determine the parameters of the working bodies. One of these parameters is the amount of effort required to separate the cones from the branches. The forces of detaching cones from trees in the European part of Russia were determined by a number of researchers. According to I.M. Zima with co-authors (1966), the force of detachment of cones in Scots pine (Pinus sylvestris L.) is 41.2 N. According to I.A. Lavrov (1970), pine cones can be torn off with a force of 21.1 N, and the cones of Siberian larch (Larix sibirica Ledeb) – with a force of 39.2 N. In Siberia, studies on the cones detachment were first carried out in 1970 by the laboratory of mechanization of the forest seeds collection and processing of the ASRIM forestry enterprise (Orlovsky et al., 2016). The detachment of Siberian larch, Scots pine and Siberian pine cones was studied in the forestry enterprises of the Krasnoyarsk and Altai regions and in the Republic of Tyva. The pull-off forces of Scots pine and Siberian larch cones were measured in the lower, middle, and upper parts of the crowns using dynamometers with a 0.1 N division value and with a maximum force recording device. The measurements were carried out along the branch, at an angle of 40°–50° and at an angle of 90° to the branch.

THERMOTHERAPY IN THE CONTROL OF Fusarium spp. IN ANGICO SEEDS [Anadenanthera colubrina (Vell.) Brenan] AND MAINTENANCE OF PHYSIOLOGICAL QUALITY

Thermal treatment is frequently used to overcome dormancy in forest seeds; however, it can also be used to control seed-born pathogens. This study aimed to evaluate the efficiency of thermotherapy in controlling Fusarium sp. in angico seeds [Anadenanthera colubrina (Vell.) Brenan] collected in the state of Paraíba, Brazil, and its effect on physiological quality. Nine seed sources located in the municipalities of São João do Cariri - PB, Boa Vista - PB, and Sumé - PB were selected for this study. For the sanitary test, the treatments were composed of untreated seeds (control), chemical treatment, and thermal treatment at temperatures of 50, 60, and 70 °C immersed for 10, 20, 30, and 40 minutes. The same treatments were used in the germination test, and the percentage of germination, first count, dead seeds, seedling length, and germination speed index were evaluated. The results showed that the thermal treatments effectively reduced Fusarium sp. in the seeds. Thermotherapy did not negatively affect the physiological quality of angico seeds and led to an increase in germination percentage.

IMPORTANCE OF SEED QUALITY FOR THE FORESTRY SECTOR

Plant production is essential for the maintenance of human activity on Earth, and as seeds are the main tool for plant propagation, obtaining high-quality seeds is essential for successful planting. Forest species are applied in diff erent areas, such as timber, the pharmaceutical industry, landscaping projects, and degraded area recovery. The search for seedlings of forest species has increased due to the intense exploitation of ecosystems and the need to recover degraded areas. Therefore, it is necessary to use high-quality seeds that are composed of a complex set of attributes, including genetic, physical, physiological, and sanitary factors that directly infl uence the performance of seeds in the fi eld and their longevity in storage. Forest seeds have peculiarities, such as variable size and shape, nonuniform water content and germination speed, as well as diff erent drying and storage capacities. In addition, they have high genetic variability, which implies diffi culties in their management, such as the presence of dormancy, which can aff ect seed quality and seedling production. Seed germination and vigor are critical factors for the quality of forest seeds, but many species have not yet identifi ed their germination requirements. The lack of information about the peculiarities of each forest species and the high genetic variability among them makes it diffi cult to standardize methods for analyzing the physiological quality of seeds, in addition to becoming an obstacle to their use in reforestation projects, since the lack of diversity in the use of native species is a concern, as it reduces variety and endangers biodiversity

Physiological Maturity of Tropical Forest Seeds: A Boon to Improved Harvest and Storage Practice of Recalcitrant Seeds?

Physiological Maturity of Tropical Forest Seeds: A Boon to Improved Harvest and Storage Practice of Recalcitrant Seeds?

Оценка качества лесосеменного материала на экспериментальном участке сосны обыкновенной (Pinus sylvestris L.) при адаптивном восстановлении лесных ландшафтов

When choosing a technology for restoring forest landscapes, the quality of forest seed material is a significant factor. To develop a reference information system to support decision-making for adaptive restoration of forest landscapes, it is necessary to have data on the types and quality of forest seed material. Existing studies directly or indirectly confirm, on the one hand, the influence of seed quality on the quality of future plantations, on the other hand, the influence of forest characteristics on the quality and quantity of seeds. Preservation of the quality of forest seed material in conditions of large-scale harvesting of Scots pine seeds (Pinus sylvestris L.) is possible with the development of permanent forest seed plots, and (or) the use of modern technologies for separating forest seeds without loss of genetic diversity and increasing not only germination and seed germination energy, but also the vitality of seedlings, their stability to the change of abiotic factors. Descriptive statistics of biometric parameters of trees and cones of Scots pine on the experimental site (N51°50.00'; E39°22.09', 113 m ASL) demonstrates the following values (average; average error): the height of the tree (186.2; 11.7), the diameter of the root neck of the tree (5.9; 0.3), the ratio of the height of the tree to the diameter of the root neck (31.90; 0.97), the number of cones (9; 4), the number of seeds (12; 5). There is a strong positive correlation at the level of p < 0.0001 between diameter and height, a strong positive correlation between the number of cones and the number of seeds (p < 0.001), a strong positive correlation (p < 0.05) between the height of the tree and the number of cones. In the future, it is planned to evaluate the relationship of accumulated degree days, accumulated precipitation, normalized difference vegetation index with the cones and seeds number.

Seed Distribution and Phenotypic Variation in Different Layers of a Cunninghamia Lanceolata Seed Orchard

The phenotypic characteristics of forest seeds are the basis of germplasm innovation, genetic improvement, and biological research, and they also are the reference for the development of seed orchards. In this study, we analyzed seed quantity characteristics, phenotypic differentiation, and variation patterns in three seed-bearing clones from different crown layers of the Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) orchard located in Fujian Province, China. We divided the clones into six layers according to crown height and the sunny and shady sides, 14 phenotypic characteristics, and five quality indexes, and we measured the germination rate of seeds. The rate of seeds filled with tannin-like substance in the upper sunny layer was low, but it was high in the lower shady layer. The germination rate was highest in the upper sunny layer and lower in the middle and lower shady sides. Values of most of the 14 phenotypic traits tested differed significantly among clones and layers. The average value of the phenotypic differentiation coefficient was 81.16%, indicating that variation among clones explained most of the total phenotypic variation. The repeatability of the 14 phenotypic traits was high (R > 0.80), indicating that these traits are highly heritable. The phenotypic characteristics of cones and seeds varied from 6.86% to 129.51%. The 14 phenotypic traits exhibited different degrees of correlation, and seed weight, seed circumference, seed width, and seed area can be used to predict other seed traits. However, the correlations between cone traits were not strong. Our results show that when establishing a dwarfing Chinese fir seed orchard, the distribution and variation of seeds in different crown layers of clones should be considered, and clones with more cones in the lower crown layer should be selected as parents.

Effects of habitat differences on the scatter-hoarding behaviour of rodents (Mammalia, Rodentia) in temperate forests.

To discover the differences in hoarding strategies of rodents for different seeds in different habitats, we labelled and released three different types of seeds, including Pinuskoraiensis, Corylusmandshurica, and Quercusmongolica, in temperate forests of northeastern China and investigated the fate of seeds in four different habitats that included a broad-leaved forest, mixed-forest edge, mixed forest, and artificial larch forest. Our research showed that the hoarding strategy of rodents was found to vary substantially in different habitats. The survival curves of seeds from different habitats showed the same trend, but the rates of consumption in different habitats varied. More than 50% of the seeds in the four habitats were consumed by the tenth day. It took 20 days to consume more than 70% of the seeds. The rate of consumption of P.koraiensis seeds reached 96.70%; 99.09% of the C.mandshurica seeds were consumed, and 93.07% of the Q.mongolica seeds were consumed. The seeds were consumed most quickly in the artificial larch forest. In general, most of the early seeds were quickly devoured. After day 20, the consumption gradually decreased. Rodents found the seeds in the artificial larch forest in a shorter average time than those in the other types of forests. The average earliest discovery time was 1.4 ± 0.9 d (1-3 d). The average earliest discovery time in all the other three habitats exceeded 7 d. The median removal times (MRT) was distributed around the seeds at 14.24 ± 10.53 d (1-60 d). There were significant differences in the MRT among different habitats. It was shortest in the artificial larch forest at 7.67 ± 6.80 d (1-28 d). In contrast, the MRT in the broad-leaved forest was the longest at 17.52 ± 12.91 d (4-60 d). There were significant differences in the MRT between the artificial larch forest and the other habitats. There was less predation of the three types of seeds at the mixed-forest edge, and the most seeds were dispersed. The rates of predation of the P.koraiensis, C.mandshurica, and Q.mongolica seeds were 28.33%, 15.83%, and 44.0%, and 59.17%, 84.17%, and 48.0% of the seeds were dispersed, respectively. The average dispersal distances of all the seeds were less than 6 m, and the longest distance recorded was 18.66 m. The dispersal distances and burial depths differed significantly among the four types of habitats. The distance of seed dispersal was primarily distributed in 1-6 m.

Seed yield structure in taiga and sub-settlement Siberian stone pine forests: level, and nature of differences

On the example of Siberian stone pine, seed productivity was analysed in two stands that differed in origin and formation conditions. The cone yield was analysed in years with different levels of seed production in the period from 2016 to 2019. In terms of the number of cones per tree, the sub-settlement Siberian stone pine forest was 2-3 times superior to the taiga Siberian stone pine forest. The level of individual variability in the number of cones in the near-settlement Siberian stone pine forest was significantly lower than in the taiga forest. There is reason to believe that the high level of variability is likely related to a more pronounced differentiation of the stand by crown size. The number of dead ovules in the Siberian stone pine forest in settlement is 60-70% higher than in the taiga forest. Due to high “mortality” of ovules and high variability of this trait, the number of filled seeds in the near-settlement Siberian stone pine forest is much lower, and variability in the number of complete seeds is much higher than in taiga Siberian stone pine forest. When there are few filled seeds in a cone, the size of each of them increases. Therefore, the average weight of one filled seed is higher in the subsettlement Siberian stone pine forest than in the taiga forest. Thus, the quality of the cones in the years of average and especially high yield in the near-settlement Siberian stone pine forest is much lower, and the level of variability of the traits that characterise it is much higher, and the distribution of the traits is characterised by a pronounced negative kurtosis. Obviously, these peculiarities of the near-settlement Siberian stone pine forest are related to human interference in the course of its development, which disturbed the course of natural selection and deformed the genotypic composition of the population.

ДВУХОСНЫЕ СОЧЛЕНЕННЫЕ ЛЕСОТРАНСПОРТНЫЕ МАШИНЫ В УСЛОВИЯХ ЛЕСОСЕКИ: ОЦЕНКА ПРИМЕНИМОСТИ

The study can provide decision-making support to loggers and participants in forest relations who are obliged to carry out reforestation activities to assess the factors that change the effectiveness of forestry and logging operations. The balance of production and environmental effects from the use of forest transport machines in the development of forestry is an important step in effective quality management of forest landscape restoration. The degree of compaction of the forest soil from the impact of propellers directly affects both the fuel consumption of the power plant of the forest transport machine and the ability of forest seeds of the main breed to germinate. The primary transportation of trees and their parts (whips, balances, assortments, waste residues and other waste of logging production) occupies an increasing volume in the energy balance of the timber transport machine. It is necessary to solve complex problems of choosing energy-efficient and maneuverable biaxial articulated timber transport vehicles in comparison with machines with a continuous frame for performing transport work in the conditions of a cutting area. In order to maximize the requirements for the efficient operation of machines in difficult cutting conditions, it is necessary to ensure, along with high operational properties (traction, cross-country ability, maneuverability, smooth running), a high level of technical and economic indicators. The assessment of the applicability of existing structures of forest transport vehicles was carried out by statistical methods of Ward and intergroup relations according to the criteria of soil compaction, patency, maneuvering, power circulation, traction losses, balance of weight distribution and purpose. When planning future research, it is necessary to answer a number of questions: which criterion should be used as a universal one for unambiguous selection of the type of forest transport vehicle? Is it possible to estimate the geomorphology of the future cutting area in advance with the use of unmanned aircraft systems and predict the effective trajectories of movement of articulated timber vehicles?

Desiccation induced physiological and biochemical changes of Gymnacranthera canarica (King.) Warb. seeds in the Myristica swamp forests, Southern Western Ghats, India

Gymnacranthera canarica (King.) Warb. is an endemic tree species that dominates the Myristica swamp ecosystem of southern Western Ghats. This tropical tree species has become more threatened due to limited natural seed germination and habitat loss. Mature seeds were collected from the myristica swamp ecosystem subjected to desiccation study. This research evaluated the physiological (moisture content, tetrazolium reduction, lipid peroxidation, electrolyte leakage) and biochemical response of seeds during different desiccation treatments. Results showed that G. canarica seeds are highly sensitive to desiccation and total viability loss was seen within 15 days following harvest indicating the active seed metabolism of mature seeds showing absence of metabolic arrest. Desiccation enhanced malondialdehyde and electrolyte leakage while reducing formazan formation. Seed desiccation increases protease activity, which peaks when viability is lost. Desiccation reduced the quantity of phenol and starch, whereas proline, fat, sucrose and total soluble carbohydrates increased. The early viability loss in G. canarica seeds could be due to loss of membrane integrity, which was linked to ROS formation and associated lipid peroxidation products indicating seeds are truly recalcitrant.

Image analysis using X-ray to evaluate seed quality of <i>Anadenanthera peregrina</i> (L) Speg

Solutions based on image analysis are a growing trend towards improving the quality of forest seeds. This study aimed to associate the information obtained through the processing of radiographic images with the physiological potential of Anadenanthera peregrina seeds. Ten seed lots from different mother trees were submitted to automated X-ray analysis to obtain variables related to seed morphology and tissue integrity. Then, the seeds were evaluated for their physiological potential through the variables germination, normal seedlings, germination speed index (GSI), seedling length, uniformity index, and vigor index. The results showed that there was a relationship between the variables obtained with the X-ray analysis and those of the physiological potential of the seeds. Most of the lots with low physiological potential had lower tissue density, circularity, and a higher positive skewness value. The X-ray technique can be considered valid to establish a relationship between the physical and physiological quality of seeds, however, it seems to be more efficient to identify seeds with low physiological potential.

Successional trajectories of seed dispersal mode and seed size of canopy tree species in wet tropical forests

Despite the critical role of seed dispersal for tree colonization during forest succession in wet tropical forests, successional trajectories of seed dispersal modes are poorly documented at the community level. Overall successional trends in wet tropical forests indicate that, over time, animal-dispersed and large-seeded species increase in relative abundance in woody vegetation, whereas wind-dispersed and small-seeded species decline. Increased abundance of animal-dispersed trees during succession may be attributed to higher rates of seed deposition by animals and higher survival rates of animal-dispersed species with larger seeds (diaspores) compared to wind-dispersed species. We compiled categorical information on seed size (maximum seed length) and dispersal mode (anemochory, autochory, or zoochory) for 240 canopy tree species in six naturally regenerating forests (11–45 years since the abandonment of pasture) and two old-growth forests in lowland wet forests in northeastern Costa Rica. We evaluated dispersal mode and seed size among tree species classified as second growth and old growth specialists, and generalists based on relative abundance data in these plots. Further, we compared long-term trajectories in the dispersal and seed-size profile for 240 species of canopy tree species for seedlings, saplings, and trees ≥5 cm dbh using annual vegetation survey data from 1997 to 2013. Seed size was significantly associated with dispersal mode, which was driven by anemochorous species with intermediate seeds 6 mm to 15 mm and autochorous seeds with large seeds >15 mm. Dispersal modes of canopy tree species exhibited clear directional trajectories, with decreasing relative abundance of anemochory and increasing relative abundance of zoochory. Zoochorous seedlings showed higher survival rates than anemochorous seedlings. Species with seeds ≤ 6 mm decreased in relative abundance through succession, while species with seeds >15 mm increased within seedling and sapling communities. Seedlings with seeds >15 mm showed higher survival rates than smaller seeds in second-growth forests. The study further demonstrates the importance of seed traits, such as dispersal mode and seed size, for community assembly during forest regrowth, and the importance of frugivorous animals in this process. The abundance of animal-dispersed tree species in different size classes can be a useful indicator of the recovery of biodiversity and species interactions during forest succession in wet tropical regions.

Correlation between Relative Humidity and Forest Seeds Moisture on the Incidence of Fungi

The objective of the research was to evaluate the effect of relative humidity (RH) and moisture content (MC) on the incidence of pathogenic fungi on the seeds of Agave lechuguilla, Lippia graveolens, and Nolina cespitifera. Seeds were stored 90 days at 60, 75, 80, and 85% RH, and results were processed with a correlation analysis in the R software using the Spearman test. Higher fungi incidence (FI) in seeds was found from 10 to 20% RH; however, correlation between RH and MC of seeds was positive with r = 0.311 and p = 2.2 × 10 − 16 . In general, RH is related to MC, but not to fungi incidence, which is related mainly to MC of seeds. Correlation between RH and FI for each seed species was not significant, r = 0.026, −0.040, and 0.071 and p = 0.687 , 0.540, and 0.272 for A. lechuguilla, N. cespitifera, and L. graveolens, respectively. There was a positive correlation between the MC of seeds with fungi incidence; a negative correlation between the RH and the FI; and a positive correlation between the RH and the MC of seeds. In this type of seeds (orthodox), the MC is probably the most important factor in determining its longevity. The seeds under study can be stored in a 60% to 75% RH. Five fungi genera were found, predominating Aspergillus with five identified species.