To determine the combining effects of nitrogen application rate and planting density on rice yield and grain quality formation under salinity conditions, a field experiment was conducted in the coastal saline area using Oryza sativa L. cv. Nangeng 9108 from 2019 to 2020. The experiment was designed with six nitrogen rates (0, 210, 255, 300, 345, and 390 kg ha⁻¹; denoted as N0-N390, respectively) and two transplanting densities (334,000 and 278,000 hills ha⁻¹; denoted as D1 and D2, respectively). The results indicated that, with the increase of nitrogen input rate, the panicles number and spikelets per panicle increased first, subsequently decreased, and peaked under 300 kg ha⁻¹ N, whereas the filled-kernel rate and grain weight displayed a decreasing trend. The panicle number and grain weight were higher under D1 treatment compared to those under D2 treatment, while the spikelet number per panicle and the filled-kernel rate displayed an opposite trend. The grain yield displayed highest under N300D1 treatment among all treatments, accompanied by the highest agronomic N use efficiency, and the actual yield reached 8060.4 kg ha⁻¹ and 7869.8 kg ha⁻¹ in 2019 and 2020, respectively. Increased nitrogen application rate significantly improved the grain processing quality and nutritional quality, while reducing the appearance quality and cooking/eating quality. Higher transplant density was conductive to grain nutritional quality, but notably reduced the processing quality, appearance quality and cooking/eating quality. Overall, a combination of 300 kg ha⁻¹ nitrogen rate and 334,000 hills ha⁻¹ planting density was recommended for relatively higher rice yield and better grain quality in the saline area.

Previous researchers have focused on the role of 24-epibrassnolide (EBR) in alleviating stresses in plants, whereas the effect of EBR on rice grain yield formation from the perspective of the whole growth stage remains less concerned. To further confirm the optimal application concentration and application periods of EBR in rice (Oryza sativa L.) under salt stress, a seed germination experiment, a seedling experiment, and a pot experiment were designed and conducted. Results showed that EBR treatment significantly enhanced germination indicators and seedling morphological traits, and the effects varied among different EBR concentrations, which were 0.5 > 1.0 > 0.1 > 0.05 mg L⁻¹. Under 0.5% salt treatments, 0.5 mg L⁻¹ EBR spraying significantly enhanced the seedling height, root length, above-/under-ground fresh weight, and above-/under-ground dry weight by 9.2%, 15.9%, 48.0%, 19.5%, 29.3%, and 12.5%, respectively. The spraying of EBR at different periods enhanced rice yield by 6.7% to 94.4% under salt stress. The relatively higher panicle number (increased by 42.9%) and spikelet number per panicle (increased by 96.1%) were the main reason resulting in higher grain yield under the S+T5 (EBR sprayed at both transplanting and heading stage) treatment. Compared to those under S treatment, catalase (CAT) activity was significantly enhanced by 25.0%, while malondialdehyde (MDA) content was dramatically decreased by 37.3% under the S+T5 treatment. The S+T5 treatment significantly enhanced the K⁺ content in rice root and leaf and decreased the Na⁺ content in rice root (by 30.4%), thereby leading to higher K⁺/Na⁺ under salt stress. The current study concluded that 0.5 mg L⁻¹ was the optimal concentration of EBR in alleviating the adverse effect of salinity. Spraying (transplanting + heading) of EBR twice displayed the best alleviating effect under salt stress, which was realized through enhanced antioxidant enzyme, higher K⁺ maintenance in leaves, and lowered absorption of Na⁺ in rice root.

Soil salinity is a major constraint to wheat production worldwide. Efficient screening of salt-tolerant cultivars is essential for breeding programs, yet a rapid and reliable evaluation system based on full-life-cycle salt stress treatment is lacking. To address this, we conducted a hydroponic experiment encompassing the entire growth cycle of 37 wheat cultivars under control and salt stress (85.5 mM NaCl). Using principal component and stepwise regression analyses on 15 agronomic and yield-related traits, we identified five key indicators—total dry weight, root dry weight, plant height, thousand-grain weight, and number of grains per spike—that effectively represent overall salt tolerance. Based on a comprehensive evaluation value (D-value), the cultivars were classified into five distinct categories: highly salt-tolerant, salt-tolerant, moderately salt-tolerant, weakly salt-tolerant, and salt-sensitive. Notably, the highly salt-tolerant cultivar ‘Yangfumai 8′ and the salt-sensitive cultivar ‘Yangmai 22’ were selected as representative extremes. A subsequent pot experiment confirmed significant physiological differences between them in antioxidant enzyme activities (SOD, POD, CAT) and proline accumulation under salt stress. This study establishes a practical and efficient screening framework, providing breeders with a simplified index set for high-throughput evaluation and offering ideal contrasting materials for in-depth physiological research on salt tolerance mechanisms in wheat.