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Actual evapotranspiration (ETa) is an important component of the surface water cycle. The geeSEBAL model is increasingly being used to estimate ETa using high-resolution remote-sensing data (Landsat 4/5/7/8). However, due to surface heterogeneity, there is significant uncertainty. By optimizing the quantile values of the reverse-modelling automatic calibration algorithm (CIMEC) endpoint-component selection algorithm under extreme conditions through 212 global flux sites, we obtained the optimized quantile values of 11 vegetation types of cold- and hot-pixel endpoint components (Ts and NDVI). Based on the observation data of the global FLUXNET tower, the sensitivity of 20 parameters in the improved geeSEBAL model was determined through Sobol's sensitivity analysis. Among them, the parameters dT and SAVI,hot were confirmed as the most sensitive parameters of the algorithm. Subsequently, we used the differential evolution Markov chain (DE-MC) method to analyse the uncertainty of the parameters in the geeSEBAL model used the posterior distribution of the parameters to modify the sensitive parameter values or ranges in the improved geeSEBAL model and to simulate the daily ETa. The results indicate that by analysing the end element components of the geeSEBAL model (Ts and NDVI), quantile numerical optimization and parameter optimization can be performed. Compared with the original algorithm, the improved geeSEBAL model has significantly improved simulation performance, as shown by higher R2 values, higher NSE values, smaller bias values, and lower RMSE values. The most suitable values of the predefined parameter Zoh were determined, and the reanalysis of meteorological data inputs (relative humidity (RH), temperature (T), wind speed (WS), and net radiation (Rn)) was also found to be an important source of uncertainty for the accurate estimation of ETa. This study indicates that optimizing the quantiles and key parameters of the model end component has certain potential for further improving the accuracy of the geeSEBAL model based on high-resolution remote-sensing data in estimating the ETa for various vegetation types. [ABSTRACT FROM AUTHOR]

Halophyte-based desalinization is emerging as a promising technology for saline agriculture. However, few studies have integrated halophytes into intercropping systems. This study investigated Suaeda salsa and soybean intercropping and the associated mechanisms, including changes in salt, nutrients, and bacterial communities at three salt treatments (control, 3‰, and 5‰). The results showed that regardless of salt treatment, soybean biomass and P content significantly increased in intercropping compared with monocropping, by an average of 32% and 51%, respectively (p < 0.05), indicating interspecific facilitation. Under 5‰ salt, soybean mortality decreased from 37% in monocropping to 10% in intercropping, and shoot Na decreased by over 60% in intercropping; the rhizosphere Na+, Cl−, and NO3−–N decreased in intercropping by over 75% compared with monocropping, and the response ratios correlated negatively with S. salsa biomass (p < 0.01). The soybean rhizosphere bacterial community in intercropping was enriched with the genera Sphingomonas, Salinimicrobium, Lysobacter, Allorhizobium–Neorhizobium–Pararhizobium–Rhizobium, and Ramlibacter, and the bacterial co-occurrence network exhibited increases in the number of nodes and edges, average degree, and average clustering coefficient. Considering the combined effects, the soybean biomass of intercropping correlated positively with bacterial co-occurrence network parameters, including average degree and number of edges, independent of tissue salt and nutrient content, and that of monocropping correlated negatively with tissue salt content. These results demonstrate that S. salsa intercropping could alleviate salt stress in soybean by creating a low-salt environment and improving its nutrient accumulation and rhizosphere bacterial community, and emphasize the importance of microbial communities in influencing soybean growth. [ABSTRACT FROM AUTHOR]

The morphological adjustments of euhalophytes are well-known to be influenced by the soil-soluble salt variation; however, whether and how these changes in morphological traits alter the biomass allocation pattern remains unclear, especially under different NaCl levels. Therefore, an allometric analysis was applied to investigate the biomass allocation pattern and morphological plasticity, and the carbon (C), nitrogen (N), and phosphorus (P) stoichiometric characteristics of the euhalophyte Suaeda Salsa (S. salsa) at the four soil-soluble salt levels of no salt (NS), light salt (LS), moderate salt (MS), and heavy salt (HS). The results showed that soil-soluble salts significantly change the biomass allocation to the stems and leaves (p < 0.05). With the growth of S. salsa, the NS treatment produced a downward leaf mass ratio (LMR) and upward stem mass ratio (SMR); this finding was completely different from that for the salt treatments. When S. salsa was harvested on the 100th day, the HS treatment had the highest LMR (61%) and the lowest SMR (31%), while the NS treatment was the opposite, with an LMR of 44% and an SMR of 50%. Meanwhile, the soil-soluble salt reshaped the morphological characteristics of S. salsa (e.g., root length, plant height, basal stem diameter, and leaf succulence). Combined with the stoichiometric characteristics, N uptake restriction under salt stress is a vital reason for inhibited stem growth. Although the NS treatment had the highest biomass (48.65 g root box−1), the LS treatment had the highest salt absorption (3.73 g root box−1). In conclusion, S. salsa can change its biomass allocation pattern through morphological adjustments to adapt to different saline–alkali habitats. Moreover, it has an optimal biological desalting effect in lightly saline soil dominated by NaCl. [ABSTRACT FROM AUTHOR]

Succulence is a key trait involved in the response of Suaeda salsa to salt stress. However, few studies have investigated the effects of the interaction between salt and drought stress on S. salsa growth and succulence. In this study, the morphology and physiology of S. salsa were examined under different salt ions (Na+, Ca2+, Mg2+, Cl−, and SO42−) and simulated drought conditions using different polyethylene glycol concentrations (PEG; 0%, 5%, 10%, and 15%). The results demonstrate that Na+ and Ca2+ significantly increased leaf succulence by increasing leaf water content and enlarging epidermal cell size compared to Mg2+, Cl−, and SO42−. Under drought (PEG) stress, with an increase in drought stress, the biomass, degree of leaf succulence, and water content of S. salsa decreased significantly in the non-salt treatment. However, with salt treatment, the results indicated that Na+ and Ca2+ could reduce water stress due to drought by stimulating the succulence of S. salsa. In addition, Na+ and Ca2+ promoted the activity of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), which could reduce oxidative stress. In conclusion, Na+ and Ca2+ are the main factors promoting succulence and can effectively alleviate drought stress in S. salsa. [ABSTRACT FROM AUTHOR]

The secondary salinization of irrigated areas poses a direct threat to both the sustainable development of oasis agriculture and ecological stability in arid regions. In this study, we conducted an experiment to examine alterations in groundwater levels and soil salinity within the plow layer, as well as their combined impact, in arid regions following extended reclamation in standard diversion irrigation areas. For this experiment, the Karamay irrigation district was selected. Four different years, namely, 1996, 2006, 2016, and 2021, were selected for soil sampling and groundwater monitoring data. Descriptive statistics, along with the use of GIS technology and Pearson's correlation, were employed to analyze the data in order to discern the patterns of soil salinity and groundwater depth within the plow layer. Additionally, this approach helped establish the correlation between these factors over the last 25 years of reclamation in the Karamay irrigation district. The results showed that, (1) due to an increase in the reclamation duration, the groundwater depth in the irrigation area decreased year by year, and the salinity of the arable soil showed an overall decreasing trend, but it increased in local low-lying areas; (2) the influence of the groundwater depth on the salinity of the arable soil had a threshold value. It decreased from 3.1 m in 2016 to 2.4 m in 2021, and a significant negative correlation was observed between salinity and the depth of groundwater. When the groundwater depth was shallower than the threshold value, the soil salinity in the plow layer was negatively correlated with the groundwater depth. In the arid irrigation zone, inadequate drainage facilities resulted in a significant rise in the groundwater table due to the excessive amount of irrigation water. This created secondary salinization of the arable soil. It is thus concluded that implementing adequate drainage systems in arid irrigation regions will help prevent secondary salinization and promote the sustainable development of agriculture in these areas. [ABSTRACT FROM AUTHOR]

In China, Wedelia trilobata (WT) is among the top most invasive plant species. The prediction of its growth, using different efficient methods under different environmental conditions, is the optimal objective of ecological research. For this purpose, Wedelia trilobata and its native plant species Wedelia chinensis (WC) were grown in mixed cultures under different levels of submergence and eutrophication. The multiple linear regression (MLR) and artificial neural network (ANN) models were constructed, with different morphological traits as the input in order to predict dry weight as the output for both plant species. Correlation and stepwise regression analysis (SWR) were used to find the best input variables for the ANN and MLR models. Plant height, number of nodes, chlorophyll content, leaf nitrogen, number of leaves, photosynthesis, and stomatal conductance were the input variables for WC. The same variables were used for WT, with the addition of root length. A network with the Levenberg–Marquart learning algorithm, back propagation training algorithm, Sigmoid Axon transfer function, and one hidden layer, with four and six neurons for WC and WT, respectively, was created. The best ANN model for WC (7-4-1) has a coefficient of determination (R2) of 0.98, root mean square error (RMSE) of 0.003, and mean absolute error (MAE) of 0.001. On the other hand, the ANN model for WT (8-6-1) has R2 0.98, RMSE 0.018, and MAE 0.004. According to errors and coefficient of determination values, the ANN model was more accurate than the MLR one. According to the sensitivity analysis, plant height and number of nodes are the most important variables that support WT and WC growth under submergence and eutrophication conditions. This study provides us with a new method to control invasive plant species' spread in different habitats. [ABSTRACT FROM AUTHOR]

Suaeda aralocaspica, which is an annual halophyte, grows in saline deserts in Central Asia with potential use in saline soil reclamation and salt tolerance breeding. Studying its genetic diversity is critical for effective conservation and breeding programs. In this study, we aimed to develop a set of polymorphic microsatellite markers to analyze the genetic diversity of S. aralocaspica. We identified 177,805 SSRs from the S. aralocaspica genome, with an average length of 19.49 bp, which were present at a density of 393.37 SSR/Mb. Trinucleotide repeats dominated (75.74%) different types of motifs, and the main motif was CAA/TTG (44.25%). We successfully developed 38 SSR markers that exhibited substantial polymorphism, displaying an average of 6.18 alleles with accompanying average polymorphism information content (PIC) value of 0.516. The markers were used to evaluate the genetic diversity of 52 individuals collected from three populations of S. aralocaspica in Xinjiang, China. The results showed that the genetic diversity was moderate to high, with a mean expected heterozygosity (He) of 0.614, a mean Shannon's information index (I) of 1.23, and a mean genetic differentiation index (Fst) of 0.263. The SSR markers developed in this study provide a valuable resource for future genetic studies and breeding programs of S. aralocaspica, and even other species in Suaeda. [ABSTRACT FROM AUTHOR]

With the increasing shortage of water resources, the current management of saline–alkali lands in semi-arid and arid areas has gradually transformed from "flooding irrigation with drainage" in the past to the combination of controlling regional water and salt balance, phytoremediation, and comprehensive utilization of halophyte resources. However, soil salinization caused by natural and anthropogenic factors has still been a major global environmental problem, which changes the chemical and physical properties of soil, deteriorates the quality of underground water, and decreases biodiversity, contributing to the loss of soil productivity and the succession of the halotolerant species. Euhalophytes, as the materials for phytoremediation, have been confirmed to be effective species in improving saline–alkali soils. They can redistribute salts in soil profile through the interaction of their desalinization potential and irrigation water leaching, thereby preventing secondary salinization and improving soil productivity for long-term reclamation of saline soil. In this review, the adaptation mechanisms of euhalophytes to saline soils are generalized from the views of morphological, physiological, and molecular aspects and evaluated for their potential to remediate saline soil through salt removal and promoting leaching. Euhalophytes can not only sequestrate salts inside the central vacuole of cells to tolerate higher salt stress by means of organ succulence, ion compartmentalization, and osmotic adjustment but facilitate water infiltration and salts leaching through root–soil interaction. The root system's mechanical penetration increases soil porosity, decreases soil density, as well as stabilizes soil aggregates. Moreover, the suitability of phytoremediation in arid situations with low precipitation and non-irrigation and some agricultural practices need to be taken into account to avoid salts returning to the soil as forms of litter and deep tillage altering salt distribution. Hence, euhalophytes planting in semi-arid and arid areas should be evaluated from their adaptation, desalinization, and prospective commercial values, such as foods, biofuels, and medical development to alleviate soil secondary salinization crisis and enhance the productivity of arable agricultural land. [ABSTRACT FROM AUTHOR]

Nitrogen accelerates salt accumulation in the root zone of an euhalophyte, which might be beneficial for inhibiting the salt damage and interspecific competition for nutrients of non-halophytes in intercropping. However, the variations in the effect of euhalophyte/non-halophyte intercropping with nitrogen supply are poorly understood. Here, we selected the euhalophyte Suaeda salsa (suaeda) and non-halophyte Zea mays L. (maize) as the research objects, setting up three cropping patterns in order to explore the influence of nitrogen application on the intercropping effect in the suaeda/maize intercropping. The results showed that the biomass of maize in the intercropping was significantly lower than that in the monoculture, while for suaeda, it was higher in the intercropping than that in the monoculture. The biomass of maize under NO3−-N treatment performed significantly higher than that under no nitrogen treatment. Moreover, under suitable NO3−-N treatment, more salt ions (Na+, K+) gathered around the roots of suaeda, which weakened the salt damage on maize growth. In the intercropping, the effect of NO3−-N on the maize growth was enhanced when compared with the non-significant effect of NH4+-N, but a positive effect of NH4+-N on suaeda growth was found. Therefore, the disadvantage of maize growth in the intercropping suaeda/maize might be caused by interspecific competition to a certain extent, providing an effective means for the improvement of saline–alkali land by phytoremediation. [ABSTRACT FROM AUTHOR]

Nitrogen (N) application might exert a great impact on root (biomass, length) distribution, which possibly contributes to ion and nutrient uptakes. Here, we address the effects of N application on these characteristics to detect how N improves its salt tolerance. Suaeda salsa was subjected to four salt levels (0.5, 1.0, 1.5, and 2.0%) and three N treatments ( NO 3 − -N: 0, 0.25, and 0.50 g·kg−1) in soil column experiments. The N applications performed a "dose effect" that significantly enhanced the growth of Suaeda at low salt levels, while negative effects were displayed at high salt levels. Moderate N markedly benefited from Na + and Cl − uptake, which was approximately 111 mg and 146 mg per plant at a salt level of 1.0%. Exposure to a certain N application significantly enhanced topsoil root length at salt levels of 0.5% and 1.0%, and it was higher by 0.766 m and 1.256 m under N50 treatment than that under N0 treatment, whereas the higher salt levels accelerate subsoil root growth regardless of N treatment. Therefore, its interactive effects on root development and ion uptake were present, which would provide further theoretical basis for improving saline soil amelioration by N application. Regression analysis always showed that topsoil root length generated more positive and significant influences on ion uptake and vegetative growth than total root length. The results suggested that N application is beneficial to salt tolerance by altering root allocation so as to raise its elongation and gather more ions for halophyte in the topsoil. [ABSTRACT FROM AUTHOR]

Halophytes possess the capacity to uptake high levels of salt through physiological processes and their root architecture. Here, we investigated whether halophyte/non-halophyte intercropping in saline soil benefits plant growth and contains root-dialogue between interspecific species. Field and pot experiments were conducted to determine the plant biomasses and salt and nutrient distributions in three suaeda (Suaeda salsa)/maize (Zea mays L.) intercropping systems, set up by non-barrier, nylon-barrier, and plastic-barrier between plant roots. The suaeda/maize intercropping obviously transferred more Na+ to the suaeda root zone and decreased salt and Na+ contents. However, the biomass of the non-barrier-treated maize was significantly lower than that of the nylon and plastic barrier-treated maize. There was lower available N content in the soil of the non-barrier treated groups compared with the plastic barrier-treated groups. In addition, the pH was lower, and the available nutrient content was higher in the nylon barrier, which suggested that rhizospheric processes might occur between the two species. Therefore, we concluded that the suaeda/maize intercropping would be beneficial to the salt removal, but it caused an adverse effect for maize growth due to interspecific competition, and also revealed potential rhizospheric effects through the role of roots. This study provides an effective way for the improvement of saline land. [ABSTRACT FROM AUTHOR]

Water conditions directly affect plant growth and thus modify reproduction allocation. However, little is known about the transgenerational effects of water conditions on xerophytes. The desert annual Atriplex aucheri produces three types of seeds (A: dormant, ebracteate black seeds; B: dormant, bracteolate black seeds; C: non-dormant, bracteolate brown seeds) on a single plant. The aim of this study was to investigate the effects of low/high water treatment (thereafter progeny water treatment) on aboveground biomass, C:N stoichiometry, and offspring seed characteristics of A. aucheri grown from brown seeds whose mother plants were under low/high water treatment (thereafter maternal water treatment). Progeny water only affected shoot dry weight and seed allocation of type A. Under low progeny water treatment, plants from parents with low maternal water treatment had the lowest biomass. Maternal water did not significantly influence the C and N content, however high maternal water increased the C:N ratio. Maternal water treatment did not significantly affect seed number. However, plants under low maternal and progeny water treatments had the lowest weight for type B seeds. When progeny plants were under low water treatment, seed allocation of type A, type B, and total seed allocation of plants under high maternal water were significantly lower than those of plants under low maternal water. These results indicate that water conditions during the maternal generation can dramatically contribute to progeny seed variation, but the transgenerational effects depend on the water conditions of progeny plants. [ABSTRACT FROM AUTHOR]

Excessive application of nitrogen fertilizers and improper methods of irrigation under conventional management are common problems in the cotton fields of northwestern China. Efficiency-enhanced management, based on the water and nitrogen dynamics and crop requirements, has been used as a valuable strategy in different crops. The present study aimed to compare efficiency-enhanced management and conventional management of irrigation and nitrogen fertilization in the cotton fields at the Junggar Basin (Shihezi) and Tarim Basin (Cele) of northwestern China. Compared with conventional management, efficiency-enhanced management reduced the amount of N fertilizer by 41% in Cele and 44% in Shihezi, and the irrigation quantity by 35% in Cele and 24% in Shihezi. However, the cotton yield under efficiency-enhanced management was similar to that found under conventional management at both the experimental sites. The efficiency-enhanced management increased the water-use efficiency (WUE) and reduced the residual soil mineralizable N (Nmin) and apparent N losses. This study indicated that efficiency-enhanced management can significantly enhance the utilization efficiency of irrigation water and N fertilizers for cotton production in the fields of northwestern China. [ABSTRACT FROM AUTHOR]

Halophytes have been studied as a model for morphological traits of adaptation to saline environments. However, little information has been given on plant growth, chlorophyll fluorescence responses, and change of ion content in halophytes grown in an aniline–salinity coexistent environment. This study hypothesized that aniline could induce alterations in plant growth, chlorophyll fluorescence, and ion content in Suaeda salsa, but salinity could promote the tolerance of halophytes to aniline. A 6 (aniline) × 3 (NaCl) factorial experiment (for a total of 18 treatments) was conducted to test the above hypothesis. After 30 d of cultivation, roots and shoots were harvested separately to analyze the effects of salinity on the seedling growth under aniline stress. Biomass accumulation was inhibited by aniline treatment, and the inhibition was significantly alleviated by 200 mM NaCl. The change in chlorophyll fluorescence in leaves with aniline stress was moderated by the addition of NaCl. The removal efficiency of aniline was significantly enhanced by moderate salinity. Aniline stress decreased the accumulation of Mg2+, but various concentrations of NaCl increased the accumulation of Mg2+, especially with 200 mM NaCl in both roots and shoots. Both aniline and salinity decreased the content of Ca2+. There was a negative correlation between the K+ and NaCl concentrations and between the Cl− and aniline concentrations. Our results indicated that Suaeda salsa may be suitable for the remediation of salinity and aniline-enriched wastewater. [ABSTRACT FROM AUTHOR]

Based on the concept of microbial community multi-processing in integrated spatial bacterial succession (ISBS), this study constructs a highly efficient cellular fixed-bed bioreactor that follows the growth of biological flora in the wastewater treatment process. The reactor is organically partitioned based on synergistic laws and in accordance with environmental and microbial metabolic changes, and sewage is subjected to unitized and specialized biological treatment under direct current conditions. The results show that the ISBS reactor exhibits stable nitrogen removal performance under a low-carbon source. Compared with traditional sewage biochemical treatment technology, the microbial concentration is increased by 2–3 times and even up to 12 times, and the ammonia nitrogen removal rate is maintained at 99%. The removal rate reaches 90% (hydraulic retention time of 14 h). High-throughput sequencing analysis based on 16S rDNA reveals the microbial community structure succession at different depths of the same section of the reactor. The microbial community is rich under the influence of environmental factors and exhibits different responses. The intervals vary. An analysis of the microbial community function explains why the ISBS reactor has high nitrogen removal efficiency. [ABSTRACT FROM AUTHOR]