Specific Root Surface Area Research Articles

Effect of CO2 Elevation on Tomato Gas Exchange, Root Morphology and Water Use Efficiency under Two N-Fertigation Levels.

Atmospheric elevated CO2 concentration (e[CO2]) decreases plant nitrogen (N) concentration while increasing water use efficiency (WUE), fertigation increases crop nutrition and WUE in crop; yet the interactive effects of e[CO2] coupled with two N-fertigation levels during deficit irrigation on plant gas exchange, root morphology and WUE remain largely elusive. The objective of this study was to explore the physiological and growth responses of ambient [CO2] (a[CO2], 400 ppm) and e[CO2] (800 ppm) tomato plant exposed to two N-fertigation regimes: (1) full irrigation during N-fertigation (FIN); (2) deficit irrigation during N-fertigation (DIN) under two N fertilizer levels (reduced N (N1, 0.5 g pot-1) and adequate N (N2, 1.0 g pot-1). The results indicated that e[CO2] associated with DIN regime induced the lower N2 plant water use (7.28 L plant-1), maintained leaf water potential (-5.07 MPa) and hydraulic conductivity (0.49 mol m-2 s-1 MPa-1), greater tomato growth in terms of leaf area (7152.75 cm2), specific leaf area (223.61 cm2 g-1), stem and total dry matter (19.54 g and 55.48 g). Specific root length and specific root surface area were increased under N1 fertilization, and root tissue density was promoted in both e[CO2] and DIN environments. Moreover, a smaller and denser leaf stomata (4.96 µm2 and 5.37 mm-2) of N1 plant was obtained at e[CO2] integrated with DIN strategy. Meanwhile, this combination would simultaneously reduce stomatal conductance (0.13 mol m-2 s-1) and transpiration rate (1.91 mmol m-2 s-1), enhance leaf ABA concentration (133.05 ng g-1 FW), contributing to an improvement in WUE from stomatal to whole-plant scale under each N level, especially for applying N1 fertilization (125.95 µmol mol-1, 8.41 µmol mmol-1 and 7.15 g L-1). These findings provide valuable information to optimize water and nitrogen fertilizer management and improve plant water use efficiency, responding to the potential resource-limited and CO2-enriched scenario.

Enhancing zinc biofortification and mitigating cadmium toxicity in soil–earthworm–spinach systems using different zinc sources

Cadmium (Cd) pollution poses significant threats to soil organisms and human health by contaminating the food chain. This study aimed to assess the impact of various concentrations (50, 250, and 500 mg·kg–1) of zinc oxide nanoparticles (ZnO NPs), bulk ZnO, and ZnSO4 on morphological changes and toxic effects of Cd in the presence of earthworms and spinach. The results showed that Zn application markedly improved spinach growth parameters (such as fresh weight, plant height, root length, and root-specific surface area) and root morphology while significantly reducing Cd concentration and Cd bioconcentration factors (BCF-Cd) in spinach and earthworms, with ZnO NPs exhibiting the most pronounced effects. Earthworm, spinach root, and shoot Cd concentration decreased by 82.3 %, 77.0 %, and 75.6 %, respectively, compared to CK. Sequential-step extraction (BCR) analysis revealed a shift in soil Cd from stable to available forms, consistent with the available Cd (DTPA-Cd) results. All Zn treatments significantly reduced Cd accumulation, alleviated Cd-induced stress, and promoted spinach growth, with ZnO NPs demonstrating the highest Cd reduction and Zn bioaugmentation efficiencies compared to bulk ZnO and ZnSO4 at equivalent concentrations. Therefore, ZnO NPs offer a safer and more effective option for agricultural production and soil heavy metal pollution management than other Zn fertilizers.

Effects of riparian pioneer plants on soil aggregate stability: Roles of root traits and rhizosphere microorganisms

Pioneer plants are vital in stabilizing soil structure while restoring reservoir drawdown areas. However, uncertainties persist regarding the mechanism of pioneer plants to soil stability in these delicate ecosystems. This study aims to unravel the plant-soil feedback mechanisms from the roles of root traits and rhizosphere microorganisms. We conducted a mesocosm experiment focusing on four common pioneer plants from the drawdown area of Three Gorges Reservoir, China. Using the wet sieving methodology, trait-based approach and high-throughput sequencing technology, we explored soil aggregate stability parameters, plant root traits and rhizosphere microbial communities in experimental plant groups. The interacting effect of pioneer plant species richness, root traits, and rhizosphere microbial communities on soil aggregate stability was quantified by statistical and machine-learning models. Our results demonstrate that diverse pioneer plant communities significantly enhance soil aggregate stability. Notably, specific species, such as Cynodon dactylon (L.) Pers. and Xanthium strumarium L., exert a remarkably strong influence on soil stability due to their distinctive root traits. Root length density (RLD) and root specific surface area (RSA) were identified as crucial root traits mediating the impact of plant diversity on soil aggregate stability. Additionally, our study highlights the link between increased rhizosphere fungal richness, accompanied by plant species richness, and enhanced soil aggregate stability, likely attributable to elevated RLD and RSA. These insights deepen our understanding of the role of pioneer vegetation in soil structure and stability, providing valuable implications for ecological restoration and management practices in reservoir drawdown areas.

Biochar addition can negatively affect plant community performance when altering soil properties in saline-alkali wetlands.

Biochar is a widely proposed solution for improving degraded soil in coastal wetland ecosystems. However, the impacts of biochar addition on the soil and plant communities in the wetland remains largely unknown. In this study, we conducted a greenhouse experiment using soil seed bank from a coastal saline-alkaline wetland. Three types of biochar, including Juglans regia biochar (JBC), Spartina alterniflora biochar (SBC) and Flaveria bidentis biochar (FBC), were added to the saline-alkaline soil at ratios of 1%, 3% and 5% (w/w). Our findings revealed that biochar addition significantly increased soil pH, and increased available potassium (AK) by 3.74% - 170.91%, while reduced soil salinity (expect for 3% SBC and 5%SBC) by 28.08% - 46.93%. Among the different biochar types, the application of 5% FBC was found to be the most effective in increasing nutrients and reducing salinity. Furthermore, biochar addition generally resulted in a decrease of 7.27% - 90.94% in species abundance, 17.26% - 61.21% in community height, 12.28% - 56.42% in stem diameter, 55.34% - 90.11% in total biomass and 29.22% - 78.55% in root tissue density (RTD). In particular, such negative effects was the worst in the SBC samples. However, 3% and 5% SBC increased specific root length (SRL) by 177.89% and 265.65%, and specific root surface area (SRSA) by 477.02% and 286.57%, respectively. The findings suggested that the plant community performance was primarily affected by soil pH, salinity and nutrients levels. Furthermore, biochar addition also influenced species diversity and functional diversity, ultimately affecting ecosystem stability. Therefore, it is important to consider the negative findings indirectly indicate the ecological risks associated with biochar addition in coastal salt-alkaline soils. Furthermore, Spartina alterniflora was needed to desalt before carbonization to prevent soil salinization when using S. alterniflora biochar, as it is a halophyte.

Responses of belowground fine root biomass and morphology in Robinia pseudoacacia L. plantations to aboveground environmental factors

The adaptation of fine roots to a variety of environmental conditions is crucial for promoting the growth and long-term survival of forest trees. To achieve sustainable forest ecology management requires a comprehensive understanding of the intricate relationships between belowground and aboveground factors in the forest ecosystem. Equally important is identifying the factors that directly affect the growth and development of fine roots belowground. This study was carried out in 25-year-old pure plantations of Robinia pseudoacacia L. within the Caijiachuan watershed, Jixian County, Shanxi Province, China. Twenty-seven permanent sample plots were established, with each plot measuring 20 × 20 m. These plots covered nine different stand densities ranging from 775 to 2975 trees/ha, with three replicates per density. Through field surveys and multivariate analysis, along with the use of a simplified Generalized Linear Model, this study revealed the alterations in belowground fine root biomass and morphology resulting from variations in stand density. Additionally, it explored the mutual relationships between belowground fine root biomass and morphology and aboveground environmental characteristics. The results show that, under different stand densities, only fine root biomass, specific fine root length, fine root tissue density, and fine root tip density displayed significant differences (P < 0.05), while specific fine root surface area exhibited a decreasing trend with increasing stand density. Moreover, lower densities (1025 and 1175 trees/ha) promoted the growth of specific fine root length and specific fine root surface area, while higher densities (2100 and 2475 trees/ha) supported the development of fine root biomass and fine root tip density. The combined contributions of semi-decomposition layer litter layer thickness (contribution value: 0.1340), mean tree height (contribution value: 0.2710), and neighborhood comparison (contribution value: 0.1840) significantly explain the variations in fine root biomass (P = 0.014) and specific fine root surface area (P = 0.031). Fine root biomass shows statistically significant correlations only with total phosphorus and available phosphorus (P < 0.05). The influence of soil factors (contribution value: 0.0306) on subterranean fine roots is much less pronounced compared to that of stand structure (contribution value: 0.1152) and other environmental factors (contribution value: 0.1128). These factors together account for the variations in subterranean fine roots, with stand structure and other environmental factors making the most significant contributions (contribution value: 0.5840). These research findings offer valuable insights into the connections between subterranean fine roots and aboveground biotic and abiotic factors in Robinia pseudoacacia L. plantations in the northern Loess Plateau region. Furthermore, they provide vital information for the prudent management and operation of low-efficiency Robinia pseudoacacia L. plantations.

Adaptation Strategies of Seedling Root Response to Nitrogen and Phosphorus Addition.

The escalation of global nitrogen deposition levels has heightened the inhibitory impact of phosphorus limitation on plant growth in subtropical forests. Plant roots area particularly sensitive tissue to nitrogen and phosphorus elements. Changes in the morphological characteristics of plant roots signify alterations in adaptive strategies. However, our understanding of resource-use strategies of roots in this environment remains limited. In this study, we conducted a 10-month experiment at the Castanopsis kawakamii Nature Reserve to evaluate the response of traits of seedling roots (such as specific root length, average diameter, nitrogen content, and phosphorus content) to nitrogen and phosphorus addition. The aim was to reveal the adaptation strategies of roots in different nitrogen and phosphorus addition concentrations. The results showed that: (1) The single phosphorus and nitrogen-phosphorus interaction addition increased the specific root length, surface area, and root phosphorus content. In addition, single nitrogen addition promotes an increase in the average root diameter. (2) Non-nitrogen phosphorus addition and single nitrogen addition tended to adopt a conservative resource-use strategy to maintain growth under low phosphorus conditions. (3) Under the single phosphorus addition and interactive addition of phosphorus and nitrogen, the roots adopted an acquisitive resource-use strategy to obtain more available phosphorus resources. Accordingly, the adaptation strategy of seedling roots can be regulated by adding appropriate concentrations of nitrogen or phosphorus, thereby promoting the natural regeneration of subtropical forests.

Evaluation of growth adaptation of Cinnamomum camphora seedlings in ionic rare earth tailings environment

The root system is an important organ for nutrient uptake and biomass accumulation in plants, while biomass allocation directly affects essential oils content, which plays an essential role in plant growth and development and resistance to adverse environmental conditions. This study was undertaken to investigate the differences and correlation of biomass allocation, root traits and essential oil content (EOC), as well as the adaptations of camphor tree with different chemical types to the ionic rare earth tailing sand habitats. Data from 1-year old cutting seedlings of C. camphora showed that the biomass of C. camphora cuttings was mainly distributed in root system, with the ratio of root biomass 49.9–72.13% and the ratio of root to canopy 1.00–2.64. The total biomass was significantly positively correlated with root length (RL), root surface area (RSA) and dry weight of fine roots (diameter ≤ 2 mm) (P < 0.05). Root biomass and leaf biomass were negatively and positively with specific root length (SRL) and specific root surface area (SRSA), respectively. Leaf biomass presented a positive effect on EOC (P < 0.05), with the correlation coefficient of 0.808. The suitability sort of these camphor trees was as follows: C. camphora β-linalool, C. camphora α-linaloolII, C. camphora α-linaloolI being better adapted to the ionic rare earth tailings substrate, C. camphora citral being the next, and C. porrectum β-linalool and C. camphora borneol being the least adaptive. EOC played a positive role in the adaptation of C. camphora (R2 = 0.6099, P < 0.05). Therefore camphor tree with linalool type is the appropriate choice in the ecological restoration of ionic rare earth tailings. The study could provide scientific recommendations for the ecological restoration of ionic rare earth tailings area combined with industrial development.

Deep phosphorus fertilizer placement increases maize productivity by improving root-shoot coordination and photosynthetic performance

It’s well known that the development and distribution of roots could be regulated to obtain deep soil resource and enhance the grain yield by increasing the depth of fertilization, but little is known about whether increasing P fertilization depth can optimize the root distribution to delay leaf senescence, enhance photosynthetic performance and root-shoot coordination or not. We conducted a field experiment that tested the following four placement depths of P fertilization: 5 cm (P5), 10 cm (P10), 15 cm (P15), and 20 cm (P20). The experiment was designed to explore the regulatory effects of the P fertilization depth on the root growth and distribution, the photosynthetic performance, the root-shoot coordination, the yield formation, the N and P fertilizer utilization of maize plants. We found that deep P placement did indeed alter the root parameters. In the 20–60 cm soil layer, both the root dry weight and length of P15 treatment were on average 23.2% higher than those of P5 treatment. The specific root length and specific root surface area of P15 treatment were 4.5% and 5.6% higher than those of P5 treatment. In addition, the P15 treatment achieved a significantly improved photosynthetic performance over the P5 treatment: The leaf area index at the R6 stage was 10.2% higher, the leaf senescence index from the R2 to the R6 stages was 31.4% lower, the photosynthetic rate at the R3 stage was 25.9% higher. The P placement depth also optimized the root-shoot coordination: The ratios of root weight to shoot weight, root surface area to leaf area, and root length to leaf area of P15 treatment were 6.7%, 13.8%, and 12.7% higher than those of P5 treatment, respectively. Finally, the root P and N uptake efficiency, the photosynthetic P-use efficiency, and the physiological P-use efficiency of P15 treatment were all significantly higher than those of P5 treatments. And together these responses had the effect of increasing the mature biomass by 12.5%, and the grain yield by 22.0%. In conclusion, increasing the P fertilization placement depth to 15 cm regulates the growth and development of the root system, which in turn improves the capability of plant to uptake and utilize N and P in the soil, delays the onset of leaf senescence, enhances its photosynthetic performance and biomass accumulation rate, and thus ultimately increases the yield.

The Relationships between Root Traits and the Soil Erodibility of Farmland Shelterbelts in the Bashang Region of China

Soil erodibility by wind is not only affected by the basic physical and chemical properties of the soil but also the functional traits of plant roots. However, the roles played by the morphological and architectural traits of plant roots on wind-based soil erodibility in the Bashang region of China are still unclear. Therefore, two typical tree shelterbelts and two shrub shelterbelts in the Bashang region were selected to assess and determine how the root traits affected soil erodibility, especially characteristics such as dry aggregate, soil organic matter, and shearing resistance. The results showed that the soil dry aggregates of the two shrubs (Lycium barbarum and Caragana korshinskii) had higher geometric mean diameters (0.40 ± 0.03 mm) and mean weight diameters (0.82 ± 0.08 mm) but a lower erodible fraction (81.81% ± 1.62%) compared to the two trees (Populus simonii and Ulmus pumila). The mean weight diameter (MWDd) and geometric mean diameter (GMDd) of dry soil aggregates were negatively correlated with the soil erodible fraction (EFd), but these parameters were positively correlated with shearing resistances. The specific root length (SRL) and surface area (SSA) of plant roots were positively correlated with the GMDd of the soils, though these two parameters negatively correlated with the soil erodible fraction. The root branching intensity (BI) was negatively correlated with the MWDd and GMDd of dry soil aggregates. The total carbon or nitrogen of the soil displayed significantly positive and negative correlations to the geometric mean diameters and erodible fractions of the soils, respectively. The findings showed that plant roots with higher SRLs, as well as lower root diameters and BIs, played positive key roles in soil stability. The same applied to soils with higher nitrogen, carbon, and water content. The results from this study suggest that L. barbarum is superior to the other three species based on root traits and wind erosion resistance. These findings provide critical information for selecting plants for the sustainable management of windbreak and sand fixation.

The Impact of Nitrogen Application on Leaf and Root Functional Traits of Davidia involucrata Saplings

Understanding the effects of nitrogen (N) deposition on plant functional traits can provide insights into their adaptation strategies. We conducted an N application experiment (0, 5, 10, 15 g N m−2) with potted saplings of the endangered species Davidia involucrata and examined 24 functional traits of both leaves and roots. We found that N application increased the leaf morphological traits, except for a significant decrease (by 19.2%–27.0%) in specific leaf area (SLA). Compared to the control treatment, N application significantly increased the specific root surface area (SRA), specific root length (SRL), and root tissue density (RTD) by 9.2%–20.1%, 20.2%–47.9%, and 30.8%–46.4%, respectively, while root diameter was conservative and insensitive to N application. Additionally, N application had contrasting effects between leaf and root carbon, N, and phosphorus contents and their stoichiometry. SRL, SRA, and RTD were positively correlated with most leaf photosynthetic traits, but negatively correlated with SLA. Moreover, root biomass and root chemical traits were also tightly correlated with leaf photosynthetic traits and chemical traits. These results suggest that N application may trigger a resource-conservative strategy for leaves but a nutrient-acquisitive strategy for roots. Future N deposition combined with other practices, such as simultaneous P fertilizer application, can be effective for the scientific conservation of D. involucrata populations in their natural habitats.

Root morphological and physiological traits are committed to the phosphorus acquisition of the desert plants in phosphorus-deficient soils

BackgroundPhosphorus (P) deficiency in desert ecosystems is widespread. Generally, desert species may allocate an enormous proportion of photosynthetic carbon to their root systems to adjust their P-acquisition strategies. However, root P-acquisition strategies of deep-rooted desert species and the coordination response of root traits at different growth stages to differing soil P availability remains unclear. In this study, a two-year pot experiment was performed with four soil P-supply treatments (0, 0.9, 2.8, and 4.7 mg P kg–1 y–1 for the control, low-, intermediate-, and high-P supply, respectively). Root morphological and physiological traits of one- and two-year-old Alhagi sparsifolia seedlings were measured.ResultsFor two-year-old seedlings, control or low-P supply significantly increased their leaf Mn concentration, coarse and fine roots’ specific root length (SRL), specific root surface area (SRSA), and acid phosphatase activity (APase), but SRL and SRSA of one-year-old seedlings were higher under intermediate-P supply treatment. Root morphological traits were closely correlated with root APase activity and leaf Mn concentration. One-year-old seedlings had higher root APase activity, leaf Mn concentration, and root tissue density (RTD), but lower SRL and SRSA. Two-year-old seedlings had higher root APase activity, leaf Mn concentration, SRL and SRSA, but a lower RTD. Root APase activity was significantly positively correlated with the leaf Mn concentration, regardless of coarse or fine roots. Furthermore, root P concentrations of coarse and fine roots were driven by different root traits, with root biomass and carboxylates secretion particularly crucial root traits for the root P-acquisition of one- and two-year-old seedlings.ConclusionsVariation of root traits at different growth stages are coordinated with root P concentrations, indicating a trade-off between root traits and P-acquisition strategies. Alhagi sparsifolia developed two P-activation strategies, increasing P-mobilizing phosphatase activity and carboxylates secretion, to acclimate P-impoverished in soil. The adaptive variation of root traits at different growth stages and diversified P-activation strategies are conducive to maintaining the desert ecosystem productivity.

重庆主城河岸带植物群落功能性状与土壤理化性质的关系

PDF HTML阅读 XML下载 导出引用 引用提醒 重庆主城河岸带植物群落功能性状与土壤理化性质的关系 DOI: 10.5846/stxb202202160368 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 重庆市科技兴林项目（2021-9）；西南大学生命科学学院科学基金项目（20212005406201）；宁夏回族自治区重点研发计划项目（2020BFG03006）；中央林业改革发展资金科技推广示范项目（渝林科推2020-2） The relationship between plant functional traits and soil physicochemical properties in the riparian zones of downtown Chongqing Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:基于功能性状视角开展植物群落与环境关系的研究有助于揭示植物的适应策略。然而，目前关于城市河岸带植物群落功能性状的研究较少。为此选取10项植物功能性状指标和14项土壤理化性质指标，探究重庆主城3种生境类型河岸带（自然型河岸带（NRZ）、农耕主导型河岸带（FRZ）和开发建设主导型河岸带（BRZ））植物群落功能性状与土壤因子特征及互作机制。结果表明：（1）与NRZ生境相比，FRZ生境中的土壤速效磷、速效钾和氧化还原电位和BRZ生境中的土壤含水量显著偏高（P<0.05）；FRZ和BRZ生境中的土壤pH值和全磷含量显著偏高，而土壤有机质、全钾和全氮含量显著偏低（P<0.05）。（2）与NRZ生境相比，FRZ生境中的比根长和比根表面积显著较高，茎干物质含量和叶干物质含量显著较低；BRZ生境中仅茎干物质含量显著较低（P<0.05）。（3）冗余分析结果表明，影响各生境类型河岸带植物群落功能性状的土壤因子不同，NRZ生境为土壤容重、含水量和硝态氮，FRZ生境为土壤铵态氮、全磷和有机质，BRZ生境则是土壤含水量、温度和速效磷。研究发现与自然状态相比，农业和建筑类型的人为干扰导致重庆主城河岸带生境发生改变，植物群落通过权衡功能性状组合的策略提高对生境变化的适应性。 Abstract:Studying the relationship between plants and the environment through plant functional traits is of help to reveal plants' adaptation strategies. At present, most researches on the relationship between plant functional traits and environmental factors have mainly focused on the terrestrial ecosystems. Very few similar studies have been carried out in the riparian ecosystems. Riparian vegetation is a prerequisite for riparian ecosystems to function properly, while maintaining healthy watercourse and landscape connectivity. Therefore, our study selected 10 plant functional trait indices and 14 soil physiochemical property indices to explore plant community functional traits, soil factor characteristics and interaction mechanisms of three habitat types (natural riparian zone (NRZ), farming riparian zone (FRZ) and building riparian zone (BRZ)) within the riparian zones of downtown Chongqing. The results showed that:(1) compared with the NRZ habitat, the soil available phosphorus, available potassium and redox potential in the FRZ habitat and the soil moisture in the BRZ habitat were significantly higher (P<0.05). The soil pH value and total phosphorus content were significantly higher in FRZ and BRZ habitats, while soil organic matter, total potassium and total nitrogen content were significantly lower (P<0.05). (2) In comparison to the NRZ habitats, the specific root length and specific root surface area in the FRZ habitats were significantly higher, and the stem dry matter content and leaf dry matter content were significantly lower. Only the stem dry matter content was significantly lower in the BRZ habitats (P<0.05). (3) The results of redundancy analysis showed that the soil factors which affected the functional traits of riparian plant communities in different habitat types were different. For the NRZ habitats, the influencing factors were soil bulk density, soil moisture and nitrate nitrogen. For the FRZ habitats, the influencing factors were soil ammonium nitrogen, total phosphorus and organic matter. For the BRZ habitats, the influencing factors were soil moisture, soil temperature, and available phosphorus. This study found that in comparison to the natural riparian state, the anthropogenic disturbance of agriculture and structural engineering related projects led to changes in the riparian habitats of downtown Chongqing, and that the plant community improved its adaptability to various habitats through trade-off combinations of functional traits. 参考文献 相似文献 引证文献

An investigation into biochar, acid-modified biochar, and wood vinegar on the remediation of saline−alkali soil and the growth of strawberries

The salinization of several hundred million hectares of land poses a serious threat to global food security and biodiversity. Biochar and wood vinegar amendment has been suggested as a possible way to promote plant productivity and improve soil qualities, whereas less emphasis has been placed on the application of biochar in saline−alkaline soils to increase plant productivity. Herein, the single and composite application of sawdust biochar, wood vinegar, and acid-modified biochar on the restoration of coastal saline−alkali soil and plant growth of strawberry seedlings was investigated. Proximate and ultimate analyses and different characterization techniques such as FTIR and scanning electron microscopy were applied to study the physicochemical characteristics of raw and modified biochar. A pot experiment was conducted to explore the effects of different soil additives on soil properties and strawberry growth. Our results revealed that acid-modified biochar shows the most significant promoting effect on strawberry growth, which could increase the weight gain rate, root length, root specific surface area, and root volume of strawberry seedlings by 41.2%, 18.9%, 23.0%, and 34.7%, respectively. Moreover, the application of acid-modified biochar can effectively alleviate soil salinization by reducing soil pH (7.65) and CEC (19.5 cmol/kg). Furthermore, the addition of biochar can significantly improve the community structure of microorganisms (Proteobacteria) and increase the content of bacteria related to soil nutrient cycling (Pseudomonadaceae and Sphingomonadaceae). Preliminary findings from this study suggested that acid-modified biochar is a potentially effective means of preventing soil salinization and increasing economic crop yields.

Response of root and root hair phenotypes of cotton seedlings under high temperature revealed with RhizoPot.

Driven by the increase in its frequency and duration, high temperature weather is increasingly seriously affecting crop development. High temperature inhibits the leaf development, flowering, and pollination of cotton, but its effects on the roots and root hair phenotypes and lifespans remain unclear. Thus, this study selected the two cotton varieties Nongda 601 (ND) and Guoxin 9 (GX) as materials and adopted the RhizoPot, an in situ root observation system, to investigate the effects of high temperature (38°C day and 32°C night) on the growth dynamics of the aboveground parts and root phenotypes of cotton at the seedling stage. The results showed that high temperature reduced the net photosynthetic rate and chlorophyll content, decreased the dry matter accumulation and transfer to the root, and lowered the root-shoot ratio (R/S ratio). The root phenotypes changed significantly under high temperature. After 7d of high temperature stress, the root lengths of ND and GX decreased by 78.14mm and 59.64mm, respectively. Their specific root lengths increased by 79.60% and 66.11%, respectively. Their specific root surface areas increased by 418.70 cm2·g-1 and 433.42 cm2·g-1, respectively. Their proportions of very fine roots increased to 99.26% and 97.16%, respectively. After the removal of high temperature (RHT), their root lengths tended to increase, and their proportions of very fine roots continued to increase. The root hairs of ND and GX were also significantly affected by high temperature. In particular, the root hair densities of ND and GX decreased by 52.53% and 56.25%, respectively. Their average root hair lengths decreased by 96.62% and 74.29%, respectively. Their root hair lifespans decreased by 7d and 10d, respectively. After the RHT, their average root hair lengths failed to recover. A principal component analysis indicated that the root architectures were significantly affected by root hair density, average root hair length, specific root length, and specific root surface area under high temperatures. In summary, cotton adapts to high temperature environments by increasing the specific root length, specific root surface area, and the proportions of very fine roots, and reducing the lifespan of root hairs.

Seedling age of Abies georgei var. smithii reveals functional trait coordination in high-altitude habitats in southeast tibet

Functional trait-based plant ecology is often used to study plant survival strategies and growth processes. In this work, the variation regularity of functional traits and their correlations were studied in Abies georgei var. smithii seedlings of different seedling ages found along the altitude gradient (3,800–4,400 m) in Sejila Mountain, Southeast Tibet. The following functional traits of seedlings in five age classes were determined: above-ground functional traits∼leaf thickness (T), leaf area (LA), specific leaf area (SLA), and leaf dry matter content (LDMC); below-ground functional traits∼specific stem length (SSL), specific root length (SRL), specific root surface area (SRA), root tissue density (RTD), and root dry matter content (RDMC). Results showed that (1) except for LDMC, most of the functional traits of the seedlings at different altitudes showed a regular change trend over time. The changes in traits caused by seedling age had significant effects on other traits (p &amp;lt; 0.05). Altitude only had significant effects on T, LA, SLA, SRA, RTD, and RDMC (p &amp;lt; 0.05). (2) The correlation between the above- and below-ground traits was more significant in 5-6-year-old seedlings than in other age classes (p &amp;lt; 0.05). Principal component analysis (PCA) results showed that LA and SLA were the dominant traits of fir seedlings in five age categories Pearson correlation analysis indicated a correlation between RTD and above-ground traits, thus validating the correlation between the above- and below-ground traits of seedlings of Abies georgei var. smithii of different ages. (3) Available potassium, total potassium, and total organic carbon (TOC) had the greatest influence on the traits of 5-6-year-old seedlings. This study revealed that the functional traits of Abies georgei var. smithii seedlings at different altitudesdynamically change with seedling age. The findings help in understanding the growth strategies of seedlings during early development. Future research on the combination of soil factors and seedling traits will provide a theoretical basis for artificial cultivation and protection of native vegetation.

Effect of Integrated Use of Rapeseed Cake, Biochar and Chemical Fertilizers on Root Growth, Nutrients Use Efficiency and Productivity of Tea

The tea root system plays a key role in the uptake of nutrients and water from the soil. The effect of integrated fertilizers (Control (CK) (no fertilizers), 100% NPK, 100% NPK withbiochar (NPK + B), 50% NPK with 50% rapeseed cake (NPK + RC), and 100% rapeseed cake (RC))on alterations in root growth characteristics and soil physical properties, nutrient uptake, NUE, and biomass production of tea (Longjing 43) was studied in an Alfisol at the greenhouse of the China Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou, during 2020–2021. The results showed that the conjunctive application of mineral fertilizers with rapeseed cake (NPK + RC) resulted in significant (p &lt; 0.05) reductions in soil penetration resistance (14.8%) and bulk density (8.7%) and improvement in porosity (9.9%) compared to the control. NPK + RC recorded significantly higher (p &lt; 0.05) root surface area, root volume, root tips, root length, and root CEC of tea than NPK (15%, 20%, 27%, 6%, and 11%) and control (40%, 165%, 49%, 68%, and 12%). The combinedapplication of RC and NPK fertilizer significantly decreased the specific root surface area (137%) and specific root length (66.8%) compared to the control. Root, stem, leaves, and total biomass were improved by integrated fertilization compared to the control and mineral fertilization. The nutrient content (N,P,K), nutrient uptake, NUE, nutrient uptake per root length, volume, and surface area of tea plants under NPK + RC and NPK + B were significantly (p &lt; 0.05) higher than RC and CK. Therefore, the integrated use of rapeseed cake with mineral fertilization in Alfisol should be practiced in tea plantations to improve soil physical environment, root proliferation and root CEC, nutrient uptake, and NUE and achieve higher tea biomass production through the efficient exploitation of nutrients.

Drought legacy effects on root morphological traits and plant biomass via soil biota feedback.

Drought causes soil feedback effects on plant performance. However, how the linkages between conditioned soil biota and root traits contribute to explain plant-soil feedback (PSF) as a function of drought is unknown. We utilized soil inoculum from a conditioning experiment where grassland species grew under well-watered and drought conditions, and their soil fungi were analyzed. Under well-watered conditions, we grew 21 grassland species with those inocula from either conspecific or heterospecific soils. At harvest, plant biomass and root traits were measured. Negative PSF (higher biomass in heterospecific than in conspecific soils) was predominant, and favored in drought-conditioned soils. Previous drought affected the relationship between root traits and fungal groups. Specific root surface area (SRSA) was higher in heterospecific than in conspecific droughted soils and was linked to an increase in saprotroph richness. Overall, root diameter was higher in conspecific soils and was linked to mutualist and pathogen composition, whereas the decrease of root : shoot in heterospecific soils was linked to pathogenic fungi. Drought legacy affects biomass and root morphological traits via conditioned soil biota, even after the drought conditions have disappeared. This provides new insights into the role that soil biota have modulating PSF responses to drought.

Effects of Forest Gap and Seed Size on Germination and Early Seedling Growth in Quercus acutissima Plantation in Mount Tai, China

Elucidating the influence mechanisms of seed germination and seedling growth is important for revealing the natural regeneration of forest plantations. We collected the seeds from 58-year-old Quercus acutissima Carruth. forest, and the seeds were further divided into three classes: large, medium, and small, and sown under the forest gaps (I, 197.82 m2; II, 91.85 m2, III, understory) to observe seed germination and early seedling growth. Precipitation in the study area and soil moisture content in the forest gaps were also observed during the trial period. The results showed that the precipitation in 2019 was similar to that in 2020; both were significantly lower than the precipitation in 2021. The difference in soil water content between gaps I and II was not significant, and both were significantly lower than III. The order of seedling emergence rate in gaps was II &gt; III &gt; I, but the minimum was almost close to zero in I. Large and medium seeds showed significantly greater emergence rate than small seeds. The seedlings of II had higher seedling height, ground diameter, ground diameter relative growth rate, seedling biomass, root surface area, and root volume than those of III. Large seeds had the highest ground diameter, ground diameter relative growth rate, biomass, root mass ratio, root shoot ratio, and root surface area. Correlation analysis showed that seedling biomass was significantly and positively correlated with root surface area and root volume, and significantly and negatively correlated with specific root length and specific root surface area. The regulation of soil moisture in the gap and the adaptability related to seed size were two key factors influencing the seed germination and early seedling growth of Q. acutissima.

Cross-inoculation of rhizobiome from a congeneric ruderal plant imparts drought tolerance in maize (Zea mays) through changes in root morphology and proteome.

SUMMARYRhizobiome confer stress tolerance to ruderal plants, yet their ability to alleviate stress in crops is widely debated, and the associated mechanisms are poorly understood. We monitored the drought tolerance of maize (Zea mays) as influenced by the cross‐inoculation of rhizobiota from a congeneric ruderal grass Andropogon virginicus (andropogon‐inoculum), and rhizobiota from organic farm maintained under mesic condition (organic‐inoculum). Across drought treatments (40% field capacity), maize that received andropogon‐inoculum produced two‐fold greater biomass. This drought tolerance translated to a similar leaf metabolomic composition as that of the well‐watered control (80% field capacity) and reduced oxidative damage, despite a lower activity of antioxidant enzymes. At a morphological‐level, drought tolerance was associated with an increase in specific root length and surface area facilitated by the homeostasis of phytohormones promoting root branching. At a proteome‐level, the drought tolerance was associated with upregulation of proteins related to glutathione metabolism and endoplasmic reticulum‐associated degradation process. Fungal taxa belonging to Ascomycota, Mortierellomycota, Archaeorhizomycetes, Dothideomycetes, and Agaricomycetes in andropogon‐inoculum were identified as potential indicators of drought tolerance. Our study provides a mechanistic understanding of the rhizobiome‐facilitated drought tolerance and demonstrates a better path to utilize plant–rhizobiome associations to enhance drought tolerance in crops.

Soil P availability and mycorrhizal type determine root exudation in sub-tropical forests

Root exudates determine plant's ability to acquire nutrients through influencing plant's interactions with soil microorganisms. Recent studies suggest that plant's associations with beneficial soil microorganisms explain variation in root exudation as plants opt to minimize the exudation cost through such symbiosis. Yet, we have a poor understanding of whether plants change their exudation rates through mycorrhizal symbiosis in soil environments with varying resource availability. Here, we report the effects of plant-mycorrhizal symbiosis on root exudation rates across a gradient of soil phosphorous (P) availability from a field experiment in subtropical forests. Root exudation rates were higher in plants partnering with arbuscular mycorrhizal fungi than those with ectomycorrhizal fungi, but this difference disappeared in soils with high P. Specific root surface area, specific root length and fine root vitality explained high root exudation in P-limited soils. These findings demonstrate that mycorrhizal symbiosis and root functional traits collectively determine the variation in root exudation in P-limited environments.