Variability of leaf functional traits of invasive tree Rhus typhina L. in North China

Functional traits, specifically leaf functional traits, are core-topics to explore importance to the invasion success of invasive plant species. This study aims to address the differences in leaf functional traits and their corresponding variability of the invasive tree staghorn sumac Rhus typhina L. with different invasion success, including lower and higher invasion success, in two climatic regions in North China, including a warm temperate region and a cold temperate region. No significant differences were found for leaf functional traits of staghorn sumac across different invasion success. However, the variability of leaf chlorophyll and nitrogen concentrations of staghorn sumac under higher invasion success were approximately 66.023% and 68.615% higher than those under lower invasion success, respectively. The leaf chlorophyll and nitrogen concentrations of staghorn sumac in the warm temperate region were approximately 18.432% and 16.337% higher than those in cold temperate region, respectively. The variability of specific leaf area of staghorn sumac in warm temperate region was approximately 59.802% higher than that in cold temperate region. Accordingly, leaf chlorophyll and N concentrations as well as specific leaf area of staghorn sumac and their corresponding variability may play an essential role in shaping ecological success of studied invader along a climatic gradient.

Assessing Adaptability of Planted Trees Using Leaf Traits: A Case Study with Robinia pseudoacacia L. in the Loess Plateau, China

Leaf trait patterns and their variations with climate are interpreted as an adaptive adjustment to environment.This study assessed the adaptability of planted black locust (Robinia pseudoacacia L.) based on the analysis of leaf traits and the comparison of its leaf traits with inter-specific ones existing in the same area.We measured some water and N use related leaf traits: leaf dry mass per unit area (LMA) and N,P and K concentrations based on both leaf area (Narea,Parea and Karea) and leaf mass (Nmass,Pmass and Kmass) of R.pseudoacacia at 31 sites along a water stress gradient in North Shaanxi Province,China.The results show that leaves of R.pseudoacacia have high Nmass and low LMA in the study area.High Nmass and low LMA are usually representative of luxurious resource use,and will advance plant resource competitiveness in high-resource conditions.As a whole,LMA-nutrient relationships of R.pseudoacacia display patterns that are fairly similar to the inter-specific relationships in both direction and intensity.The tendency for LMA and Narea to increase with decreasing water availability and the positive correlation between LMA and Narea reflect the trend for R.pseudoacacia to enhance water use efficiency (WUE) at the expense of down-regulated photosynthetic N use efficiency (PNUE) and high construction cost in dry conditions.However,the positive relationship between LMA and Narea in high mean annual precipitation (MAP) area is either unremarkable or reversed with decreasing water availability.This implies a lower photosynthetic capacity and a higher construction cost for high-LMA leaves.The inter-specific relationship between LMA and Narea is positive and does not change with water availability.This difference between inter-species and intra-species may be due to more diversified anatomies and more specialised structures for inter-species than intra-species.The failure of R.pseudoacacia adaption to dry conditions reflected by LMA-Narea relationship may be partially responsible for the emergence of rampike and dwarf forms found frequently in dry conditions.Incorporating intrinsic characteristics of planted trees into vegetation restoration project will be instructive and meaningful for species selection.

Effects of harvesting on productivity of bay leaf tree(Cinnamomum tamala Nees & Eberm):Case from Udayapur district of Nepal

Cultivation of bay leaves （Cinnamomum tamalaNees ＆ Eberm） to fulfil household income needs is a long established practice in Udayapur district of Nepal. The practices adopted by farmers for bay leaf harvesting have not, however, been validated by scientific investigation for their sustainability. To investigate the impacts of harvesting on the yield of branch, leaves and biomass of leaves, a two-year research project was conducted in farm fields at Kopche village of Routa VDC in Udayapur district, Nepal. Four different harvesting treatments, the orien-tation and the order of branches were taken as independent variables to test their effects on number of branches, leaves and biomass of leaves. Orientation, harvesting treatments and order of branches had a significant effect on the number of branches, but not on the number of leaves or biomass （fresh and dry weight） of leaves in the year of harvest. Between two consecutive harvests there was no significant difference in the num-ber of branches, leaves or biomass. Lower two-thirds portion of the trees produced the largest number of leaves and branches of the fourth order in both years. Therefore, lower two-thirds portion of the trees were suitable for harvesting. Our findings support farmer experience that no change in productivity of leaves is observed when harvesting each year. For long term sustainability, harvesting should be conducted without debarking of trees or damage to branches. Our findings could be extrapolated to and tested in other areas with different access and user rights where the rota-tion for harvest is fixed or regulated without research evidence.

Resources of Colored-leaf Trees and Their Phenological Ornamental Characteristics in Lhasa City

By using biological five points,expert consultation and fuzzy comprehensive evaluation,the species,phenological ornamental characteristics,and landscape application of colored-leaf trees in Lhasa City were surveyed systematically. The results show that there are 42 species of colored-leaf trees in Lhasa City,belonging to 31 genera and 18 families,of which there are 5,19,and 18 species of spring,autumn,and common colored-leaf trees,accounting for 11.90%,45.24% and 42.86% of total number of the investigated tree species respectively. It is clearly seen that there are too few species of spring colored-leaf trees in the city. There are 19 and 17 species of trees possessing red and yellow leaves,while the leaves of other 6 species of colored-leaf trees are shown in other colors,and the number of their species accounts for 45.24%,40.48% and 14.28% of total number of the investigated tree species respectively. The best ornamental periods of spring,autumn and common colored-leaf trees in Lhasa City average 38.4,41.8 and 251.8 d respectively. Prunus cerasifera Ehrhar f. atropurpurea Rehd.,Ulmus pumila L.,Populus × beijingensis W. Y. Hsu,and Salix alba are applied most frequently in Lhasa City,and their relative frequency is 18.67%,10.29%,9.91% and 8.95% respectively. According to the comprehensive assessment value of their ornamental characteristics,the ornamental characteristics of 15 species of colored-leaf trees in Lhasa City are good or very good,and there is a positive correlation between the comprehensive assessment value and relative frequency. Based on the investigation,the current application situation and problems of colored-leaf trees in Lhasa City were analyzed,and solutions to the problems were proposed.

Effects of Different Water and Fertilizer Combinations on Tree Structure,Leaf Parameters and Photosynthesis of Apple Saplings

[ Objective] This study aimed to investigate the effects of different water and fertilizer combinations on apple saplings. [ Method] ＇ Tianhong 2＇ Fuji /SH40/Malus robusta Rehd. was used as the experimental material to analyze the effects of different irrigation modes and combinations of basal fertilizer and dressing fertilizer on tree structure, leaf parameters and photosynthesis of apple saplings. [ Result] The results showed that different water and fertilizer combinations ex- hibited varying effects on tree structure, leaf parameters and photosynthesis of apple saplings. To be specific, applying 432 000 kg/hm2 basal fertilizer, 480 kg/hm2 urea and 915 kg/hmz organic fertilizer ＋ 0 ＋ 915 kg/hm2 organic fertilizer as dressing fertilizer, and 1% urea as leaf fertilizer was conducive to promoting growth of branches and leaves, increasing leaf thickness, individual leaf area and SPAD, and improving photosynthesis of apple saplings under half root irrigation and whole root irrigation conditions. In addition, the effects were more significant under whole root irrigation conditions. [ Conclusion] Selecting the appropriate water and fertilizer combination is conducive to the growth of apple saplings.

Photoelectric Characterization of Dye Sensitized Solar Cells Using Natural Dye from Pawpaw Leaf and Flame Tree Flower as Sensitizers

Natural dyes from flame tree flower, Pawpaw leaf and their mixtures were used as sensitizers to fabricate dye-sensitized solar cells (DSSC). The photoelectrochemical performance of the Flame tree flower dye extract showed an open-circuit voltage (VOC) of 0.50 V, short-circuit current density (JSC) of 0.668 mA/cm2, a fill factor (FF) of 0.588 and a conversion efficiency of 0.20%. The conversion efficiency of the DSSCs prepared by pawpaw leaf extract was 0.20%, with VOC of 0.50 V;short-circuit current density, JSC of 0.649 mA/cm2 and FF of 0.605. The conversion efficiency for the flame tree flower and pawpaw leaf dye mixture was 0.27%, with VOC of 0.518 V, JSC of 0.744 mA/cm2 and FF of 0.69. Although the conversion efficiencies, Jsc and the Voc of the prepared dye cells were lower than the respective 1.185%, 7.49 mA/cm2 and 0.64V reported for ruthenium, their fill factors (FF) were higher than that of ruthenium (0.497). It was also observed that both the short-circuit current density and the fill factors of the cells were enhanced using mixed dye.

Wind induced deformation and vibration of a Platanus acerifolia leaf

Deformation and vibration of twig-connected sin- gle leaf in wind is investigated experimentally. Results show that the Reynolds number based on wind speed and length of leaf blade is a key parameter to the aerodynamic prob- lem. In case the front surface facing the wind and with an in- crease of Reynolds number, the leaf experiences static defor- mation, large amplitude and low frequency sway, reconfigu- ration to delta wing shape, flapping of tips, high frequency vibration of whole leaf blade, recovery of delta wing shape, and twig-leaf coupling vibration. Abrupt changes from one state to another occur at critical Reynolds numbers. In case the back surface facing the wind, the large amplitude and low frequency sway does not occur, the recovered delta wing shape is replaced by a conic shape, and the critical Reynolds numbers of vibrations are higher than the ones correspond- ing to the case with the front surface facing the wind. A pair of ram-horn vortex is observed behind the delta wing shaped leaf. A single vortex is found downstream of the conic shaped leaf. A lift is induced by the vortex, and this lift helps leaf to adjust position and posture, stabilize blade distortion and reduce drag and vibration.

Competition-density effect of tree organs in Acacia auriculiformis stands

The competition-density (C-D) effects for mean mass for tree, stem, branch and leaf were analyzed in Acacia auriculiformis stands. Mean tree mass-density and mean organ mass-density were well explained by the C-D equation of tree and the C-D equation of tree organ, respectively. An equation describing the relationship between mean leaf area u and density was formulated that fit the u-data well. The relationship between mean tree mass w and the ratio of each organ to mean tree mass (wo/ w) was examined. With increasing w, the stem mass ratio wS/w increased, whereas the branch mass ratio wB/w and the leaf mass ratio wL/w decreased. The yield difference between the lowest-density stand and the high-density stand became greater with stand growth. However, the yield of the mid-density stand was slightly lower than the yield of the high-density stand during the experimental period. To produce the most desirable combination of demanding individual-tree size and relative high stem yield, the mid-density is recommended as proper planting density for future management of A. auriculiformis stands.

Tracking leaf area index and coefficient of light extinction over the harvesting cycle of black wattle

The amount of photosynthetic radiation inter- cepted by a crop is a function of the incident solar radiation on the plants, the leaf area index （LAI）, and the light extinction coefficient （k）. We quantified LAI and k in stands of black wattle （Acacia mearnsii De Wild.） over a 7-year growth cycle at two locations in the state of Rio Grande do Sul, Brazil. Our study was conducted in commercial stands in agroecological regions with high densities of black wattle plantations. LAI was calculated as the ratio between the leaf area of a tree and its planting space, and k was derived from Beer＇s law. LAI depends on the planting site and stand age. Between the two sites, the LAI was similar over time, the amount of variation differed. Values of k depended only on stand age, with the highest average observed for stands up to 5 years old. The trend of k during the plantation cycle was inversely proportional to LAI and was correlated with LAI, leaf area, leaf dry mass, canopy volume, height, branches dry mass, total dry mass, and crown diameter.

Effect of Leaf Litter Treatment on Soil Microbial Biomass

Soil microbial biomass is an active fraction of soil organic matter. It shows quicker response than soil organic matter to any change in the soil environment. Being an index of soil fertility, it plays a key role in the decomposition of litters and fast release of available nutrients. Leaf litters of leguminous and non-leguminous species in alone and mixed form were applied as treatments in the soil to observe the changes in the magnitude of soil microbial biomass. Soil microbial biomass C and N were determined by chloroform fumigation extraction method. Increment in the concentration of microbial biomass C and N was higher in the treatments with leguminous leaf litter (497 - 571 μgCg?1, 48 - 55 μgNg?1) than the non-leguminous one (256 - 414 μgCg?1;22 - 36 μgNg?1). However, when non-leguminous litters were mixed with leguminous litters then the values increased distinctly (350 - 465 μgCg?1, 28 - 48 μgNg?1). On the basis of increment in soil microbial biomass, leaf litters of the species considered potential to improve soil nutrients are—Cassia siamea and Dalbergia sissoo from leguminous trees, Anthocephalus + Cassia and Shorea + Dalbergia from mixed form of non-leguminous and leguminous one and Eichhornia crassipes, an alien aquatic macrophyte. The leaf litters of these species can be used as source of organic matter to improve the crop yield.

Responses of Native Tree Species to Soil Water Stress in a Tropical Forest on Limestone,Vietnam

Forests over limestone in the tropics have received little attention and limestone forests in Vietnam have been overlooked to an even greater extent in terms of tree physiology. In Ba Be National Park, Vietnam, soil water availability in limestone forests seems to be the most limiting factor in the dry season. Therefore, in order to enhance the preliminary knowledge of choosing native tree species for enrichment planting in the restoration zone, characteristics of the 20 native tree species to soil water stress were investigated in a limestone forest. One-ha plot each consisting of twenty-five 20 m × 20 m plots was established in undisturbed forests. All trees ≥ 10 cm DBH were measured in 20 m × 20 m plots, while twenty-five 5 m × 5 m subplots were established in order to sample the regeneration of tree species with a DBH < 10 cm. The Scholander apparatus and freezing point osmometry were used in order to measure the leaf water potential (Ψw) and leaf osmotic potential (Ψπ) of the 20 native tree species, respectively in this study. 61 species belonging to 34 families of all trees with a DBH ≥ 10 cm were recorded in one ha, while 31 species representing 18 families of trees < 10 cm DBH were identified in 625 m2. The 20 species’ leaf water and osmotic potential values revealed significant differences among species. The maximum leaf water potential was not affected by any anticipated sources of variation, while the minimum water potential, however, showed significant variation to soil water stress. The results in the study area emphasized the importance of water factors in influencing tree species distribution;it could be concluded that native species with wide water potential ranges would be better able to withstand water changes and might be thus good candidates for reforestation (enrichment planting) in limestone areas.

Evaluation of subtropical ornamental trees for reclaiming salinity affected lands

This study was conducted to evaluate the tolerance of 1-year-old seedlings of ten subtropical ornamental tree species against a range of salinity levels of Na Cl from May 2015 to October 2015. The levels were further enhanced from November to April 2017 as 100% survival was observed in the initial concentrations for all species.The seedlings were grown during the first week of April2015 in 1000 earthen pots containing soil: farmyard manure(2:1), irrigated with tap water for 1 month followed by saline irrigation in May by maintaining electrical conductivity at 0.75, 1.00, 1.25, 1.50, 2.25, and 3.00 d S/m for 30,40, 50, 60, 90, and 120 m M Na Cl. Every 3 months,heights, relative leaf water content, and percent survival were determined;total soluble sugars of the upper leaves of each tree were quantified. All species exhibited consistent early growth and survival when supplied with 30, 40, 50 and 60 m M of Na Cl. Koelreutaria paniculata, Ficus benjamina, Putranjiva roxburghii, Bauhinia purpurea and Millettia ovalifolia were sensitive to elevated salinity levels and did not survive at the highest salt concentrations of 90 and 120 m M.

Litter cover of the invasive tree <i>Melaleuca quinquenervia</i>influences seedling emergence and survival

Exotic tree Melaleuca quinquenervia (melaleuca) deposits large quantities of slowly decomposing litter biomass that accumulates over time and covers forest floors in its adventive habitats in Florida (USA). Herein, we assessed the influence of melaleuca litter cover, seed addition, and seeding date on seedling emergence and survival. The assessment was conducted by ma-nipulating litter cover and seed inputs of melaleuca and two native species at different dates in two soil types. Litter cover was either removed or left in place in organic and arenaceous soils within melaleuca stands. Each of the three treatment plots were seeded with melaleuca, wax myrtle or sawgrass, while the fourth plot was not seeded and served as the control. Seedlings were counted at 2-wk intervals to determine cumulative seedling emergence and survival during the experimental period. The experiment was repeated four times within a year. Soil type did not influence seedling emergence of all three species but influenced survival of wax myrtle. Litter removal increased the emergence of melaleuca, sawgrass, and wax myrtle and increased the survival of melaleuca. Seed addition increased the emergence and survival of sawgrass and wax myrtle but made no difference for melaleuca. Seeding during the periods of high soil moisture content had positive effects on the emergence and survival of melaleuca, wax myrtle, and sawgrass seedlings. These findings are deemed useful in planning active restoration for melaleuca invaded sites.

Heavy Metal Contamination of Tree Leaves

The study of heavy metal (HMs) contamination of environment is of great interest due to their serious health hazard. In this work, the contamination of tree leaves with the HMs in the most polluted industrial city, Korba, India is described. The leaves of common trees i.e. Azadirachta indica, Butea monosperma, Eucalyptus, Ficus religiosa, Mangifera indica and Tectona grandis were selected for assessment of the HMs contamination as bioindicator. The elevated concentration of HMs (i.e. As, Fe, Cr, Mn, Cu, Zn, Cd, Pb and Hg) in the tree leaves was observed, ranging from 2.8 - 43, 728 - 5182, 8.6 - 49, 48 - 1196, 43 - 406, 79 - 360, 1.12 - 1.65, 1.6 - 16.4 and 0.13 - 0.76 mg/kg, respectively. The concentration, enrichment and sources of the HMs in the leaves are described. Azadirachta indica leaves, accumulating higher concentration of the HMs, showed a higher efficiency as bioindicator for the urban pollution.

Control Mechanisms and Simulation of <i>Populus simonii</i>Leaf Unfolding

Populus simonii Carr., one of the main poplar tree species, is cultivated widely in Northeast and Northwest China in protection and timber forests. Plant phenology plays an important role in timber production by controlling the growing period (i.e., the period between the leaf unfolding and the leaf turning yellow). It is important to understand this control mechanism and to improve the accuracy of the simulation of leaf unfolding phenology for P. simonii in order to determine accurately the timber production of P. simonii plantations. In this study, based on phenological observation data from 10 agricultural meteorological stations in Heilongjiang Province, China, model simulation was employed to determine the control mechanism of leaf unfolding of P. simonii. Furthermore, the predicting effects of nine phenology-simulating models for P. simonii leaf unfolding were evaluated and the distribution characteristics of P. simonii leaf unfolding in China in 2015 were simulated. The results show that P. simonii leaf unfolding is sensitive to air temperature;consequently, climate warming could advance the P. simonii leaf unfolding process. The phenological model based on air temperature could be better suited for simulating P. simonii leaf unfolding, with 76.7% of the calibration data of absolute error being less than three days. The performance of the models based solely on forcing requirements was found superior to that of the models incorporating chilling. If it was imperative that the chilling threshold is reached, the south of the Yunnan, Guangdong, and Guangxi provinces would be unsuitable for planting P. simonii. In this regard, the phenology model based on the chilling threshold as necessary condition was indicated a more reasonable model for the distribution characteristics of P. simonii leaf unfolding.

Deep Convolutional Neural Networks for South Indian Mango Leaf Disease Detection and Classification

The South Indian mango industry is confronting severe threats due to various leaf diseases,which significantly impact the yield and quality of the crop.The management and prevention of these diseases depend mainly on their early identification and accurate classification.The central objective of this research is to propose and examine the application of Deep Convolutional Neural Networks(CNNs)as a potential solution for the precise detection and categorization of diseases impacting the leaves of South Indian mango trees.Our study collected a rich dataset of leaf images representing different disease classes,including Anthracnose,Powdery Mildew,and Leaf Blight.To maintain image quality and consistency,pre-processing techniques were employed.We then used a customized deep CNN architecture to analyze the accuracy of South Indian mango leaf disease detection and classification.This proposed CNN model was trained and evaluated using our collected dataset.The customized deep CNN model demonstrated high performance in experiments,achieving an impressive 93.34%classification accuracy.This result outperformed traditional CNN algorithms,indicating the potential of customized deep CNN as a dependable tool for disease diagnosis.Our proposed model showed superior accuracy and computational efficiency performance compared to other basic CNN models.Our research underscores the practical benefits of customized deep CNNs for automated leaf disease detection and classification in South Indian mango trees.These findings support deep CNN as a valuable tool for real-time interventions and improving crop management practices,thereby mitigating the issues currently facing the South Indian mango industry.

Leaf stable carbon isotope composition in Picea schrenkiana var. tianschanica in relation to leaf physiological and morphological characteristics along an altitudinal gradient

To understand the effects of leaf physiological and morphological characteristics on δ13C of alpine trees, we examined leaf δ13C value, LA, SD, LNC, LPC, LKC, Chla+b, LDMC, LMA and Narea in one-year-old needles of Picea schrenkiana var. tianschanica at ten points along an altitudinal gradient from 1420 m to 2300 m a.s.l. on the northern slopes of the Tianshan Mountains in northwest China. Our results indicated that all the leaf traits differed significantly among sampling sites along the altitudinal gradient(P<0.001). LA, SD, LPC, LKC increased linearly with increasing elevation, whereas leaf δ13C, LNC, Chla+b, LDMC, LMA and Narea varied non-linearly with changes in altitude. Stepwise multiple regression analyses showed that four controlled physiological and morphological characteristics influenced the variation of δ13C. Among these four controlled factors, LKC was the most profound physiological factor that affected δ13C values, LA was the secondary morphological factor, SD was the third morphological factor, LNC was the last physiological factor. This suggested that leaf δ13C was directly controlled by physiological and morphological adjustments with changing environmental conditions due to the elevation.

控释尿素与普通尿素配施对橡胶树叶片和胶乳养分及产量的影响

为了明确控释尿素与普通尿素配施在橡胶树上的应用效果,通过2年田间试验,研究了减氮条件下控释尿素与普通尿素不同比例配施对橡胶树产量、叶片和胶乳矿质养分及土壤氮含量的影响,为橡胶树栽培管理中合理施氮提供技术支撑。结果表明:控释尿素与普通尿素配施可提高橡胶树干胶产量和叶片氮含量,与常规施肥相比,橡胶树干胶产量增幅为16.28%~39.13%(2021年)和7.94%~9.69%(2022年),叶片氮含量增幅为10.54%~19.17%(2021年)和10.24%~21.50%(2022年),控释尿素与普通尿素配施处理叶片氮含量均处于正常值以上。控释尿素与普通尿素配施还能够增加胶园肥穴土壤碱解氮含量,较常规施肥增加了11.27%~80.36%。控释尿素与普通尿素配施比例为50∶50时,橡胶树干胶产量(2022年)、叶片氮含量(2021—2022年)和土壤碱解氮含量(2021—2022年)均显著高于常规施肥。综上所述,在本试验条件下,控释尿素与普通尿素配施比例为50∶50能够获得较高的干胶产量,可改善叶片营养状况,维持土壤氮水平,有利于实现橡胶树施肥管理的绿色协同增效。

万州不同种植区域川中小叶种红茶滋味品质分析

为探明万州川中小叶种制作红茶滋味品质,该文以9个不同区域和表型特征的川中小叶种制备红茶,采用靶向检测方法,分析茶汤中儿茶素类、游离氨基酸类、生物碱类、黄酮醇及其苷类、有机酸类和可溶性糖组分6大类滋味成分,以感官分析,多元统计法,结合滋味贡献度(dove-over-threshold,Dot)分析川中小叶种茶树的滋味特征。结果表明:所有茶样分为4类,Ⅰ类茶样中包含C4,C5,C6,C8以及2个对比样,各滋味成分含量相对较为均衡;Ⅱ类茶样具备类似的林下栽培环境,黄酮苷类物质含量低,没食子酸、咖啡碱(caffeine,CAFF)、儿茶素类以及氨基酸类物质含量高,表现出醇厚、鲜爽度高的滋味特征;Ⅲ类茶样为叶形较大的种质,黄酮苷类、琥珀酸为其特征滋味成分,儿茶素类、茶氨酸和CAFF含量低,涩味和鲜爽度较高;Ⅳ类茶样儿茶素类、CAFF含量较高,Thea含量低,滋味浓强,但欠鲜爽。该研究对万州区不同区域川中小叶种制备红茶的品质特性进行了梳理,为该类种质资源进一步改进工艺和开发利用提供理论依据。

光谱技术在果树叶片营养诊断上的应用研究进展

光谱技术具有分析速度快、操作简单、多元素同时监测、不需要消耗化学药品、自动化程度较高等特点,其可以实现作物单株和大样本的营养诊断和分析。综述了光谱技术在果树叶片大量元素(N、P、K)、中微量元素(Ca、Mg、Fe、Mn、Cu、Zn)营养诊断上的应用研究进展,并讨论了该领域今后进一步的研究方向。