Coastal Saline Land Research Articles

Sensitivitas Bibit Jewawut (Setaria Italica (L.) P. Beauv) di Lahan Salin Pantai Cilacap

The objectives of this study were to determine the criteria of foxtail millet seedlings in coastal area and the effects of N, P, K fertilizer and water hyacinth ameliorant powder on growth characters of young foxtail millet plant in coastal saline land. The study was conducted at south coast, Bunton Village, Adipala District, Cilacap Regency in May-October 2019. Study in coastal saline land with factorial Randomized Complete Block Design with four replications. The treatment consisted of two factors, namely the dosage of N, P, K fertilizer (N, P, K = 25%, 50%, 75%, and 100% recommended dosage) and the water hyacinth powder ameliorant dose i.e. 0 t / ha, 1.5 t / ha and 2.5 t / ha. Observation variables on seedling morphology viz. seedling height, leaf length, stem diameter, number of leaf and leaf greenness, and on.the field viz. plant height, number of leaf, fresh and dry root weights, total root length, and fresh and dry shoot weights. The results showed that good seedling criteria was. Plant height (24-26 cm), leaf length (15-17 cm), leaf number (3-6), stem diameter (3,2-3,6 cm) and leaf greeness (18,6-20,9 unit). Application of fertilizer dosages of N, P, K 50% + without ameliorant gained the greater plant height of 62.76 cm and number of leaf of 7.28 than other treatments

Cultivation of dandelion (Taraxacum erythropodium) on coastal saline land based on the control of salinity and fertilizer

Abstract Dandelion (Taraxacum spp.) is a widely distributed weed; in China, however, dandelion has been considered to be a kind of medicinal and edible vegetable in recent years. This transition from weed to vegetable requires corresponding cultivation and management. Thus, the production of dandelion on saline land was conducted based on the evaluation of dandelion salt tolerance. Low soil salt content (< 0.3%) did not significantly affect dandelion growth, and the salt tolerance threshold of dandelion ranged from 0.4% to 0.43% according to the correlation between salt content and morphological and physiological parameters, which was for guiding the preparation of saline land for dandelion field cultivation. Different fertilizer treatments significantly affected the leaf yield of dandelion, and the maximum fresh leaf yield of ~10.5 t ha−1 was obtained when urea was applied in batches at a ratio of 2:2:1 in the sowing, seedling and flowering stages, respectively. This research provided the theoretical and technical support for the cultivation on saline land, laying the foundation for further study of quality control for the cultivation of dandelion on saline land.

The Evapotranspiration of Tamarix and Its Response to Environmental Factors in Coastal Saline Land of China

(1) Background: As a halophytic species, Tamarix (Tamarix chinensis) can be used for saline soil rehabilitation in China. The reclamation and rehabilitation of saline soil depend on the water consumption of plants. However, whether water resources in saline soil can support the construction of Tamarix vegetation is still unknown. (2) Methods: In this study, we measured the transpiration (T) of Tamarix for 3 years using sap flow and the evaporation (E) for 1 year using a micro-lysimeter in Tamarix land. The evaporation values in 2016 and 2017 were estimated with the soil crop coefficients obtained in 2018. (3) Results: The evapotranspiration (ET) ranged from 514.2 to 573.8 mm and was greatly affected by the wind speed, VPD and groundwater table. Transpiration was the main form of water consumption in this region, accounting for 60.2% of the total evapotranspiration. Compared with bare land, vegetation construction increased soil moisture dissipation by 377.6 mm in 2018. According to on-site measurements and estimates, the water shortage in the dry year was 107.2 mm, and the residual water values in the normal year and wet year were 77.8 mm and 187.5 mm, respectively. May and September were months of widespread water shortages in different precipitation years. Although the cultivation of this plant increased water consumption, the groundwater table remained at approximately 0.5 m during the study year. (4) Conclusions: These results indicated that planting Tamarix in coastal saline soil was feasible for the reclamation and rehabilitation of saline soil. In the dry year (2017), the consumption of evapotranspiration exceeded the precipitation. The inverse occurred in the normal year (2016) and wet year (2018). Taken together, our findings showed that the water resources in the coastal saline soil of China could tolerate vegetation construction and laid a strong foundation for saline soil rehabilitation.

Carbon assimilation and sequestration by industrial crop Jerusalem artichoke in coastal saline land

Understanding the role of Jerusalem artichoke grown in low fertility coastal saline soil in carbon sequestration is important for characterizing the relationship between soil use in agriculture production and carbon sequestration. In the present study, the mechanisms of photosynthesis and carbon distribution were studied in three saline soils with different salt contents (Xinyang 0.6–1.0 g salt/kg; Dafeng 1.5–2.4 g salt/kg; Shuntai 3.8–4.5 g salt/kg) by characterizing the biomass production, carbon storage, and carbon sequestration in the soil under Jerusalem artichoke. The biomass production and carbon storage during the growth cycle of Jerusalem artichoke were significantly higher in Dafeng than the other plots. The highest carbon sequestration was found in the Xinyang plot. The organic matter content in the rhizosphere soil was 28–44% higher than that in the non-rhizosphere soil. The soil organic carbon content in the rhizosphere soil was higher than that in the non-rhizosphere soil. High soil salinities decreased the carbon storage of Jerusalem artichoke. Carbon sequestration in soil decreased with the increase in soil salinity.

Supplementary potassium and calcium improves salt tolerance in olive plants

Soil salinization increase, aggravated by the foreseen low precipitation related to climate change, is a worldwide problem causing crop yield reductions, affecting population and environmental issues due to the salt-containing low-quality water. Enhancing the salt tolerance of plants, especially crops, is an interesting and effective solution to minimize salt-related crop problems. Toward this goal, we evaluated in this study the effect of potassium (K) and calcium (Ca) application on plant growth, nutrient uptake, water status and electrolyte and potassium leakage of two-year-old potted olive plants grown under saline conditions (100 and 200 mM NaCl). Results showed that all measured parameters were affected by salinity. However, the application of K and Ca enhanced the growth parameters, improved the water status and reduced the electrolyte and K leakage, the latter reflecting a positive effect in membrane integrity. The nutritional balance was moderately improved in salt-stressed plants treated with K and Ca. The significant reduction in sodium (Na) concentration in both leaves and roots, and the enhancement of K and Ca concentration in the different plant tissues indicated that the K and Ca supply raised the Na exclusion mechanism. The largest positive effect of K was observed with 40 mM KNO3 dose at both salinity levels. Furthermore, the beneficial effect of Ca was achieved with 40 and 10 mM CaCl2 in plants grown at 100 and 200 mM NaCl, respectively. Thus, for this relatively salt-tolerant and economically important crop, K and Ca are recommended to supply in order to mitigate the harmful effects of salinity and to develop saline agriculture in, for instance, coastal saline land.

Metabarcoding reveals differences in fungal communities between unflooded versus tidal flat soil in coastal saline ecosystem

In the saline-affected ecosystem, fungi have huge potential to promote growth, induce disease resistance and enhance tolerance against salt-stress of host plants. Since areas of plowland are gradually decreasing, the reclamation of coastal saline lands could play a crucial role in maintaining agricultural productivity and crop security globally. Therefore, it is of great significance to explore the fungal diversity in the coastal saline ecosystem. Here, we collected saline soil samples from unflooded areas and tidal flat areas, the two typical distinct landforms in coastal saline ecosystems, and used ITS metabarcoding to depict the diversity of fungal communities. We found that fungal species evenness had a remarkably higher variation from the tidal flat compared to unflooded soil samples. Furthermore, we also confirmed that the fungal niches differentiation reports in the coastal saline ecosystem. Our ITS based DNA sequencing revealed that both unflooded and tidal flat soil were mainly composed of amplicon sequence variants (ASVs) belonging to Ascomycota (93.43% and 86.91% respectively). Based on our findings, understanding the associations and distinctions of fungal microbiome between unflooded soil and tidal flat could provide the basis for the development of reclamation in coastal saline lands.

Response of soil properties and vegetation to reclamation period using drip irrigation in coastal saline soils of the Bohai Gulf

Soil salinization is a major soil degradation threat worldwide. Sparse vegetation and soil desertification are widespread phenomena in coastal saline land due to high salt content in soil, poor soil structure and freshwater shortages. In recent years, a method of vegetation reconstruction using water–salt regulation by drip-irrigation technology combined with agronomic engineering has been developed and successfully applied in coastal regions around Bohai Gulf, China. This study aimed to investigate the effect of this reconstruction method on soil properties and vegetation during reclamation periods of 0–3 years. The results showed that soil salinity and sodium adsorption ratios decreased with time that significantly reduced in the first year and gradually became stable after that, especially at shallow soil depths. Soil microbial numbers especially bacteria significantly increased and followed a linear relationship with time. Weeds eventually germinated naturally in soils; thus, vegetation coverage and species number significantly increased from initial values of 1.67% and 1 to 82.67% and 15, respectively. These findings showed that a good soil and plant ecosystem was established after reclamation and offered insight into ecosystem restoration and construction in coastal saline land.

Assessing soil spatial variability and delineating site-specific management zones for a coastal saline land in eastern India

ABSTRACTThe present study was to delineate management zones (MZs) in salt affected Mahakalpada block in eastern India by capturing both spatial variability of soil parameters along with satellite derived Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI). Grid wise 237 soil samples collected from the study area were analyzed and spatial maps were generated for physicochemical properties, DTPA extractable micronutrients, i.e. iron, zinc, copper, and manganese and major nutrients, i.e. available nitrogen (AN), phosphorous (AP), and potassium (AK). Soil electrical conductivity and AK showed a high CV of 100% and 56.7%, respectively. Principal component analysis was performed using the soil spatial maps, NDVI and EVI maps and only four principal components which produced eigenvalues > 1 and accounting for 75.4% of the total variability were retained for further analysis. Further, fuzzy c-mean clustering was used to delineate the MZs based on fuzzy performance index (FPI) and normalized classification entropy (NCE) was used for identifying the three MZs. There was a significant difference between MZ1 and MZ2 for all the variables except AN and EVI whereas all the variables were significantly different between MZ1 and MZ3 highlighting the usefulness of MZs delineation technique for site-specific nutrient management.

Simultaneous HPTLC quantification of three caffeoylquinic acids in Pluchea indica leaves and their commercial products in Thailand

In Thai traditional medicine, Pluchea indica (L.) Less., Asteraceae, leaf has been widely used for the treatment of diabetes mellitus, tumors, hypertension, cystitis, and wounds. P. indica herbal tea is commercially available in Thailand as a health-promoting drink. The study was conducted to develop and validate a high-performance thin-layer chromatography (HPTLC) method for the quantitative analysis of chlorogenic acid, 3,4-O-dicaffeoylquinic acid, and 3,5-O-dicaffeoylquinic acid in P. indica leaf extract and their commercial products in Thailand. The method was validated according to ICH guidelines. The proposed HPTLC method showed acceptable validation parameters. The content of chlorogenic acid, 3,4-O-dicaffeoylquinic acid, and 3,5-O-dicaffeoylquinic acid in P. indica leaves from seven different provinces in Thailand was in the range of not detectable −1.94±0.02%w/w, 0.71±0.01–1.89±0.05%w/w, and 1.00±0.01–2.18±0.03%w/w, respectively, while in the commercial products, it was in the range of 0.59±0.03–2.17±0.05%w/w, 0.53±0.04–3.77±0.03%w/w, and 0.88±0.05–4.72±0.10%w/w, respectively. The results indicated that plantation of P. indica in coastal saline land would be beneficial as it would increase the concentration of its active compounds and improve its medicinal quality. The developed high-performance thin-layer chromatography could be used as a rapid, reliable, less demanding, and cost-effective analytical method.

Effects of continuous application flue-gas desulfurization gypsum and brackish ice on soil chemical properties and maize growth in a saline soil in coastal area of China

ABSTRACTThe reclamation potential of applying combined brackish ice and flue-gas desulfurization (FGD) gypsum to a coastal saline soil was evaluated in a raised bed agroecosystem. Experimental plots in the raised bed were exposed to the following six treatments: 0, 4,000, and 8,000 m3ha−1 brackish ice mulch with and without FGD-gypsum. Although FGD-gypsum incorporation still increased the electrical conductivity of a saturated soil paste extract (ECe) in the 0–20 cm soil layer after brackish ice melted in the second year (April 2013), they had not increased soil ECe at harvest especially in the second year. FGD-gypsum incorporation reduced soil pH not only after brackish ice melted in the second year but also at harvest in the first and second years. At harvest in the second year, FGD-gypsum incorporation significantly decreased soil Na adsorption ration (SAR) of the 0–20 cm layer with different volumes of brackish ice compared with the treatments without FGD-gypsum. The incorporation of FGD-gypsum increased the root dry weight per plant compared with the treatment without FGD-gypsum after harvest in the first year. The incorporation of FGD-gypsum increased organic matter in the 0–20 cm soil layer in the raised bed after harvest only in the first year. The application of brackish ice increased the emergence rate of maize in spring. Soil pH in all treatments tended to increase as time increased in the 0–20 and 20–40 cm soil layers in the raised bed. The results of the present study suggest that brackish ice and FGD-gypsum application further improve soil properties and crop growth, which might accelerate the reclamation process of the coastal saline land.

Energy use efficiency and economic feasibility of Jerusalem artichoke production on arid and coastal saline lands

Jerusalem artichoke (Helianthus tuberosus L.) is a potential biofuel feedstock crop in China. To conduct a comprehensive evaluation of energy use efficiency and economic perspectives for this crop, face-to-face surveys were collected from farmers in Gansu and Shandong provinces. The results demonstrated highest energy use efficiency (2.47 in Gansu and 2.37 in Shandong), net energy (59,926 MJ/ha in Gansu and 55,298 MJ/ha in Shandong) and energy productivity (0.77 kg/MJ in Gansu and 0.74 kg/MJ in Shandong) for Jerusalem artichoke plantation size ranging from 4.0–20.0 ha in Gansu and for plantation sizes >35.0 ha in Shandong. Moreover, the lowest total production costs, namely, 9913 CNY/ha and 12,264 CNY/ha, were incurred by plantation size of 20.1–35.0 ha in size in both Gansu and Shandong, respectively. In addition, the highest benefit/cost ratio and economic productivity values were observed for plantation size of 4.0–20.0 ha in Gansu (2.60 and 2.89 kg/CNY, respectively) and >35.0 ha in Shandong (1.96 and 2.17 kg/CNY, respectively). Consequently, plantation size of <35.0 ha in Gansu and >35.0 ha in Shandong are recommended for Jerusalem artichoke production with the use of mechanization in conjunction with the use of Jerusalem artichoke straw for bioenergy production. Therefore, Jerusalem artichoke may make a large contribution in meeting the growing future challenges for bioenergy production for an expanding population.

Spatiotemporal heterogeneity of soil water and salinity after establishment of dense-foliage Tamarix chinensis on coastal saline land

Dense-foliage tamarisk (Tamarix chinensis) varieties are widely planted for landscape construction projects in the highly saline coastal soil of northern China. Because these plants are salt-secreting halophytes, their growth in arid land usually leads to soil salinization and water loss. In this work, a tamarisk plantation was established in a coastal area within a semi-arid region of China, and the water content, salinity levels and spatial distribution patterns in the soil were analysed in 1×1m grids of a 10×10m sample plot in July 2014 and July 2016. Four layers of soil within the 0–80cm profile were sampled, and the soil water, salt, Na+ and Cl− contents and pH were determined. In 2016, the soil water content had decreased slightly, and the soil salt content had increased by 0.49gkg−1, representing a 7.0% increase compared with the value in 2014. Both the soil Cl− and Na+ content increased from 2014 to 2016, accounting for a greater fraction of the total salt, and the mean soil pH also increased by approximately 0.4. The spatial variation was weaker in the deeper layers but moderate in the surface layer. After tamarisk establishment, the spatial variation in soil salinity declined and showed a trend toward homogeneity. The secreted salt and litterfall from the tamarisk might explain the higher soil salinity and increased homogeneity, which suggests that tamarisk growth will lead to increased soil salinity and a more homogeneous salt distribution throughout the soil.

Effects of water application intensity of microsprinkler irrigation on water and salt environment and crop growth in coastal saline soils

Laboratory and field experiments were conducted to investigate the effects of water application intensity (WAI) on soil salinity management and the growth of Festuca arundinacea (festuca) under three stages of water and salt management strategies using microsprinkler irrigation in Hebei Province, North China. The soil water content (è) and salinity of homogeneous coastal saline soils were evaluated under different water application intensities in the laboratory experiment. The results indicated that the WAI of microsprinkler irrigation influenced the è, electrical conductivity (ECe) and pH of saline soils. As the WAI increased, the average values of è and ECe in the 0–40 cm profile also increased, while their average values in the 40–60 cm profile decreased. The pH value also slightly decreased as depth increased, but no significant differences were observed between the different treatments. The time periods of the water redistribution treatments had no obvious effects. Based on the results for è, ECe and pH, a smaller WAI was more desirable. The field experiment was conducted after being considered the results of the technical parameter experiment and evaporation, wind and leaching duration. The field experiment included three stages of water and salt regulation, based on three soil matric potentials (SMP), in which the SMP at a 20-cm depth below the surface was used to trigger irrigation. The results showed that the microsprinkler irrigation created an appropriate environment for festuca growth through the three stages of water and salt regulation. The low-salinity conditions that occurred at 0–10 cm depth during the first stage (–5 kPa) continued to expand through the next two stages. The average pH value was less than 8.5. The tiller number of festuca increased as SMP decreased from the first stage to the third stage. After the three stages of water and salt regulation, the highly saline soil gradually changed to a low-saline soil. Overall, based on the salt desalinization, the microsprinkler irrigation and three stages of water and salt regulation could be successfully used to cultivate plants for the reclamation of coastal saline land in North China.

Influence of mulches on urban vegetation construction in coastal saline land under drip irrigation in North China

In order to generate information for reclaiming coastal saline sandy-loam soil for urban vegetation construction around Bohai Bay in North China, a field experiment combined with drip irrigation and setting a gravel–sand layer beneath the saline soil but above the water table was conducted to study the effect of mulches on irrigated water amount, soil salt control and willow (Salix babylonica L.) growth, and construction costs were also estimated during 2012 and 2013. The three mulch treatments were control treatment with no mulch (C1), black shading net mulch (C2) and straw mulch (C3). In order to leach salts in the soil profile, irrigation was triggered by the soil matric potential threshold at 20-cm soil depth of −5kPa in the early stage, and this was changed to −10kPa until the end of the first growing year, and to −20kPa for the second year. The results showed that (1) the straw mulch consumed the least irrigation water, followed by the black shading net mulch and the control treatment. Compared to the control treatment, the amount of irrigation for the straw mulch had decreased by 12% in 2012 and 27% in 2013. (2) The salinity reduction was mainly related to rainfall and the strategy of drip irrigation; and the mulches, especially straw mulch, decreased the risk of salt accumulation in early spring. (3) The best growth characteristic of plants and the optimal investment cost were for straw mulch, and the high investment cost in 2012 was due to soil preparation cost and the willows, gravel and sand cost was high and then it had decreased by 90% in 2013. From the combined points of water saving, plant growth and investment cost, the use of straw mulch with drip irrigation could aid in urban vegetation construction on coastal saline land in North China.

Chinese rose (Rosa chinensis) cultivation in Bohai Bay, China, using an improved drip irrigation method to reclaim heavy coastal saline soils

This study investigated whether an improved drip irrigation method for reclaiming heavy coastal saline silt-soils could improve the growth of salt-sensitive plants threatened by soils with high salt contents and poor soil structures in Bohai Bay, China. Chinese rose (Rosa chinensis), an ornamental salt-sensitive plant, was chosen as the experiment material. The improved method used a non-saline root environment during the early stages of salt-leaching, a gravel–sand layer settled below the saline soil but above the water table and optimal soil moisture conditions. To determine the optimal soil moisture conditions, five soil matric potentials (SMPs) at 20cm depth at −5, −10, −15, −20 and −25kPa were studied. The results indicated that the mean soil electrical conductivity of the saturated paste extracts (ECe) and the sodium adsorption ratio (SAR) significantly declined in all five treatments. After three growing seasons, the highest desalinization ratios and SAR reductions reached 89% and 73%, respectively, compared with their initial values and these occurred in the roots of the seedlings exposed to the −5kPa treatment. The mean ECe and SAR values increased linearly as the SMP declined. The plant survival ratio was not affected by the SMP treatment in the first growing season, due to the non-saline root zone, but decreased significantly as the SMP threshold fell in the spring of the second year, and then remained stable in the following season. The highest survival ratio reached 97% for the −5kPa SMP treatment after three growing seasons. Stem diameter and plant height increased during three growing seasons and the largest increases occurred when the SMP was −5kPa in first year, −10kPa in second year and −20kPa in third year. The largest crown diameters were recorded in the −5kPa treatment plots in second year and −20kPa in third year. After three years of reclamation, our results showed that this improved method, which utilized a non-saline root environment during the early stages of salt-leaching, a gravel–sand layer below the saline soil and controlled the SMP threshold of −5kPa in the first year, −10kPa in second year and −20kPa in third year, can be used to reclaim coastal urban saline land for vegetation rehabilitation around Bohai Bay, China.

Productivity and preference of salt tolerant Boro rice varieties in saline non-gher and gher ecosystems

Use of marginal coastal saline lands for rice cultivation is one of the options to sustain the net rice cropped area and rice production. On-farm farmer’s participatory field trial was conducted in Bangladesh during 2012 and 2013 in non-gher and gher of medium saline ecosystems. The objective of the study was to identify suitable Boro variety for medium saline soils. Salt tolerant rice varieties, BRRI dhan47 and Binadhan-8 were evaluated along with widely adopted BRRI dhan28 in non-gher area. BRRI dha47, Binadhan-8 and Binadhan-10 were tested in saline ghers. Crops were irrigated with water of 1.89 to 3.5 dS m-1 at different growth stages respectively. In saline non-gher, where soil salinity went up to 6.35 dS m-1, the highest grain yield was produced by Binadhan-8 (4.57 t ha-1) followed by BRRI dhan28 (4.23 t ha-1). The highest grain yield was recorded in Binadhan-10 (5.14 t ha-1) in ghers which was 6 and 12% higher than BRRI dhan47 and Binadhan-8 respectively at soil salinity of 7.43 dS m-1. Farmers preferred Binadhan-10 as a salt tolerant variety for its higher grain yield and medium grain quality.Bangladesh Rice j. 2014, 18(1&amp;2): 18-23

Effect of Nitrogen Application Amounts on Uptake and Utilization of Potassium in Cotton Grown in Improved Coastal Saline Land Regions

A field experiment using transgenic cotton cultivar Xiangzamian 8 with different nitrogen application amounts(0, 150, 300, 375, 450, and 600 kg N ha–1) was carried out in the coastal improved saline land region of Dafeng City in 2010 and 2012. Results showed that the nitrogen application increased potassium uptake of cotton at different growth stages, with the highest increment at the peak flowering-boll opening stage, and the percentages of potassium uptake decreased from seedling to peak flowering stages, but increased from peak flowering to boll maturing stages. In addition, nitrogen application lowered the decreasing speed of potassium concentration in middle and upper fruiting branches at later growth stages, but had less influence on lower fruiting branches. The marginal effect of potassium uptake(promoted amount of potassium uptake due to 1 kg increase of N application) showed an upward-downward trend with the increase of nitrogen application rate. The higher the position of fruiting branches grown, the more the nitrogen amount demanded to meet the highest marginal effect of potassium uptake. Under the nitrogen application of 300–375 kg ha–1, the economic coefficient of biomass and potassium was relatively high, eigenvalues of dynamic model of potassium content and potassium accumulation were relatively coordinate, and the marginal effect of potassium uptake and lint production efficiency of potassium were relatively high in middle and upper fruiting branches. Excessively high nitrogen application resulted in a relatively narrow rise of yield, and the marginal effect of potassium uptake and lint production efficiency of potassium were relatively low; excessively low nitrogen application, however, also resulted in a lower yield, as economic coefficient of biomass and potassium was relatively low.

The Effects of Farmyard Manure and Mulch on Soil Physical Properties in a Reclaimed Coastal Tidal Flat Salt-Affected Soil

Careful soil management is important for the soil quality and productivity improvement of the reclaimed coastal tidal flat saline land in northern Jiangsu Province, China. Farmyard manure (FYM) and mulch applications, which affect soil characteristics and plant significantly, are regard as an effective pattern of saline land improvement. As a conventional management in the study region, FYM and mulch are used for the amendment of the new reclaimed tidal flat regularly, but little is known about their effects on soil physical properties functioning. A study was conducted on a typical coastal tidal flat saline land, which was reclaimed in 2005, to evaluate the effects of FYM, polyethylene film mulch (PM), straw mulch (SM), FYM combined with PM (FYM+PM), FYM combined with SM (FYM+SM), on soil hydraulic properties and soil mechanical impedance. CK represented conventional cultivation in study area without FYM and mulch application and served as a control. The experiment, laid out in a randomized complete block design with three replications, was studied in Huanghaiyuan Farm, which specialized in the agricultural utilization for coastal tidal flat. Result showed that capillary water holding capacity (CHC), saturated water content (SWC), saturated hydraulic conductivity (Ks) and bulk density (BD), cone index (CI) were affected significantly by the FYM and mulch application, especially in the 0-10 cm soil layer. FYM and mulch management increased CHC, SWC and Ks over all soil depth in the order of FYM+SM>FYM+PM>FYM>SM>PM>CK. With the contrary sequence, BD and CI decreased significantly; however, FYM and mulch application affected BD and CI only in the upper soil layers. CHC, SWC and Ks decreased significantly with the increasing of soil depth, BD and CI, and a significant liner equation was found between CHC, SWC, Ks and BD, CI. With the highest CHC (38.15%), SWC (39.55%), Ks (6.00 mm h−1) and the lowest BD (1.26 g cm−3) and CI (2.71 MPa), the combined management of FYM and SM was recommend to be an effective method for the melioration of reclaimed coastal tidal flat saline soil.

Spatial and seasonal variations of soil salinity following vegetation restoration in coastal saline land in eastern China

Ecological restoration by plants on coastal saline lands affects salt accumulation, distribution patterns and related mechanisms. In Chongmind Island, eastern China, we explored the way vegetation restoration affected the profile distributions of soil moisture and salinity in various seasons in naturally salt-affected coastal saline land. In four types of vegetation, five soil cores were acquired in the ∼80cm depth range and the sampling depths of the five cores were respectively 0–10cm, 10–20cm, 20–40cm, 40–60cm, and 60–80cm. Soil moisture firstly decreased and then increased with the depth in woodland and shrubland, while soil moisture consistently increased in grassland and control plots. Salt profiles showed the higher values in surface soil in control plots, whereas the pattern of soil salinity showed the reverse trend under vegetation. The effect of vegetation restoration on the profile distributions of salt is significant. In control plots, soil moisture and salinity showed a clear seasonal trend. Soil moisture values were the highest in spring and the lowest in autumn, when values of soil salinity were the highest in summer and the lowest in winter. Relative to control plots, the seasonal trend of soil moisture and salinity under vegetation appeared to be complex for no clear trend was observed. It can be concluded that plant communities significantly affect the spatial–temporal distribution of soil salinity. The selection of plant species is important in the reclamation of costal saline land.

Physiological mechanisms for high salt tolerance in wild soybean (Glycine soja) from Yellow River Delta, China: photosynthesis, osmotic regulation, ion flux and antioxidant capacity.

Glycine soja (BB52) is a wild soybean cultivar grown in coastal saline land in Yellow River Delta, China. In order to reveal the physiological mechanisms adapting to salinity, we examined photosynthesis, ion flux, antioxidant system and water status in Glycine soja under NaCl treatments, taking a cultivated soybean, ZH13, as control. Upon NaCl exposure, higher relative water content and water potential were maintained in the leaf of BB52 than ZH13, which might depend on the more accumulation of osmotic substances such as glycinebetaine and proline. Compared with ZH13, activities of antioxidant enzymes including superoxide dismutase, catalase, ascorbate peroxidase and contents of ascorbate, glutathione and phenolics were enhanced to a higher level in BB52 leaf under NaCl stress, which could mitigate the salt-induced oxidative damage in BB52. Consistently, lipid peroxidation indicated by malondialdehyde content was lower in BB52 leaf. Photosynthetic rate (Pn) was decreased by NaCl stress in BB52 and ZH13, and the decrease was greater in ZH13. The decreased Pn in BB52 was mainly due to stomatal limitation. The inhibited activation of rubisco enzyme in ZH13 due to the decrease of rubisco activase content became an important limiting factor of Pn, when NaCl concentration increased to 200 mM. Rubisco activase in BB52 was not affected by NaCl stress. Less negative impact in BB52 derived from lower contents of Na+ and Cl- in the tissues, and non-invasive micro-test technique revealed that BB52 roots had higher ability to extrude Na+ and Cl-. Wild soybean is a valuable genetic resource, and our study may provide a reference for molecular biologist to improve the salt tolerance of cultivated soybean in face of farmland salinity.