Joint Impacts of Meloidogyne incognita and Soil Nutrition on Solanum lycopersicum var. cerasiforme.

Strategies for plant nutrient resource allocation under Meloidogyne spp. infection and different soil nutrient conditions are not well established. In response, the objectives of this research are to determine if increased vegetative growth of Solanum lycopersicon var. cerasiforme (cherry tomato) under high nutrition enhances resistance to M. incognita and whether adaptive strategies for growth, reproduction, and nutrient uptake by cherry tomato infected with M. incognita alter nutrient availability. The study was conducted under greenhouse conditions using high, medium, and low soil nutrient regimes. The research results indicate that the total biomass of cherry tomato was less in the presence of M. incognita infection under all three nutrient conditions, compared with plants grown in the absence of this nematode. However, the increase in the root/shoot ratio indicates that cherry tomato allocated more resources to belowground organs. Under the combined impacts of M. incognita infection and low or medium soil nutrition, the nitrogen content in root system tissues and the phosphorus content in shoot system tissues were increased to meet the nutrient requirements of galled root tissue and plant fruit production. It is suggested that plants increase the allocation of reproductive resources to fruits by improving phosphorus transportation to the aboveground reproductive tissues under low and medium nutrient conditions. Overall, the study highlights a significant impact of soil nutrient levels on the growth and resource allocation associated with M. incognita-infected cherry tomato. In response, soil nutrient management is another practice for reducing the impacts of plant-parasitic nematodes on crop production.

Effects of Seed Size and Frequency on Seed Dispersal and Predation by Small Mammals.

Frequency-dependent predation is common in predator-prey interactions. Size is an important characteristic of seeds and is crucial in the regeneration stage of plant seeds. However, the frequency dependence of animal predation on seed size has not been reported. In this study, we conducted a field experiment and used different sizes of Liaodong oak (Quercus wutaishanica) seeds to test the frequency dependence of intraspecific seed size selection in rodents. We used the number ratio of large to small seeds as the frequency. The results show that the rate of small seeds being eaten in situ was significantly higher than that of large seeds (p < 0.05). The rates of different-sized seeds being eaten after removal decreased with increasing frequencies, and there was no significant difference between frequencies except for 1:9 and 9:1. The rates of large seeds being scatter-hoarded were significantly higher than those of small seeds at different frequencies (p < 0.05). The eating distances after removal of large seeds were significantly longer than those of small seeds at the same frequencies (p < 0.05). Furthermore, the scatter-hoarding distances of large seeds were significantly longer than those of small seeds at three frequencies (1:9, 3:7, and 9:1) (p < 0.05). That is, rodents consumed more small seeds in situ, dispersed and scatter-hoarded more large seeds, and dispersed large seeds over longer distances. Rodents exhibited a negative frequency dependence for small seeds and a positive frequency dependence for large seeds on being eaten in situ. Moreover, rodents exhibited a negative frequency dependence for large seeds and a positive frequency dependence for small seeds on being eaten after removal and scatter-hoarding. These results reveal the frequency dependence of rodent selection on seed size and provide new insights into animal-mediated seed dispersal and the regeneration of plant populations.

Effects of Seed Size and Cache Density on the Seed Fate of Quercus wutaishanica Mediated by Rodents.

Animal-mediated seed dispersal is very important for plant population regeneration and the stability of forest ecosystems. Seed size and cache density are important factors for seed dispersal, but we still know little about seed size selection at different cache densities. Here, we conducted field experiments in a Larix principis-rupprechtii plantation in the Liupan Mountains in Ningxia province to investigate the effects of tag-marked Quercus wutaishanica seeds of different sizes and cache densities on predation and the scatter-hoarding behavior of rodents. The results showed lower proportions of intact in situ (IIS) and eaten in situ (EIS) large seeds than small seeds at all levels of cache density, with the exception of IIS seeds at a 6.25 seed·m-2 cache density. A higher proportion of small seeds were eaten after removal (EAR), but a higher proportion of large seeds were scatter-hoarded (SH) by rodents at most cache densities. Furthermore, rodents preferentially removed large seeds farther away for eating or scatter-hoarding. The IIS and EIS proportions of both large and small seeds declined, but the proportion of the two types of seeds that were EAR fluctuated, increasing with increasing cache density. Rodents preferred to increase the proportion of scatter-hoarding of large seeds with increasing cache density, whereas the proportion of scatter-hoarding of small seeds was maximized at a cache density of 6.25 seed·m-2. Both the eaten distance after removal (EDAR) and scatter-hoarded distance (SHD) increased with increasing cache density. These results suggest that large seeds are more likely to be scatter-hoarded and removed to longer distances than small ones. Rodents tended to reduce the seed proportion of EIS seeds and increased the proportion of seeds EAR and SH, and accordingly increased EDAR and SHD with increasing cache density. This study provides some scientific basis for animal-mediated seed dispersal.

The Response of Oxytropis aciphylla Ledeb. Leaf Interface to Water and Light in Gravel Deserts.

In arid areas, the scarcity of rainfall severely limits the growth of plants in the area. In arid sandy deserts, plants survive by deeply rooting to absorb groundwater. In arid gravel soil deserts (Gobi), the gravel in the soil layer limits the growth and water absorption of local plant roots. Therefore, the strategies adopted by local plants to obtain water to sustain life have become crucial. Oxytropis aciphylla Ledeb. is a perennial, strongly xerophytic, cushion-shaped semi-shrub plant widely distributed in arid gravel desert areas. Its plant height is relatively short, its crown width is not large, and its root system is also underdeveloped. There are small and curly pinnate compound leaves and dense hairy fibers on the surface of the leaves. In this study, we focused on the function of leaf surface trichomes by observing the leaf submicroscopic structure, conducting in situ water harvesting experiments, measuring reflectance spectra, and analyzing chloroplast genomes of O. aciphylla leaves. The experimental results indicate that the surface of the leaves of O. aciphylla is densely covered with hair-like fiber arrays, and these hair-like fiber surfaces have micro and nanoscale protrusions. These structures can quickly capture moisture in the air and filter out ultraviolet and infrared rays from the sun, without affecting the normal photosynthesis of the chloroplasts inside the leaves. The important findings of this study are the nanostructures on the surface of the hair-like fibers on the leaves of O. aciphylla, which not only have a water capture function but also reflect light. This has important theoretical significance for understanding how plant leaves in gravel deserts adapt to the environment.

Quercus wutaishanica shrub affects temperate forest community composition and soil properties under different restoration stage.

Quercus wutaishanica is the dominant tree species in the natural ecosystem restoration of temperate forests in China, and it plays an active role in maintaining ecological balance. However, little is known about how ecosystem versatility develops during the restoration of forest ecosystems dominated by Q. wutaishanica. In this study, we investigated the species composition of the Q. wutaishanica community, soil nutrients, and their functional traits at various restoration stages, and comprehensively analyzed the correlations among them. At the early stage of restoration (10 years of restoration), there were Spiraea pubescens and Syringa pubescens in Q. wutaishanica community (87% of the total species), while had a larger niche width. In the middle of restoration (30 years of restoration), shannon and evenness indices were the largest, while soil total carbon, ammonium nitrogen and chlorophyll content of Q. wutaishanica leaves were the highest; among them, soil total carbon was 15.7% higher than that in 10 years of restoration, 32.4% higher than that in 40 years of restoration, ammonium nitrogen was 71.7% higher than that in 40 years of restoration, and chlorophyll content was 217.9% higher than that in 10 years of restoration, and 51.8% higher than that in 40 years of restoration. At the later stage of restoration (40 years of restoration), Lonicera ferdinandii occupied the dominant ecological niche, and soil available nitrogen, available phosphorus content and leaf thickness were the largest; while AN was 10.9% higher than that of 10 years of restoration, 16.5% higher than that of 30 years of restoration, AP was 60.6% higher than that of 10 years of restoration, 21.6% higher than that of 30 years of restoration, leaf thickness was 22.3% higher than that of 10 years of restoration, 84.9% higher than that of 30 years of restoration. However, the restriction of various soil nutrients was reduced. Our study highlighted the effectiveness of soil resource availability in plant communities during restoration, reduced competition for light among plants, and altered species richness. Furthermore, changes in the interrelationship between plant community composition and leaf functional traits of the dominant species responded positively to community restoration. These results further deepen our understanding of forest management and restoration of forest communities. In the future, it is necessary to comprehensively consider the influence of various factors on forest community restoration.

Density-Dependent Seed Predation of Quercus wutaishanica by Rodents in Response to Different Seed States.

The predation and/or dispersal of Quercus seeds by rodents play an important role in the creation of the tree species. The present study examined the effects of community habitats on the predation and dispersal of Quercus wutaishanica seeds by rodents. We released seeds with densities set at 2, 4, 8, 16, and 32 seed square meter with litter cover, soil burial, and bare ground in the Liupan Mountains National Nature Reserve in the Ningxia Hui Autonomous Region, northwest China. The results showed that (1) the litter cover and soil burial significantly increased the seed survival probability compared with bare ground treatments, especially the predation in situ (PIS) (p < 0.05). Both the scatter hoarding (SH) and larder hoarding (LH) for litter cover and soil burial were significantly increased compared with bare ground (p < 0.05). (2) The large seeds are preferentially predated after dispersal and their long-distance dispersal (>5 m) was significantly greater than that of small seeds (p < 0.05), while small seeds are more likely to be preyed on in situ or during short-distance dispersal (<3 m). (3) The Q. wutaishanica seed predation by rodents increased at a high density rather than at a low density, indicating a negative density-dependent predation. These findings provide insights into the ecological characteristics of Quercus tree regeneration and shed light on the coexistence between rodents and different-sized seeds.

Nutrition regulates sex expression in a gender diphasy plant, Lilium concolor var. megalanthum.

Introduction: The evolution and maintenance of plant polymorphism have always received much attention. Gender diphasy is a rare sexual system. Plant individuals with gender diphasy can adjust the resource allocation of different functional organs according to the changes of environmental conditions to regulate the sex expression of individuals, and the sex expression can be converted between years. However, our understanding of sex expression in plants is still very insufficient. In this study, we explored whether the perennial plant Lilium concolor var. megalanthum has a gender diphasy system and whether environmental resource availability affects its resource allocation and sex expression. Method: By collecting the bulbs of two sexual phenotypes (male and hermaphrodite) in the field and simulating the application of different levels of nutrients under the same habitat conditions, the growth and reproduction indexes and sex expression of plants in two years (2021 and 2022) were measured to evaluate the resource allocation strategy and sex expression pattern of Lilium concolor var. megalanthum. Results: We found that the sex expression of Lilium concolor var. megalanthum was variable in continuous years. Under limited resources, Lilium concolor var. megalanthum increases the biomass resources of the leaves and has a longer flowering period. Resource availability regulates the growth, reproduction and sex expression of Lilium concolor var. megalanthum. Bulb size is the main factor affecting its growth, reproduction and sex expression after accumulating sufficient resources. Discussion: This study confirms that Lilium concolor var. megalanthum has gender diphasy system. There is a strong trade-off between growth and reproduction under limited resources. Nutrient levels can regulate the reproduction and sex expression process of Lilium concolor var. megalanthum. With the growth of Lilium concolor var. megalanthum in consecutive years, the size dependence of bulbs may be the decisive factor in its sex expression.

Isolation of cadmium-resistant microbial strains and their immobilisation of cadmium in soil.

Six cadmium (Cd)-resistant microbial strains were isolated and their ability to immobilise Cd2+ in soil investigated. Cd-1, Cd-2, Cd-5, and Cd-6 were identified as Stenotrophomonas sp., Cd-3 as Achromobacter sp., and Cd-7 as Staphylococcus sp. The six strains showed a wide adaptation range for salinity and a strong tolerance to Cd2+. The effects of the initial Cd2+ concentration (1-100 mg/L), duration (18-72 h), temperature (10-40 °C), and pH (5.0-9.0) on the efficiency of Cd2+ removal were analysed. The results revealed that the Cd2+ removal rate was higher at an initial Cd2+ concentration of 5-100 mg/L than at 1 mg/L. The maximum Cd2+ removal effect was at a culture duration of 36 h, temperature of 10-35 °C, and pH of 5.0-7.0. X-ray diffraction (XRD) analysis revealed that the Cd2+ was immobilised by Stenotrophomonas sp. Cd-2 and Staphylococcus sp. Cd-7 through bio-precipitation. X-ray photoelectron spectroscopy (XPS) revealed that the Cd2+ was adsorbed by Stenotrophomonas sp. Cd-2, Achromobacter sp. Cd-3, and Staphylococcus sp. Cd-7. Fourier transform infrared spectroscopy (FTIR) analysis revealed that the isolates reacted with the Cd2+ mainly through the O-H, protein N-H, C-N, lipid C-H, fatty acid COO, polysaccharide C-O, P-O, and other functional groups, as well as with lipid molecules on the cell wall surfaces. Scanning electron microscopy (SEM) analysis revealed that there was little difference in the cells after Cd2+ treatment. The results of the soil remediation experiments indicated that the toxicity of Cd in soil could be effectively reduced using certain strains of microbe.

Allelopathic inhibition effects and mechanism of phenolic acids to Microcystis aeruginosa.

Allelochemicals are essential agents for the biological control of harmful blooms. It is crucial to identify efficient algal suppressors and understand their mechanisms. This study reports the inhibition of Microcystis aeruginosa growth by 6 phenolic acids derived from plants' secondary metabolites. The inhibitory effect of phenolic acids was significantly influenced by exposure dose and phenolic acid species. Caffeic acid has the most efficient algal inhibition ability (96 h-EC50 of 5.8 mg/L). In contrast, the other 5 analogs (cinnamic acid, p-coumaric acid, 3-hydroxycinnamic acid, ferulic acid, and isoferulic acid) showed a weak inhibition effect or promotion effect with the exposure dose of 5-100 mg/L. ROS and chlorophyll a content tests combined with metabolomics analysis revealed that caffeic acid could induce the ROS accumulation of M. aeruginosa. They mainly disturbed nucleotide, amino acid, and fatty acid metabolism, leading to the downregulation of most metabolites, including toxins of microcystin LR and cyanopeptolin A, and the precursors of some unpleasant terpenoids. It has been suggested that caffeic acid is an effective agent for controlling M. aeruginosa blooms.

A comparison of microbial composition under three tree ecosystems using the stochastic process and network complexity approaches.

Soil microbes act as "players" in regulating biogeochemical cycles, whereas environmental heterogeneity drives microbial community assembly patterns and is influenced by stochastic and deterministic ecological processes. Currently, the limited understanding of soil microbial community assembly patterns and interactions under temperate forest stand differences pose a challenge in studying the soil microbial involvement during the succession from coniferous to broad-leaved forests. This study investigated the changes in soil bacterial and fungal community diversity and community structure at the regional scale and identified the pathways influencing soil microbial assembly patterns and their interactions. The results showed that broad-leaved forest cover in temperate forests significantly increased soil pH, and effectively increased soil water content, total carbon (TC), total nitrogen (TN), and total phosphorus (TP) contents. Both soil bacterial and fungal alpha diversity indices were correlated with soil physicochemical properties, especially in broad-leaved forest. The bacterial and fungal community composition of coniferous forest was dominated by deterministic process (bacteria: 69.4%; fungi: 88.9%), while the bacterial community composition of broad-leaved forest was dominated by stochastic process (77.8%) and the fungal community composition was dominated by deterministic process (52.8%). Proteobacteria, Acidobacteriota, Actinobacteriota, and Verrucomicrobiota were the dominant phyla of soil bacterial communities in temperate forests. Whereas Ascomycota, Mortierellomycota, Basidiomycota, and Rozellomycota were the dominant phyla of soil fungal communities in temperate forests. Most members of dominant phylum were regulated by soil physical and chemical properties. In addition, the succession from temperate coniferous forest to broad-leaved forest was conducive to maintaining the complex network of soil bacteria and fungi, and the top 20 degree of the major taxa in the network reflected the positive response of microbial interactions to the changes of soil nutrients during forest succession. This study not only shows the mechanism by which species differences in temperate forests of northern China affect soil microbial community assembly processes, but also further emphasizes the importance of the soil microbiome as a key ecosystem factor through co-occurrence network analysis.

Dose-effect and structure-activity relationships of haloquinoline toxicity towards Vibrio fischeri.

Many quinoline (QL) derivatives are present in the environment and pose potential threats to human health and ecological safety. The acute toxicity of 30 haloquinolines (HQs) was examined using the photobacterium Vibrio fischeri. IC50 values (inhibitory concentration for 50% luminescence elimination) were in the range 5.52 to >200 mg·L-1. The derivative 5-BrQL exhibited the highest toxicity, with 3-ClQL, 3-BrQL, 4-BrQL, 5-BrQL, 6-BrQL, and 6-IQL all having IC50 values below 10 mg·L-1. Comparative molecular field analysis modeling based on the steric and electrostatic field properties of the HQs was used to quantify the impact of halogen substituents on their toxicity. QL derivative rings with larger substituents at the 2/8-positions and less negative charge at the 4/5/6/8-positions were positively correlated with acute toxicity towards V. fischeri.

Mechanism of bio-electrokinetic remediation of pyrene contaminated soil: Effects of an electric field on the degradation pathway and microbial metabolic processes.

In this study, the mechanism of bio-electrokinetic (BIO-EK) remediation to improve the degradation of pyrene was evaluated based on an analysis of the intermediate products and the microbial community. The results show that BIO-EK remediation has a higher pyrene degradation efficiency on pyrene and its intermediate products than the bioremediation and electrokinetic (EK) remediation processes. A series of intermediate products were detected. According to the type of the intermediate products, two degradation pathways, biological metabolism and electrochemical oxidation, are proposed in the BIO-EK remediation of pyrene. Furthermore, the primary microbial taxa involved in the pollutant degradation changed, which led to variations in the functional gene components. The abundant and functional genes related to metabolism were specifically analyzed. The results indicate that the electric field promotes the expression of metabolisms associated with 14 carbohydrates, 13 lipids, 13 amino acids, five energies, and in particular, 11 xenobiotics. These results suggest that in addition to the promotion effect on the microbial metabolism caused by the electric field, BIO-EK remediation can promote the degradation of pollutants due to the coexistence of a microbial metabolic pathway and an electrochemical oxidation pathway.

Characterization of the complete chloroplast genome of Astragalus galactites (Fabaceae).

Astragalus galactites is a medicinal plant. The total plastome length of A. galactites is 126,117 bp. It contains a large single-copy region of 69,805 bp, two inverted repeat regions of 20,638 bp, and a small single-copy region of 15,036 bp. The cp genome contains 110 complete genes, including 75 protein-coding genes (75 PCGs), 4 ribosomal RNA genes (4 rRNAs), and 30 tRNA genes (30 tRNAs). The overall GC content of cp DNA is 33.9%, the corresponding values of the LSC, SSC, and IR regions are 33.0%, 30.4%, and 43.3% respectively. The phylogenetic tree shows that A. galactites has the closest relationship with A. laxmannii.

[Effects of seed size and drought stress on the growth and physiological characteristics of Quercus wutaishanica seedlings]. / ç§å­å¤§å°å’Œå¹²æ—±èƒè¿«å¯¹è¾½ä¸œæ Žå¹¼è‹—ç”Ÿé•¿å’Œç”Ÿç†ç‰¹æ€§çš„å½±å“.

The effects of seed size and drought stress on the growth and physiological characteristics of Quercus wutaishanica seedlings were investigated under shading conditions of a pot experiment in greenhouse. There were four treatments, including 80% field water content (FWC), 60% FWC, 40% FWC, and 20% FWC [CK, light drought stress (LDS), medium drought stress (MDS), and high drought stress (HDS), respectively]. The results showed that leaf area per plant, total dry mass, and root-shoot ratio of Q. wutaishanica seedlings regenerated from large seeds (3.05±0.38 g) were significantly higher than those from small seeds (1.46±0.27 g) in all four treatments. Shoot height, basal stem diameter, leaf number, specific leaf area, relative growth rate, and net assimilation rate of the seedlings from large seeds were higher than those of seedlings from small seeds under the treatments of LDS, MDS and HDS. Activities of peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) in large-seeded seedlings were higher than those of small-seeded seedlings under all treatments, while the contents of MDA, soluble protein, free proline, and total chlorophyll of large-seeded seedlings were higher than those of small-seeded seedlings only under some drought stress treatments. All growth parameters except the root-shoot ratio decreased with the increases of drought stress. The HDS treatment resulted in 19.4% and 20.0% decline in total dry mass of large- and small-seeded seedlings respectively, compared with those of CK. With increasing drought stress, the activities of POD, CAT, and SOD decreased after an initial increase. POD activity of large- and small-seeded seedling under MDS treatment was 126.7% and 142.1% higher than CK, while CAT was 170.0% and 151.9% higher than CK, respectively. However, the MDA content of seedlings from large and small seeds under HDS treatment was 86.5% and 68.9% higher than that of CK, respectively. The contents of soluble protein, free proline, and total chlorophyll rose at first and then fell with increasing drought stress, and soluble protein content in large- and small-seeded seedlings experienced MDS enhanced 320.7% and 352.7%, respectively. Those results indicated that large-seeded seedlings of Q. wutaishanica had stronger drought tolerance than small-seeded seedlings due to their growth and physiology advantages. Large-seeded seedlings with stronger resistance to drought stress should be applied to artificial regeneration of the degraded secondary Q. wutaishanica plantations.

[Growth status of children under 7 years in Wuzhong City, Ningxia Hui Autonomous Region, China and its influential factors].

OBJECTIVE: To investigate the growth status of children under 7 years in Wuzhong City, Ningxia Hui Autonomous Region, China and its influential factors, and to provide a basis for related intervention measures. METHODS: Children under 7 years were selected from two county-level districts in Wuzhong by stratified cluster sampling, and their growth status were evaluated by the Z score method. RESULTS: The prevalence rates of growth retardation, underweight, and wasting were 12.58%, 5.71%, and 5.55% respectively. The height-for-age Z score, weight-for-age Z score, and weight-for-height Z scores were -0.26±2.50, 0.29±4.54. and 0.65±3.02 respectively. There were significant differences in the prevalence rate of wasting among children of different ethnic groups (P<0.05); also, there were significant differences in the prevalence rates of growth retardation and underweight among children from different regions and with different age (P<0.05). The main influential factors for growth retardation were region (OR=0.369, P<0.001), ethnic groups (OR=1.694, P=0.027), and age (OR=1.143, P=0.002). The main influential factors for underweight were region (OR=0.453, P=0.001) and age (OR=1.204，P=0.002). The main influential factor for wasting was nation (OR=1.735, P=0.024). CONCLUSIONS: In Wuzhong, children under 7 years have poor growth status, which are related to ethnic groups, region, and age.

[Predation and removal of rodents on the seeds with different size and pericarp traits].

A field survey was conducted in the Quercus wutaishanica shrubs in Liupan Mountains of Ningxia, Northwest China to study the predation and removal of rodents on the seeds of Q. wutaishanica, Prunus salicina and Pinus armandii, aimed to explore the effects of seed size and pericarp traits on the predation and removal behaviors of rodents. The in situ seed predation rates of smaller Q. wutaishanica seeds and P. armandii seeds were significantly higher than those of larger Q. wutaishanica seeds and P. salicina seeds. The P. salicina seeds with hard and thick pericarp (endocarp) had the highest predation rate and hoarding rate after the removal by rodents. The movement distance of larger Q. wutaishanica seeds during predation events was the longest (3.10 m), and the seed hoarding distance of this species (6.48 m) was significantly longer than that of the three other types of seeds. Over 80% of sites were used as the predation sites by rodents for the seeds, except that the P. salicina seeds contained only a single seed and the cache sites contained a single seed accounted for over 90% for all types of seeds. Few predation and cache sites containing over two seeds were detected. Higher proportion of P. armandii seeds were predated in microhabitats except at the base of shrubs and in the holes after removal by rodent, while the seeds of other three types were predated mainly at the base of shrubs and in the holes after removal by rodents. The seed hoarding patterns after removal by rodents were primarily determined by pericarp traits, and higher proportion of soil burial that the rodents hoarded seeds with hard pericarp (endocarp) was detected.

Paternal deprivation alters play-fighting, serum corticosterone and the expression of hypothalamic vasopressin and oxytocin in juvenile male mandarin voles.

Although early paternal deprivation significantly affects offspring behavioral and neuroendocrine development, the link between paternal deprivation and social play behavior remains unclear. Mandarin voles (Microtus mandarinus) are socially monogamous and display bi-paternal care. The present study examined the development of social play in juvenile male mandarin voles and the paternal influence on play-fighting, vasopressin- and oxytocin-immunoreactive neurons and serum corticosterone and testosterone levels. The results show that social play was more pronounced during postnatal days 28-35, differing from the ontogenetic pattern of other forms of social behavior. On postnatal day 35, the peak in play-fighting activity, paternal deprivation reduced boxing/wrestling levels and vasopressin-immunoreactive neurons in the anterior hypothalamus and oxytocin-immunoreactive neurons in the paraventricular nucleus, but increased vasopressin-immunoreactive neurons in the paraventricular nucleus and corticosterone levels. These results suggest that mandarin voles engage in social play according to an inverted U-shaped curve in ontogeny, and paternal deprivation influences the development of offspring play-fighting; hypothalamic vasopressin, oxytocin and serum corticosterone may play a modulatory role in the alteration of play-fighting elicited by paternal deprivation; decreased play-fighting may correlate with depressed vasopressin levels in the anterior hypothalamus.

[Effects of light intensity on Quercus liaotungensis seed germination and seedling growth].

This paper studied the effects of different shading (55.4%, 18.9%, 5.5%, 2.2%, 0.5% , and 0.3% natural sunlight) on the seed germination and seedling growth of Quercus liaotungensis. The seed germination rate and germination index were the highest (72.5% and 0.22, respectively) at 55.4% natural sunlight, declined with decreasing light intensity, and were the lowest (42.5% and 0.11, respectively) at 0.3% natural sunlight. Strong light had definite delaying effect on the germination. The index of germination vigor increased with decreasing light intensity, being the maximum at 0.5% natural sunlight. The delay of seed germination under strong light could be the selective tradeoff on varied seed fates. Strong light benefited the basal stem diameter and root system growth and dry mass accumulation of Q. liaotunensis seedling, but resulted in the minimum seedlings height (6.06 cm). Greater morphological plasticity was observed for the seedlings under different shading, which lent support to the higher adaptability of the seedlings to light environment. For example, the specific leaf area, specific shoot length, specific root length, and chlorophyll b and total chlorophyll contents were the maximum at 0.5% natural sunlight, being 142.57 cm2 x g(-1), 156.86 cm x g(-1), 271.87 cm x g(-1), 0.07 g x cm(-2), and 0.24 g x cm(-2), respectively, and the minimum at 55.4% natural sunlight, being 44.89 cm2 x g(-1), 52.84 cm x g(-1), 101.98 cm x g(-1), 0.04 g x cm(-2), and 0.15 g x cm(-2), respectively. The variation of the root/shoot ratio of Q. liaotungensis seedlings under different shading could be the effects of the combination of light intensity and water availability.

[Effects of forest gap on the seedling growth of a canopy tree species Pometia tomentosa in tropical rainforest of Xishuangbanna].

In this paper, the seedling's early growth and establishment of Pometia tomentosa, a canopy tree species in Xishuangbanna tropical seasonal rainforest, were investigated under different illumination gradients (gap center, gap edge, and under canopy). The seedling height, basal stem diameter, total dry mass, leaf area per seedling, and relative growth rate at early stage peaked in gap center, with the values of 24.45 cm, 3.17 mm, 0.79 g, 122.45 cm2, and 14.78 x 10(-3) g x d(-1), respectively. The seedlings had a higher root-shoot ratio under canopy (0.87) than in gap center (0.20) due to the influence of both illumination and water. The brighter illumination in gap center facilitated the growth of established seedlings, with the peaks of seedling height (31.48 cm), basal stem diameter (3.80 mm), total dry mass (2.22 g), leaf area per seedling (174.52 cm2), relative growth rate (2.29 x 10(-3) g x d(-1)), and net assimilation rate (2.54 x 10(-5) g x cm(-2) d(-1)) attained by the end of the investigation. The death of established seedlings might be closely related to water stress. Under canopy, the death rate caused by water stress was the highest (26.88%) but that caused by the predation of vertebrates was the lowest (2.93%), which in final, induced the highest survival rate (70.19%) of the seedlings. Illumination was the important factor affecting the morphological regulation of P. tomentosa seedlings. In gap center, the specific leaf area of the seedlings at their different growth stages was the smallest, but their relative growth rate and net assimilation rate were the greatest. The root-shoot ratio of established seedlings peaked at gap edge (0.33), suggesting that water stress and illumination were the important factors affecting the biomass allocation of established seedlings.

[Effects of light intensity on seed germination and seedling early growth of Shorea wantianshuea].

With shading experiment, this paper studied the seed germination and seedling early growth of Shorea wantianshuea, a representative species in Xishuangbanna seasonal rain forest under different light intensity and forest habitat. The results showed that both 100% light and deepest shading did not facilitate the germination of S. wantianshuea seed, while medium shading accelerated the seed germination. Gap center was more appropriate to the seed germination than gap edge and under-canopy. The seeds in gap center had the highest germination rate and rapid germination. Under partially shading, the seedling height, diameter of basal stem, and leaf area per seedling were in their peak, while the root-shoot ratio decreased with increasing shading and achieved its maximum under 100% light. The specific leaf area increased with increasing shading in a certain range, and peaked under 4.2% light. Gap center was beneficial to the early seedling growth, with all growth parameters except root-shoot ratio peaked there. The effects of environmental factors, mainly light intensity and quality, on the seed germination and seedling growth of S. wantianshuea were discussed.