Straw return is an important farmland management practice that influences the activity of soil nitrogen. Few studies have examined the distribution of soil nitrogen and its components in wheat–rice cropping fields in subtropical China. This study assesses the influence of different years of straw return on the distribution and variation of total soil nitrogen (TN), light fraction nitrogen (LFN), heavy fraction nitrogen (HFN), particulate nitrogen (PN), and mineral-bound nitrogen (MN). We conducted a field experiment with eight years of straw retention treatments in 2017 (no straw retention, NR; 1 year of straw retention, SR1; 2 years of straw retention, SR2; 3 years of straw retention, SR3; 4 years of straw retention, SR4; 5 years of straw retention, SR5; 6 years of straw retention, SR6; 7 years of straw retention, SR7) and one more treatment in 2018 (8 years of straw retention, SR8) in a rice–wheat cropping system at Yangzhou University Experimental Station in China. The results demonstrated that as the number of years of treatment increases, the content of TN, LFN, HFN, PN, and MN at each soil layer gradually increases. Compared with NR, the highest increase in TN, LFN, HFN, PN, and MN under SR1-SR8 in the 0–20 cm soils was 38.10%, 150.73%, 35.61%, 79.97%, and 27.71%, respectively, but increases in TN, HFN, and MN content gradually slowed after six years of straw return. The contents or variation of TN were extremely significantly correlated (p < 0.01) with that of LFN, HFN, PN, and MN, while LFN had the highest variation. In general, straw return could improve the quality of the 0–20 cm nitrogen pool. LFN was the best indicator of changes to the soil nitrogen pool affected by years of straw return.

Crop straw is an important natural resource in China because it is rich in nutrients. When returned to fields after harvests, the straw can improve soil quality and the next crop's yield. Evaluating the economic values of the main ecological services of a farmland ecosystem while implementing the straw return technique can be a more systematic and comprehensive approach to better understand the contribution of straw return to the development of ecological agriculture. Based on the data of a field experiment established in 2010 with varying numbers of years of straw return, four ecological services, i.e., agricultural product and industrial raw materials, atmospheric regulation and purification, soil nutrient accumulation, and water conservation, were selected to estimate a net ecosystem service value (ESV) of a wheat field's ecosystem services. Agro-ecosystem service appraisal theories were applied to estimate the economic value of each service. Results showed that straw returning improved the total ESV in the wheat system. Compared to the no straw return treatment, 1 year, 3 years, 5 years or 7 years of straw returning altered the economic value of the agricultural product and industrial raw materials (EVAIM) by -5.93% to 7.84% and improved atmospheric regulation (EVAR) by 13.66%-30.80%, soil nutrient accumulation (EVSNA) by 59.87%-233.31% and water conservation (EVWC) by 2.60%-13.26%. The total ESV of wheat plots with 1-7 years of straw returning was 3.67%-27.41% higher than that with no straw return, and the total ESV increased with the increase in years of straw return. The proportion of EVAIM out of the total ESV in this wheat field system was highest (accounted for 47.09%-55.64%), followed by EVAR and EVWC. The value of EVSNA was the lowest. However, the proportion of EVSNA was higher than that of water conservation after the fifth year of straw return. In general, the adoption of continuous straw returning in a wheat field ecosystem is ecologically valuable. The results can inform the development and implementation of ecological compensation policies involving straw return.

The TUBBY gene family is a group of transcription factors found in animals and plants with many functions. TLP genes have a significant role in response to different abiotic stresses. However, there is limited knowledge regarding the TUBBY gene family in T. aestivum. Here we identified 40 TaTLP genes in wheat to reveal their potential function. This study found that TUBBY (TaTLP) genes are highly conserved in wheat. The GO analysis of TaTLP genes revealed their role in growth and stress responses. Promoter analysis revealed that most TaTLPs participate in hormone and abiotic stress responses. The heatmap analysis also showed that TaTLP genes showed expression under various hormonal and abiotic stress conditions. Several genes were upregulated under different hormonal and temperature stresses. The qRT-PCR analysis confirmed our hypotheses. The results clearly indicate that various TaTLP genes showed high expression under temperature stress conditions. Furthermore, the results showed that TaTLP genes are expressed in multiple tissues with different expression patterns. For the first time in wheat, we present a comprehensive TaTLP analysis. These findings provide valuable clues for future research about the role of TLPs in the abiotic stress process in plants. Overall, the research outcomes can serve as a model for improving wheat quality through genetic engineering.

Cold stress in spring is an abiotic stress limiting the growth and productivity of winter wheat. A controlled pot experiment was done to explore the possibility of applying urea to alleviate the low temperature (3°C/−4°C, day/night)damage to wheat cultivar Yangmai 16 at jointing stage. Urea at different rates was applied at the 5th day after cold stress. Cold stress decreased grain yield and plant height. Compared with the unstressed control, the content of soluble sugar, proline, zeatin riboside (ZR), and abscisic acid (ABA) in the leaves was increased under longer cold stress. These above parameters in the stressed treatments without urea amendment were higher than those with urea amendment on the 10th day. The change in GA3 concentration was opposite to the concentrations of ABA and ZR. The decline in the concentrations of osmotic adjustment substances, balanced hormone concentrations, and increased grain number per ear and ear number were the main reasons for the increased grain yield after urea application. Remedial effects was enhanced with the higher urea remedial level under the same cold stress duration. Our study suggested that suitable urea remedial rates are recommended based on the freezing index in wheat to alleviate the impacts of low temperature on wheat production at jointing stage.

It is of great significance to explore the effects of different tillage practices on total nitrogen and its components in rice-wheat rotation farmland. The experiment was carried out in Jiangyan County, Jiangsu Province of China, and a total of four treatments were set up: minimum tillage (MT), rotary tillage (RT), conventional tillage (CT), and conventional tillage without straw retention (CT0). The total nitrogen (TN), light fraction nitrogen (LFN), heavy fraction nitrogen (HFN), particulate nitrogen (PN), and mineral-associated nitrogen (MN) in 0-20 cm soil were determined. The results show that MT increased TN concentration by2.26%-27.57% compared with the other treatments in 0-5 cm soil, but it lost this advantage in 5-10 cm and 10-20 cm soil. MT altered the concentration of LFN by 6.03%-95.86%, of HFN by 1.68%-20.75%, of PN by 12.58%-96.83%, and of MN by −1.73%-9.83% as compared to RT, CT, and CT0 in 0-5 cm soil, respectively. With the deepened of soil depth, the concentration of TN, LFN, HFN, PN, and MN decreased quickly in MT, which was lower than that in RT and CT at 10-20 cm soil depth. Straw return increased the concentration of TN and its components in 0-20 cm soil. The concentration of TN was extremely significantly positively correlated with that of LFN, HFN, PN, and MN (p<0.01). The variation of TN was significantly positively correlated with that of LFN, HFN, PN, and MN (p<0.01), and LFN showed the highest sensitivity to tillage practice. In general, minimum tillage combined with straw retention increased the concentration of soil TN and its components in topsoil. LFN was the best indicator to indicate the change in soil total nitrogen affected by tillage practice.