Cadmium (Cd) contamination in wheat farmland is increasing at an alarming rate, posing threats to food security and public health.  Breeding and utilizing wheat varieties characterized by low Cd accumulation levels constitute an effective strategy in the battle against wheat Cd contamination.  The adoption of molecular marker-assisted approaches can greatly expedite the selection and enhancement of wheat varieties with low Cd accumulation.  Nonetheless, research concerning the genes associated with wheat cadmium accumulation remains scarce.  In this study, a high-density 660K SNP array was employed for conducting a genome-wide association study (GWAS) on the grain Cd concentration (GCdC), bioconcentration factor (BCF) and translocation factor (TF) in 175 wheat germplasms.  The findings revealed 401 significant SNPs identified across three diverse environments.  Linkage disequilibrium analysis revealed 30 core quantitative trait loci (QTLs) capable of reliably modulating wheat Cd accumulation phenotypes.  Through gene annotation, transcriptomics, and gene molecular features, four candidate genes (TraesCS7B02G000200, TraesCS4A02G035900, TraesCS4A02G040900, and TraesCS5D02G564000) were identified as potential constituents in the biological process of wheat Cd accumulation.  Furthermore, six wheat germplasms exhibiting low grain Cd accumulation were isolated, and two kompetitive allele specific PCR (KASP) markers conducive to breeding selection were developed.  These findings provide valuable genetic resources for cultivating wheat with low Cd accumulation and establish a foundation for understanding the molecular mechanisms underlying low Cd accumulation in wheat.  The candidate genes and KASP markers elucidated in this research have potential for effective use in genetic enhancement and marker-assisted selection in the breeding of wheat with low Cd accumulation.

Cultivar mixtures increase crop diversification and grain yield stability.  Achieving high grain yield and nitrogen use efficiency (NUE) with environmentally friendly practices is a major challenge, but it is currently unclear whether maize cultivar mixtures can improve NUE.  A two-year field experiment was conducted using two maize cultivars with different roots angles and leaf angles planted in monoculture or in mixtures under four nitrogen levels N0 (0 kg N ha^–1), N140 (140 kg N ha^–1), N280 (280 kg N ha^–1) and N340 (340 kg N ha^–1).  Cultivar mixtures significantly increased light interception of the middle canopy, dry matter accumulation and total root length under N0, N140, and N280 conditions.  Light interception of the middle canopy was positively related to dry matter accumulation and thus increased grain yield.  In addition, light interception of the whole canopy was positively related to total lateral root length, while the greater total lateral root length of outer nodal roots significantly improved nitrogen accumulation and NUE.  Thus, cultivar mixtures promoted an optimal canopy structure and good root growth, thereby improving grain yield and NUE.  These findings deepen our understanding of the facilitating effect of canopy structure and root traits of cultivar mixtures on the combined promotion of grain yield and NUE. 

As a multifunctional crop, rapeseed provides vegetables by picking shoots.  Shoot removal reduced yield, while nitrogen (N) application results in efficiency gains.  However, the effect of N rate on pod growth, N use efficiency (NUE) and seed yield after shoot removal is unclear.  A 2-year field experiment was set with four N rates (0 [N0], 90 [N1], 180 [N2], and 270 [N3] kg ha^-1) and two shoot treatments (no shoot removal [CK], shoot removal [SR]).  Results showed the shoot removal decreased population biomass (PB) at maturity across all N levels.  Conversely, N application increased the PB after shoot removal and elevated soluble sugar and protein in shoots.  Shoot removal increased the seeds per pod (13.5-26.9%), reduced the pods per plant (33.1-45.8%) and population seed yield (19.5-38.4%).  N application effectively increased the yield related index, and led to an increase in population seed yield by 187.2 - 465.0% in the CK group, and by 185.6 - 430.7% in the SR group.  Moreover, the seed yield reached its maximum under the N3 in both groups.  The leaf N content per area (N_a) and net photosynthetic rate (P_n) were increased, but leaf photosynthetic N use efficiency (PNUE) were decreased at 20 days after shoot removal, which lead to a significant decrease in N use efficiency(NUE).  N supply increased the plant organ N content and PB, but decreased the NUE at maturity stage.  P_n of the pod wall at 25 days after flowering was elevated due to its optimized chloroplasts ultrastructure and increased rubisco and sucrose synthase activities under shoot removal and more N.  However, the greater amino acid/soluble sugar ratio (A/S) of the pod wall significantly increased the seed protein content and decreased the oil content.  Though the oil yield was reduced by 63.8-71.0% under SR×N3 treatment compared with CK×N3, it was comparable to that of CK with 90 kg N ha^-1 treatment.  The results indicated that N applying improves the carbon metabolism of the pod wall and alleviates yield reduction after shoot removal but reduces NUE and seed oil content of rapeseed.  The findings guide the balancing of rapeseed’s vegetable and oil production, and optimize N fertilization for sustainable, efficient rapeseed farming.