【Objective】Deciphering the effects of different potassium (K) additions on the total amount and main components of volatile secondary metabolites (VOCs) in the leaves and twigs can provide guidance for the multifunctional management of Phoebe bournei. 【Method】Here, the 10-year-old P. bournei monoculture plantations in Jindong Forestry Farm were selected as research objects, and five potassium fertilizer (K2O>52%) levels (CK, 0 g/individual; K1, 60 g/individual; K2, 120 g/individual; K3, 180 g/individual; K4, 240 g/individual) were employed and conducted. The samples were collected in January and July after the amendment of potassium fertilizer (in summer). The determinations and extractions of plant VOCs were using hydro distillation and Gas Chromatography-Mass Spectrometry (GC-MS). 【Result】The potassium fertilization level had a significant effect on the content of VOCs in P. bournei. The VOCs content in leaves and twigs showed a trend of initially increasing and then decreasing. In January, the highest extraction rate (mass fraction) was observed in the K2 treatment (in leaves 0.48‰, in twigs 0.55‰), while the highest extraction rate (mass fraction) was observed in the K1 treatment (in leaves 0.47‰, in twigs 0.34‰) in July. Alloaroma dendrene, caryophyllene and (-)-alpha-pinene in leaves was the feature components in leaves of P. bournei VOCs, and beta-caryophyllene, (-)-alpha-pinene and (-)-alpha-bisabolene were the characteristic components of VOCs in twigs. The VOCs were mainly composed of olefins, naphthalenes, and alcohols. The relative content of olefins and naphthalenes in the leaves increased significantly under the K2 treatment in both seasons, while the relative content of alcohols decreased significantly after fertilization. In addition, leaf nutrients had a positive effect on the content of VOCs in twigs, and the path coefficient was extremely significant. Twig nutrients had a positive effect on the relative content of various types of VOCs in the leaves. 【Conclusion】The application of potassium fertilizer significantly affects the amount and components of VOCs and nutrient content in the leaves and twigs of P. bournei, when the application is 60-180 g/individual, the total content of VOCs in the leaves and twigs of P. bournei reaches its highest level. Overall, K3 is the optimal treatment in January, while K2 is the optimal treatment in July. The model demonstrates that nutrient elements have a positive impact on the synthesis of sesquiterpenes such as alkenes and naphthalenes in the VOCs found in leaves and twigs.
【Objective】This research aims to explore the feasibility of utilizing terrestrial laser scanning (TLS) technology for acquiring stem form characteristics of trees and to evaluate and select elit of Korean pine (Pinus koraiensis), providing a theoretical basis for the comprehensive evaluation of superior provenances.【Method】Using 26 P. koraiensis provenances from the provenance test forest in Maoershan, Heilongjiang Province, as experimental materials, TLS was employed to scan sample plots. Data preprocessing was conducted using LiDAR360 software, and parameters such as tree height, diameter at breast height (DBH), and diameters at different heights extracted by TLS were evaluated. Four stem form parameters (breast-height form factor, breast-height form quotient, experimental form factor, and height-to-diameter ratio) were calculated. Additionally, taper equations based on provenance effects were constructed using diameters at different heights extracted by TLS to describe stem form variations among different provenances.【Result】TLS achieved high accuracy in extracting individual tree parameters. The extraction accuracy for DBH (coefficient of determination R2= 0.979 6) was superior to that for tree height (R2=0.811 4) and volume (R2=0.911 9). As the stem height increased, the R2 for diameters at relative heights gradually increased, reaching its peak at 0.08h(R2=0.984 0, where h represents tree height). Beyond 0.08h, the R2 for diameters at relative heights gradually decreased. Variance analysis of stem form indicators for the 26 P. koraiensis provenances showed that all indicators exhibited significant differences among provenances (P<0.05). Introducing provenance variables into the base model improved the fitting accuracy, and constructing a nonlinear mixed model with replication as a random effect further enhanced model precision. By plotting stem form graphs for different provenances, it was observed that the trends in stem form variation were generally consistent across provenances, but growth rates differed.【Conclusion】TLS demonstrated high accuracy in extracting individual tree parameters. All stem form indicators showed significant differences among provenances, indicating good potential for selection. Based on stem form indicators and the optimal taper equation incorporating provenance effects, a group of superior provenances was identified, providing a foundation for genetic improvement and widespread utilization of P. koraiensis.
【Objective】A system of stand-level growth models with diameter-class disaggregation was developed for Korean pine (Pinus koraiensis) plantations in Heilongjiang Province to optimize stand management strategies, providing model support for developing management schedules and enhancing forest quality.【Method】Based on the remeasurement data from 218 permanent plots in Korean pine plantations in Heilongjiang Province during 1980—2023, a model system consisting of models for mortality, dominant height, stand basal area and diameter-class disaggregation was constructed. The Weibull function was used to disaggregate the predictions over diameter classes. The parameters of the growth models were estimated using the Gauss-Newton method and seemingly unrelated regression. The method of moments was used to recover the diameter distribution parameters for the diameter-class disaggregation. To verify the applicability of the model system, the study used the differential evolution (DE) algorithm with a model system to perform stand-level management optimization to find the rotation length that maximized wood production in different site indices (11.2, 14.2, 16.0 m).【Result】The components of the dynamic growth model explained over 90% of the variation in the modelling data. The final critical errors for stand mortality and basal area model obtained using seemingly unrelated regression were 16.769% and 17.685%, respectively. When applying the method of moments for parameter estimation of the Weibull equation, the pass rate of the Kolmogorov-Smirnov test was 96.946%. When using the growth with diameter-class disaggregation for predicting stand volume, using an existing taper model, the critical error was 14.612%. The optimization results indicated that, for the three stands, the thinning is by 1-3 years later as site index improves by 2 m, with the final harvest age ranging from 72 to 75 years.【Conclusion】The growth model constructed in this study satisfies the basic assumptions of path-invariance, consistency, and causality during management simulations, thereby allowing reliable growth simulations. Integrating the model with the DE algorithm provides effective forest management prescriptions, offering useful advise for the management decisions of Korean pine plantations.
【Objective】This research aims to study the effect of photosynthesis, nitrogen metabolism key enzyme activities and other related indexes of poplar main planting varieties under different water and fertilizer management, and to provide a theoretical basis for the construction of efficient and precise water and fertilizer management system of poplar plantations, especially for the cultivation of large diameter timber.【Method】Taking the 11-year-old Populus × euramericana ‘Neva’ plantation in the sandy area of north China as the research object. Seven water and fertilizer management treatments were set up: conventional furrow irrigation (CK), drip irrigation (ND), controlled-release fertilizer + drip irrigation (CD), and water-soluble fertilizer + drip irrigation (M1D, M2D), formula fertilizer + drip irrigation (F1D, F2D). During the growing season (July to September), continuous monitoring was performed to assess key physiological and biochemical indices associated with photosynthesis and nitrogen metabolism in poplar leaves across the different treatments. Subsequently, we analyzed and compared the physiological and biochemical responses of the plantation under varying management regimes. Finally, a comprehensive evaluation of the effects of different water and fertilizer strategies was conducted using subordinate function analysis.【Result】Different water and fertilizer management on nitrogen metabolism (nitrate reductase (NR), glutamate synthase (GOGAT), Glutamate dehydrogenase (GDH)), photosynthesis (ribulose-1,5-diphosphate carboxylase/oxygenase (Rubisco), fructose-1,6-bisphosphate phosphatase (FBA)) key enzyme activities, soluble sugar (SS) and chlorophyll (Chl) content were significantly affected (P < 0.05), and the values of each index showed a continuous increasing trend with month, and the interaction between month and treatment was highly significant (P < 0.01). Under all water and fertilizer management, the overall trend of each index showed continuous increase with increasing months and reached the maximum value of each index in September. NR, GOGAT, GDH, Rubisco, FBA activity and SS content were increased under ND treatment compared to CK, but the overall difference was not significant; compared with ND these physiological and biochemical indexes were significantly increased by 13.60%-188.56% under different water-fertilizer-coupled management (CD, M1D, M2D, F1D, F2D); compared with CD, drip fertigation (M1D, M2D, F1D, F2D) significantly increased the activities of key enzymes of photosynthesis and nitrogen metabolism and the SS content by 11.22%-68.78%. The Chl content was significantly increased mainly in F1D and F2D in August and September, and was significantly increased by 31.29%-123.55% over M1D and M2D. The analysis of the subordinate function analysis showed that the F2D treatment had the greatest effect on the physiological and biochemical indexes of poplar, followed by F1D and M2D.【Conclusion】Different water and fertilizer management can significantly affect the physiological and biochemical indexes of photosynthesis and nitrogen metabolism enzyme activities in poplar plantation, among which the drip fertigation measures have the greatest impact, significantly higher than other measures, and the addition of medium and trace elements helps to significantly increase the chlorophyll content. Drip fertigation measures were adopted, in which the annual fertilizer ratios were N(520 g per tree), P2O5(169 g per tree) K2O(312 g per tree), and the annual addition of 5 g per tree of trace elements (including Fe, Ca, Mn and Zn) had the greatest impact on the physiological and biochemical characteristics of poplar plantation. The results provide theoretical and technical references for the construction of a precise water and fertilizer management system for efficient cultivation of poplar plantation in sandy areas of north China and similar ecological conditions, especially for large diameter timber.
【Objective】Cyclocarya paliurus is a multifunctional tree species. This study investigated the impacts of biochar types and their addition doses on soil chemical properties, leaf photosynthetic pigment content, and growth of C. paliurus seedlings, aiming to provide a scientific basis for biochar application in future C. paliurus plantations.【Method】A two-factor randomized block experimental design was employed to investigate the effects of three biochar types (C. paliurus biochar, straw biochar, and bamboo biochar) and three application rates (5%, 15% and 25% V/V, equivalent to 1.0%, 3.5%, and 6.5% m/m) on soil chemical properties, seedling growth, and leaf photosynthetic pigment content through a pot experiment.【Result】After 200 days of treatment, biochar application significantly increased soil pH, ammonium nitrogen, nitrate nitrogen, available phosphorus, and available potassium levels, while also enhancing chlorophyll a, chlorophyll b, and carotenoid contents in C. paliurus leaves. Application rate had a more pronounced effect on soil chemical indices than biochar type (P<0.05). Notably, adding 25% C. paliurus biochar increased soil pH by 32.1%, and 25% straw biochar significantly elevated available phosphorus and potassium levels by 145.3% and 250.0%, respectively, compared to the control. Biochar application also significantly influenced seedling growth and biomass production (P<0.05), with the 5% C. paliurus biochar treatment showing the most notable promotion in biomass production. Compared to the control, biomass in leaves, stems, roots, and total increased by 55.6%, 47.6%, 43.0%, and 47.0%, respectively, in the 5% C. paliurus biochar treatment. Correlation analysis revealed that seedling height and diameter growth were significantly positively correlated with leaf photosynthetic pigment contents. Additionally, all photosynthetic pigments were significantly and positively correlated with soil nitrate nitrogen (P<0.01), while only soil available potassium showed a significant correlation with carotenoid content (P<0.05).【Conclusion】Appropriate biochar application effectively enhances soil fertility and promotes C. paliurus seedling growth. Among treatments, the 5% C. paliurus biochar application proved optimal for maximizing biomass production.
【Objective】Woody plants typically have long growth cycles and limited regenerative capacity, which significantly restricts the efficiency of forest tree breeding. In vitro culture techniques can overcome seasonal constraints and accelerate propagation. Calcium, as an essential nutrient and a critical intracellular second messenger, plays a vital role in plant growth and development. However, its specific regulation in woody plant tissue culture remain unclear. Systematic investigation of calcium treatment under the in vitro condition is of great significance for improving tissue culture efficiency and supporting breeding strategies in forestry.【Method】We treated shoots of the woody model speices hybrid poplar ‘84K’ (Populus alba × P. glandulosa) in vitro under Ca2+ concentrations of 0, 1.5, 3.0, 6.0, 9.0 and 15.0 mmol/L. The effects of Ca2+ on shoot growth and adventitious root induction were systematically analyzed.【Results】Within the 0-9.0 mmol/L range, increasing Ca2+ concentrations enhanced shoot growth. The maximum plant height was observed at 6.0 mmol/L Ca2+, while leaf expansion was most pronounced at 9 mmol/L, indicating an optimal concentration range of 6.0-9.0 mmol/L. Complete calcium deficiency(0 mmol/L) disrupted apical dominance, resulting in shoot tip necrosis and excessive elongation and thickening of the primary root. In contrast, high Ca2+ concentration (15 mmol/L) significantly inhibited overall growth, with reduced plant height and smaller leaves. Ca2+ promoted stem elongation mainly by increasing internode length rather than node number. While the response intensity varied across different basal salts, the overall trend was consistent. Different concentration of Ca2+ treatments had no significant effect on the number of adventitious roots, but calcium deficiency led to pronounced elongation and thickening of adventitious roots, suggesting a specific root morphogenetic response to Ca2+ dificiency.【Conclusion】Ca2+ exerts concentration-dependent and tissue-specific effects on poplar in vitro. Moderate Ca2+ levels help maintain apical dominance and promote shoot elongation, while the Ca2+ deficiency triggers architectural remodeling in roots. These findings provide preliminary insights into the differential regulation of shoot and root development by Ca2+ in woody plants and lay a theoretical foundation for improving tissue culture systems and calcium-mediated molecular breeding in forestry.
【Objective】This study aims to identify optimal agroforestry management patterns for Pinus koraiensis plantations and establish a scientific foundation for decision-making in compound management practices.【Method】Three agroforestry systems (forest-fungi, forest-medicine, and forest-vegetable) within P. koraiensis plantations were investigated. Quadrat surveys and high-throughput sequencing were integrated to assess species diversity, soil nutrient dynamics, enzymatic activities, and microbial community structures. Full-length 16S rRNA and ITS amplicon sequencing were utilized to characterize bacterial and fungal communities across soil depths of (0,10] and (10,20] cm.【Result】(1)During initial management stages, species diversity indices in agroforestry systems were lower than those in the control (monoculture plantation).(2)The forest-fungi and forest-vegetable systems exhibited higher soil nutrient accumulation (e.g., organic carbon, total nitrogen), whereas forest-vegetable and forest-medicine systems demonstrated superior nutrient conversion efficiency.(3)Soil catalase activity ranked as forest-fungi > forest-medicine > forest-vegetable, while cellulase activity peaked in the forest-medicine system, with significantly higher values in the (0,10] cm layer than in the (10,20] cm layer (P< 0.05). No significant differences were observed in sucrase or acid phosphatase activities among systems. (4)The α-diversity of soil fungal and bacterial communities was significantly different in richness,and not significantly different in biodiversity,microbial communities across all systems were dominated by mortierellomycota, ascomycota, actinobacteriota, and proteobacteriota, with ascomycota and actinobacteriota identified as key taxa driving nutrient utilization under agroforestry practices. (5)Partial Mantel test revealed than the dominant factors influencing bacterial and fungal communities were soil organic carbon,total nitrogen(TN)and plant Simpson index(P<0.001).In the forest-funus system,both catalase activity and cellulase activity exhibited significant effects on fungal communities,whereas in the forest-vegetable system,soil organic carbon content and C to N ratio,along with the plant Simpson index in control plots,showed notable impacts on fungal communities(P<0.05).Additionally,the plant Shannon index and soil sucrase activity in control plots were indentified as the primary drivers of bacterial community composition(P<0.05).【Conclusion】Agroforestry management initially disrupts understory communities and soil ecosystems, but gradually enhances species richness, nutrient cycling efficiency, and microbial functional stability.
【Objective】 This study elucidated the horizontal and vertical distribution patterns of Chimonobambusa in China. Using model simulation methods, we analyzes the key factors influencing its distribution, providing a scientific basis for the development, utilization, and conservation of Chimonobambusa germplasm resources.【Method】 The study employed the ArcGIS spatial analyst tools and the MaxEnt model, integrating eight environmental variables and 340 distribution records. We examined the spatial distribution, distribution types, density, species richness, and influencing factors of Chimonobambusa. 【Result】Chimonobambusa species are widely distributed, with their primary centers located in Yunnan, Guizhou, Sichuan, and Chongqing. They are predominantly found in the middle subtropical broadleaf evergreen forest northern subzone, with altitudes between 1 000 and 2 000 meters exhibiting the highest species diversity. Intrageneric differences in spatial distribution are significant. Model simulations reveal that precipitation and temperature are the primary factors limiting the distribution of Chimonobambusa. Furthermore, the potential distribution areas predicted by the model closely align with the actual observed distributions. 【Conclusion】 China possesses abundant Chimonobambusa resources, with their distribution strongly correlated with the country’s vegetation and climatic regionalization. These plants thrive in environments characterized by relatively low temperatures, humid climates, and high rainfall. The findings hold significant value for the sustainable development and conservation of local bamboo resources and the preservation of species diversity in China.
【Objective】 This study investigated the effects of soil amendments on the color changes in Acer×freemanii leaves and explored the relationship between leaf color changes and leaf mineral element content. The findings aim to provide a theoretical basis for addressing the issue of non-red coloration in Acer×freemanii leaves.【Method】Six-year-old Acer×freemanii trees were used as the experimental material. Five gradient treatments combining sulfur powder and desulfurization gypsum as soil alkaline amendments were applied. Leaf color changes were observed during four autumn time periods, with measurements of leaf pigments and the contents of ten mineral elements.【Result】Soil alkaline amendment treatments significantly influenced the contents of chlorophyll, carotenoids, and anthocyanins in leaves, as well as leaf color parameters (L*, a* and b* values). Among the treatments, T5 (1.94 kg/m3 sulfur powder and 2.33 kg/m3 desulfurized gypsum) resulted in the most vibrant leaf coloration and an extended period of color development. The treatments also significantly affected the content and variation trends of mineral elements in leaves. Correlation analysis revealed that nitrogen (N) showed a strong positive correlation with chlorophyll and carotenoids (P<0.01) and a strong negative correlation with anthocyanins (P < 0.01). Potassium (K) showed a significant negative correlation with carotenoids (P<0.05). Calcium (Ca) and Magnesium (Mg) showed a strong negative correlation with chlorophyll (P<0.01) and a significant positive correlation with anthocyanins (P<0.05). Manganese (Mn) showed a strong positive correlation with carotenoids (P<0.01).【Conclusion】Lowering soil pH within a certain range enhances the coloration of Acer×freemanii leaves. Soil amendments have a significant impact on pigment and mineral element contents in the leaves. Mineral elements, particularly N, K, Ca, Mg, and Mn, show strong correlations with leaf color changes, emphasizing their importance in managing leaf coloration.
【Objective】This study aims to explore the changes in leaf pigment content and color response of different genetic materials over various periods and to analyze the key factors influencing leaf coloration in five families of Triadica cochinchinensis from physiological and tissue structural perspectives. The findings are expected to provide a theoretical basis for selecting superior landscape varieties of T. cochinchinensis.【Method】 Five families of T. cochinchinensis with a height of 50 cm were selected as research materials. The leaf color changes of six time points (S1. 2021-10-29; S2. 2021-11-05; S3.2021-11-12; S4. 2021-11-19; S5. 2021-11-26; S6: 2021-12-03) were observed under natural conditions. Leaf color parameters (L*, a*, b*), pigment content (chlorophyll, carotene, anthocyanin), and anatomical structure (upper and lower epidermis, palisade tissue, spongy tissue) were measured regularly. The dynamic changes in leaf color and genealogy selection of T. cochinchinensis were analyzed.【Result】(1)The leaf color of each T. cochinchinensis genealogy during the S1—S6 period primarily transitioned from light green to dark brownish yellow, then to reddish brown, and finally to bright red, with the ornamental period concentrated in the S5—S6 period. Among them, the SD8 family exhibited the highest ornamental value, with a color-changing period from the onset of discoloration (S2) to complete defoliation lasting 37 days.(2)The leaf color parameter a* value of each family showed a linear upward trend, while the L* and b* values exhibited different change patterns. Specifically, greener leaves corresponded to lower a* values, whereas redder leaves corresponded to higher a* values, making a* a representative parameter for the reddish leaf color of the five families.(3)Throughout the entire cycle, the chlorophyll and carotenoid contents of all T. cochinchinensis families decreased, while anthocyanin content increased, reaching a maximum at S3. The change from green to red leaves was mainly due to the proportionate distribution of pigment content. Before S3, chlorophyll content dominated the green leaf stage, and after S3, anthocyanin content dominated the red leaf stage.(4)During the color change from green to red, leaf thickness measurements indicated that pre-color change thickness was greater than post-color change thickness. The SD4 family experienced a significant 29.17% decrease in leaf thickness compared to other families (P<0.05). The upper epidermis thickness was greater than the lower epidermis across all families. Before the color change, the upper epidermis thickness of the SD6 family was significantly smaller than that of other families (P<0.05). Post-color change, the combined upper and lower epidermis thickness of the SD6 family accounted for the largest proportion among all families, significantly differing from others (P<0.05). Spongy tissue thickness exceeded palisade tissue thickness. The SD4 and SD6 families exhibited the most significant changes in spongy tissue thickness before and after the color change, at 30.59% and 0.87%, respectively. Palisade tissue thickness in the SD8 family significantly differed from other families (P<0.05), with a maximum change range of 29.92%.(5)Post-veraison, the leaf tissue structure of most T. cochinchinensis families showed that decreased leaf thickness, palisade tissue, and spongy tissue thickness facilitated anthocyanin accumulation, turning leaves red. No obvious variation attachments, such as particles or wax, were observed in leaf tissue, and no large air chambers appeared.【Conclusion】Leaf color change in T. cochinchinensis is primarily influenced by pigment dynamics, with anthocyanins being the main factor causing leaf reddening. Among the five families studied, the SD8 family demonstrated the most outstanding leaf color change and high ornamental value, making it particularly suitable for landscape greening. This study provides robust theoretical support for selecting T. cochinchinensis varieties and evaluating their ornamental value.
【Objective】 The study aimed to investigate the response of the fine roots of the 2-year-old ‘Beilin 1’ cultivar of young Populus tomentosa to variations in the species composition of trees and stand density, and to study their distribution and adaptation strategies following variations in species composition and stand density at the young stand stage. The initial plantation and the mixed configuration were used as references.【Method】A mixed P. tomentosa forest (plant spacing 3 m × 6 m) and pure biennial P. tomentosa forests of three different densities (3 m × 3 m, 3 m × 6 m, and 6 m × 6 m) were selected as the research objects. The root drilling method was used for sampling, and the samples were collected from a depth of 150 cm in the vertical direction, with every 10 cm representing a different layer. The sampling points were located at distances of 10, 30, 50, 100, 150, 200, 250 and 300 cm from the trees in the horizontal direction, while the sampling points for the 3 m × 3 m stand were located at distances of 10, 30, 50, 100 and 150 cm, a total of 1 305 root samples were obtained. The obtained root samples were scanned, dried, and weighed for measuring the dry mass. The morphological characteristics of the fine roots and the biomass data at various depths and horizontal distances were assessed across different species compositions and stand densities. 【Result】The findings revealed that the species composition did not significantly affect the fine root biomass density, but significantly affected the root length density and root surface area density. The characteristics of the fine roots of P. tomentosa in the pure and mixed forests did not exhibit any alterations in the vertical direction, all decreased with an increase in soil depth. The fine root biomass density of P. tomentosa in the mixed and pure forests was primarily concentrated at distances of 0-50 and 0-10 cm, respectively, from the trees in the horizontal direction. The biomass density of fine roots of P. tomentosa in mixed forests was mainly concentrated at 0-50 cm. Analysis of the two-dimensional distribution revealed that the fine roots of P. tomentosa were more densely distributed at greater depths in the mixed forest, their horizontal distribution was relatively uniform, and the horizontal lateral roots were more elongated. The stand density did not significantly affect the fine root biomass density, and the root length density, root surface area density, and average diameter of the roots in the high-density stands were significantly greater than those of the other two stands with different densities. The fine root biomass density in the 40-50 cm soil layer of the 3 m × 3 m stand was significantly higher than that of the other two stands (P < 0.05). The finer roots were more densely distributed in the deeper soil layers. The fine root biomass density in the 3 m × 6 m and 6 m × 6 m stands decreased gradually at increasing soil depths, while that of the 3 m × 3 m stand gradually increased in the 0-60 cm soil layer, indicating a unimodal distribution pattern. The root length density and root surface area density of the 3 m × 3 m stand at 150 cm from the trees in the horizontal direction were significantly higher than those of the other two stands of different densities. Analysis of the two-dimensional distribution pattern revealed that the fine roots in the 3 m × 3 m stand were more densely distributed at greater depths, while those in the 3 m × 6 m stand were more horizontally elongated.【Conclusion】Mixing significantly reduced the root density and root surface area density of P. tomentosa. An increase in stand density caused the fine roots to be gradually elongated with depth, and increased their distribution in the deeper soil layers. The fine root biomass density gradually decreased in the horizontal direction at increasing distances from the trees in the high-density stand. The species composition and stand density did not significantly alter the fine root biomass density of young 2-year-old P. tomentosa trees, but the root length density and root surface area density in the pure forest and the 3 m × 3 m stand were significantly higher than those of the mixed forest and the other two stands with different densities. The growth of the fine roots of P. tomentosa was most vigorous in the pure forest and in the 3 m × 3 m high-density stand. The soil water and nutrients were fully utilized by morphological plasticity rather than by alterations in biomass, and the soil resources were more effectively utilized in the young forest than in the mixed forest and in the forest stands of varying densities.
【Objective】This study evaluates the adaptability and stability of Corymbia citriodora subsp. variegata (CCV) provenances introduced to Guangxi, China, providing a theoretical basis for their selection and extension. 【Method】The tree height of six-year-old CCV specimens established in Nanning, Yulin and Liuzhou was measured. An analysis of tree height and survival for each provenance was conducted to assess growth adaptability. The additive main effects and multiplicative interaction (AMMI) model and genotype main effect plus genotype-environment interaction (GGE) biplot were employed to analyze the stability of provenances, classify suitable extension areas, and identify superior provenances. 【Result】The average tree height of all CCV provenances in sixth years was 13.0 m, with individual provenance survival rates ranging from 21.23% to 54.81%. Significant differences were observed in tree height among provenances, and the interaction with the site was also significant, suggesting a need for further decomposition of the interaction effect. The AMMI model results indicated that one interaction principal component axis achieved a significant level, accounting for 79.9% of the interaction effect. The stability Di index for each provenance was calculated, revealing the following order of stability ranking: 19694, 19691, 20883, 19664, 20396, 20756, 20787, 20753, 19665 and 19666. Provenances 20883, 20756 and 19694 were identified as fast-growing and stable. The GGE biplot demonstrated that the three trial sites could be divided into two ecological regions, with Nanning and Yulin falling within one region and Liuzhou representing the other. Provenance 20883 emerged as the most suitable provenance for introduction to Guangxi. 【Conclusion】The CCV provenances introduced to Guangxi exhibited strong growth adaptability. The selection of provenances can significantly enhance planting outcomes. Provenances 20883, 20756 and 19694 are recommended for Nanning and Yulin, while provenance 20787 is suitable for Liuzhou.
【Objective】This study investigated the dynamic changes in the growth and root development of one-year-old container seedlings under different fertilization levels to overcome the late emergence and slow seedling growth in the cultivation of container seedlings of Cyclobalanopsis gilva. Moreover, the adaptation strategies of root morphology to different fertilization levels were explored to improve the cultivation level of container seedlings and to promote the early emergence of seedlings by enhancing their growth and root development.【Method】Slow-release fertilizer addition tests were conducted on container seedlings at five levels (1.50, 2.25, 3.00, 3.75 and 4.50 kg/m3). Seedling growth indicators such as the seedling height, ground diameter, and dry mass of roots, stems, and leaves of seedlings (ages from 9 to 11 months) were continuously monitored during the rapid growth period. Root development indexes of different diameter grades including root length and root surface area were analyzed using a plant root scanner (EPSON Perfection V700/V750 3.83) and root analysis system software (WinRHIZO). SPSS 20.0 was employed to conduct one-way ANOVA to determine the variation of different slow-release fertilizer supplemental levels in promoting seedling growth and root development, as well as the adaptation strategies of seedling root morphology to different fertilization levels. 【Result】The effects of different fertilization levels on leaf, stem and root biomass and the root-top ratio increased gradually with the growth of C. gilva seedlings. The seedling height of 9-month-old container seedlings was not sensitive to change in the fertilizer application amount, However, the response of seedling height of 10 and 11-month-old container seedlings to such a change increased significantly. The optimal slow-release fertilizer addition amount was determined as 3.00 kg/m3. The ground diameter of the container seedlings was not sensitive to changes in fertilizer application amount. The growth indexes of container seedlings exhibited an increasing trend with the container seedling age. In particular, the root system of the container seedlings increased its contact area with the soil through continuous lateral growth, thus absorbing more nutrients. Moreover, the effect of slow-release fertilizer addition on seedling growth and root development was continuously enhanced, and the appropriate fertilization level was able to promote the root development of seedlings. The addition of 1.50 kg/m3 slow-release fertilizer had a better effect on the growth and root development of 9-month-old container seedlings compared to 10 and 11-month-old seedlings, while the addition of 2.25-3.00 kg/m3 slow-release fertilizer had a better effect on the growth of 10 and 11-months- seedlings. From 9 to 10 months of seedling growth, the fractal dimension of container seedlings was relatively low, while that for 11-month-old container seedlings increased significantly. The maximum root fractal dimension of container seedlings of different ages was observed at 4.50 kg/m3, while the root tip number of container seedlings was maximized at 1.50 kg/m3. The number of root tips decreased with the increase in slow-release fertilizer. In addition, the slow-release fertilizer addition of 3.75 kg/m3 resulted in the highest specific root length and specific surface area of container seedlings. From 9 to 11 months of seedling age, the root length of C. gilva container seedlings was the highest in the 0-0.2 mm diameter class, and the root length of different diameter classes showed a significant decreasing trend with the increase in diameter class. The adaptation strategies of container seedling roots to the nutrient status varied with the growth stage. For the 9 and 10-month-old seedlings, more roots were formed under the relatively low-nutrient status, while the medium nutrient status was conducive to the formation of more roots in the 11-month-old seedlings. Under different fertilization levels, the difference in the root diameter class distribution of container seedlings gradually increased with the seedling age. The correlation between root growth and the development indexes also changed markedly with the increase in seedling age. The correlation between the fractal dimension and other indexes increased significantly, while the correlation between other indexes decreased. 【Conclusion】Significant differences were observed in the response of C. gilva container seedlings at different seedling ages to slow-release fertilizer. The low-nutrient environment of container seedlings with a seedling age of less than 9 months can ensure the high growth of seedlings and aid in forming a better root structure. The root growth of container seedlings is vigorous during the rapid growth period of 10-11 months, and the nutrient content of the substrate should be appropriately increased to meet the growth needs of seedlings. A relatively low-nutrient environment is conducive to the growth and root development of the seedlings after 4-months-old container seedling transplanting. When the seedlings are 10-11 months old, an appropriate topdressing should be applied to promote the root development of seedlings to save fertilizer and cultivate high-quality container seedlings.
【Objective】This study investigates the growth response and nutrient utilization of the Camellia oleifera root system across different root orders under drought and nitrogen application. It aims to analyze how water and nitrogen affect root growth, nitrogen uptake, distribution and utilization, and to provide theoretical support for understanding the relationship between plant root architecture and nutrient strategies under climate warming. 【Method】 Two-year-old C. oleifera ‘Changlin 53’ trees were used. A pot experiment with 15N isotope tracing technology was conducted, setting two drought levels: normal irrigation (soil moisture content 75% ± 5%) and drought (soil moisture content 30%±5%). Two nitrogen application levels were used: no nitrogen and 15N-labeled ammonium nitrate (2.88 g/plant). After 75 days of drought treatment, the biomass, total nitrogen content, percentage of nitrogen from fertilizer (Ndff), and nitrogen use efficiency of roots of different diameter classes of C. oleifolia seedlings were measured. 【Result】 Under drought stress, there was a negative correlation between biomass and nitrogen content in grade 1-3, grade 5, and grade 6 roots, while a positive correlation was observed in grade 4 roots. Drought significantly affected 15N content and Ndff in all root diameter classes (P < 0.05). Drought inhibited 15N accumulation in all root diameter classes, with Ndff in grades 1-3 being most affected. Drought increased nitrogen distribution in roots, especially in grade 5 roots, which saw a 93.10% increase. However, the nitrogen use efficiency was inhibited to varying degrees across different root diameter classes. 【Conclusion】Nitrogen application increased root biomass and nitrogen allocation to coarse roots under drought but reduced fine root biomass and nitrogen accumulation. Drought significantly impacted the absorption, utilization, and distribution of fertilizer nitrogen in roots of all levels, enhancing nitrogen distribution, particularly in roots above grade 5, but inhibiting 15N absorption and utilization in roots of grades 1-4.
【Objective】There are correlations between phenotypic traits and fruit qualities. This study clarifies the relationships between nuts’ phenotypic traits and kernels’ qualities in early-fruiting walnuts from the Beijing-Hebei region, aiming to construct association models that provide a basis for preliminarily distinguishing nut qualities through phenotypic traits. 【Method】 The research focused on the superior genotypes of early-fruiting walnuts (Juglans regia) in the selection nursery at the Beijing Academy of Agricultural and Forestry Sciences. Nine nut phenotypic traits and four kernel qualities were measured during the fruit ripening stage. Based on these data, coefficients of variation, correlations, and variances were analyzed, and suitable regression models were constructed through fitting verification. 【Result】(1) The variation across 13 nut indices reaches a very significant level (P<0.01), with the coefficients of variation ranging from 5.43% to 28.63%. Except for sphericity, geometric average diameter, kernel yield, oil content, and protein content, the coefficients of variation for all other indicators exceed 10%. (2) Nut qualities exhibit intercorrelations. Oil content is closely related to the kernel yield and shows a significant positive correlation with soluble sugar content, but it is not closely related to starch or protein content. The protein and soluble sugar content demonstrate similar relationships with nut phenotypic traits, showing a significant negative correlation with nut size and dry weight and a significant positive correlation with volume kernel yield. Both are also significantly negatively correlated with starch content; the starch content is positively correlated with nut size and dry weight but negatively correlated with volume kernel yield.(3) Regression models are constructed based on the correlations between nut phenotypic traits and kernel qualities. There is a linear relationship between oil content and kernel yield, a parabolic relationship between soluble sugar content and volume kernel percentage, a linear relationship between starch content and nut volume, and a linear relationship between protein content and geometric average diameter. The models are validated by model fitting, with the difference between the predicted and actual values within the 95% limits of agreement (LOA) accounting for more than 95% of the total, demonstrating the models’ reasonableness and reliability. 【Conclusion】 Reliable regression models are constructed based on the close relationship between nut phenotypic traits and kernel qualities. These models can preliminarily distinguish nut quality and are helpful for the initial screening of suitable cultivars or strains.
【Objective】The frequent extreme weather events that are likely to be associated with global climate change may have an impact on plant water use. The aim of this study was to explore how mixed forest species adapt by accessing different water sources in the southern hilly region of China under different precipitation conditions.【Method】The stable hydrogen and oxygen isotopes in the xylem, soil, and groundwater from mixed Quercus acutissima and Pinus massoniana forests in the southern hilly region were measured and multi-source linear mixed models (Iso-Source) used to compare and analyze the water use in the forest under different precipitation gradients.【Result】Q. acutissima was found to mainly use soil water from the shallow layer ([10,30) cm) under low precipitation conditions, with a utilization rate of 62.0%; however, under heavier rain the species turns to deep soil water ([80,100) cm) and groundwater, with utilization rates of 34.2% and 44.6%, respectively. P. massoniana mainly uses groundwater and deep soil water ([80,100) cm) with utilization rates of 21.2% and 21.1%, respectively, under low precipitation conditions; however, the species changes to use soil water from depths of (0,10) cm and [10,30) cm layers, with utilization rates of 27.2% and 53.3%, respectively, when precipitation increases.【Conclusion】Q. acutissima and P. massoniana adapt differently to precipitation changes in terms of the water source used, and the depth from which water is sourced changes under different precipitation gradients. The different water use patterns of these species will reduce water competition under the expected frequent extreme precipitation events expected in the future. The results of the study provide a theoretical basis for the implementation of improved forest management.
【Objective】 This study aims to understand the leaf phenotypic diversity of holly (Ilex spp.) germplasm resources, elucidate the mechanisms behind this diversity, and support the introduction, cultivation and breeding of new varieties. 【Method】 We observed 18 phenotypic traits across 42 holly germplasm resources and analyzed the phenotypic variation using differential analysis, variance analysis, principal component analysis (PCA), and cluster analysis. 【Result】 There was significant variation in the leaf phenotypic traits among the holly germplasm resources, particularly in leaf area. The Shannon diversity index ranged from 1.00 to 2.03, indicating rich phenotypic diversity primarily due to interspecies variation. Correlation analysis showed a significant negative relationship between external leaf traits and anatomical traits. PCA identified four principal components, namely leaf length, tissue compactness, palisade tissue thickness, and stomatal density, that accounted for 85.20% of the variation, effectively capturing the overall characteristics of the holly plants. Cluster analysis grouped the 42 resources into four categories based on their leaf traits: large leaf with large petiole, small leaf with small petiole, medium leaf with hard serrations, and medium leaf with thin texture. 【Conclusion】 The study confirms substantial intrageneric phenotypic diversity in holly, driven predominantly by interspecies differences. External leaf traits were pivotal in phenotypic differentiation. The identified principal components, namely leaf length, compactness, palisade structure, and stomatal density, are crucial for classifying and identifying holly germplasm resources. Based on the leaf phenotypes, the resources were categorized into four distinct groups, providing a theoretical foundation for further classification, resource utilization, and breeding within the genus Ilex L.
【Objective】 The effects of different fertilization regimes and rates on the growth of Pinus armandii seedlings and the contents of mineral nutrient elements and non-structural carbohydrates in their needles were investigated to provide a scientific reference for the cultivation of high-quality seedlings with abundant nutrition reserves. 【Method】 P. armandii seedlings were separately reared in the presence of four different doses of N (100, 200, 300 and 400 mg N per seedling) using a compound fertilizer (25% N, 10% P2O5 and 20% K2O) under conventional and exponential fertilization regimes. The control setup was not treated with the fertilizer. The fertilizer was applied 12 times at 2-week intervals. The shoot height, root collar diameter, biomass and the contents of N, P, K, soluble sugar, starch and non-structural carbohydrates in the needles were measured after two weeks of the last application of the fertilizer. 【Result】 The shoot height, root collar diameter and biomass increased at first but subsequently decreased as the rate of the fertilizer was increased, under both application regimes. The shoot height, root collar diameter and biomass were the highest at the dose of 300 mg N per seedling under the exponential fertilization regime, being 1.29, 1.15 and 1.53 fold those of the control. Fertilization enhanced the content of N in the needles, and the N content increased as the rate of the fertilizer was increased. The N content in the needles was higher under the exponential fertilization regime than under the conventional fertilization regime for the same doses of the fertilizer. There were no significant differences in the P content of the needles. The K content in the needles increased at increasing rates of the fertilizer under the conventional fertilization regime. However, the K content increased at first but decreased subsequently at increasing rates of the fertilizer under the exponential fertilization regime. The content of soluble sugar decreased significantly following fertilization, and the contents decreased at first but increased subsequently at increasing rates of the fertilizer. The contents of starch and non-structural carbohydrates in the needles increased significantly under the rational fertilization regime, and exponential fertilization was more preferable. 【Conclusion】 The exponential application of 1.2 g of the fertilizer (300, 120 and 240 mg of N, P2O5 and K2O, respectively) per seedling was found to be the optimal fertilization regimen for cultivating high-quality P. armandii seedlings.
Magnolia biondii is an economically important tree in China, serving various medicinal, material and ornamental purposes. The species has extensive use in landscaping and practical applications. Despite numerous studies focusing on the growth and breeding characteristics of M. biondii, there remains a lack of a systematic summary of the results from basic biological research. This paper comprehensively reviews research advancements in various aspects of M. biondii, including individual growth and development characteristics, rapid propagative techniques, germplasm resource selection, genomics overview and other research areas. We present essential findings from basic biological research and discuss future research directions. Emphasis is given to furthering research efforts in breeding techniques, innovating germplasm resources, screening for quality and functional traits, and elucidating regulatory mechanisms. This will establish a scientific foundation for studying on development and application of M. biondii germplasm resource, and for understanding the growth regulation mechanisms within Magnoliaceae.
【Objective】This study evaluated the soil conservation and spatial distribution characteristics of the Natural Forest Protection Project in Qinghai Province over the past 20 years, to understand the ecological and environmental protection status of this area, and provide a theoretical reference for the promotion of local ecological construction and economic development.【Method】Based on the universal soil loss equation (USLE) model, combined with land use data, terrain data, multi-year climate data, and soil data, the soil conservation of Qinghai Province was calculated and spatially analyzed through a GIS platform (ArcGIS 10.4) to verify the land use types, administrative districts, and topography factors during 2000-2020. Additionally, the benefits of soil conservation under the implementation of the Natural Forest Protection Project were evaluated. 【Result】(1) The grassland and bare land were the main land use types in Qinghai Province from 2000 to 2020. The implementation of the Natural Forest Protection Project, resulted in the expansion of land use as forests and a decrease in the bare land. The shrubland and grassland in the east were transformed into forests, which became the main sources of forest growth. (2) Under the implementation of the Natural Forest Protection Project, soil conservation increased by 4.950×106 t. The amount of soil conservation was higher in the east and south, but lower in the northwest. (3) Different land use types had different soil conservation capacities and soil conservation per unit area was highest in the forests. The total amount of soil conservation in the shrublands increased the most over the 20 years. (4) The amount of soil conservation in Haidong, Xining and Huangnan increased the most during 2000-2020. (5) In terms of altitude and slope, the soil conservation per unit area was highest at an altitude gradient of 1 667-2 600 m and steeper slopes (15°-25°). 【Conclusion】The implementation of the Natural Forest Protection Project has prominently enhanced the soil conservation function in the Qinghai Province and the expansion of shrubs and forests further contribute to soil conservation. Thus, land areas at an altitude of 1 667-2 600 m and steep slopes (15°-25°) should be protected in the future.
【Objective】Our objectives are to study the morphological and photosynthetic physiological changes of Pteroceltis tatarinowii under different nitrogen application levels, and screen nitrogen response related genes in order to provide reference for further research on the molecular mechanisms how nitrogen application trigger changes in P. tatarinowii. 【Method】A pot experiment was conducted with the cuttings of P. tatarinowii fertilized with Hocking’s complete nutrient solution with 0 (limiting, N0), 2 (intermediate, N2) and 50 mmol/L (luxuriant, N50) NH4NO3, respectively. The physiological and photosynthetic morphological parameters were determined at day 28. SMRT-seq, performed with the pooled sample of P. tatarinowii treated with different nitrogen application levels, provided full length transcriptome data as a reference for the RNA-seq. Differentially expressed genes responding to different nitrogen levels were screened using bioinformatics methods. Then, the KEGG pathway enrichment analysis was conducted. The expression of the differentially expressed genes enriched in roots and leaves was quantified by RT-qPCR. 【Result】The physiological and morphological observations, determined at day 28 after being fertilized with different nitrogen application levels, showed that the values of height, stem diameter, number of leaves, leaf area, specific leaf area, biomass of leaves, biomass of stems, N concentration in roots, leaves and stems increased with the increase of nitrogen concentration, while the values of the total root length, total root surface area, total root volume, specific root length, root to shoot ratio, and biomass of roots, all decreased with the increase of nitrogen concentration. The chlorophyll a, chlorophyll b, carotenoid content, net photosynthetic rates and stomatal conductance were significantly promoted by the luxuriant nitrogen level. Of the differentially expressed genes among different nitrogen levels based on the global transcriptomic profiling by RNA-seq, 76 genes were up-regulated following the increase of nitrogen application levels, while 32 genes were opposite. The KEGG pathway enrichment analysis of the 108 genes showed that the top two pathways were photosynthesis and nitrogen metabolism. The photosynthesis pathway was enriched with OEE2, OEE3, PSBR, PSB27, PSAF and PSAK, while the nitrogen metabolism pathway was enriched with two NR genes and one NiR gene. The expression analysis showed that the nine genes were with similar expression patterns in roots and leaves, lowest expression levels in limiting nitrogen level while highest expression levels in luxuriant nitrogen. The expression levels of six genes of photosynthesis pathway in leaves were higher than that in roots under each nitrogen level. 【Conclusion】 Following the increase of nitrogen application levels, photosynthesis pathway genes were up-regulated, which promoted photosynthesis, while, nitrate reductase genes and nitrite reductase genes were up-regulated, which improved the nitrate assimilation efficiency. In the absence of a reference genome sequence, our results provided a basis for exploring the molecular mechanisms and discovering key candidate genes how nitrogen trigger changes in P. tatarinowii.
【Objective】Analyzing distribution suitability of forest protection tree species in seven coastal cities of Shandong Province can comprehensively reflect the impacts of different site factors on each forest protection tree species, thereby enabling further scientific forest protection tree species planning. 【Method】The distribution suitability of the tree species in protection forests within seven coastal cities of the Shandong Province was analyzed with the LandUSEM model using survey data of ‘One map’ of forest resource management in Shandong Province, as well as the 1∶106 digital soil map and DEM data as auxiliary data. 【Result】There were 26 species which were significantly affected by geomorphological factors. Furthermore, it was found that the soil types were relatively sensitive to the influence of dominant tree species and that the suitability of dominant tree species varied greatly depending on the different forest types. The average relative weights of the seven factors on the 49 dominant tree species were as follows: landform (0.19) > soil type (0.15) = slope (0.15) = soil thickness (0.15) > forest species (0.14) > slope position (0.13) > slope aspect (0.09). In the protection forests dominated by Pinus thunbergii, P. densiflora and Robinia pseudoacacia, the relative suitabilities of the first two species were higher than that of the latter; 90.48% of R. pseudoacacia forests were not suitable or critically suitable. This suggests that Pinus thunbergii, P. tabulaeformis, Quercus acutissima, Crataegus pinnatifida, Eucommia ulmoides, Q. mongolica, Q. spp., Cerasus pseudocerasus, Cerasus pseudocerasus, Ziziphus jujuba var. spinosa and other tree species should be mixed in low mountains and hilly areas where R. pseudoacacia forests have poor distribution suitability to improve the ecological benefits of R. pseudoacacia forests. 【Conclusion】 The distribution suitabilities of tree species in the protective forests within the seven selected cities along the coast of the Shandong Province are generally good, and the LandUSEM model analysis provides reliable information on tree species distribution suitability.
【Objective】Phenotypic analyses are the bases for improving variety breeding. Therefore, we analyzed phenotypic diversity of walnuts, and the nut characteristics were comprehensively evaluated to screen excellent walnut lines. 【Method】In this study, 109 high-yield walnut trees in the selective nursery of the Beijing Academy of Agricultural and Forestry Sciences were selected as research subjects. Based on the phenotypic data of nuts, the variation coefficient, diversity index, correlation, principal component, and cluster analysis were analyzed, and the nut characteristics were comprehensively evaluated. 【Result】(1)The variation of 18 phenotypic characteristics of the nuts contributed toward the observed statistically significant differences observed in the nuts, and the variation coefficient and the genetic diversity index ranged from 4.70% to 25.00%, and 2.849 to 3.023, respectively. The indicators representing nut size and dry weight had a high degree of dispersion among individuals, whereas the variation in nut shape was slight. (2) The dry weight index of each part of the nut had a significant positive correlation with indices reflecting nut size. The nut shape indices were closely related to nut diameters. The seed shell thickness and seed shell weight significantly affected the kernel percentage. (3) Nut size, shape and quality indicators can reflect most information on nut phenotypic traits. The total contribution of these three principal components was 91.596%. Eight main nut traits were screened: geometric average diameter, nut volume, dry weight of a single nut and kernel, sphericity, shell thickness, kernel percentage, and volume kernel percentage. (4) The 109 walnut germplasm resources were clustered into four groups at a Euclidean distance of 9.0, which could be used as hybrid materials for specific breeding purposes. (5) According to the integrated score of nut phenotypic traits of various germplasm resources and the general characteristics of ideal nuts, the excellent lines XJ45, A068, E030, XJ59 and W27 were selected. 【Conclusion】Through the screening of key evaluation indicators, combined with principal component analysis and the membership function method, the evaluation criteria for walnut germplasm resources could be preliminarily constructed, which would provide a breeding basis for effectively creating new varieties with commercial value in this region.
