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Saline-alkali soil imposes severe adverse effects on soil utilization and agriculture production worldwide. Amelioration of saline-alkali soil is crucial to ensure global food security and promote sustainable agricultural development. Here, the effects of the combined application of soil amendment desulfurization gypsum (G) and KIA (K, an industrial organic by-product) on soil improvement and plant growth were investigated. Two experiments, a soil column leaching test and a pot experiment for plant growth, were carried out. The results showed that the combined application of G and K reduced soil pH significantly. Although the soil Na+ contents had no change in the combined treatments, the K+, Ca2+ and Mg2+ contents were significantly higher, and the HCO3− and Cl− contents were significantly lower, compared to the control. Furthermore, maize plants exhibited a higher photosynthetic rate and greater dry weight in the combined treatments. Additionally, after plant growth, the soil enzyme activities increased. These results showed that the combined application of G and K could have a more favorable impact on soil improvement by reducing soil pH, enhancing soil ion exchange, increasing soil nutrient contents, and promoting plant growth. Our study suggests that KIA is an effective and eco-friendly soil amendment for improving saline-alkali soil.

In drylands, where the annual precipitation is low and erratic, improving the water storage capacity and the available water in the soil is crucial for crop production. To explore the effect of long-term agronomic management on water storage capacity and available water in the soil, four agronomic management systems were used (including the farmer’s management model (FM), the high nitrogen input model (HN), the manure amendment model (MM), and the biochar amendment model (BM)) for eight consecutive years, and the variation in wheat yield and soil hydraulic, physical, and chemical properties in the 0–100 cm soil profile were investigated. The management practices varied in terms of seeding rates, nitrogen (N)-application strategies, and the application of manure or biochar. The results showed that, under the manure amendment model (MM), the wheat yield was increased by 17–35%, and the water-use efficiency was increased by 14–29% when compared to the farmer’s management model (FM) and the high nitrogen input model (HN). However, no significant differences in wheat yield and water-use efficiency were found under the biochar amendment model (BM) compared to the HN. The high yield and water-use efficiency under the MM were mainly due to the higher saturated hydraulic conductivity, soil saturated water content, field capacity, and soil available water content, which led to an increase in the available water storage in the 0–100 cm soil profile by 29–48 mm. Furthermore, the MM also improved soil organic matter, porosity, root length density, and root weight density and reduced the soil bulk density, which are beneficial for the improvement of the above soil hydraulic properties. Therefore, it is a practical way to ensure high yield and high efficiency of crops in dryland by improving water storage capacity and the available water in the soil, which can be profoundly regulated by agronomic management.

Exploring the effects of different additives on the improvement of newly cultivated farmland in mountainous areas can provide rational soil fertilization plans for regions lacking means of production. We conducted a paddy planting experiment in Ankang City, Shaanxi Province. Six treatments were set up, including sole chemical fertilizer (CK); fertilizer + bacteria agent (NB); chemical fertilizer + alginate bio-organic fertilizer (NO); fertilizer + fulvic acid biomass nutrient solution (NF); chemical fertilizer + acid soil conditioner (NC); fertilizer + silicon–calcium–magnesium–potassium fertilizer (NSi). We collected topsoil samples after paddy harvest, analyzed their physical, chemical, and biological properties, and selected indicators to construct a Total Data Set (TDS) and a Minimum Data Set (MDS). The Soil Quality Index (SQI) was used to evaluate the soil improvement effects after different fertilization regimes. The SQI calculated by the TDS and the MDS showed that the SQI after NF treatment was higher than that under other treatments. The SQI based on the TDS (SQITDS) and the SQI based on the MDS (SQIMDS) were significantly positively correlated with yield. The SQI calculated based on both the TDS and the MDS can objectively reflect the soil fertility quality. The paddy yield and total dry matter accumulation were the highest under the NF treatment, and the SQI was the largest. Thus, the effect of chemical fertilizer combined with fulvic acid biomass nutrient solution on soil fertility was the most significant.

Sandy soil, one of the most abundant soil types in the world, often has lower crop productivity because of poor water and fertilizer retention capacity. The objective of this study was to investigate the effects of the new soil conditioner DewEco (fermented organic material consisted mainly of salt of L-lysine and citric acid) on sandy soil quality and plant growth. Serial dosages of DewEco and nitrogen (N) fertilizer were mixed into sandy soils and planted maize in a greenhouse. DewEco application increased large soil particle composition and decreased small soil particle composition. Soil porosity and the liquid phase increased as the DewEco dosage increased. DewEco also decreased soil pH and increased soil electrical conductivity, soil organic matter content, total nitrogen and available potassium. DewEco significantly enhanced the soil water-holding capacity and soil effective water content although it also increased the wilting coefficient. Finally, DewEco markedly promoted maize growth while improving water use efficiency (WUE) and nitrogen use efficiency (NUE). In addition, there was an interaction effect between DewEco and nitrogen fertilizer, such that the combined effects of DewEco and N exceeded the sum of their respective effects promoting plant growth. Thus, DewEco application can significantly enhance soil water content and nutrient levels by alleviating sandy soil’s physical and chemical properties, thereby promoting plant growth, WUE and NUE. This study indicates that DewEco is a useful eco-friendly sandy soil conditioner for arid and semi-arid regions.

Monogalactosyldiacylglycerol (MGDG) is the most abundant lipid on earth and constitutes about 50% of the polar lipids in the thylakoid membrane of higher plants. MGDG synthase (MGD) is the key enzyme responsible for MGDG synthesis in plants. However, so far, the function of the MGD gene in plant stress responses is still unknown, especially in crop plants. In this study, the performances of wild-type rice (Oryza sativa L. Nipponbare), OsMGD overexpression, and RNA interference lines were analyzed under salt stress to clarify the role of OsMGD in rice under salt stress. The results showed that, after 6 days of NaCl treatment, OsMGD-overexpressing rice seedlings had higher biomass than the wild-type rice, with significantly lower Na+ content and Na+ to K+ ratio in the shoots. Meanwhile, overexpression lines showed a significant increase in the contents of chlorophyll a and carotenoid and photosynthetic capabilities, including the net photosynthetic rate, maximal quantum yield (Fv/Fm), effective PSII quantum yield (ΦPSII), electron transport rate (ETR), and coefficient of photochemical quenching (qP), compared with the wild-type line. Also, OsMGD overexpression lines contained higher MGDG and 18:3 unsaturated fatty acid levels under salt stress. These results indicate that OsMGD participates in the regulation of improving salt tolerance through protecting photosynthetic capabilities and ion balance in rice.

Melatonin has been confirmed extensively for the positive effects on increasing plant tolerance to various abiotic stresses. However, the roles of melatonin in mediating different stresses still need to be explored in different plants species and growth periods. To investigate the role of melatonin in mitigating salt stress, maize (Zea mays L.) seedlings growing in hydroponic solution were treated with 100 mM NaCl combined with or without 1 μM melatonin. Melatonin application had no effects on maize growth under normal condition, while it moderately alleviated the NaCl-induced inhibition of plant growth. The leaf area, biomass, and photosynthesis of melatonin-treated plants were higher than that of without melatonin under NaCl treatment. The osmotic potential was lower, and the osmolyte contents (including sucrose and fructose) were higher in melatonin-treated plants. Meanwhile, the decreases in Na+ content and increases in K+/Na+ ratio were found in shoots of melatonin-applied plant under salt stress. Moreover, both enzymatic and nonenzymatic antioxidant activities were significantly increased in leaves with melatonin application under salt treatment. These results clearly indicate that the exogenous melatonin-enhanced salt tolerance under short-term treatment could be ascribed to three aspects, including osmotic adjustment, ion balance, and alleviation of salt-induced oxidative stress.

The effects of exogenous application of melatonin (MEL) on promoting plant growth and alleviating environmental stresses are already known, but the potential value in crop production is still poorly understood. In this study, the effects of seed pre-soaking with MEL on winter wheat (Triticum aestivum L.) growth and yield were investigated in a continuous two-year pot experiment and another year of field experimentation. Results showed that seed pre-soaking with different concentrations of MEL (10, 100 and 500 μM) for 24 h increased grain yields per plant from 29% to 80% in pot experiment and increased grain yield per area from 4−19% in field experiment, compared with the controls. Further analysis showed that the beneficial effects of MEL on improving wheat grain yield can be ascribed to: (1) increased spike number by enhancing tiller number; (2) enhanced carbon assimilation capacity by maintaining large leaf area, high photosynthetic rate and delaying leaf senescence; (3) promoted growth in root system. The result of this study suggests that MEL could be considered as an effective plant growth regulator for improving grain production in winter wheat.