Salt stress represents a significant abiotic stress factor that impedes the growth of rice. Nano-silicon has the potential to enhance rice growth and salt tolerance. In this experiment, the rice variety 9311 was employed as the test material to simulate salt stress via hydroponics, with the objective of investigating the mitigation effect of foliar application of nano-silicon on rice seedlings. The results demonstrated that NaCl stress markedly impeded the growth of rice seedlings after seven days of NaCl treatment. The foliar application of nano-silicon followed by NaCl stress alleviated the growth of rice seedlings, markedly improved the spatial conformation of the root system, and enhanced photosynthesis compared with that of NaCl stress alone. The activities of antioxidant enzymes were improved. The contents of antioxidants were increased, and the over-accumulation of ROS was reduced. Furthermore, the foliar application of nano-silicon was found to enhance the uptake of Si⁴⁺, K⁺, and Ca²⁺ in plants, while simultaneously reducing Na⁺ and Cl⁻ accumulation. Additionally, the content of IAA, CTK, GA, JA, and SA was increased, and ABA was decreased. In conclusion, the foliar application of nano-silicon has been demonstrated to alleviate salt stress injury and improve the growth of rice seedlings.

Salt stress is an important factor affecting the growth and development of rice, and prohexadione calcium (Pro-Ca) plays an important role in alleviating rice salt stress and improving rice yield. However, there are few studies on how Pro-Ca improves rice yield under salt stress by regulating the source–sink metabolism. In this study, we used Guanghong 3 (salt-tolerant variety) and Huanghuazhan (salt-sensitive variety) as experimental materials to investigate the dynamic changes in the synthesis and partitioning of nonstructural carbohydrates among source–sink, the dynamic changes in related enzyme activities, the effects of the source–sink metabolism on yield in rice under salt stress and the effect of Pro-Ca during the filling period. The results of this study showed that Pro-Ca improved photosynthetic efficiency by increasing leaf photosynthetic gas exchange parameters and other stomatal factors on the one hand and, on the other hand, promoted sugar catabolism and reduced sugar synthesis by increasing leaf sucrose synthase activity and decreasing sucrose phosphate synthase activity, alleviating the inhibitory effect of high concentrations of sugars in the leaves on photosynthesis. Meanwhile, Pro-Ca promotes the transport of sugars from source (leaves) to sink (seeds), increases the sugar content in the seeds, and promotes starch synthesis in the seeds by increasing starch phosphorylase, which promotes seed filling, thus increasing the number of solid grains on the primary and secondary branches of the panicle in rice, increasing the 1000-grain weight, and ultimately increasing the seed setting rate and yield. These results indicated that Pro-Ca alleviated the inhibitory effect of salt stress on rice leaf photosynthesis through stomatal and non-stomatal factors. Meanwhile, Pro-Ca promotes the transport of rice sugars from source to sink under salt stress, regulates the source–sink relationship during the filling period of rice, promotes starch synthesis, and ultimately improves rice yield.

Salt stress is one of the principal abiotic stresses limiting agricultural production and seriously inhibiting seed germination rates. This study selected the salt-tolerant rice variety HD961 and the salt-sensitive rice variety 9311 as experimental materials to investigate the physiological and metabolic effects of exogenous Spd seed priming on rice seeds and seedlings under NaCl stress. The experiment involved treating rice seeds with 0.1 mmol·L⁻¹ Spd and then subjecting them to 100 mmol·L⁻¹ NaCl stress for 24 h, with sampling for analysis at the 24 h and the four-leaf-one-heart stage. The results indicated that under NaCl stress, the rice’s germination and vigor indices significantly decreased. However, exogenous Spd seed priming reduced the accumulation of malondialdehyde, enhanced the capacity for osmotic adjustment, and increased the amylase and antioxidant activity by 50.07% and 26.26%, respectively. Under NaCl stress, the morphological development of rice seedlings was markedly inhibited, whereas exogenous Spd seed priming improved the aboveground and belowground biomass of the rice under stress conditions, as well as the content of photosynthetic pigments. It also reduced the damage to seedlings from electrical conductivity, helped maintain ionic balance, and promoted the excretion of Na⁺ and Cl⁻ and the absorption of K⁺ and Ca²⁺. In the salt-sensitive rice variety 9311, the soluble protein content increased by 15.12% compared to the salt-tolerant rice variety HD961, especially under 100 mmol·L⁻¹ NaCl stress, when the effect of exogenous Spd seed priming was more pronounced. In summary, these findings might provide new research perspectives and strategies for improving the salt tolerance of rice under NaCl stress.

Dragon fruits have abundant nutritional and antioxidant properties. High temperatures limit the growth and production of dragon fruits. Hemin can effectively alleviate abiotic stress in plants. However, the regulatory effect of Hemin on dragon fruit under heat stress remains unclear. In this study, we explored the impacts of foliar application of Hemin on dragon fruit size, yield and quality during the high temperatures of the summer season. In this experiment, dragon fruit variety ‘Jindu No. 1’ was used as material and treated with three Hemin concentrations, i.e., H1: 1 μmol.L⁻¹, H2: 10 μmol.L⁻¹, H3: 100 μmol.L⁻¹, compared with CK: control. The results show that exogenous Hemin increased the single fruit weight, yield, fruit shape index and edible rate. It also improved pericarp L* value, a* value, C* and decreased h^o, improving the peel colour; exogenous Hemin enhanced soluble solids content and phenolic compounds content and antioxidant enzyme activities in the pulp of dragon fruit. In addition, exogenous Hemin increased the content of chlorophyll content in dragon fruit stems. Differential metabolites determined by metabolomic assay also indicated that Hemin significantly increased the content of active substances such as selagin. Additionally, the Hemin treatment H2 also activated the activity of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), which helps to mitigate the effects of high temperatures on dragon fruit. The current findings strongly advocate that H2 treatment may effectively counteract the adverse effects of heat stress by regulating the morph-physiological and antioxidant traits.

In recent years, pigment rice has been the focus of much attention due to its high nutritional value and ornamental value. To gain a better understanding of pigmented rice, we studied the morphological, physiological, and yield characteristics of four varieties, i.e., light green (LG), deep purple (DP), black-purple (BP), and white rice (WR), as plant material. The field experiment was conducted using a randomized complete block design at Guangdong ocean university research farm during 2023 and 2024. The data of the pigmented rice varieties regarding their morphological, physiological, and antioxidant traits were compared with CK. Leaf area and dry matter accumulation were significantly higher in BP than in the other rice varieties, with BP being the best performer and WR being the worst. The internode length, leaf area, and dry matter accumulation of BP were markedly higher than the rest of the rice varieties. The chlorophyll content of BP was significantly higher. The antioxidant enzyme activities were significantly different among all the varieties. The antioxidant enzyme activities of BP were significantly higher than those of the other rice varieties. Seed yield varied significantly, with BP showing the highest yield. The morphophysiological characteristics of BP and DP suggest that these two varieties can alleviate the response to salinity stress, thereby increasing rice yield.