Interspecific hybridization of rapeseed is an important way to innovate breeding resources. This research used Brassica napus and Brassica rapa for artificial synthesis interspecific hybridization of F₁. The F₁ self-fruiting rate was particularly low. By comparing the fertilization rate and seed setting rate of nine crosses and selfing combinations of interspecific hybrid progeny F₁ and control B. napus, the results proved that the genetic stability of egg cells was greater than that of sperm cells, so the F₁ could get seed by artificial pollination with other normal pollen. Based on these results, interspecific maternal inbred offspring (induced F₁) from egg cells was obtained by emasculation and pollination with the pollen of DH inducer Y3380. It was found through morphological analysis, flow cytometry identification, and meiotic observation of induced F₁, the plants had most normal fertile tetraploid and the meiosis was normal. The FISH results showed that the induced F₁ were B. napus (2n = 4x = 38, AACC), 20 A and 19 C chromosomes. The results of SNP chip detection and genetic cluster analysis found that the genetic variation between interspecies could be preserved or broadened in the induced F₁. The use of DH inducer created special breeding resources for interspecific hybridization and distant hybridization of rapeseed while shortening time, improving efficiency, and providing a new insight into innovate breeding resources.

When homozygously fertile plants were induced using doubled haploid (DH) induction lines Y3380 and Y3560, the morphology of the induced F₁ generation was basically consistent with the female parent, but the fertility was separated, showing characteristics similar to cytoplasmic male sterile (CMS) and maintainer lines. In this study, the morphology, fertility, ploidy, and cytoplasm genotype of the induced progeny were identified, and the results showed that the sterile progeny was polima cytoplasm sterile (pol CMS) and the fertile progeny was nap cytoplasm. The molecular marker and test-cross experimental results showed that the fertile progeny did not carry the restorer gene of pol CMS and the genetic distance between the female parent and the offspring was 0.002. This suggested that those inductions which produced sterile and fertile progeny were coordinated to CMS and maintainer lines. Through the co-linearity analysis of the mitochondrial DNA (mtDNA), it was found that the rearrangement of mtDNA by DH induction was the key factor that caused the transformation of fertility (nap) into sterility (pol). Also, when heterozygous females were induced with DH induction lines, the induction F₂ generation also showed the segregation of fertile and sterile lines, and the genetic distance between sterile and fertile lines was approximately 0.075. Therefore, the induction line can induce different types of female parents, and the breeding of the sterile line and the maintainer line can be achieved through the rapid synchronization of sister crosses and self-crosses. The induction of DH inducer in B. napus can provide a new model for the innovation of germplasm resources and open up a new way for its application.

Genome-wide association studies (GWAS) are a powerful approach for elucidating the genetic architecture of complex traits. The widespread application of GWAS across diverse crop species has generated vast amounts of GWAS summary statistics, creating a pressing need for effective tools to identify high-confidence quantitative trait loci (QTLs) from these data. Here, we present Candidate QTL Detector (CQD), a tool that enables the rapid and accurate identification of confident QTL regions from GWAS summary statistics. To evaluate the performance of CQD, we reanalyzed 64 phenotypic traits from a previously published maize diversity panel. CQD identified 108 high-confidence QTLs from 4179 significant GWAS signals, and these QTLs harbored several well-characterized genes, including NS2 (a regulator of tassel branch number), DRL1 (a key regulator of plant architecture), and ZmACS6 (an ACC synthase involved in ethylene biosynthesis), demonstrating the reliability of the QTLs detected by CQD. Overall, CQD provides an efficient and flexible framework for extracting robust QTLs from GWAS summary statistics, thereby facilitating the genetic improvement of complex traits and advancing crop functional genomics.

To support low-cost, non-destructive crop growth monitoring, this study systematically compared different vegetation indices, voxel sizes, and camera angles using a point cloud voxelization approach combined with a vegetation index weighted canopy volume index (CVM_VI) to assess aboveground biomass (AGB) in winter oilseed rape (Brassica napus L.). Field experiments were conducted from 2021 to 2024 at the Yangma Experimental Base of the Chengdu Academy of Agricultural and Forestry Sciences. Red, green, blue (RGB) imagery of oilseed rape was acquired using an unmanned aerial vehicle (UAV) during the following five key growth stages: seedling, bolting, flowering, podding, and maturity. Collected images were processed to generate point clouds, which were subsequently voxelized at four resolutions (0.03, 0.05, 0.07, and 0.1 m). CVM_VI was constructed by integrating vegetation indices (VIs) derived from the RGB data and the voxelized canopy structural information. Regression models were established between the CVM_VI values and field-measured AGB to estimate biomass. Model performance was evaluated using the coefficient of determination (R²), root mean square error (RMSE), and relative error (RE). There were strong correlations (r > 0.80) between the estimated and measured AGB across all voxelization treatments throughout the growth period. Among the 20 VIs tested, regression methods based on the blue green ratio index (BGI), color intensity index, blue red ratio index, vegetative index, and green red ratio index consistently showed superior estimation performance across three consecutive years, demonstrating their good applicability for estimating AGB in oilseed rape under varying agronomic conditions (different varieties, densities, and sowing dates). The cubic regression model CVM_BGI performed best under a 45° UAV camera angle, with the highest R² and lowest RMSE and RE (2021–2022: R² = 0.864, RMSE = 2414.18 kg/ha, RE = 14.8%; 2022–2023: R² = 0.754, RMSE = 2550.53 kg/ha, RE = 14.9%; 2023–2024: R² = 0.863, RMSE = 1953.61 kg/ha, RE = 22.9%). Since the estimation performance showed negligible differences among voxel sizes, and the 0.1–m voxel offered the smallest data volume and shortest analysis time, the CVM_BGI model with a 0.1–m voxel was selected as the preferred approach, providing a practical balance between estimation performance and processing demand. These findings highlight the application potential of point cloud voxelization technology for crop biomass estimation. This study proposes a novel, non-destructive, and efficient framework for estimating field crop AGB using low-cost UAV RGB imagery, facilitating the wider adoption of UAV technology in practical agricultural production.

Although heterosis plays a crucial role in enhancing crop yield and stress resistance, its underlying genetic mechanism remains not yet fully understood. Previous studies have shown that heterosis tends to increase with greater genetic distance in the absence of reproductive isolation barriers. However, whether variation in parental genome size alone can generate heterosis under near-isogenic backgrounds has not been thoroughly explored. Here, we used a rapeseed double haploid (DH) inducer line to generate progeny from the Pol CMS three-line hybrid Rongyou 18 (RY18). Although the progeny maintained the same ploidy level as the parents, their genome sizes showed notable variation (818.99–1024.88 Mb). To eliminate genetic distance effects, multiple DH progeny carrying restorer genes were crossed as paternal parents with the female parent 0068A of RY18, creating novel F₁ hybrids. Using RY18 as the control, we observed a marked reduction in the genetic distance between the newly induced restorer line and the female parent (0068A). Correlation analysis further revealed a significant negative correlation (r = −0.310 *) between the paternal genome size and heterosis for thousand-seed weight (TSW). Furthermore, the genomic expansion in hybrid offspring relative to the male parent showed that significant correlations were observed between paternal genome size and heterosis over the standard for both TSW (r = 0.300, p < 0.05) and plot yield (r = 0.326, p < 0.05). Resequencing of high-and low-yielding F₁ hybrids identified SNP sites, indicating that under an identical genetic background, heterosis for yield was more pronounced on chromosome A and chromosome C04. The doubled haploid (DH) induction line facilitates the generation of parental lines with distinct genome sizes, potentially providing a potential novel approach for studying heterosis research in Brassica napus.