Long-term soil salinization easily contributes to soil hardness, soil nutrient imbalance, and soil microbial diversity reduction, resulting in low rice yields in the salinized fields, and microbial remediation is one of the important measures to improve salinized soil. To verify the effect of biofertilizer based on halotolerant microorganisms on promoting rice growth and alleviating saline stress, this study discussed the effects of biofertilizer on soil microbial diversity and community structure and analyzed the correlation between the formation of microbial community structure and soil nutrient factors in the salinized field. The result, in comparison with applying inorganic fertilizer (referred to as CK), showed that notably increased soil available nitrogen, available phosphorus, available potassium, and rice paddy yield (p < 0.05) and significantly decreased soil electrical conductivity (p < 0.05) were achieved via biofertilizer (referred to as G2). Additionally, the application of biofertilizer contributes to the increase in soil microbial diversity and reorganization of microbial community structure, and through the analysis of linear discriminant analysis effect size, a notable difference in relative abundance was found in 13 genera, 6 families, and 3 orders between the control group and experimental groups (p < 0.05), and by linear discriminant analysis, Desulfomonas was further identified as the differentiated indicator. The redundancy analysis showed that available phosphorus and cation exchange capacity were the key environmental factors that affected microbial community structure and composition. Through bacterial functional prediction, increased rhizosphere soil bacterial metabolism, enzyme activity, membrane transport, and other potential functions were achieved by applying biofertilizer. Therefore, the application of biofertilizer could significantly alleviate rice growth stress and increase nutrient supply capacity in saline soil. These findings provide theoretical support for soil microbial improvement technology in the salinized field.

Plant lipid transfer proteins (LTPs) are encoded by multigene families and play important roles in plant physiology. One full-length cDNA encoding an Arabidopsis LTP3 homologue was isolated from maize by RT-PCR and named as ZmLTP3. RT-PCR analysis indicated that the ZmLTP3 expression is induced by salicylic acid (SA), mannitol and salt. Furthermore, in different tissues the ZmLTP3 displayed different expression patterns, indicating that ZmLTP3 may play multiple roles in stress resistance. Over-expression of ZmLTP3 in wild-type Arabidopsis resulted in the increased salt tolerance. Under salt stress condition, compared to wild-type (WT) plants, transgenic Arabidopsis grew better, had higher seedling fresh (FW), dry weight (DW), seed yields, proline content and lower MDA content and relative electric conductivity level. Our results suggest that maize ZmLTP3 might encode a member of LTPs family and play roles in salt resistance.

Prohexadione-calcium (Pro-Ca) has been proved to play an important role in releasing abiotic stress in plants. However, there is still a lack of research on the mechanism of Pro-Ca alleviating salt stress in rice. To explore the protective effects of Pro-Ca on rice seedlings under salt stress, we investigated the effect of exogenous Pro-Ca on rice seedling under salt stress by conducting the following three treatment experiments: CK (control), S (50 mmol·L⁻¹ NaCl saline solution) and S + Pro-Ca (50 mmol·L⁻¹ NaCl saline solution + 100 mg·L⁻¹ Pro-Ca). The results indicated that Pro-Ca modulated the expression of antioxidant enzyme-related genes (such as SOD2, PXMP2, MPV17, E1.11.1.7). Spraying Pro-Ca under salt stress significantly increased in ascorbate peroxidase, superoxide dismutase, and peroxidase activity by 84.2%, 75.2%, and 3.5% as compared to the salt treatment, as demonstrated by an example of a 24-hour treatment. Malondialdehyde level in Pro-Ca was also dramatically decreased by 5.8%. Moreover, spraying Pro-Ca under salt stress regulated the expression of photosynthesis genes (such as PsbS, PsbD) and chlorophyll metabolism genes (heml, PPD). Compared to salt stress treatment, spraying Pro-Ca under salt stress significantly increased in net photosynthetic rate by 167.2%. In addition, when rice shoots were sprayed with Pro-Ca under salt stress, the Na⁺ concentration was considerably reduced by 17.1% compared to salt treatment. In conclusion, Pro-Ca regulates antioxidant mechanisms and photosynthesis to aid in the growth of rice seedlings under salt stress.

In order to explore the regulating role and the physiological and biochemical mechanisms of trans-abscisic acid (hereinafter referred as S-ABA) in the process of rice growth and development under salt stress, we took Chaoyou 1000 and Yuxiangyouzhan as materials and set up three salt concentration treatments, CK0 (Control treatment), N1 (50 mmol L⁻¹ NaCl), and N2 (100 mmol L⁻¹ NaCl), in potted trials; we aimed to study the mechanism of rice’s response to salt stress from the perspective of agricultural traits and physiological biochemicals and to improve rice’s resistance to salt stress through exogenously applying the regulating technology of S-ABA. The following results were obtained: Under salt stress, the growth of rice was significantly suppressed compared to CK0, exhibiting notable increases in agricultural indicators, photosynthesis efficiency, and the NA⁺ content of leaves. However, we noted a significant decrease in the K⁺ content in the leaves, alongside a prominent increase in NA⁺/K⁺ and a big increase in MDA (malondialdehyde), H₂O₂ (hydrogen peroxide), and O₂⁻ (superoxide anion). This caused the cytomembrane permeability to deteriorate. By applying S-ABA under salt stress (in comparison with salt treatment), we promoted improvements in agronomic traits, enhanced photosynthesis, reduced the accumulation of NA⁺ in leaves, increased the K⁺ content and the activity of antioxidant enzymes, and reduced the active oxygen content, resulting in a sharp decrease in the impact of salt stress on rice’s development. The application of S-ABA decreased the endogenous ABA (abscisic acid) content under salt stress treatment but increased the endogenous GA (gibberellin) and IAA (indole acetic acid) contents and maintained the hormonal homeostasis in rice plants. To summarize, salt stress causes damage to rice growth, and the exogenous application of S-ABA can activate the pouring system mechanism of rice, suppress the outbreak of active oxygen, and regulate NA⁺/K⁺ balance and hormone homeostasis in the blades, thus relieving the salt stress.

Soil salinity represents a significant factor affecting agricultural productivity and crop quality. The present study was conducted to investigate the effects of soil conditioner (SC) comprising halotolerant microorganisms on the soil fertility, yield, rice quality, and the physicochemical and structural properties of starch in hybrid rice under saline conditions. The experimental treatments were composed of two high-quality hybrid rice varieties, i.e., ‘Y Liangyou 957’ (YLY957) and Jing Liangyou 534 (JLY534), and two soil amendment treatments, i.e., the application of SC at control levels and 2250 kg hm⁻², or ‘CK and SC’, respectively. The crop was subjected to a mixture of fresh and sea water (EC 11 dS/m). The results demonstrated that the application of SC significantly enhanced the rice yield under salt stress conditions owing to an increase in the number of grains per panicle. Furthermore, SC was found to be effective in improving the organic matter and soil nutrient content. Furthermore, the application of SC resulted in an improvement in antioxidant defense, higher leaf SPAD values, and greater crop biomass, as well as the translocation of photo-assimilates at the heading stage. The application of SC not only improved the milling and appearance quality but also enhanced the taste value of rice by increasing the amylose and reducing the protein content. Furthermore, the application of SC also decreased the indentations on the surfaces of starch granules and cracks on the edges of the granules. The rice varieties subjected to SC exhibited excellent pasting properties, characterized by reduced proportions of amylopectin short chains and a lower gelatinization temperature and enthalpy of gelatinization. Overall, these findings serve to reinforce the efficacy of soil conditioner as a valuable tool to improve rice productivity and sustainability with improved rice grain quality under saline conditions.

Salt stress exerts a notable influence on rice’s normal growth and development process. It causes a decline in rice yield, and in certain extreme cases can lead to the complete failure of rice crops. Abscisic acid, also known as S-ABA, may play an important role in regulating rice plant responses to various stressors and promoting crop growth against adversity. In this research, the impact of externally applied S-ABA (0.03% S-ABA, diluted 100 times) on the growth and yield of rice was explored. The experiment made use of the traditional rice variety Huanghuazhan as the test material. The study focused on how S-ABA affected rice at various growth phases under salt-stress conditions. The effects of S-ABA sprayed once (three-leaf/one-heart stage) and twice (three-leaf/one-heart stage, break stage) on the photosynthetic characteristics, antioxidant metabolism, membrane lipid peroxidation products, osmotic regulation, and yield of rice under 0.4% NaCl were studied. The experimental outcomes indicated that the presence of salt stress had a restraining effect on the growth of rice. There was a notable decline in the net photosynthetic rate; moreover, the yield was diminished by 26.90%. Salt-induced stress clearly imposed negative impacts on these aspects of rice’s physiological functions and productivity. The exogenous application of S-ABA was highly effective in mitigating the inhibitory influence of salt stress on the growth of rice. When S-ABA was sprayed on two occasions, there was a notable increase in the total chlorophyll content within the rice leaves, ranging from 7.40% to 80.99%. This led to an enhancement in the photosynthetic ability of the plants. Additionally, the growth of rice seedlings was significantly promoted. The activity of antioxidant enzymes also witnessed an upward trend, and the content of soluble protein increased by 0.87–2.60%. The content of malondialdehyde and hydrogen peroxide were decreased by 4.18–12.49% and 13.71–52.18%, respectively, the damage to membrane lipid peroxidation was alleviated, and rice yield was increased by 14.84% and 29.29% after spraying S-ABA once or twice under salt stress, respectively. In conclusion, salt stress inhibits the growth and development of rice during grouting and destroys the antioxidant system of the rice plant, thus reducing its yield. Leaf spraying with S-ABA can alleviate the degradation of chlorophyll, enhance the photosynthesis, antioxidant system, and osmotic regulation ability of rice, reduce salt-stress damage, and thus alleviate the yield loss under salt stress to a certain extent. In addition, the regulation effect of two sprayings of S-ABA is better than that of one spraying. The results of this study revealed the physiological regulation mechanism of S-ABA at different growth stages of rice under salt stress, and provided theoretical support for the reduction of salt-stress damage to rice. This suggests that S-ABA has potential applications in the improvement of salt tolerance in rice.