Drought is the most common environmental stress and has had dramatic impacts on soybean (Glycine max L.) growth and yield worldwide. Therefore, to investigate the response mechanism underlying soybean resistance to drought stress, the drought-sensitive cultivar “Liaodou 15” was exposed to 7 (mild drought stress, LD), 17 (moderate drought stress, MD) and 27 (severe drought stress, SD) days of drought stress at the flowering stage followed by rehydration until harvest. A total of 2214, 3684 and 2985 differentially expressed genes (DEGs) in LD/CK1, MD/CK2, and SD/CK3, respectively, were identified by RNA-seq. Weighted gene co-expression network analysis (WGCNA) revealed the drought-response TFs such as WRKY (Glyma.15G021900, Glyma.15G006800), MYB (Glyma.15G190100, Glyma.15G237900), and bZIP (Glyma.15G114800), which may be regulated soybean drought resistance. Second, Glyma.08G176300 (NCED1), Glyma.03G222600 (SDR), Glyma.02G048400 (F3H), Glyma.14G221200 (CAD), Glyma.14G205200 (C4H), Glyma.19G105100 (CHS), Glyma.07G266200 (VTC) and Glyma.15G251500 (GST), which are involved in ABA and flavonoid biosynthesis and ascorbic acid and glutathione metabolism, were identified, suggesting that these metabolic pathways play key roles in the soybean response to drought. Finally, the soybean yield after rehydration was reduced by 50% under severe drought stress. Collectively, our study deepens the understanding of soybean drought resistance mechanisms and provides a theoretical basis for the soybean drought resistance molecular breeding and effectively adjusts water-saving irrigation for soybean under field production.

Drought indices have been commonly used in drought monitoring and assessments, but selecting the most appropriate one under different geographical and climatic conditions is difficult. We constructed a multi-timescale integrated drought index, the Ensemble Drought Index (EDI), for more robust and reliable drought assessments with the widely used Standardized Precipitation Index (SPI), the Palmer Drought Severity Index (PDSI), the selfcalibrated Palmer Drought Severity Index (scPDSI), and the Standardized Precipitation Evapotranspiration Index (SPEI) using the Thornthwaite and the Penman-Monteith methods. The EDI can more accurately describe the major historical drought events, and has high and significant correlation with historical monthly soil moisture and annual runoff data all over China, regardless of regional differences. in region among those indices participating in integration. We also showed that the EDI greatly improved monitoring accuracy in the arid and semi-arid regions of China, where the assessments are always thorny. In the meantime, we revealed how the reference period of fitting statistical parameters affects the accuracy of drought assessments, and concluded that the long-term stationary climate variables series (i.e., without trend) can bring more accurate conclusions.

Maintaining or increasing grain yields while also reducing the emissions of field agricultural greenhouse gases is an important objective. To explore the multifactor effects of nitrogen fertilizer on nitrous oxide (N2O) emissions and the yield of potato fields and to verify the applicability of the DeNitrification-DeComposition (DNDC) model when used to project the N2O emission load and yield, this research chooses a potato field in Shenyang northeast China from 2017~2019 as the experiment site. The experiment includes four nitrogen levels observed the emission of N2O by static chamber/gas chromatograph techniques. The results of this study are as follows: (1) DNDC has a good performance regarding the projection of N2O emissions and yields. The model efficiency index EFs were 0.45~0.88 for N2O emissions and 0.91, 0.85 and 0.85 for yields from 2017~2019. (2) The annual precipitation, soil organic carbon and soil bulk density had the most significant influence on the accumulated N2O emissions during the growth period of potato. The annual precipitation, annual average temperature and CO2 mass concentration had the most significant influences on yield. (3) Under the premise of a normal water supply, sowing potatoes within 5 days after the 5-day sliding average temperature in this area exceeds 10 °C can ensure the temperature required for the normal growth of potatoes and achieve the purpose of maintaining and increasing yield. (4) The application of 94.5 kg•hm -2 nitrogen and 15 mm irrigation represented the best results for reducing N2O emissions while also maintaining the yield in potato fields.

Drought indices have been commonly used in drought monitoring and assessments, but selecting the most appropriate one under different geographical and climatic conditions is difficult. We constructed a multi-timescale integrated drought index, the Ensemble Drought Index (EDI), for more robust and reliable drought assessments with the widely used Standardized Precipitation Index (SPI), the Palmer Drought Severity Index (PDSI), the self-calibrated Palmer Drought Severity Index (scPDSI), and the Standardized Precipitation Evapotranspiration Index (SPEI) using the Thornthwaite and the Penman-Monteith methods. The EDI can more accurately describe the major historical drought events, and has high and significant correlation with historical monthly soil moisture and annual runoff data all over China, regardless of regional differences. in region among those indices participating in integration. We also showed that the EDI greatly improved monitoring accuracy in the arid and semi-arid regions of China, where the assessments are always thorny. In the meantime, we revealed how the reference period of fitting statistical parameters affects the accuracy of drought assessments, and concluded that the long-term stationary climate variables series (i.e., without trend) can bring more accurate conclusions.

No abstract