Seed priming is an effective method for imparting stress tolerance to plants. This study aimed to analyze the effects of solid matrix priming (SMP) on cauliflower and broccoli seed germination and early seedling growth under suboptimal temperature conditions. The SMP method used in this study included the following steps: (1) mixing seeds with vermiculite and water at a ratio of 2:3:2.5 (w/w/v) and incubating for 2 days in the dark at 20°C; (2) drying the SM-primed seed; (3) germinating the SM-primed and the nonprimed seeds at 10, 15, 20, and 25°C; (4) analyzing the antioxidant enzyme activities of SM-primed and nonprimed germinating broccoli and cauliflower seeds in the early germination stage at 10, 15, 20, and 25°C; and (5) testing the emergence of SM-primed and nonprimed control seeds in the early spring glasshouse. The results showed that the SMP improved seed germination vigor and early seedling growth and increased the activities of peroxidase and ascorbate peroxidase in the germinating cauliflower and broccoli seeds under the suboptimal temperature conditions in the early germination stage compared with nonprimed seeds. It was observed that the suboptimal temperature conditions (i.e., 10 and 15°C) suppressed SM-primed and nonprimed seed germination and early seedling growth of cauliflower and broccoli. Inside a greenhouse, the SMP improved the emergence of cauliflower and broccoli seeds during the early spring season. SMP is an effective method for improving seed germination and the emergence of cauliflower and broccoli under suboptimal temperature conditions.

Low-temperature stress during early spring critically limits seed germination and seedling establishment in solanaceous crops. This study investigated the effects of seed treatment (ST) combined with foliar spraying of oligosaccharides (FSO) on improving seed germination and early seedling growth of pepper and tomato under constant 15°C conditions. The seed treatment (ST) involved soaking seeds in a tri-component oligosaccharides solution (0.11 g/L of a 1:1:1 ratio of chitosan oligosaccharide, D-cellobiose, xylo-oligosaccharide) for 24 h at 20°C, followed by solid matrix priming (SMP) with vermiculite (seed:vermiculite:water, 1:2:1.8, w/w/w) for 72 h at 20°C and subsequent air-drying. The treated and control seeds were germinated at 25°C for 3 days prior to being transferred to 15°C. Seedlings from treated seeds received two foliar sprays of the same oligosaccharides solution (0.11 g/L) at 14 and 18 days after sowing. The results showed that seed treatment (ST) significantly enhanced all emergence parameters and reduced the mean emergence time in both species compared to the untreated control. Statistical analysis indicated a significant species × treatment interaction for most emergence parameters, with a more pronounced promotive effect in pepper. The integrated ST + FSO treatment significantly improved seedling growth parameters. Significant species × treatment interactions were observed for stem diameter and fresh weight, with tomato exhibiting a greater relative increase in fresh weight. ST + FSO enhanced the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPX), and increased soluble sugar content in both species. However, a significant increase in glutathione reductase (GR) activity and soluble protein content occurred specifically in pepper, highlighting a species-specific physiological response. In conclusion, the combination of seed treatment and foliar spraying of oligosaccharides (ST + FSO) is an effective strategy for enhancing low-temperature tolerance in solanaceous crops, although its efficacy and underlying physiological mechanisms exhibit significant species-specific variation.