The wheat–soybean double-cropping system enables the continuous production of preceding and succeeding crops within the same growing season, providing an important approach for improving arable land-use efficiency, increasing output per unit area, and optimizing cropping structure. In Liaoning Province, where thermal resources and the frost-free period are relatively limited, this system places high requirements on the growth duration, yield stability, and succession compatibility of the preceding wheat crop with the succeeding soybean crop. To identify spring wheat cultivars suitable for this system, field trials were conducted from 2021 to 2023, using three representative ecological regions of Liaoning Province. Ten widely grown spring wheat cultivars were evaluated for major agronomic traits, grain quality, and disease resistance, and their stability and system adaptability were analyzed using a mixed linear model, GGE biplot analysis, and TOPSIS. The results showed clear differences among cultivars in growth duration, wheat yield, and succeeding soybean yield. Liaochun 33 and Liaochun 18 had relatively short growth durations of 78–84 days and 79–83 days, respectively, and showed favorable performance in wheat yield, succeeding soybean yield, and stability. Combined with grain quality, disease resistance, and TOPSIS-based comprehensive evaluation, Liaochun 33 showed the best overall performance, while Liaochun 18 also exhibited strong system adaptability. Overall, cultivar selection for the wheat–soybean double-cropping system in Liaoning Province should shift from single wheat-yield evaluation to overall system-benefit evaluation. Liaochun 33 and Liaochun 18 can be recommended as preferred spring wheat cultivars for this cropping system.

Seed coat color is an important quality trait in mung bean (Vigna radiata) and is closely associated with seed appearance, commercial value, and phytochemical composition. To investigate the genetic basis of black seed coat formation, six F₂ populations were derived from reciprocal crosses between the black-seeded accession LZL115 and the green-seeded accession LZL156. Among 755 F₂ plants, 559 produced black-coated seeds and 196 produced green-coated seeds, conforming to a 3:1 segregation ratio (χ² = 0.37, p = 0.54). These results indicated that black seed coat color was dominant and consistent with the control by a single dominant locus, designated VrScL115, in the LZL115 × LZL156 genetic background. Bulked segregant analysis sequencing (BSA-seq) initially mapped VrScL115 to an approximately 2.90 Mb region on chromosome 4. Using newly developed KASP markers and recombinant screening in expanded F₂ populations, the locus was further delimited to a 121.79 kb interval between markers LS_K3333 and LS_K3379. Of the 11 annotated genes within this interval, LOC106758748 was the only gene containing high-confidence coding-sequence variants between the parents. This gene encodes a putative R2R3-MYB transcription factor homologous to MYB90. Comparative sequence analysis identified several allelic variants potentially associated with black seed coat color, and protein structure prediction indicated local structural differences between the parental proteins. LOC106758748 showed consistently higher expression in the developing seed coats of LZL115 than in those of LZL156 at 10, 15, and 20 days after pollination, with expression peaking at 15 days. Haplotype analysis of 246 mung bean accessions showed that the LZL115-associated allele combination at LS_K3352, LS_K3365, LS_K3367, and LS_K3370 was present in 21 of 27 black-seeded accessions (77.8%) and absent from all 219 non-black accessions, corresponding to a specificity of 100% and a false-negative rate of 22.2%. These findings support LOC106758748 as the leading candidate gene for VrScL115; however, direct in vivo functional validation is still required to confirm its causal role in black seed coat formation. The four-marker combination may be useful for identifying germplasm carrying the LZL115-associated allele, although further validation in independent germplasm populations is required.