Glutathione S-transferases (GST) are a large family of polymorphous proteins that play important roles in herbicide detoxification and stress response. Nicosulfuron is the most broadly used herbicide in maize fields, and it can cause different injuries to maize varieties, but little is studied about the systemic and comprehensive GST gene family responding to nicosulfuron stress in maize. In this research, pre-treatment with glutathione S-transferase inhibitor 4-chloro-7-nitrobenzoxadiazole (NBD-Cl) increased nicosulfuron phytotoxicity to both sensitive and tolerant maize genotypes. A total of 55 ZmGST genes belonging to six major sub-classes were identified in the maize genome and named according to the nomenclature system. Based on phylogenetic analyses, highly conserved gene structure and motif distribution were detected in the same class. Chromosome mapping results showed that ZmGST genes were distributed over the 10 chromosomes unevenly. There were thirteen and eight gene pairs identified as tandem and segmental duplication events, respectively, which played important roles in the expansion of the GST gene family in maize. RNA-seq and qRT-PCR analyses showed that there were great dissimilarities in ZmGST gene expression patterns between the tolerant and sensitive maize plants. More highly expressed ZmGST genes were found in the tolerant than in the sensitive without nicosulfuron stress. However, under 60 g a.i. ha⁻¹ nicosulfuron stress, more ZmGST genes were significantly upregulated in HB41 than in HB09. This study provided experimental evidence showing that glutathione S-transferases were involved in nicosulfuron stress in maize. It will contribute to the further functional analysis of the GST gene family in maize.

Foxtail millet is an important characteristic grain crop in northern China. However, weeds compete seriously with foxtail millet and have long been a biological factor that has plagued foxtail millet production. Rotation requires determining the species and sequence of crops, and reasonable rotation has many benefits for agriculture, including reducing the damage by weeds. In order to clarify the combination effects of foxtail millet–soybean rotation sequence and herbicide on weed control and crop yield, fixed-position experiments were designed in three growing seasons. Foxtail millet and soybean were planted following the sequence below in successive years (FFF, foxtail millet–wheat–foxtail millet–wheat–foxtail millet; SFF: soybean–wheat–foxtail millet–wheat–foxtail millet; SSF, soybean–wheat–soybean–wheat–foxtail millet; SSS, soybean–wheat–soybean–wheat–soybean), and weed density, biodiversity, weed seedbank, and crop yield were examined and analyzed. The results showed that the average weed density of SFF and SSF was reduced by 61.7% and 66.3% compared with FFF in the three years and by 16.5% and 26.6% compared with SSS, separately. Foxtail millet–soybean rotation (SFF and SSF) increased the species richness and the Margalef species richness index of the weed community and reduced the Simpson index compared with the continuous foxtail millet and the continuous soybean cropping (FFF and SSS). The weed seedbank of SFF and SSF was 45.7% and 55.8% smaller than that of FFF and increased by 92.7% and 56.7% compared with SSS, respectively. The weed density in the FFF treatment was significantly correlated with the 0–5 cm grass seedbank size, while there was no significant correlation in the other three treatments. Benefiting from the lower weed damage intensity, the yield of foxtail millet in SFF and SSF increased by 54.05% and 221.81% compared with FFF, respectively. The research results revealed that both SFF and SSF can effectively reduce the damage of weeds and help improve biodiversity. SSF has a higher weed control effect and higher foxtail millet yield than SFF. This study contributes to the understanding of crop–weed interactions in foxtail millet–soybean rotation and can be applied to areas with similar environments.

Using an intelligent plant protection machine for spraying herbicides at a real-time variable rate plays a key role in improving the utilization efficiency of herbicides and reducing environmental pollution. Spraying volume (SV) and nozzle size (NS) are key factors influencing droplet deposition and herbicide efficacy and safety. A three-way split-split plot design experiment was conducted in the winter wheat field, with SV 180 L·ha⁻¹ and 150 L·ha⁻¹ in the main plot, a turbo air induction nozzle TTI11004 and TTI11003 in the subplot, herbicide flucarbazone-Na 70% WG mixed with florasulam 50 g·L⁻¹ SC as the recommended dose, and a 20% reduced dose in the sub-subplot. Droplet deposition and weed control efficacy treated by these three factors and their combination were evaluated. Results indicated that there was a significant influence of SV on droplet coverage and density, but no significant influence of NS and its interaction with SV. A droplet coverage and density of treatment at 180 L·ha⁻¹ were both significantly higher than at 150 L·ha⁻¹. The influence of SV and its interaction with NS on weed control efficacy were significant. The efficacy of treatment TTI11004 at SV 180 L·ha⁻¹ was the highest but decreased when NS was switched to TTI11003 and the SV was decreased to 150 L·ha⁻¹. There was no significant effect of all the treatments on winter wheat yield and its components, but the yield loss could be reduced by 2.36% when the herbicide input was reduced by 20%. We can conclude that herbicide input can be reduced by at least 20% using the intelligent machine while equipped with the right NS at the right SV, which would increase the safety of winter wheat production.

Flixweed (Descurainia sophia) is a weed that seriously affects wheat fields in China. Over the past 20 years, it has evolved resistance to the herbicide tribenuron-methyl. In the present study, a resistant D. sophia population with a Pro-197-Thr mutation of acetolactate synthetase (ALS) was found to have a resistance index of 457.37 for tribenuron-methyl. Under the same growth conditions, the seeds of resistant (R) and susceptible (S) populations exhibited similar vitality but the germination rates of R seeds were higher than those of S seeds. This result demonstrated that seed dormancy periods were shorter in the R seeds. RNA-Seq transcriptome analysis was then used to choose candidate genes that could regulate seed dormancy pathways in the R population. A total of 504,976,046 clean reads were selected from nine RNA-Seq libraries and assembled into 79,729 unigenes. Among these, 33,476 unigenes were assigned to 51 GO subgroups, and 26,117 unigenes were assigned to 20 KEGG secondary metabolic pathways. Next, 2473 differentially expressed genes (DEGs) were divided into three groups, as follows: G-24 h (germinating seeds) vs. D (dormant seeds); G-48 h (germinated seeds) vs. D; and G-48 h vs. G-24 h. From these 2473 DEGs, 8 were selected as candidate dormancy unigenes for the R population if their expression levels continuously decreased during the seed germination progress and their functional annotations were related to plant seed dormancy. One candidate unigene was annotated as CYP707A2; two unigenes were annotated as the transcription factors TGA4 and TGA2; one unigene was annotated as the cystathionine beta-synthase gene; and four unigenes could not be annotated as any gene listed in the six public databases. However, qRT-PCR-validated results showed that, during the germination of R seeds, the expression of the three candidate unigenes first decreased and then increased, indicating that they may have other growth-regulating functions in R populations. In brief, the dormancy function of the eight candidate dormancy unigenes needs to be further studied.