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Soil salinization has become one of the major abiotic stresses limiting agricultural production globally. The full utilization of coastal saline-alkali land is of great significance for agricultural development. Among them, fertilizer management and planting density are crucial for promoting crop growth and productivity in saline soils. Field experiments were conducted to study the effects of different nitrogen application rates and planting densities on the growth, yield, and quality of alfalfa. Using alfalfa variety WL919 as the experimental material, three seeding rates of 15.0 kg·ha−1 (D1), 30.0 kg·ha−1 (D2), and 45.0 kg·ha−1 (D3) as well as three nitrogen application rates of 150.0 kg·ha−1 (N1), 225.0 kg·ha−1 (N2), and 300.0 kg·ha−1 (N3) were set. The results showed that under the same density, different nitrogen application rates had a positive impact on the agronomic traits and yield of alfalfa on saline-alkali land. Physiological and biochemical properties (chlorophyll and sucrose) increased with increasing nitrogen application, and (starch) increased initially and then decreased with increasing nitrogen application. Forage quality attributes (crude protein and crude ash) had a significant impact, while crude fat had no significant effect. Under the same nitrogen application, the yield of alfalfa increased with increasing density but then decreased after reaching a peak, while other traits initially increased and then decreased. In conclusion, the nitrogen fertilizer was superior in promoting alfalfa growth, biomass yield, and forage yield, while planting density was more suitable at D2. Although both D2N2 and D2N3 treatments were superior to others, considering economic benefits and environmental factors, it is recommended to use D2N2 as the appropriate treatment. [ABSTRACT FROM AUTHOR]

Plant growth often encounters diverse abiotic stresses. As a global resource-based ecological problem, salinity is widely distributed and one of the major abiotic stresses affecting crop yields worldwide. Sorghum, a cereal crop with medium salt tolerance and great value for the development and utilization of salted soils, is an important source of food, brewing, energy, and forage production. However, in soils with high salt concentrations, sorghum experiences low emergence and suppressed metabolism. It has been demonstrated that the effects of salt stress on germination and seedling growth can be effectively mitigated to a certain extent by the exogenous amendment of hormonal gibberellin (GA). At present, most of the studies on sorghum salt tolerance at home and abroad focus on morphological and physiological levels, including the transcriptome analysis of the exogenous hormone on sorghum salt stress tolerance, the salt tolerance metabolism pathway, and the mining of key salt tolerance regulation genes. The high-throughput sequencing technology is increasingly widely used in the study of crop resistance, which is of great significance to the study of plant resistance gene excavation and mechanism. In this study, we aimed to review the effects of the exogenous hormone GA on leaf morphological traits of sorghum seedlings and further analyze the physiological response of sorghum seedling leaves and the regulation of sorghum growth and development. This review not only focuses on the role of GA but also explores the signal transduction pathways of GA and the performance of their responsive genes under salt stress, thus helping to further clarify the mechanism of regulating growth and production under salt stress. This will serve as a reference for the molecular discovery of key genes related to salt stress and the development of new sorghum varieties. [ABSTRACT FROM AUTHOR]

Fertilizer management is one of the easiest and most practical ways of combating salt stress. This study was done to evaluate the alleviative effects of nitrogen and phosphorus on the growth and salt tolerance of salt-affected sorghum. A controlled study organized in a randomized block design with three replications was conducted, testing three nitrogen rates (N0: 0 kg ha−1, N1: 180 kg ha−1, N2: 360 N kg ha−1) and phosphorus rates (P0: 0 P2O5 kg ha−1, P1: 60 P2O5 kg ha−1, P2: 120 P2O5 kg ha−1). Nitrogen and phosphorus application had positive effects on morphological indexes (plant height, stem diameter), some physiological and biochemical attributes (the content of proline and soluble protein, and the activities of superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase), and aerial biomass (fresh and dry weight) of sorghum grown in saline soils. Reactive oxygen species accumulation and cell membrane damage were decreased with the application of nitrogen and phosphorus. Compared with sole fertilizer, the combined application of nitrogen and phosphorus showed better performance in alleviating salt damage on sorghum. Despite the fact that the maximum of most of the measured parameters and the minimum of reactive oxygen species accumulation and cell membrane damage were generally obtained at N1P1 and N2P2 treatment, N1P1 was recommended to be the suitable treatment considering economic benefits and environmental protection. [ABSTRACT FROM AUTHOR]

Soil salinization is more aggravating than ever before and techniques are needed to mitigate this problem; understanding salinity-fertilizer relationship is of considerable economic importance for promoting crop growth and productivity in saline soil. A pot experiment was done in a greenhouse to determine whether the N could alleviate the negative effect of different salts compositions on the growth, and physiological attributes of the two most used Sudan sorghum (Sorghum bicolor (L.) Moench) cultivars (Wadahmed and Tabat). The plant was subjected to the salt stress at 0, 0.3419 M NaCl, and 0.1408 M Na2SO4, and four levels of N application 0, 4, 8, and 12 g N kg-1 soil, designated as N0, N1, N2, and N3, respectively. Results showed that Na2SO4 was reduced plant height, leaf area index, number of leaves, dry weight (DW), chlorophyll a, total chlorophyll content, and increased soluble protein content, activities of peroxidase (POD) and catalase (CAT) activities by 16.4%, 29.7%, 61.5%, 28.7%, 39.6%, 12.7%, 99.7%, 34.3%, 51.8%, respectively, when compared with the non-saline treatment. The Na2SO4 salt had a more harmful effect than NaCl. This study revealed that N fertilizer was successful for alleviating the adverse impacts of both types of salt. In this study, 12 g N kg-1 soil was most effective on most of the measured parameters of two sorghum cultivars. These findings demonstrated that the N soil amendment application could alleviate the harmful impact of salinity. 'Wadahmed' was more tolerant to salinity stress than 'Tabat' during the boot stage of sorghum plant. [ABSTRACT FROM AUTHOR]

Sorghum ("Jitian 3") is a salt-tolerant seed cultivar used regularly in marginal lands, such as those with saline soils. Herein, we examined the potential of employing gibberellic acid (GA3) as an inducer of sorghum development during salt stress. Thus far, there have been no reports on the signaling network involved in the GA3-mediated regulation of sorghum development. In this study, we demonstrated that the stimulating properties of 50 mg/L GA3 on sorghum development was far superior to other GA3 concentrations under a 150 mM NaCl salinity condition. Furthermore, using methylated RNA immunoprecipitation sequencing (MeRIP-seq), we established an m6A methylation (m6A-M) profile in sorghum following exposure to 50 mg/L GA3. Overall, 23,363 m6A peaks and 16,200 m6A genes were screened among the GA3-treated and control leaves. These identified peaks were shown to be primarily enriched in the coding, as were the 3′- and 5′-untranslated regions. In addition, we employed m6A and transcript expression cross-analysis to identify 70 genes with differential transcript expression and simultaneous m6A-M. Intriguingly, the principal gene, LOC8066282, which is associated with LOC8084853, was shown to be intricately linked to the phosphatidylinositol signaling, which in turn regulates sorghum development and response to salt stress. This investigation presents a novel RNA m6A-M profile in sorghum, which may facilitate new insights into the underlying signaling behind salt stress resistance. This work will also benefit future investigations on foreign GA3 administration of sorghum. [ABSTRACT FROM AUTHOR]

Crop yield is the ultimate manifestation of all physiological changes of crops and external environmental influence. A controlled study was conducted to investigate the effects of exogenous gibberellin on the morphological and physiological characteristics and yield formation of sesbania pea grown in saline soils. Seeds were presoaked with four levels of Gibberellin (GA3) solutions (0, 202.1, 404.2 and 606.3 µM) for 6 h, and then manually direct-sown with a seeding rate of 45 kg ha−1. The morphological parameters (plant height, root length, dry weight), photosynthesis (chlorophyll a and b content), the activities of antioxidant enzymes (superoxide dismutase (SOD); peroxidase (POD); catalase (CAT)), the contents of soluble protein and NSC (non-structural carbohydrates), and seed yield increased with the application of exogenous gibberellin, especially at the level of 404.2 µM GA3. But GA3 had no significant effects on 1000-seed weight. Our study suggested that the appropriate application of exogenous gibberellin could improve the yield of sesbania pea grown in saline soils by increasing photosynthesis and antioxidative defense. [ABSTRACT FROM AUTHOR]

Salinity is a growing problem worldwide, and techniques are needed to mitigate this problem. This study was conducted to determine if biochar (BC) can alleviate the adverse impacts of salinity stress on sorghum (Sorghum bicolor L.) seedling growth. Sorghum variety Kambal was sown in salinized soils at levels of 1.2, 3.1, and 7.3 dS m−1. The saline soils were treated with four BC rates of 0, 2, 4, and 8% (w/w). The test was a factorial design arranged as a completely randomized design with three replications. Seedling emergence percentage; root and shoot length; root and shoot dry weight; relative water content (RWC); and the activity of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) were affected by the interaction between salinity and BC. At the 7.3 dS m−1 salinity level, 2% BC increased seedling emergence percentage by 25.0% (P =.012). At the 7.3 dS m−1 salinity level, 4% BC level increased root and shoot length (P =.009) and RWC by 46.0, 28.0, and 19.8% respectively. At the 7.3 dS m−1 salinity level, 8% biochar decreased CAT by 50.6%. At the high salinity level, 4% BC decreased POD and SOD by 24.9 and 23.4%, respectively. Biochar amendment proved to be more useful to alleviate the effects of salinity on the seedling growth stage. These findings suggest that using BC in suitable amounts could mitigate the adverse effects of salinity, but excess BC application may have negative influences on seedling growth. [ABSTRACT FROM AUTHOR]

Soil salinization is more aggravating than ever before; suitable fertilizer application is essential for promoting crop growth and productivity in saline soils. A field experiment was conducted to study the effects of different types of fertilizers on oat (Avena sativa L.) growth and associated physiological mechanism in saline soils. Two oat varieties (V1 = Baiyan 2 and V2 = Baiyan 7) were used and four fertilizer treatments (T1 = control, T2 = nitrogen fertilizer, T3 = Giza Fertile fertilizer, T4 = Powder fertilizer) were evaluated in this study. The results showed that fertilizer treatments significantly improved plant growth and associated physiological traits, grain yield, forage yield, and forage quality of both oat varieties. Plant height, leaf area, superoxide dismutase, peroxidase, proline, forage yield, panicles, spikelets per panicle, grain weight, and grain yield were significantly increased by fertilizer application, and the maximum values were all produced under T2 (nitrogen fertilizer). But the highest values of catalase, soluble sugar, and crude fat were observed under T4 (powder fertilizer). On the contrary, malondialdehyde and crude fiber were significantly decreased by fertilizer application, and the highest value was recorded under T2 and T4, respectively. V2 was superior in plant growth, grain yield, forage yield, and forage quality than V1. This study suggested that nitrogen fertilizer was superior in promoting growth, biomass yield and grain yield production, and Powder fertilizer was better in enhancing forage quality of oat in saline soils. [ABSTRACT FROM AUTHOR]

• Salt stress adversely affected the photosynthesis and biochemical traits of forage sorghum. • Jasmonic acid and humic acid in regulating stress responses, plant growth and development. • Jasmonic acid and humic acid may be used as a tool to mitigate salinity-induced photosynthesis and biochemical parameters injury in forage sorghum Soil salinity, whether natural or induced, is one of the most serious environmental stresses limiting crop production in the world. In this study, the impacts of foliar application of jasmonic acid and soil amendment with humic acid on growth parameters, forage yield, chlorophyll content, and physiological characteristics of forage sorghum were studied to mitigate salinity in combination with different concentrations under greenhouse conditions. The plants were subjected to salinity at 0.26 (S0), 2.3 (S1), and 4.7 dS m−1 (S2), different rates of humic acid at 0, 373.21, and 746.42 kg HA ha−1, were designed as HA0, HA1, and HA3 respectively, and jasmonic acid at 0 (JA0), 5 (JA1) and 10 mM (JA2) as a foliar application. Salinity stress had detrimental effects on all the parameters and they were gradually reduced with increased salinity. Applications of humic acid and jasmonic acid mitigated the inhibitory effects of salt stress on these variables at all salinity levels. The rate of HA1 increased fresh weight, chlorophyll a and b , transpiration rate, relative humidity, stomatal conductance to CO 2 and stomatal conductance by 14.2%, 45.6%, 41.8%, 50.2%, 11.2%, 32.1% and 18.5% respectively, under S2. In addition, jasmonic acid at JA1 treatment increased plant height, elongation percentage, fresh and dry weight, chlorophyll a and b , relative humidity, and stomatal conductance to CO 2 under S2. Interaction between JA2 and HA1 improved all the traits except plant height, elongation percentage, and leaf area, suggesting that JA and HA can reduce the negative effects of salinity on the sorghum. In conclusion, jasmonic acid and humic acid treatments improved the forage sorghum performance under salinity conditions through anthesis stages, better photosynthetic and growth parameters, which reduced the impacts of salinity, and resulted in better plant growth and biomass production, and help the plant to improved salt tolerance. [ABSTRACT FROM AUTHOR]

Accurate and timely information on soil salinity is crucial for vegetation growth and agricultural productivity in coastal regions. This study investigates the potential of using Wifi POGO, an in situ electromagnetic sensor, for soil salinity assessment over saline coastal regions in eastern China. The sensor readings, soil moisture, and temperature-corrected apparent electrical conductivity (ECa) were used to generate models for EC1:5 (a surrogate for soil salinity) estimation. Two salty areas with distinct soil textures, sandy loam (Shuntai) and clay (Dongxin), were selected. This study revealed that the difference between soil salinity and the in situ measured soil ECa (i.e., EC1:5-ECa) had a strong curvilinear relationship with soil moisture. Such a relationship allows for the direct estimation of soil salinity from soil ECa with the aid of soil moisture information. Both ECa and soil moisture can be measured in situ using a Wifi POGO, a low-cost ground-based soil sensor. By using the leave-one-out cross-validation (LOOCV), the achieved root mean square error (RMSE) and relative RMSE (RRMSE) in EC1:5 estimation were 0.0109 S/m and 19.24% respectively in Shuntai, and 0.0157 S/m and 16.05%, in Dongxin. This new method offers a simple, cost-effective and reliable tool for assessing soil salinity in dynamic coastal regions. [ABSTRACT FROM AUTHOR]

In recent years, a large number of salterns have been converted into rice fields in the coastal region of Jiangsu Province, Eastern China. The high spatial heterogeneity of soil salinity has caused large within-field variabilities in grain yield of rice. The identification of low-yield areas within a field is an important initial step for precision farming. While optical satellite remote sensing can provide valuable information on crop growth and yield potential, the availability of cloud-free optical image data is often hampered by unfavorable weather conditions. Synthetic aperture radar (SAR) offers an alternative due to its nearly day-and-night and all-weather capability in data acquisition. Given the free data access of the Sentinels, this study aimed at developing a Sentinel-1A-based SAR index for rice yield estimation. The proposed SAR simple difference (SSD) index uses the change of the Sentinel-1A backscatter in vertical-horizontal (VH) polarization between the end of the tillering stage and the end of grain filling stage (SSDVH). A strong exponential relationship has been identified between the SSDVH and rice yield, producing accurate yield estimation with a root mean square error (RMSE) of 0.74 t ha−1 and a relative error (RE) of 7.93%. [ABSTRACT FROM AUTHOR]

Castor bean (Ricinus communis L.), a promising bioenergy crop, is readily planted in marginal lands like saline soils. A controlled experiment was conducted to explore the possibility of using gibberellic acid (GA3) as a promoter for caster bean grown under NaCl conditions and to try to determine the most appropriate concentration of GA3 for seedling growth. The seeds of salt-tolerant cultivar Zibi 5 were firstly soaked with 0, 200, 250, and 300 µM GA3 for 12 h and then cultured with 1/2 Hoagland solution containing 0, 50, and 100 mM NaCl in pots filled with sand. Plant height, stem diameter, leaf area, dry mater of each organ, activity of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), soluble protein, and proline content in the leaves were examined. Plant height and stem diameter, SOD, and POD activity was significantly highest in the treatment of 250 µM GA3 under salt concentration of 50 mM NaCl among all the testing days; protein content was highest when GA3 concentration was 250 µM under 100 mM NaCl treatment. This indicated that caster bean seed soaking with 250 µM GA3 could be the most suitable concentration for promoting seedling growth of caster bean, improving their stress resistance. [ABSTRACT FROM AUTHOR]

• A SVR model was proposed to provide accurate moisture estimation for saline soil. • It does not require prior information like soil surface roughness and soil salinity. • The new SVR model outperformed RFR and MLR in soil moisture estimation. • Sentinel-1A provides a SAR data source to timely map coastal saline soil moisture. Accurate and timely information on soil moisture (SM) is crucial for better understanding the hydrological and ecological processes in humid saline regions. This study investigated the potential of using Sentinel-1A Synthetic Aperture Radar (SAR) imagery and Machine Learning Algorithms for SM mapping in China's east coast. This study used the recursive feature elimination (RFE) technique to select optimum SAR indices from the backscattering coefficients of the sampling date as well as the averaged backscattering coefficients of the neighbouring dates. The newly developed support vector regression (SVR) model provided more accurate SM estimation than that from the random forest regression (RFR) and multivariate linear regression (MLR) models. By using the leave-one-out cross-validation (LOOCV), the achieved coefficient of determination (R2), root mean square error (RMSE), and the relative RMSE (RRMSE) in SM estimation were 0.77, 1.82%, and 10.29%, respectively. The SVR model was able to map the SM effectively over a large area under the condition that the information of soil surface roughness, soil salinity, and land cover types was unknown. Results from this study demonstrate that high-temporal-resolution Sentinel-1A SAR, with its free-accessibility, offers a great source for the SVR model to provide frequent and accurate SM mapping over coastal saline regions. [ABSTRACT FROM AUTHOR]

• JIH exhibited yield superiority over IH not only in non-saline fields, but also in saline fields. • Limited shoot and root growth were responsible for the yield penalty of rice under saline field conditions. • The improved agronomic and physiological traits of JIH facilitated superior grain yield over IH in saline fields. It is of great interest to utilize saline fields to promote rice production in China. Previous studies reported greater yield productivity of japonica/indica hybrids (JIH) over indica hybrids (IH) under nonsaline fields. It has still not been established how salinity stress intervenes with rice yield and whether JIH would exhibit superior grain yield than IH under saline field conditions. This study investigated three JIH and three IH cultivars grown at the two sites that differed significantly in soil salinity, namely, nonsaline (Wulie, abbreviated as WL) and saline (Tiaozini, abbreviated as TZN) fields, in Yancheng, Jiangsu, China. The panicles per m2, spikelets per panicle, filled-kernel percentage, and kernel weight of JIH and IH were reduced, and a 36.0 %–43.5 % loss in grain yield was observed with salinity stress at TZN compared with WL. For JIH and IH, the shoot biomass and leaf area index (LAI) at jointing, heading, and maturity were all reduced at TZN compared to those at WL; similar results were also detected for root biomass, root length and volume, and root bleeding rate after heading. Compared with IH, JIH produced a 24.8 % higher grain yield under saline field conditions at TZN across two years. Four agronomic and physiological traits were summarized for superior grain yield of JIH compared to that of IH with salinity stress under field conditions. First, JIH had an enlarged sink size potential of a greater number of spikelets per panicle. Second, a synergistically increased biomass accumulation and harvest index of JIH, supported by higher biomass accumulation and LAI at the main growth stages and improved NSC remobilization after heading. Third, JIH had an improved stay-green characteristic, indicated by a higher leaf area per plant, SPAD values, and leaf photosynthetic rate after heading. Fourth, JIH exhibited a better root morpho-physiology than that of IH after heading, showing a larger and deeper root structure and higher root bleeding rate. These results indicated that the limited shoot and root growth were responsible for the yield penalty of rice under saline field conditions. JIH's improved agronomic and physiological traits facilitated superior yield performance over IH with salinity stress under field conditions. [ABSTRACT FROM AUTHOR]