Agronomy

Editorial

3 pages, 181 KiB

Open AccessEditorial

The Diversification of Adaptive Strategies for Karst-Adaptable Plants and the Utilization of Plant Resources in Karst Ecosystems

by Yanyou Wu and Yansheng Wu

Agronomy 2023, 13(8), 2135; https://doi.org/10.3390/agronomy13082135 - 15 Aug 2023

Viewed by 621

Abstract

Karst landforms, which account for approximately 15% of the world’s total land area, are mainly concentrated in low latitudes, including Southeast Asia, the European Mediterranean, the east coast of North America, the west coast of South America, and the marginal areas of Australia [...] Read more.

Karst landforms, which account for approximately 15% of the world’s total land area, are mainly concentrated in low latitudes, including Southeast Asia, the European Mediterranean, the east coast of North America, the west coast of South America, and the marginal areas of Australia [...] Full article

(This article belongs to the Special Issue Emerging Research on Adaptive Plants in Karst Ecosystems)

Research

Jump to: Editorial, Review

14 pages, 2483 KiB

Open AccessArticle

Appropriate Sodium Bicarbonate Concentration Enhances the Intracellular Water Metabolism, Nutrient Transport and Photosynthesis Capacities of Coix lacryma-jobi L.

by Haitao Li, Jiamei Lv, Yue Su and Yanyou Wu

Agronomy 2023, 13(7), 1790; https://doi.org/10.3390/agronomy13071790 - 03 Jul 2023

Cited by 2 | Viewed by 2068

Abstract

Karst ecological stresses are harmful to plant growth, especially high bicarbonate concentrations, drought, high pH, etc. In this study, the effects of 0, 2.0, 7.0 and 12.0 mmol L⁻¹ sodium bicarbonate concentrations on the biomass, electrophysiological properties, intracellular water metabolism, nutrient transport, [...] Read more.

Karst ecological stresses are harmful to plant growth, especially high bicarbonate concentrations, drought, high pH, etc. In this study, the effects of 0, 2.0, 7.0 and 12.0 mmol L⁻¹ sodium bicarbonate concentrations on the biomass, electrophysiological properties, intracellular water metabolism, nutrient transport, photosynthesis and chlorophyll fluorescence of Coix lacryma-jobi L. were investigated. The results show that 2.0 mmol L⁻¹ sodium bicarbonate effectively improved the biomass formation of Coix lacryma-jobi L., notably increased its intrinsic capacitance (IC) and decreased its intrinsic resistance (IR), intrinsic impedance (IZ), intrinsic capacitive reactance (IXc) and intrinsic inductive reactance (IXL) as well as reliably enhanced its intracellular water metabolism, nutrient transport and photosynthetic capacities. However, 7.0 and 12.0 mmol L⁻¹ sodium bicarbonate concentrations exhibited marked inhibitory effects on the plants’ photosynthetic rate, stomatal conductance, transpiration rate and dry weight, whereas they did not significantly change the intracellular water metabolism or the nutrient transport capacity of Coix lacryma-jobi L. This study highlights that appropriate bicarbonate levels could enhance the intracellular water metabolism, nutrient transport, photosynthesis and growth of Coix lacryma-jobi L., which can be rapidly monitored by the plant’s electrophysiological properties. Importantly, plant electrophysiological measurement is significantly superior to photosynthesis measurement. In the future, plant electrophysiological measurement can be used as a means to quickly and effectively evaluate the physiological response of plants to the external environment. Full article

(This article belongs to the Special Issue Emerging Research on Adaptive Plants in Karst Ecosystems)

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15 pages, 4073 KiB

Open AccessArticle

Stable Nitrogen Isotopes as an Effective Tool for Estimating the Nitrogen Demand of Broussonetia papyrifera (L.) Vent Seedlings under Variable Nitrate Concentrations

by Kaiyan Zhang, Furong Zhang, Haitao Li, Yue Su and Yanyou Wu

Agronomy 2023, 13(6), 1663; https://doi.org/10.3390/agronomy13061663 - 20 Jun 2023

Cited by 1 | Viewed by 1072

Abstract

Poor growth is often observed in artificial young forests due to insufficient inorganic nitrogen in karst soils. However, little is known about the assimilatory demand of the whole plant for nitrate and the partitioning of nitrate assimilation in roots and leaves in woody [...] Read more.

Poor growth is often observed in artificial young forests due to insufficient inorganic nitrogen in karst soils. However, little is known about the assimilatory demand of the whole plant for nitrate and the partitioning of nitrate assimilation in roots and leaves in woody plants grown in karst habitats. In this study, Broussonetia papyrifera (L.) Vent (B. papyrifera) seedlings were grown under nearly hydroponic conditions. The isotope mass balance approach was employed to quantify the δ¹⁵N values of the N assimilates in plant organs and in whole plants for B. papyrifera seedlings grown at different nitrate concentrations. The δ¹⁵N values of the N assimilates in the whole B. papyrifera seedlings showed a rising trend with increasing nitrate concentration. Increasing the supply of nitrate decreased the leaf–root difference in the δ¹⁵N values of the N assimilates for B. papyrifera seedlings. Quantifying the δ¹⁵N values of N assimilates in the whole B. papyrifera seedlings grown under different nitrate concentrations contributes to estimating the assimilatory demand of the B. papyrifera seedlings for nitrate. The leaf–root difference in the δ¹⁵N values of the N assimilates can be used to estimate the partitioning of nitrate assimilation in the roots and leaves. Full article

(This article belongs to the Special Issue Emerging Research on Adaptive Plants in Karst Ecosystems)

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20 pages, 4674 KiB

Open AccessArticle

Study on the Regulation Mechanism of 1-MCP Combined with SO₂ Treatment on Postharvest Senescence of Bamboo Shoots (Chimonobambusa quadrangularis) in Karst Mountain Area

by Jinyang Xu, Ning Ji, Rui Wang, Chao Ma, Jiqing Lei, Ni Zhang, Renchan Liu and Yunbing Deng

Agronomy 2023, 13(4), 1122; https://doi.org/10.3390/agronomy13041122 - 14 Apr 2023

Cited by 2 | Viewed by 1123

Abstract

Fresh bamboo shoots (Chimonobambusa quadrangularis) are subjected to senescence (e.g., lignification and browning) during postharvest storage. This study investigated the effects of 1-MCP and SO₂ treatment on bamboo shoot senescence and its regulation mechanism in order to extend bamboo shoot [...] Read more.

Fresh bamboo shoots (Chimonobambusa quadrangularis) are subjected to senescence (e.g., lignification and browning) during postharvest storage. This study investigated the effects of 1-MCP and SO₂ treatment on bamboo shoot senescence and its regulation mechanism in order to extend bamboo shoot storage time. 1-MCP and SO₂ treatments significantly inhibited the browning and lignification of fresh bamboo shoots during storage, according to the results. Its lower browning index and lignin content are directly related to its lower lignin content compared to the CK control group. The browning index and lignin content of the 1-MCP + SO₂ treatment during the late storage period were 90.55% and 81.50% of the CK treatment, respectively. The result of the in-depth analysis suggested that 1-MCP and SO₂ treatments reduced nutrient loss and maintained the nutritional value of bamboo shoots by inhibiting respiration and physiological metabolism. The PPO activity was inhibited to inhibit the browning process. Moreover, the scavenging ability of ROS was enhanced, the accumulation of MDA was inhibited, and the senescence of bamboo shoots was delayed after higher contents of total flavonoids and ascorbic acid were maintained and the activities of ascorbic acid peroxidase and superoxide dismutase were stimulated. Furthermore, lignin biosynthesis was hindered, and the lignification of bamboo shoots was delayed after the activities of POD and PAL were inhibited. In brief, 1-MCP + SO₂ treatment is capable of inhibiting the physiological metabolism, browning, and lignification of bamboo shoots, maintaining good quality during storage, and delaying the senescence of bamboo shoots. Clarifying the senescence mechanism of bamboo shoots is of great significance for expanding the bamboo shoot industry and slowing down rocky desertification in karst mountainous areas. Full article

(This article belongs to the Special Issue Emerging Research on Adaptive Plants in Karst Ecosystems)

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16 pages, 3192 KiB

Open AccessArticle

Regulation of Cell Wall Degradation and Energy Metabolism for Maintaining Shelf Quality of Blueberry by Short-Term 1-Methylcyclopropene Treatment

by Han Yan, Rui Wang, Ning Ji, Jiangkuo Li, Chao Ma, Jiqing Lei, Liangjie Ba, Guangzhong Wen and Xiaobo Long

Agronomy 2023, 13(1), 46; https://doi.org/10.3390/agronomy13010046 - 23 Dec 2022

Cited by 2 | Viewed by 1373

Abstract

In order to study a short-term and efficient technology by 1-methylcyclopropene (1-MCP) in blueberry, the fruit was treated with 0, 0.5, 1 and 3 μL/L 1-MCP for 2 h then stored at 25 ± 1 °C with 40–50% relative humidity (RH) for 9 [...] Read more.

In order to study a short-term and efficient technology by 1-methylcyclopropene (1-MCP) in blueberry, the fruit was treated with 0, 0.5, 1 and 3 μL/L 1-MCP for 2 h then stored at 25 ± 1 °C with 40–50% relative humidity (RH) for 9 d. The weight loss, decay incidence, respiration rate, firmness, soluble solid content (SSC), titratable acid (TA), Brix-acid ratio (BAR), sensory evaluation, content of cell wall polysaccharide, activities of cell wall composition-related enzymes and energy metabolism in blueberry were determined during shelf life. The results showed that the weight loss, decay incidence and respiration rate were reduced by 3 μL/L 1-MCP treatment. Compared to other groups, the firmness, the content of TA and anthocyanins were maintained in 3 μL/L 1-MCP-treated blueberry. In contrast, the SSC and BAR were lower compared to those untreated. However, the sensory evaluation of “taste” and “aroma” value showed no differences in all fruits. The content of protopectin, cellulose and hemicellulose was higher in 1-MCP-treated blueberry, accompanied by a decrease in polygalacturonase (PG) and pectin methyl esterase (PME) activity. The content of water-soluble pectin (WSP) was lower in 1-MCP-treated blueberry than untreated ones. The activity of phenylalanine ammonia lyase (PAL), peroxidase (POD), cinnamyl alcohol dehydrogenase (CAD) and 4-coumarate-CoA ligase (4CL) was higher in 1-MCP-treated blueberry than the untreated, which induced more serious lignification. The results of energy metabolism also showed that the 1-MCP treatment could ensure sufficient intracellular energy supply. The 3 μL/L 1-MCP treatment could maintain the shelf quality and retard decomposition of cell wall polysaccharide by ensuring sufficient intracellular energy supply and inhibiting cell wall-degrading enzymes activity. Taken together, this study highlighted an efficient and short-term 1-MCP treatment technique. Full article

(This article belongs to the Special Issue Emerging Research on Adaptive Plants in Karst Ecosystems)

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13 pages, 1429 KiB

Open AccessArticle

Diurnal Variation in Transport and Use of Intracellular Leaf Water and Related Photosynthesis in Three Karst Plants

by Xiaojie Qin, Deke Xing, Yanyou Wu, Weixu Wang, Meiqing Li and Kashif Solangi

Agronomy 2022, 12(11), 2758; https://doi.org/10.3390/agronomy12112758 - 06 Nov 2022

Cited by 3 | Viewed by 1204

Abstract

Except for transpired water, the intracellular water stored in leaves accounts for only 1–3% of the water absorbed by roots. Understanding water transport and use, as well as the related photosynthetic response, helps with determining plant water status and improving the revegetation efficiency [...] Read more.

Except for transpired water, the intracellular water stored in leaves accounts for only 1–3% of the water absorbed by roots. Understanding water transport and use, as well as the related photosynthetic response, helps with determining plant water status and improving the revegetation efficiency in fragile karst habitats. In this study, we conducted experiments on 8 year old naturally growing plants of Coriaria nepalensis Wall., Broussonetia papyrifera (L.) Vent., and Elaeocarpus decipiens Hemsl. in karst areas. We determined the diurnal variations in leaf electrophysiology, water potential, gas exchange, and chlorophyll fluorescence parameters. The results indicated that C. nepalensis plants maintained a high photosynthetic rate, with a high root water uptake ability and leaf intracellular water-holding capacity (LIWHC). The stomata quickly closed to conserve water within cells and protect the photosynthetic structure. B. papyrifera maintained stable intracellular water transport rate (LIWTR), and the photosynthetic efficiency was increased with increasing intracellular water-use efficiency (LIWUE). B. papyrifera also maintained its photosynthesis by efficiently using the transpired water when the LIWHC was increased. The inter- and intracellular water in the leaves of E. decipiens remained stable, which could be attributed to the leathery leaves and its high water-holding capacity. The photosynthesis of E. decipiens was low and stable. Compared with the high photosynthesis, high transpiration, and low instantaneous water-use efficiency (WUE_i) pattern in C. nepalensis plants, E. decipiens plants exhibited low photosynthesis, low transpiration, and low WUE_i, whereas B. papyrifera plants presented high photosynthesis, low transpiration, and high WUE_i. Plants in karst regions change their transport and use of intracellular leaf water to regulate the photosynthetic performance, which differs among different plant species. Full article

(This article belongs to the Special Issue Emerging Research on Adaptive Plants in Karst Ecosystems)

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18 pages, 3150 KiB

Open AccessArticle

Species-Specific and Altitude-Induced Variation in Karst Plants’ Use of Soil Dissolved Inorganic Carbon

by Sen Rao and Yanyou Wu

Agronomy 2022, 12(10), 2489; https://doi.org/10.3390/agronomy12102489 - 12 Oct 2022

Cited by 2 | Viewed by 1623

Abstract

Root-derived carbon sources supporting photosynthesis have been demonstrated to contribute to plant carbon gain in many laboratory experiments. However, it remains largely unknown whether and to what extent soil dissolved inorganic carbon (DIC) influences leaf photosynthesis in karst habitats characterized by alkaline soils [...] Read more.

Root-derived carbon sources supporting photosynthesis have been demonstrated to contribute to plant carbon gain in many laboratory experiments. However, it remains largely unknown whether and to what extent soil dissolved inorganic carbon (DIC) influences leaf photosynthesis in karst habitats characterized by alkaline soils with low water content. We explored this relationship by measuring the concentrations and carbon isotope signals (δ¹³C) of soil DIC, as well as the δ¹³C of water-soluble organic matter (δ_WSOM) in leaves of nine woody species across an altitudinal gradient in karst habitats. The δ_WSOM varied among species by 7.23‰ and deviated from the δ¹³C of photosynthates solely assimilated from atmospheric CO₂ (δ_A) by 0.44–5.26‰, with a mean value of 2.20‰. This systematical discrepancy (δ_A − δ_WSOM) could only be explained by the contribution of soil DIC to leaf total photosynthesis (f_{DIC_soil}). The average values of f_{DIC_soil} considerably varied among the nine species, ranging from 2.48% to 9.99%, and were comparable with or slightly lower than those of previous laboratory experiments. Furthermore, the f_{DIC_soil} of two species significantly increased with altitude, whereas another species exhibited an opposite pattern, suggesting a highly spatial heterogeneity of DIC utilization. The present study improved our understanding of how plants adapt to the alkaline–drought soil conditions of karst habitats and thus acquire additional carbon for growth. Full article

(This article belongs to the Special Issue Emerging Research on Adaptive Plants in Karst Ecosystems)

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17 pages, 3382 KiB

Open AccessArticle

Differential Responses of Nitrate/Ammonium Use to Bicarbonate Supply in Two Brassicaceae Species under Simulated Karst Habitat

by Antong Xia and Yanyou Wu

Agronomy 2022, 12(9), 2080; https://doi.org/10.3390/agronomy12092080 - 31 Aug 2022

Cited by 2 | Viewed by 1198

Abstract

In the karst habitats with nitrate-abundant and ammonium-rare soil, the bicarbonate supply plays a crucial role in both inorganic carbon and nitrogen assimilation in various plant species. Consequently, two carbon sources, carbon dioxide (CO₂) and bicarbonate (HCO₃⁻), and [...] Read more.

In the karst habitats with nitrate-abundant and ammonium-rare soil, the bicarbonate supply plays a crucial role in both inorganic carbon and nitrogen assimilation in various plant species. Consequently, two carbon sources, carbon dioxide (CO₂) and bicarbonate (HCO₃⁻), and two nitrogen sources, namely nitrate (NO₃⁻) and ammonium (NH₄⁺) are available for plants. However, variations in the absorption and utilization of nitrate, ammonium, and inorganic carbon during bicarbonate supply in different plants are not well-depicted. In this study, we evaluated the nitrate/ammonium use efficiency and their contributions to the total nitrogen assimilation/utilization capacity at different bicarbonate levels using a bidirectional stable nitrogen isotope tracer approach. The inorganic carbon assimilation, such as the photosynthesis, carbon/nitrogen enzymatic activities, carbon/nitrogen content, nitrogen assimilation/utilization capacity, and nitrate/ammonium contributions to plant growth, were also evaluated to decipher the responses of both carbon and nitrogen metabolism to bicarbonate supply in karst habitats. With the increasing bicarbonate level, Orychophragmus violaceus (Ov) was found to be more available for nitrate to total nitrogen assimilation and utilization than Bn (Brassica napus). Further, it enhanced the contributions of nitrate and nitrogen accumulation/utilization capacity and inorganic carbon assimilation, increasing photosynthesis, carbon/nitrogen enzymatic activities, and carbon accumulation, and promoted the growth in Ov. Though the highest bicarbonate level was conducive to ammonium utilization and water use efficiency in both Ov and Bn, it inhibited total inorganic carbon and nitrogen assimilation, leading to growth suppression in Bn compared to Ov. Moreover, considering the optimistic responses of both carbon and nitrogen assimilation to the high bicarbonate supply in nitrate-abundant, as well as ammonium-rare, environments, we conclude that Ov was more adaptable to the karst habitats. This study provides a novel approach to elucidate the responses of nitrate/ammonium utilization and inorganic carbon assimilation to bicarbonate. Furthermore, the current study reveals the complex interactions among different carbon–nitrogen metabolism pathways in various plants and their adaptations to karst habitats. Full article

(This article belongs to the Special Issue Emerging Research on Adaptive Plants in Karst Ecosystems)

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15 pages, 1380 KiB

Open AccessArticle

Leaf Functional Traits and Relationships with Soil Properties of Zanthoxylum planispinum ‘dintanensis’ in Plantations of Different Ages

by Yanping Song, Yanghua Yu and Yitong Li

Agronomy 2022, 12(8), 1891; https://doi.org/10.3390/agronomy12081891 - 12 Aug 2022

Cited by 7 | Viewed by 1395

Abstract

To explore the changes of leaf functional traits of Zanthoxylum planispinum ‘dintanensis’ with growth and development and its relationship with soil properties, which can clarify the response of the plantation to soil properties and suitable strategy. The research results can provide a scientific [...] Read more.

To explore the changes of leaf functional traits of Zanthoxylum planispinum ‘dintanensis’ with growth and development and its relationship with soil properties, which can clarify the response of the plantation to soil properties and suitable strategy. The research results can provide a scientific basis for plantations management. We explored the response of leaf functional traits to soil by using redundancy analysis in 5–7-, 10–12-, 20–22-, and 28–32-year Z. planispinum ‘dintanensis’ plantations. The results showed that: (1) The coefficients of variation of leaf traits ranged from 0.41% to 39.51%, with mostly medium and low variation, with the lowest variability in leaf water content (0.51–0.85%); The 5–7, 10–12, 20–22-year-old plantations were laid at the “slow investment-return” end of the economic spectrum while 28–32-year plantations were close to “fast investment-return” end. (2) The Z. planispinum ‘dintanensis’ tended to suit the environment via making trade-off and coordination of leaf functional traits. Leaf dry matter content decreased with an increase in leaf carbon/leaf nitrogen ratio, which is the trade-off between nitrogen usage efficiency and nutrient fixation capacity in Z. planispinum ‘dintanensis’. (3) Redundancy analysis suggested that soil carbon/nitrogen ratio, soil total calcium, soil water content, soil available phosphorus, soil carbon/calcium ratio were highly correlated with leaf functional traits, while soil elemental stoichiometry had a greater reflection on leaf functional traits than their own content. Full article

(This article belongs to the Special Issue Emerging Research on Adaptive Plants in Karst Ecosystems)

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18 pages, 19465 KiB

Open AccessArticle

Comparison of Aboveground Vegetation and Soil Seed Bank Composition among Three Typical Vegetation Types in the Karst Regions of Southwest China

by Yili Guo, Yufei Li, Jianxing Li, Jiaqi Li, Shujun Wen, Fuzhao Huang, Wen He, Bin Wang, Shuhua Lu, Dongxing Li, Wusheng Xiang and Xiankun Li

Agronomy 2022, 12(8), 1871; https://doi.org/10.3390/agronomy12081871 - 08 Aug 2022

Cited by 3 | Viewed by 1537

Abstract

Rural agricultural activity generates cropland, secondary vegetation and straggling primary forest and can modify the soil seed bank (SSB), potentially impacting the restoration of preferred species. The interaction between vegetation and seed banks during the recovery process is dependent on management practices and [...] Read more.

Rural agricultural activity generates cropland, secondary vegetation and straggling primary forest and can modify the soil seed bank (SSB), potentially impacting the restoration of preferred species. The interaction between vegetation and seed banks during the recovery process is dependent on management practices and recovery pathways. This study was carried out in Guilin of southwest China to assess the variation in plant diversity and species composition of both aboveground and soil seed banks across three typical vegetation types with different human interventions: orchard, bamboo shrub and primary forest. The results show that there were significant differences in the species composition and diversity of aboveground vegetation and SSB, as well as in soil properties among three typical vegetation types. The primary forest had the highest aboveground species diversity, while the orchard had the highest species diversity and seed density of SSB. In addition, principal component analysis (PCA) and canonical correspondence analyses (CCAs) showed that the species composition and plant life forms of the three typical vegetation types were significantly influenced by soil properties. Based on these findings, the characteristics of aboveground vegetation and the soil seed bank and their correlations with soil properties are expected to drastically change with human intervention. These results imply that unsustainable land use has greatly impacted soil properties, and consequently, the aboveground vegetation and SSB. Nevertheless, vegetation will recover quickly after farming is abandoned. The successful restoration of fragmented ecosystems requires the addition of seeds and seedlings of target species, especially perennial woody plants from the relevant natural ecosystems, to accelerate succession from bamboo shrub to forest. Full article

(This article belongs to the Special Issue Emerging Research on Adaptive Plants in Karst Ecosystems)

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15 pages, 1565 KiB

Open AccessEditor’s ChoiceArticle

Stoichiometry of Soil, Microorganisms, and Extracellular Enzymes of Zanthoxylum planispinum var. dintanensis Plantations for Different Allocations

by Yitong Li, Yanghua Yu and Yanping Song

Agronomy 2022, 12(7), 1709; https://doi.org/10.3390/agronomy12071709 - 19 Jul 2022

Cited by 6 | Viewed by 1692

Abstract

Plantations with different allocation patterns significantly affect soil elements, microorganisms, extracellular enzymes, and their stoichiometric characteristics. Rather than studying them as a continuum, this study used four common allocations of plantations: Zanthoxylum planispinum var. dintanensis (hereafter Z. planispinum) + Prunus salicina, [...] Read more.

Plantations with different allocation patterns significantly affect soil elements, microorganisms, extracellular enzymes, and their stoichiometric characteristics. Rather than studying them as a continuum, this study used four common allocations of plantations: Zanthoxylum planispinum var. dintanensis (hereafter Z. planispinum) + Prunus salicina, Z. planispinum + Sophora tonkinensis, Z. planispinum + Arachis hypogaea, and Z. planispinum + Lonicera japonica plantations, as well as a single-stand Z. planispinum plantation as a control. Soil samples from depths of 0–10 and 10–20 cm at the five plantations were used to analyze the element stoichiometry, microorganisms and extracellular enzymes. (1) One-way analysis of variance (ANOVA) showed that the contents of soil organic carbon (C), nitrogen (N), phosphorus (P), and potassium (K) of Z. planispinum + L. japonica plantation were high, while those of calcium (Ca) and magnesium (Mg) were low compared to the Z. planispinum pure plantation; soil microbial and enzyme activities were also relatively high. Stoichiometric analysis showed that soil quality was good and nutrient contents were high compared to the other plantations, indicating that this was the optimal plantation. (2) Two-way ANOVA showed that stoichiometry was more influenced by plantation type than soil depth and their interaction, suggesting that plantation type significantly affected the ecosystem nutrient cycle; soil microbial biomass (MB) C:MBN:MBP was not sensitive to changes in planting, indicating that MBC:MBN:MBP was more stable than soil C:N:P, which can be used to diagnose ecosystem nutrient constraints. (3) Pearson’s correlation and standardized major axis analyses showed that there was no significant correlation between soil C:N:P and MBC:MBN:MBP ratios in this study; moreover, MBN:MBP had significant and extremely significant correlations with MBC:MBN and MBC:MBP. Fitting the internal stability model equation of soil nutrient elements and soil MBC, MBN, and MBP failed (p > 0.05), and the MBC, MBN, and MBP and their stoichiometric ratios showed an absolute steady state. This showed that, in karst areas with relative nutrient deficiency, soil microorganisms resisted environmental stress and showed a more stable stoichiometric ratio. Overall stoichiometric characteristics indicated that the Z. planispinum + L. japonica plantation performed best. Full article

(This article belongs to the Special Issue Emerging Research on Adaptive Plants in Karst Ecosystems)

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12 pages, 2171 KiB

Open AccessArticle

Contrasting Adaptation Mechanisms of Golden Camellia Species to Different Soil Habitats Revealed by Nutrient Characteristics

by Xianliang Zhu, Jianmin Tang, Huizhen Qin, Kundong Bai, Zongyou Chen, Rong Zou, Shengyuan Liu, Quanguang Yang, Xiao Wei and Shengfeng Chai

Agronomy 2022, 12(7), 1511; https://doi.org/10.3390/agronomy12071511 - 23 Jun 2022

Cited by 6 | Viewed by 2896

Abstract

Golden Camellia species are highly specific to certain soil environments. Most species are only native to calcareous soils in karst regions, except for a few that grow only in acidic soils. Our aim is to elucidate the adaptation mechanisms of the species of [...] Read more.

Golden Camellia species are highly specific to certain soil environments. Most species are only native to calcareous soils in karst regions, except for a few that grow only in acidic soils. Our aim is to elucidate the adaptation mechanisms of the species of calcareous-soil golden Camellia (CSC) and acidic-soil golden Camellia (ASC) to habitat soils through plant–soil nutrient characteristics and their relationships. We investigated 30 indices for soils and plants. Compared with ASC, CSC had more fertile soil, while their plant tissues exhibited stronger Ca, P, and Mn and weaker K storage, which may be important mechanisms for adapting to habitat soils. However, ASC showed a higher biological absorption coefficient (BAC) for nutrients, which may contribute to the adaptation of ASC to relatively barren acidic soils. Both CSC and ASC showed much higher BAC and accumulation of Ca than other nutrients. We also found that the concentrations of nutrients in the different tissues varied considerably between species. Correlation analysis revealed 135 significant relationships between the 30 indices, with the soil pH and soil Ca levels being the most important factors influencing the nutrient uptake network. This information helps in understanding the adaptation mechanisms of karst plants to habitat soils. Full article

(This article belongs to the Special Issue Emerging Research on Adaptive Plants in Karst Ecosystems)

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13 pages, 2890 KiB

Open AccessArticle

Competition and Niche Differentiation of Water and Nutrients between Broussonetia papyrifera and Platycladus orientalis under Prolonged Drought Stress

by Kai Yao, Yanqing Wang and Yanyou Wu

Agronomy 2022, 12(7), 1489; https://doi.org/10.3390/agronomy12071489 - 22 Jun 2022

Cited by 2 | Viewed by 1384

Abstract

Little is known about the competition between and niche differentiation of water and nutrients between angiosperm and gymnosperm tree species under prolonged drought stress, especially in fragile environments. We imposed 21 d drought and competition treatments on Broussonetia papyrifera and Platycladus orientalis and [...] Read more.

Little is known about the competition between and niche differentiation of water and nutrients between angiosperm and gymnosperm tree species under prolonged drought stress, especially in fragile environments. We imposed 21 d drought and competition treatments on Broussonetia papyrifera and Platycladus orientalis and measured water, N, and P contents, the isotopic composition of N and C, the activity of P assimilation enzymes, and stomatal conductance under solo planting and mixed planting to characterize resource diversity and competition in response to treatments. The N content, δ¹³C, δ¹⁵N, phosphomonoesterase, phosphodiesterase, g_s, and foliage water content were significantly affected by the soil water content. The δ¹⁵N content in young leaves showed that N competition between these two plants could be alleviated through niche differentiation, but the changes in the PDE: PME ratio for these two plants indicated that they lost the niche differentiation of the P source under drought stress. Additionally, it was observed that foliage water content, WUE, N contents, and N and P sources were significantly affected by interspecific competition, and Broussonetia papyrifera benefited from water competition under moderate drought. Our results indicate that plants have different competition and niche differentiation modes to different nutrients under drought stress, and the effect of interspecific water competition should be seriously considered in mixed forests in semiarid areas. Full article

(This article belongs to the Special Issue Emerging Research on Adaptive Plants in Karst Ecosystems)

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12 pages, 1600 KiB

Open AccessArticle

Carbon and Nitrogen Stable Isotope Abundance and Soil Stoichiometry of Zanthoxylum planispinum var. dintanensis Plantations of Different Ages

by Yanghua Yu, Yingu Wu, Yanping Song and Yitong Li

Agronomy 2022, 12(6), 1248; https://doi.org/10.3390/agronomy12061248 - 24 May 2022

Cited by 7 | Viewed by 1429

Abstract

Understanding the relationships between carbon; nitrogen, their stable isotopes δ¹³C and δ¹⁵N, and soil stoichiometry may further our understanding of the regulatory mechanisms of the soil quality index on the equilibrium on isotopic fractionation. Four plantations of Zanthoxylum planispinum [...] Read more.

Understanding the relationships between carbon; nitrogen, their stable isotopes δ¹³C and δ¹⁵N, and soil stoichiometry may further our understanding of the regulatory mechanisms of the soil quality index on the equilibrium on isotopic fractionation. Four plantations of Zanthoxylum planispinum var. dintanensis (5–7, 10–12, 20–22 and 30–32 years) in the karst plateau gorge area, Guizhou Province, China, were selected to determine the variation characteristics and interactions between leaves, leaf litter, soil carbon (C), soil nitrogen (N) and their isotopes with plantation age, and to explore the relationship between soil stoichiometry and the isotopes δ¹³C and δ¹⁵N. The results were as follows: (1) the δ¹³C in leaves, litter, and soil were −28.04‰ ± 0.59‰, −26.85‰ ± 0.67‰, and −19.39‰ ± 1.37‰, respectively. The contents of δ¹⁵N were 2.01‰ ± 0.99‰, 2.91‰ ± 1.32‰, and 3.29‰ ± 0.69‰, respectively. The contents of δ¹³C and δ¹⁵N were ranked in the order, soil > litter > leaf. (2) With increasing plantation age, the soil ¹³C decreased; the leaf and the litter δ¹⁵N increased first then decreased, and the litter δ¹³C and the soil δ¹⁵N did not vary significantly. (3) The litter layer was positively correlated with soil δ¹³C and negatively correlated to δ¹⁵N. (4) Redundancy analysis showed that the soil microbial biomass carbon (MBC) and the bacteria/fungi (BAC/FUN) were the dominant factors affecting the natural abundance of C and N isotopes Full article

(This article belongs to the Special Issue Emerging Research on Adaptive Plants in Karst Ecosystems)

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18 pages, 1584 KiB

Open AccessArticle

Karst Soil Patch Heterogeneity with Gravels Promotes Plant Root Development and Nutrient Utilization Associated with Arbuscular Mycorrhizal Fungi

by Qing Li, Muhammad Umer, Yun Guo, Kaiping Shen, Tingting Xia, Xinyang Xu, Xu Han, Wenda Ren, Yan Sun, Bangli Wu, Xiao Liu and Yuejun He

Agronomy 2022, 12(5), 1063; https://doi.org/10.3390/agronomy12051063 - 28 Apr 2022

Cited by 9 | Viewed by 1839

Abstract

Arbuscular mycorrhizal (AM) fungi associated with plant roots play an essential role in the belowground ecological process in karst habitats with high spatial and substrate heterogeneity. However, the effects of AM fungi on root morphology and nutrient uptake under different soil patch sizes [...] Read more.

Arbuscular mycorrhizal (AM) fungi associated with plant roots play an essential role in the belowground ecological process in karst habitats with high spatial and substrate heterogeneity. However, the effects of AM fungi on root morphology and nutrient uptake under different soil patch sizes and gravel content in karst habitats are still unclear. A controlled experiment was conducted using a square device divided into 16 grid patches. This experiment had three treatments, including the mycorrhizal fungal treatment inoculated with (M⁺) or without Glomus etunicatum Becker & Gerd (M⁻), the patch heterogeneity treatment through the homogeneous patch (Homo), heterogeneity-large patch (Hetl) and heterogeneity-small patch (Hets), and substrate heterogeneity treatment through the gravel-free substrate (GF), gravel-low substrate (GL), and gravel-high substrate (GH). Root traits and nutrients of Bidens pilosa L were analyzed, and the result showed the AM fungi significantly increased the dry weight, length, surface area, average diameter, volume, tips, branching points, and N, P, and K acquisitions of B. pilosa roots, but significantly decreased the specific root length. The Hets with soil and gravel increased the dry weight, length, surface area, tips, branching points, and N, P, and K acquisitions of B. pilosa roots compared with Hetl regulated by AM fungi. The GL and GH treatments also increased the dry weight, length, surface area, tips, branching points, and N, P, and K acquisitions of B. pilosa roots compared with GF regulated by AM fungi. These results indicate that the B. pilosa roots’ nutritional acquisition benefits were higher in Hets mixed with gravel for its root morphological development regulated by AM fungi in karst soil. In conclusion, we suggest that soil patch heterogeneity with gravels promotes root morphological development and nutrient utilization to karst plants associated with arbuscular mycorrhizal fungi. Full article

(This article belongs to the Special Issue Emerging Research on Adaptive Plants in Karst Ecosystems)

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14 pages, 1844 KiB

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The Increase in the Karstification–Photosynthesis Coupled Carbon Sink and Its Implication for Carbon Neutrality

by Yanyou Wu and Yansheng Wu

Agronomy 2022, 12(9), 2147; https://doi.org/10.3390/agronomy12092147 - 09 Sep 2022

Cited by 12 | Viewed by 2404

Abstract

Two of the most important CO₂ sequestration processes on Earth are plant photosynthesis and rock chemical dissolution. Photosynthesis is undoubtedly the most important biochemical reaction and carbon sink processes on Earth. Karst geological action does not produce net carbon sinks. Photosynthesis and [...] Read more.

Two of the most important CO₂ sequestration processes on Earth are plant photosynthesis and rock chemical dissolution. Photosynthesis is undoubtedly the most important biochemical reaction and carbon sink processes on Earth. Karst geological action does not produce net carbon sinks. Photosynthesis and karstification in nature are coupled. Karstification–photosynthesis coupling can stabilize and increase the capacity of karstic and photosynthetic carbon sinks. Bidirectional isotope tracer culture technology can quantify the utilization of different inorganic carbon sources by plants. Bicarbonate utilization by plants is a driver of karstification–photosynthesis coupling, which depends on plant species and the environment. Carbonic anhydrase, as a pivot of karstification–photosynthesis coupling, can promote inorganic carbon assimilation in plants and the dissolution of carbonate rocks. Karst-adaptable plants can efficiently promote root-derived bicarbonate and atmospheric carbon dioxide use by plants, finally achieving the conjugate promotion of karstic carbon sinks and photosynthetic carbon sinks. Strengthening karstification–photosynthesis coupling and developing karst-adaptable plants will greatly improve the capacity of carbon sinks in karst ecosystems and better serve the “Carbon peak and Carbon neutralization” goals of China. Full article

(This article belongs to the Special Issue Emerging Research on Adaptive Plants in Karst Ecosystems)

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