Maize tassel detection is essential for future agronomic management in maize planting and breeding, with application in yield estimation, growth monitoring, intelligent picking, and disease detection.  However, detecting maize tassels in the field poses prominent challenges as they are often obscured by widespread occlusions and differ in size and morphological color at different growth stages.  This study proposes the SEYOLOX-tiny Model that more accurately and robustly detects maize tassels in the field.  Firstly, the data acquisition method ensures the balance between the image quality and image acquisition efficiency and obtains maize tassel images from different periods to enrich the dataset by unmanned aerial vehicle (UAV).  Moreover, the robust detection network extends YOLOX by embedding an attention mechanism to realize the extraction of critical features and suppressing the noise caused by adverse factors (e.g., occlusions and overlaps), which could be more suitable and robust for operation in complex natural environments.  Experimental results verify the research hypothesis and show a mean average precision (mAP_@0.5) of 95.0%.  The mAP_@0.5, mAP_@0.5–0.95, mAP_{@0.5–0.95 (area=small)}, and mAP_{@0.5–0.95 (area=medium)} average values increased by 1.5, 1.8, 5.3, and 1.7%, respectively, compared to the original model.  The proposed method can effectively meet the precision and robustness requirements of the vision system in maize tassel detection.

Nitrogen (N) and seeding rates are important factors affecting grain yield and N use efficiency (NUE) in direct-seeded rice.  However, these factors have not been adequately investigated on direct-seeded and double-season rice (DDR) in Central China.  The objective of this study was to evaluate the effects of various N and seeding rates on the grain yield and NUE of an ultrashort-duration variety grown under DDR.  Field experiments were conducted in 2018 in Wuxue County and 2019 in Qichun County, Hubei Province, China with four N rates and three seeding rates.  The results showed that the grain yield of the ultrashort-duration variety ranged from 6.32 to 8.23 t ha^–1 with a total growth duration of 85 to 97 days across all treatments with N application.  Grain yield was increased significantly by N application in most cases, but seeding rate had an inconsistent effect on grain yield.  Furthermore, the response of grain yield to the N rates was much higher than the response to seeding rates.  The moderate N rates of 100–150 and 70–120 kg N ha^–1 in the early and late seasons, respectively, could fully express the yield potential of the ultrashort-duration variety grown under DDR.  Remarkably higher N responses and agronomic NUE levels were achieved in the early-season rice compared with the late-season rice due to the difference in indigenous soil N supply capacity (INS) between the two seasons.  Seasonal differences in INS and N response should be considered when crop management practices are optimized for achieving high grain yield and NUE in ultrashort-duration variety grown under DDR.

The border effect (BE) is widely observed in crop field experiments, and it has been extensively studied in many crops.  However, only limited attention has been paid to the BE of ratoon rice.  We conducted field experiments on ratoon rice in Qichun County, Hubei Province, Central China in 2018 and 2019 to compare the BE in the main and ratoon crops, and to quantify the contribution of BE in the main crop to that in the ratoon crop.  The BE of two hybrid varieties was measured for the outermost, second outermost, and third outermost rows in each plot of both crops.  To determine the contribution of BE between the two crops, portions of hills in the outermost and second outermost rows were uprooted during the harvest of the main crop so that the second and third outermost rows then became the outermost rows in the ratoon crop.  Overall, the BE on grain yield was greater in the main crop than in the ratoon crop.  In the main crop, the BE on grain yield was 98.3% in the outermost row, which was explained by the BE on panicles m^–2, spikelets/panicle, spikelets m^–2, and total dry weight.  In the ratoon crop, the BE on grain yield was reduced to 60.9 and 27.6% with and without the contribution of the BE in the main crop, respectively.  Consequently, 55.1% of the BE on grain yield in the ratoon crop was contributed from the main crop.  High stubble dry weight and non-structural carbohydrate (NSC) accumulation at the harvest of the main crop were responsible for the contribution of BE in the main crop to that in the ratoon crop.  Our results suggest that increases in stubble dry weight and NSC accumulation at the harvest of the main crop could be important strategies for developing high-yielding cropping practices in the rice ratooning system.

Organic acids are one of the most important factors influencing fruit flavors. The predominant organic acid in most pear cultivars is malic acid, but the mechanism controlling its accumulation remains unclear. In this study, by comparing gene expression levels and organic acid content, we revealed that the expression of PbPH5, which encodes a P_3A-ATPase, is highly correlated with malic acid accumulation in different pear species, with correlation coefficients of 0.932^**, 0.656^*, 0.900^**, and 0.518^* (^*, P<0.05 or ^**, P<0.01) in Pyrus bretschneideri Rehd., P. communis Linn., P. pyrifolia Nakai., and P. ussuriensis Maxim., respectively. Moreover, the overexpression of PbPH5 in pear significantly increased the malic acid content. In contrast, silencing PbPH5 via RNA interference significantly decreased its transcript level and the pear fruit malic acid content. A subcellular localization analysis indicated that PbPH5 is located in the tonoplast. Additionally, a phylogenetic analysis proved that PbPH5 is a PH5 homolog gene that is clustered with Petunia hybrida, Malus domestica, and Citrus reticulata genes. Considered together, these findings suggest PbPH5 is a functionally conserved gene. Furthermore, the accumulation of malic acid in pear fruits is at least partly related to the changes in PbPH5 transcription levels.

The Huang-Huai-Hai wheat region (HHHR) is characterized by the largest cultivation area and yield among all the major wheat-producing regions in China.  Over the past 70 years, significant advances in wheat breeding have been achieved in this region, resulting in high and stable yields as well as improved disease resistance.  However, there is a notable deficiency in the systematic molecular-level analyses of wheat breeding advantages in HHHR.  To bridge this gap, we used a Wheat 55K SNP array to evaluate 384 accessions from a core collection of wheat germplasms across China to systematically analyze the distribution patterns of beneficial haplotypes associated with traits related to yield and powdery mildew resistance specific to HHHR.  Our findings indicate that varieties from HHHR demonstrate significantly superior performance in terms of yield-related traits and powdery mildew resistance compared to those from other wheat regions.  Using genome-wide association studies (GWAS) analysis, we identified the QTNs associated with both grain yield and powdery mildew resistance.  Importantly, beneficial haplotypes were found at significantly higher frequencies in the HHHR than in other wheat-growing regions.  Based on these haplotypes, the MFP-a gene was identified as potentially regulating jasmonic acid synthesis while also playing a role in grain development and conferring powdery mildew resistance.  Furthermore, identity by descent (IBD) analysis revealed specific conserved genomic segments that have become fixed through selective breeding practices in HHHR, which may serve as invaluable resources for the targeted enhancement of yield and disease resistance traits in other wheat-growing areas.  Finally, using the Aimengniu breeding lineage as a case study, we elucidated the genetic basis underlying the key founder parental formations utilized in breeding programs.  This study not only provides essential references and guidance for future molecular breeding initiatives in China but also has implications for enhancing wheat production worldwide.

Exploring the suitability of biochar for improving soil quality under different water and salt conditions is important for maintaining soil health and productivity in the arid regions of Northwestern China. We compared the effects of biochar application practices on soil physical, chemical and biological properties under different irrigation and water salinity levels in a two-year field experiment in a mulched and drip-irrigated maize field in Gansu province, China. Eight treatments in total included the combination of two biochar addition rates of 0 t ha^-1 (B0) and 60 t ha^-1 (B1), two irrigation levels of full (W1) and deficit irrigation (W2; W2=1/2 W1) and two water salinity levels of fresh water (S0, 0.71 g L^-1) and brackish water (S1, 4.00 g L^-1). The minimum dataset method was used to calculate the soil quality index (SQI) under different treatments. Deficit and brackish water irrigation significantly reduced SQI by 3.80-9.80% through reducing some soil physical, chemical and biological properties. Biochar application significantly increased the SQI by 6.13 and 10.40% under full irrigation with fresh and brackish water, respectively. Biochar addition enhanced the relative abundance of beneficial bacteria (e.g., Proteobacteria, Patescibacteria) in the soil in all water-salt treatments. The partial least squares path model showed that biochar application significantly enhanced the SQI mainly by improving soil aggregation and pore structure under particular water-salt conditions. This research provides an important basis for utilizing biochar to improve soil quality in arid regions of Northwest China under various water-salt conditions.