Innovative Artificial Agro-Ecosystems Enhance Soil Carbon Sequestration in Coastal Zones of Southeast China

Tidal flats, which are important reserved land resources, have a vital role in climate change. To evaluate the contribution of coastal saline soils to carbon sequestration, field tests were performed over a 3 year period at the Dafeng Wanggang Experimental Station in Jiangsu Province, China. Six artificial agro-ecosystems, including wasteland (WL), freshwater fish culture (FC), Sesbania culture (SC), barley culture (BC), mixed culture of fish and Sesbania (MCFS) and mixed culture of fish and barley (MCFB), were established according to developmental processes of coastal saline soils. At the initial stage of tidal flat reclamation, the soil organic carbon (SOC) increased by 59.4tha-1 in the FC system during 3 years, which was much higher than that of the WL system (40.7tha-1). When the tidal flats evolved into high saline soils, the MCFS system sequestered SOC more effectively than the FC or SC systems with increases of 53.1, 16.9 and 8.3tha-1, respectively. Subsequently, in the low saline soils, the maximum soil carbon sequestration was obtained in the MCFB system (35.8tha-1) followed by the BC (17.5tha-1) and FC (13.5tha-1) systems. Therefore, proper development of tidal flats to farmland and the subsequent establishment of optimised artificial agro-ecosystems make an important contribution to carbon sequestration and climate changes in coastal areas.Tidal flats, which are important reserved land resources, have a vital role in climate change. To evaluate the contribution of coastal saline soils to carbon sequestration, field tests were performed over a 3 year period at the Dafeng Wanggang Experimental Station in Jiangsu Province, China. Six artificial agro-ecosystems, including wasteland (WL), freshwater fish culture (FC), Sesbania culture (SC), barley culture (BC), mixed culture of fish and Sesbania (MCFS) and mixed culture of fish and barley (MCFB), were established according to developmental processes of coastal saline soils. At the initial stage of tidal flat reclamation, the soil organic carbon (SOC) increased by 59.4tha-1 in the FC system during 3 years, which was much higher than that of the WL system (40.7tha-1). When the tidal flats evolved into high saline soils, the MCFS system sequestered SOC more effectively than the FC or SC systems with increases of 53.1, 16.9 and 8.3tha-1, respectively. Subsequently, in the low saline soils, the maximum soil carbon sequestration was obtained in the MCFB system (35.8tha-1) followed by the BC (17.5tha-1) and FC (13.5tha-1) systems. Therefore, proper development of tidal flats to farmland and the subsequent establishment of optimised artificial agro-ecosystems make an important contribution to carbon sequestration and climate changes in coastal areas

Use of saline aquaculture wastewater to irrigate salt-tolerant Jerusalem artichoke and sunflower in semiarid coastal zones of China

In 2004 and 2005, the feasibility of agricultural use of saline aquaculture wastewater for irrigation of Jerusalem artichoke and sunflower was conducted in the Laizhou region using saline aquaculture wastewater mixed with brackish groundwater at different ratios. Six treatments with different electrical conductivities (EC) were included in the experiment: CK1 (rainfed), CK2 (irrigation with freshwater, EC of 0.02 dS m-1), and saline aquaculture wastewater (EC of 39.2 dS m-1) mixed with brackish groundwater (EC of 4.4 dS m-1) at volumetric ratios of 1:1, 1:2, 1:3, and 1:4 with corresponding EC of 22.0, 16.1, 13.2, and 11.4 dS m-1. Soil electrical conductivity (ECe) in the saline aquaculture wastewater irrigation treatments was significantly higher (P Jerusalem artichoke Sunflower Saline aquaculture wastewater irrigation Yield Nutrient removal

The physiological and biochemical responses of a medicinal plant (Salvia miltiorrhiza L.) to stress caused by various concentrations of NaCl.

Salvia miltiorrhiza, which is commonly known as Danshen, is a traditional Chinese herbal medicine. To illustrate its physiological and biochemical responses to salt stress and to evaluate the feasibility of cultivating this plant in saline coastal soils, a factorial experiment under hydroponic conditions was arranged on the basis of a completely randomised design with three replications. Five salinity treatments (0, 25, 50, 75 and 100 mM NaCl) were employed in this experiment. The results showed that salinity treatments of <100 mM NaCl did not affect the growth of Salvia miltiorrhiza in a morphological sense, but significantly inhibit the accumulation of dry matter. Salinity treatments significantly decreased the Chl-b content but caused a negligible change in the Chl-a content, leading to a conspicuous overall decrease in the T-Chl content. The Na(+) content significantly increased with increasing hydroponic salinity but the K(+) and Ca(2+) contents were reversed, indicating that a high level of external Na(+) resulted in a decrease in both K(+) and Ca(2+) concentrations in the organs of Salvia miltiorrhiza. Salt stress significantly decreased the superoxide dismutase (SOD) activity of Salvia miltiorrhiza leaves in comparison with that of the control. On the contrary, the catalase (CAT) activity in the leaves markedly increased with the increasing salinity of the hydroponic solution. Moreover, the soluble sugar and protein contents in Salvia miltiorrhiza leaves dramatically increased with the increasing salinity of the hydroponic solution. These results suggested that antioxidant enzymes and osmolytes are partially involved in the adaptive response to salt stress in Salvia miltiorrhiza, thereby maintaining better plant growth under saline conditions

Spatio-Temporal Differences in Nitrogen Reduction Rates under Biotic and Abiotic Processes in River Water of the Taihu Basin, China

Understanding spatio-temporal differences in nitrogen (N) transformation, transport and reduction rates in water bodies is critical to achieve effective mitigation of river eutrophication. We performed culture experiments in six rivers in the Taihu Basin using a custom made in-situ experimental apparatus. We investigated spatio-temporal differences in reduce processes and rates of different N forms and assessed the contribution of biological processes to dissolved inorganic N (DIN) reduce. Results showed that biological processes played a major role in N reduction in summer, while non-microbial processes were dominant in winter. We observed significant spatial and temporal differences in the studied mechanisms, with reduction rates of different N compounds being significantly higher in summer and autumn than spring and winter. Reduction rates ranged from 105.4 &#177; 25.3 to 1458.8 &#177; 98.4 mg&#183;(m3&#183;d)&#8722;1 for total N, 33.1 &#177; 12.3 to 440.9 &#177; 33.1 mg&#183;(m3&#183;d)&#8722;1 for ammonium, 56.3 &#177; 22.7 to 332.1 &#177; 61.9 mg&#183;(m3&#183;d)&#8722;1 for nitrate and 0.4 &#177; 0.3 to 31.8 &#177; 9.0 mg&#183;(m3&#183;d)&#8722;1 for nitrite across four seasons. Mean DIN reduction rates with and without microbial activity were 96.0 &#177; 46.4 mg&#183;(m3&#183;d)&#8722;1 and 288.1 &#177; 67.8 mg&#183;(m3&#183;d)&#8722;1, respectively, with microbial activity rates accounting for 29.7% of the DIN load and 2.2% of the N load. Results of correlation and principal component analysis showed that the main factors influencing N processing were the concentrations of different N forms and multiple environmental factors in spring, N concentrations, DO and pH in summer, N concentrations and water velocity in autumn and N concentrations in winter

The effects of various NaCl concentrations on the osmolyte contents of <i>Salvia miltiorrhiza</i> leaves.

<p>The osmolyte contents measured in the experiment include the soluble protein and soluble sugar contents. <i>Salvia miltiorrhiza</i> seedlings were cultivated in 1/2 Hoagland nutrient solution for 3 weeks and were later exposed to salt stress by adding NaCl up to 25, 50, 75 and 100 mM of the hydroponic solution for 30 days. Non-treated plants were used as controls (0 mM NaCl). Error bars represent the standard errors (SE) of the means.</p

The effects of various NaCl concentrations on the plant height, root length, fresh weight and dry weight of <i>Salvia miltiorrhiza</i> seedlings.

<p>The seedlings were cultivated in 1/2 Hoagland nutrient solution for 3 weeks and were later exposed to salt stress by adding NaCl to concentrations of 25, 50, 75 and 100 mM of the hydroponic solution for 30 days. Non-treated plants were used as controls (0 mM NaCl). Each value represents the mean of three replicates. Treatments with the same letters are not statistically different (P≥0.05).</p

The effects of various NaCl concentrations on the photosynthetic pigments of <i>Salvia miltiorrhiza</i> leaves.

<p>The photosynthetic pigments measured in the experiment include chlorophyll a (Chl-a), chlorophyll b (Chl-b) and total chlorophyll contents (T-Chl). <i>Salvia miltiorrhiza</i> seedlings were cultivated in 1/2 Hoagland nutrient solution for 3 weeks and were later exposed to salt stress by adding NaCl up to concentration of 25, 50, 75 and 100 mM of the hydroponic solution for 30 days. Non-treated plants were used as controls (0 mM NaCl). Error bars represent the standard errors (SE) of the means.</p

Effects of Balancing Exchangeable Cations Ca, Mg, and K on the Growth of Tomato Seedlings (<i>Solanum lycopersicum</i> L.) Based on Increased Soil Cation Exchange Capacity

(1) Background: Previous research has demonstrated that the cation exchange capacity (CEC) of soil and the balance of exchangeable cations Ca, Mg, and K are key factors affecting plant growth and development. We hypothesized that balancing exchangeable cations based on increased CEC would improve plant growth and development. (2) Methods: This study conducted a two-phase experiment to evaluate methods for increasing soil CEC and the effects of increasing CEC and balancing Ca, Mg, and K on plant growth. Therefore, we first conducted a soil culture experiment using organic fertilizer, montmorillonite, and humic acid to investigate fertilizers that can effectively increase CEC in the short term. Then, a tomato seedling pot experiment was conducted using the control (CK) and OMHA fertilizer-treated soils collected from soil culture experiments. The CK and OMHA treatment soils were constructed with balanced exchangeable cations and an unbalanced control, respectively. (3) Results: The soil culture experiments revealed that the combination of organic fertilizer, montmorillonite, and humic acid (OMHA treatment) had the most significant effect on increasing CEC. The CEC of the OMHA treatment increased by 41.07%, reaching 27.10 cmol·kg−1. The tomato pot experiments demonstrated that balancing the exchangeable cations in OMHA soil improved the Mg and K nutrition of tomato seedlings and significantly increased SPAD, leaf nitrogen content, and dry weight, while balancing the exchangeable cations in CK soil improved only the K nutrition of tomato seedlings. (4) Conclusions: Overall, balancing exchangeable cations based on increasing CEC can improve soil nutrient availability and alleviate the competition effects of Ca, Mg, and K cations. Low CEC and imbalanced exchangeable cations can be detrimental to tomato seedling growth

Multiple NUCLEAR FACTOR Y Transcription Factors Respond to Abiotic Stress in <i>Brassica napus</i> L

<div><p>Members of the plant NUCLEAR FACTOR Y (NF-Y) family are composed of the NF-YA, NF-YB, and NF-YC subunits. In <i>Brassica napus</i> (canola), each of these subunits forms a multimember subfamily. Plant NF-Ys were reported to be involved in several abiotic stresses. In this study, we demonstrated that multiple members of thirty three <i>BnNF-Y</i>s responded rapidly to salinity, drought, or ABA treatments. Transcripts of five <i>BnNF-YA</i>s, seven <i>BnNF-YB</i>s, and two <i>BnNF-YC</i>s were up-regulated by salinity stress, whereas the expression of thirteen <i>BnNF-YA</i>s, ten <i>BnNF-YB</i>s, and four <i>BnNF-YC</i>s were induced by drought stress. Under NaCl treatments, the expression of one <i>BnNF-YA10</i> and four <i>NF-YB</i>s (BnNF-YB3, BnNF-YB7, BnNF-YB10, and BnNF-YB14) were greatly increased. Under PEG treatments, the expression levels of four <i>NF-YA</i>s (BnNF-YA9, BnNF-YA10, BnNF-YA11, and BnNF-YA12) and five <i>NF-YB</i>s (BnNF-YB1, BnNF-YB8, BnNF-YB10, BnNF-YB13, and BnNF-YB14) were greatly induced. The expression profiles of 20 of the 27 salinity- or drought-induced <i>BnNF-Y</i>s were also affected by ABA treatment. The expression levels of six <i>NF-YA</i>s (BnNF-YA1, BnNF-YA7, BnNF-YA8, BnNF-YA9, BnNF-YA10, and BnNF-YA12<i>)</i> and seven <i>BnNF-YB</i> members (BnNF-YB2, BnNF-YB3, BnNF-YB7, BnNF-YB10, BnNF-YB11, BnNF-YB13, and BnNF-YB14) and two <i>NF-YC</i> members (BnNF-YC2 and BnNF-YC3) were greatly up-regulated by ABA treatments. Only a few <i>BnNF-Y</i>s were inhibited by the above three treatments. Several NF-Y subfamily members exhibited collinear expression patterns. The promoters of all stress-responsive <i>BnNF-Y</i>s harbored at least two types of stress-related <i>cis</i>-elements, such as ABRE, DRE, MYB, or MYC. The <i>cis</i>-element organization of <i>BnNF-Ys</i> was similar to that of <i>Arabidopsis thaliana,</i> and the promoter regions exhibited higher levels of nucleotide sequence identity with <i>Brassica rapa</i> than with <i>Brassica oleracea</i>. This work represents an entry point for investigating the roles of canola NF-Y proteins during abiotic stress responses and provides insight into the genetic evolution of <i>Brassica</i> NF-Ys.</p></div

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