Although plastic film mulching is commonly utilized to enhance crop water use efficiency (WUE) in semi-arid areas, the combined effect of plastic film mulching and fertilizer application on Tartary buckwheat yield is still unknown. To address this gap, a four-year field experiment was conducted from 2018 to 2021 to investigate the effect of plastic film mulching and fertilizers on the soil water storage, plant growth, yield, and WUE of Tartary buckwheat in semi-arid environments. The treatments comprised traditional planting without fertilizer (TNF), traditional planting with fertilizer application (N–P2O5–K2O: 40–30–20 kg ha−1) (TF), plastic film mulching with fertilizer application (N–P2O5–K2O: 40–30–20 kg ha−1) (MF), and plastic film mulching without fertilizer (MNF). The results indicated that MF treatment significantly increased leaf area index and SPAD values compared to the other treatments. The yield of Tartary buckwheat under the film mulching increased by 23.3% in comparison to no-mulching treatments, and under fertilizer application it increased by 18.2% compared to no fertilizer. WUE under film mulching exhibited an increase of 3.1% in 2018, 34.9% in 2019, 45.5% in 2020, and 34.6% in 2021, respectively, compared to no mulching. The impact of film mulching on WUE was more significant in years with lower precipitation compared to those with normal or higher precipitation levels. Overall, MF significantly enhanced both the yield and WUE of Tartary buckwheat. This approach proved to be an effective strategy for bolstering drought-resistant yield and optimizing resource efficiency in Tartary buckwheat cultivation in semi-arid regions. Moreover, the positive effects of plastic mulching and fertilizer application on grain yield and water use efficiency were more pronounced in drier years.

Codonopsis pilosula (Franch.) Nannf. is an essential traditional medicinal herb in China. Soil sickness caused by continuous cropping is the main reason for the yield reduction of C. pilosula. However, because of the lack of systematic research on the mechanism of continuous cropping obstacles in C. pilosula, there is a lack of effective measures to reduce or even restrain the disorder of continuous cropping obstacles in C. pilosula. The root system, inter-root soil microorganisms and non-inter-root soil of C. pilosula under a continuous cropping system (e.g. crop rotation, two consecutive crops and three consecutive crops) as well as under different mulching methods (the mulched film and the uncovered) were used as experimental materials for the study. The plant growth of C. pilosula was significantly inhibited when continuous cropping reached 2 years. At the same time, the mulched film significantly (p < .05) promoted the development of C. pilosula under continuous cropping and considerably mitigated the plant death rate of C. pilosula in all fields. The content of soil nutrients, such as organic matter and inorganic nitrogen, decreased with increasing years of continuous cropping. In contrast, the mulched film improved this soil nutrient in continuous cropping. There was a tendency for the number of endemic operational taxonomic units (OTUs) to decrease in continuous cropping. Additionally, the mulched film altered the distribution of shared and endemic OTUs in the samples and had a recruiting effect on inter-root microorganisms in continuous cropping. Betaproteobacteriales flora abundance decreased with increasing years of continuous cropping, which showed a strong positive correlation with the immune system and environmental adaptation function. The mulched film increased the abundance of beneficial microorganisms, such as AKAU4049, Betaproteobacteriales and Gaiellales, to adapt and improve the continuous crop disorder of C. pilosula. In conclusion, mulching can enhance the soil environment and facilitate the growth and development of C. pilosula during continuous cultivation.

With the continuation of intensive and monoculture production in modern agriculture, the harm of continuous cropping obstacles is becoming more prominent. Pea has important nutritional and economic value, but it is easy to have continuous cropping obstacles in production. However, there is limited knowledge of the regulatory mechanisms of pea to cope with continuous cropping obstacles. In this study, we found that the number of differential expressed genes (DEGs) and differential metabolites (DAMs) increased in the pea roots with increasing continuous cropping times, and the number of DEGs and DAMs in roots of sensitive pea was more than that of continuous cropping tolerant pea. Comprehensive analysis of the omics data revealed that the flavonoid and isoflavonoid biosynthesis pathways play key roles in the response of pea roots to the continuous cropping obstacles. Most of the DEGs involved in these two pathways were up-regulated. Meanwhile, most of the flavonoid compounds and total flavonoid content increased. With increasing continuous cropping times, the isoflavones category in DAMs increased, and the isoflavones category in the roots of continuous cropping tolerant pea were higher than in sensitive pea. Additionally, the isoflavonoid (biochanin A, calycosin, genistein) in the roots of continuous cropping tolerant pea have the ability to inhibit the growth of fungi in pea soil and possess antioxidant activity. These findings revealed the important role of flavonoids in pea continuous cropping obstacles and laid a foundation for effectively alleviating pea continuous cropping obstacles in the future.

Excessive nitrogen fertilizer application is the main driving force threatening soil health and reducing multiple soil functions. The enhanced-efficiency nitrogen fertilizers （EENFs）, such as urease inhibitors （NBPT）, nitrification inhibitors （DCD）, and coated controlled-release urea （RCN）, have been proven to be effective measures for reducing nitrogen fertilizer application. However, the effects of EENFs on soil quality （SQI）, microbial metabolic characteristics, and soil ecosystem multifunctionality （EMF） and their internal relationships are still unclear. Therefore, based on the field positioning experiment started in 2019 by Pengyang Experimental Station of Guyuan City, Ningxia Hui Autonomous Region, we studied the effects of different fertilization strategies （no nitrogen fertilizer （N0）, mineral nitrogen fertilizer （N200）, DCD, NBPT, and RCN） on SQI, soil enzyme stoichiometry, and EMF under white plastic film mulching. The results revealed that： ① Compared with that under N0, N200 and EENFs increased soil total nitrogen （TN）, microbial biomass carbon （MBC）, and microbial biomass nitrogen （MBN） contents. Compared to the SQI of N0 and N200, that of NBPT and DCD significantly increased by 59.97%-104.78% and 43.28%-83.42%, respectively, while RCN showed no significant change. ②EENFs can alleviate microbial carbon and nitrogen limitations better than N200 and increase soil EMF by 21.97% -51.53%. ③ The MBC, MBN, available nitrogen （AN）, available phosphorus （AP）, and water content （SWC） of soil factors were the common main factors affecting microbial C limitation, N limitation, and soil EMF. Moreover, the improvement in soil quality and alleviating microbial C and N limitation were conducive to improving soil EMF. Overall, the NBPT and DCD application under white plastic film mulching can achieve a win-win situation of soil health and EMF in the short term, which can provide references for optimizing local fertilization management measures.

Mulching is widely adopted in arid regions to improve soil environment and crop productivity. However, our understanding of the underlying mechanisms of such improvements from enzyme activity and rhizosphere microbial community structure perspectives remain poor. To fill the gap, soil zymography was coupled with high-throughput sequencing to investigate enzyme activities and bacterial community structure in a 10-year field experiment in a semi-arid region. We examined the effects of two mulching measures (plastic film mulching [FM] and straw mulching [SM], with no mulching as the control [CK]) on the maize rhizosphere extent of β-glucosidase and leucine aminopeptidase activities and the abundance of the bacterial genes encoding these two enzymes. The enzyme activity in the SM and FM measures was higher compared to the CK measures (P < 0.05). SM had higher influence than FM on β-glucosidase activity and its rhizosphere extent. This was related to the increase in soil organic carbon (SOC) content and the stable bacterial community structure and interactions under SM. In contrast, leucine aminopeptidase activity was the highest under FM due to the higher soil temperature and moisture content under FM which further intensified nutrient competition among microorganisms or between microorganisms and plants. In addition, Proteobacteria and Acidobacteria were the major contributors to β-glucosidase activity despite their genes encoding β-glucosidase not increasing under SM. Conversely, the copy number of genes encoding leucine aminopeptidase and the genes encoded by Proteobacteria (the main contributor) decreased under FM. Therefore, total gene number is not a stable indicator of microbial function (such as enzyme activity) and cannot explain enzyme activity adequately. Overall, this study establishes a connection between rhizosphere enzyme activity and bacterial communities, revealing the mechanisms by which changes in environmental nutrient supply and bacterial community composition under straw mulching and plastic film mulching measures lead to variations in enzyme efficiency.

Density and fertilization mode are the key factors regulating crude protein synthesis in forage maize; however, there is a lack of systematic understanding of the regulation mechanism. Here, the nitrogen/potassium ratio (N/K), free amino acid (AA) content, crude protein synthesis key enzyme activities (nitrate reductase (NR), glutamine synthetase (GS) and glutamic pyruvic transaminase (GPT)) and crude protein content and yield in leaves, stems, and grain of forage maize, as well as the relationships among them, were explored. The results showed that the N/K of DL-40 (60,000 plants per ha−1, 40% N topdressing at large trumpet stage) and DH-50 (75,000 plants per ha−1, 50% N topdressing at large trumpet stage) significantly increased in leaves, stems, and grain, and correspondingly, NR, GS, and GPT activities in leaves, NR activities in stems, NR and GPT activities in grain, and delayed the decline in AA content. After tasseling, for DL-40 and DH-50 the crude protein content increased by 74.1% and 39.8% in leaves, respectively, 19.9% and 25.6% in grain, respectively, and crude protein yield increased by 16.7% and 35.2% in leaves, respectively, and 23.5% and 25.9% in grain, respectively. There were significant quadratic parabolic relationships of NR, GS, and GPT activities with proportion of topdressing. There was a significant relationship of crude protein content with NR activity in leaves, with NR, GS, and GPT activities in stems and with GPT activity in grain. Regulating the key enzyme activity by adjusting the density and fertilization can significantly improve the crude protein yield of forage maize. Treatments DL-40 and DH-50 significantly increased crude protein content and yield by increasing plant N/K, NR activity in leaves, NR activity in stems, and GPT activity in grain, but slowed the decrease in AA content in leaves, stems, and grain.

Drought severely affects potato yield and quality. The overexpression of dehydration-responsive element binding proteins/C-repeat-binding factor (DREB1A/CBF3) was previously reported to significantly increase the drought tolerance in transgenic potato (Solanum tuberosum L.), but its molecular mechanism is poorly understood. In the present study, potato cultivar Longshu No. 3 (NT) and its derived transgenic plants (T) with the Arabidopsis DREB1A gene driven by stress-inducible promoter rd29A were used as materials to study drought-stress responses of AtDREB1A in transgenic potato. The results showed, under drought stress, that the AtDREB1A gene was overexpressed in T and T presented a healthier phenotype, higher biomass, higher content of proline and lower content of malondialdehyde than the control NT, indicating that AtDREB1A overexpression improved potato drought tolerance. As the main organ of absorbing and transporting water and nutrients in soil, roots are the first to feel the stress of drought stress. Transcriptome analysis of roots showed that compared with control NT, a total of 533 annotated genes with at least two-fold changes were found to be differentially expressed in transgenic potato roots, comprising 262 up-regulated and 271 down-regulated genes. Among them, the expression of a large number of genes related to abscisic acid metabolism, receptor-like protein kinases, cytochrome P450, the glycosyl hydrolase family, peroxidase, F-box proteins and the heat shock protein family changed greatly, indicating that these genes were responsive to AtDREB1A expression and play important roles in improving drought tolerance of AtDREB1A transgenic potato. This study lays a foundation for further understanding the regulatory network of AtDREB1A gene in improving drought tolerance in potato.

The Yellow River Basin, which accommodates the second longest river in China - Yellow River, covers a total area of 795,000 km(2) and plays an important role in the national agricultural production, economy, and culture. However, the Basin also faces enormous challenges related to sustainable water management in agriculture as driven by both drought and flood. In this special issue, we collected 64 articles across the Basin to improve our understanding of agricultural water management needs and demonstrate efficacies of management practices to improve the water management. The articles present exciting research on regional soil water storage and dynamics, soil moisture conservation in rain-fed agriculture, crop water demand, irrigation effects, water-nutrient coupling, water management and soil salinity, soil and nutrient losses, groundwater science and management. Findings of studies revealed: (1) the importance of mulching, drip and negative pressure irrigation, water and nutrient coupling (i.e., fertigation) in achieving both crop production and environmental protection objectives; (2) emerging research for better understanding of regional water resources and allocation of the water resources among different agricultural land uses and cropping systems, new approaches for conserving water and soil and mitigating soil salinity, system-level integrated rainfall and irrigation management, and improved knowledge on groundwater quantity and quality management; and (3) need of future research to understand processes and efficiencies of management practices in variable landscapes and cropping systems and variable and changing climates, and system-level linkages and analyses of water balance - soil water availability and conservation - water and soil losses - agricultural and environmental sustainability.

为探求旱地冬小麦全生物降解地膜绿色覆盖栽培条件下有机肥氮替代化肥氮的适宜比例,于2020-2021年在甘肃定西布设大田试验,比较分析了单施化肥(CK)、15％有机肥氮替代化肥氮(OR15)、30％有机肥氮替代化肥氮(OR30)、45％有机肥氮替代化肥氮(OR45)处理下旱地冬小麦干物质积累、籽粒产量、耗水量、水分利用效率、氮素效率等的差异.结果表明,与CK相比,适宜比例的有机肥替代化肥可有效调节冬小麦生长发育,优化干物质积累和耗水过程,提高籽粒产量和水肥利用效率.有机肥替代处理的花前群体干物质积累量均显著低于CK,而OR15和OR30处理的花后群体干物质积累量分别较CK增加了 20.22％和5.39％,OR45处理则降低21.84％;与CK相比,OR15处理增产6.15％,OR30和OR45处理分别减产2.87％和10.43％;OR15和OR30处理的水分利用效率较CK提高了 7.76％和3.78％,OR45处理降低了 1.89％;OR15、OR30和OR45处理的生育期耗水量分别较CK低1.53％、6.43％和8.67％,而花后耗水量分别高7.46％、1.82％和0.80％;相比于CK,适宜比例的有机肥替代化肥主要通过增加小麦穗数和千粒重提高籽粒产量;有机肥替代处理均显著提高了冬小麦氮素利用效率、氮素收获指数和化肥氮偏生产力,且分别平均较CK提高了 10.36％、4.46％和42.16％;OR15处理的籽粒氮积累量较CK增加了 7.81％,OR30和OR45处理分别降低了 8.63％和20.35％.通过综合分析,有机肥氮15％替代化肥氮可作为陇中旱地冬小麦全生物降解地膜绿色覆盖栽培条件下实现小麦稳产增产及提质增效的氮素管理模式.

Reducing the amount of plastic film while maintaining high water use efficiency & soil health is a huge challenge globally. A two-year field investigation showed that full and half plastic film mulching harvested greater in-season rainfall infiltration into soils, and significantly greater grain yield and water use efficiency under the no-tillage conditions than under the tillage conditions. Among the no-tillage treatments, half plastic film mulching resulted in significantly greater soil light fraction organic carbon by 42.7% and particulate organic carbon by 41.2% than full plastic film mulching respectively, due to its enhanced extramatrical hyphal length, glomalin production and root biomass input. Owing to higher water availability, soil nutrient uptake was accordingly enhanced under no-tillage. This phenomenon was tightly correlated with the improved abundance of arbuscular mycorrhizal fungi. Therefore, it might be feasible and efficient to massively reduce plastic mulching but improve water use efficiency and soil health in semiarid environment.

Integrated hole-sowing, fertilization, and plastic mulching techniques are common agronomic practices applied to collect rainwater and to improve rainwater utilization in semiarid rain-fed regions. However, little is known about the growth responses of tartary buckwheat (Fagopyrum tataricum L.) to the practices adopted in semiarid areas of Loess Plateau in Northwest China. To address the concerns, a long-term field experiment was conducted in 2015–2017. Four fertilization levels, namely, high fertilization level (N–P2O5–K2O: 120–90–60 kg ha−1, HF), moderate fertilization level (80–60–40 kg ha−1, MF), low fertilization level (40–30–20 kg ha−1, LF), and zero fertilization level (ZF), were applied to hole-sown tartary buckwheat with whole plastic mulching, in comparison to the control with no-mulching and zero fertilization (CK). Several key growth-influencing indicators were measured in the consecutive experimental years, including soil temperature (Ts), soil water storage (SWS), leaf area index (LAI), dry matter (DM), and grain yield. The results showed that in different precipitation years, 2015 (193 ± 23 mm), 2016 (149 ± 19 mm), and 2017 (243 ± 28 mm), the ZF, LF, MF, and HF treatments had the potential to optimize Ts in 0~25 cm soil layers (at 5 cm interval). The four treatments improved SWS in 0~300 cm soil layers by 3.5% and increased soil water consumption in the pre-anthesis period by 22.4%, compared with CK. Moreover, the four treatments shortened the pre-anthesis growth period by 0.4~5.4 d, while extended the post-anthesis growth period by 5.7~10.0 d, giving rise to an overall extension of 0.6~5.0 d for a whole growth period of tartary buckwheat. Furthermore, the ZF, LF, MF, and HF treatments increased LAI by 4.4~225.3% and DM weight by 41.5~238.0%. The rain yield of the four treatments was increased by 14.0~130.4%, and water use efficiency (WUE) was improved by 11.3~102.7%, especially for the LF treatment, compared with CK. The study indicated that the technique of hole-sowing and plastic mulching combined with a low fertilization rate was an effective measure for tartary buckwheat to optimize crop growth and to boost grain yield and WUE on semiarid lands.

针对目前马铃薯原原种生产所用的蛭石资源短缺,造成生产成本高和污染环境严重等问题,研究了中药材秸秆腐熟后用于马铃薯原原种生产,通过与其他材料进行合理配比的中药材秸秆基质对马铃薯脱毒苗农艺性状及原原种产量的影响.结果表明:中药材秸秆基质在马铃薯脱毒苗生长中后期优势更加明显,能够给脱毒苗生长提供更多的养分,有利于马铃薯原原种的结薯和膨大,特别是处理T2(100%黄芪秸秆基质)表现最为突出,T7(50%黄芪加 50%党参复合秸秆基质加 15%蛭石)次之;但是脱毒苗生长前期矿物质基质持水稳定性和脱毒苗成活率均好于中药材基质.

Ridge and furrow plastic film mulching (RFM) has improved net primary productivity (NPP) to a high level in semi-arid rainfed agricultural regions. Yet, it is unclear whether there is still a room for further improvement on NPP while stabilizing soil organic carbon through returning previous maize stover pieces. To address this issue, maize stubbles were smashed into pieces and in situ ploughed into 30 cm topsoil at a semi-arid site in northwest China from 2016 to 2017. This was done using the Pioneer 335 maize variety with three treatments (CK, ridge and furrow without mulching; RFM, ridge and furrow with plastic mulching; RFML, 3.49 t ha(-1) of maize stover returning in RFM; RFMH, 5.24 t ha(-1) of returning in RFM). The results indicated that maize stover returning exhibited similar trend as RFM at early cool seedling stage, raising the topsoil temperature. However, in warm and dry silking stage (2017), both stover returning rates reduced soil temperatures by 1.33 and 0.8 C-degrees relative to RFM and CK (P < 0.05), respectively. The soil water storage increased significantly in RFMH by 17.3% and RFML by 28.5% relative to that of RFM, in a warm and dry growing season (2017). Critically, stover returning increased (P < 0.05) soil organic carbon and light fraction organic carbon turnover across the two growing seasons. By improving hydrothermal conditions, stover returning in RFM increased biomass accumulation and grain yield (P < 0.05), leading to higher (P < 0.05) net economic benefit, with greater above-ground biomass NPP (74.5-93.2%) and below-ground biomass NPP (88.5-89.4%), compared with CK. In conclusion, maize stover returning of stover pieces into topsoil might be a promising solution to enhance carbon turnover for higher net primary productivity on the basis of plastic film mulching in semiarid rainfed region.

Plants cannot grow or develop properly without the support of their roots. Gravity plays an essential role in the formation of the root structure, but it is not clear how roots respond to gravity signals or how downward growth occurs. The two best-known models for root gravity sensing affirm the importance of starch. After the hyper-sensitive root crown perceives a gravity signal, starch granules within the rootlet cells settle to the endoplasmic reticulum in the direction of the signal, where they bind to specific receptors or open ion channels and release downstream signaling molecules. This triggers a series of signal transduction mechanisms, and this process involves signaling molecules such as indole-3‐acetic acid (IAA), reactive oxygen species, and calcium signaling, which ultimately induce groundward root growth. This review summarizes the mechanism of action underlying, and a research overview of, how plant roots sense and respond to gravity. The role of key signals such as starch, IAA, and calcium ions in root gravitropism is analyzed by integrating available information. The results provide a more complete theoretical basis for how roots grow toward gravity, which will contribute to our understanding of gravitropism and lay the foundation for discovering new directions of scientific research. The graphics developed in this article are done by Microsoft Office PowerPoint 2010, Adobe Illustrator 2018 and ChemDraw 20.0.

Background Continuous cropping is a significant obstacle to sustainable development in the pea ( Pisum sativum L.) industry, but the underlying mechanisms of this remain unclear. In this study, we used 16 S rDNA sequencing, transcriptomics, and metabolomics to analyze the response mechanism of roots and soil bacteria to continuous cropping and the relationship between soil bacteria and root phenotypes of different pea genotypes (Ding wan 10 and Yun wan 8). Results Continuous cropping inhibited pea growth, with a greater effect on Ding wan 10 than Yun wan 8. Metabolomics showed that the number of differentially accumulated metabolites (DAMs) in pea roots increased with the number of continuous cropping, and more metabolic pathways were involved. Transcriptomics revealed that the number of differentially expressed genes (DEGs) increased with the number of continuous cropping. Continuous cropping altered the expression of genes involved in plant-pathogen interaction, MAPK signal transduction, and lignin synthesis pathways in pea roots, with more DEGs in Ding wan 10 than in Yun wan 8. The up-regulated expression of genes in the ethylene signal transduction pathway was evident in Ding wan 10. Soil bacterial diversity did not change, but the relative abundance of bacteria significantly responded to continuous cropping. Integrative analysis showed that the bacteria with significant relative abundance in the soil were strongly associated with the antioxidant synthesis and linoleic acid metabolism pathway of pea roots under continuous cropping once. Under continuous cropping twice, the bacteria with significant relative abundance changes were strongly associated with cysteine and methionine metabolism, fatty acid metabolism, phenylpropanoid biosynthesis, terpenoid backbone biosynthesis, linoleic acid, and amino sugar and nucleotide sugar metabolism. Conclusion Ding wan 10 was more sensitive to continuous cropping than Yun wan 8. Continuous cropping times and pea genotypes determined the differences in root metabolic pathways. There were common metabolic pathways in the two pea genotypes in response to continuous cropping, and the DEGs and DAMs in these metabolic pathways were strongly associated with the bacteria with significant changes in relative abundance in the soil. This study provides new insights into obstacles to continuous cropping in peas.

由于甘肃省中西部大面积耕地不同程度沙化,严重影响作物生长和该区农业发展.通过近几年对沙化土壤改良剂配方、施用量、施用时间和方法等进行多年试验、示范并反复验证,研究提出了甘肃中西部灌区沙化土地改良技术,为了提高该技术的应用效果,从技术范围,规范性引用文件,术语定义,沙化土地改良技术的选地、整地平地、改良剂施用、施肥翻耕、第 1 茬作物选择、播种、田间管理、轮作模式、收获和改良效果等方面规范了甘肃中西部灌区沙化土地改良技术,以期为甘肃省及我国西北灌区的沙化地改良种植提供了科学依据,促进甘肃省乃至全国沙化地生态修复.

Appropriate crop rotations are beneficial for food security and carbon sequestration. In cool and semiarid rain-fed areas, however, the effect on carbon sequestration in soil and the soil-crop system is not clear. In this study, a crop rotation field experiment was carried out on the Loess Plateau, China, involving (1) wheat continuous cropping (WCC), (2) maize continuous cropping (MCC), (3) potato continuous cropping (PCC) and (4) wheat-maize-potato rotating cropping (RC). All treatments were tilled once, and then, plastic mulched immediately to inhibit evaporation. We found that the rotating cropping system improved water storage in the 0-300 cm soil profile by 65.8 mm through the 6 years, while MCC depleted deep soil moisture. In a drought year, total dry matter (DM) for the rotating cropping was greater by 23.9% and 79.3% and harvested carbon quantity (HCQ) by 0.6 and 1.8 Mg ha(-)(1) compared with WCC and MCC systems, respectively. Total evapotranspiration significantly decreased by 14.5% compared with MCC, with no significant change compared with WCC and PCC. The soil organic carbon (SOC) concentration at 20-30 cm depth in the rotating cropping system was 36.0%, 28.0% and 30.3% greater than those of WCC, MCC and PCC, respectively. Similarly, the SOC sequestration rate at this depth was higher by 3.8, 3.2 and 3.4 Mg ha(-)(1), respectively. The pure carbon accumulation (PCA) of the rotating cropping system significantly increased compared with WCC and PCC, resulting in increased water use efficiency of pure carbon accumulation (WCP) by 11.1, 2.2 and 3.1 Mg ha(-)(1) mm(-)(1) compared with the WCC, MCC and PCC systems, respectively. Overall, the rotating cropping (RC) system maintained better soil water conditions, sustained crop development and SOC sequestration, especially optimizing the relationship between crop water utilization and SOC sequestration in soil-crop system in the cool semiarid rain-fed area.

Autotoxicity is one of the main problems in continuous cropping. The aims of this study were to identify potential autotoxins in soil where pea（Pisum sativum） had been cultivated and to explore their autotoxic effects. We collected rhizosphere soil from two pea genotypes（cultivars Ding wan 10 and Yun wan 8） in the field, and used gas chromatography-mass spectrometry（GC-MS） to identify potential autotoxins in these soil samples. Then, the effects of potential autotoxins at different concentrations on the seed germination, seedling growth, and physiological indexes of pea（cultivars Ding wan 10 and Yun wan 8） were evaluated using a hydroponic system. Erucamide was detected as a potential autotoxin in both pea genotypes. Erucamide at a concentration of 0. 1 mmol·L -1 promoted the germination of Ding wan 10 seeds, and erucamide at concentrations of 0. 10, 0. 25 and 0. 50 mmol·L -1 promoted the germination of Yun wan 8 seeds. It was found that erucamide at different concentrations significantly decreased the activities of superoxide dismutase（SOD） and peroxidase（POD）, and increased the malondialdehyde（MDA） content in Ding wan 10. A high concentration of erucamide significantly increased the MDA content in Yun wan 8, and decreased the proline（Pro） content and POD activity in pea roots. These analyses of the allelopathic effects of potential autotoxins on pea plants revealed that erucamide inhibited the growth of two pea genotypes, with a stronger inhibitory effect on Ding wan 10 than on Yun wan 8. Thus, erucamide is a potential autotoxin in pea rhizosphere soil, and its effects depend on its concentration. A low concentration can promote seed germination but higher concentrations can inhibit seed germination and plant growth. The degree of promotion and inhibition varies among different pea genotypes.

Fully biodegradable (Bio) plastic film is an alternative option to replace widely used polythene film in semiarid rainfed regions. However, its productivity and environmental friendliness remain unclear. Field observations were conducted using maize variety Pioneer 335 to evaluate the effects of Bio film mulching on soil hydrothermal status, carbon sequestration, and water productivity in a semiarid site of northwest China from 2016 to 2017. Six treatments were designed as (1) CK-1, ridge and furrow (RF) without mulching, (2) CK-2, conventional flat planting without mulching, (3) RFT, RF with transparent polyethylene film mulching, (4) RFB, RF with black polyethylene mulching, (5) RFS, RF with wheat straw mulching, and (6) RFBIO, RF with Bio film mulching. The results indicated the growth prophase of maize from sowing to silking stage received 160 mm of rainfall in cool and wet 2016, but decreased to 119.8 mm in warm and dry 2017. Bio film degradation was advanced at the mid stages of maize growth by 10 days in 2017 compared with 2016. Similarly to RFT, RFBIO significantly improved soil hydrothermal conditions compared with RFS, CK-1, and CK-2; however, its magnitude decreased at the maturity stage (P < 0.05). Both RFT and RFB had significantly higher grain yields, economic benefits and water use efficiencies than RFBIO and RFS did across two growing seasons (P < 0.05). RFBIO led to a steady improvement in soil organic carbon, light fraction organic carbon, and carbon to nitrogen ratio, which were better than those of RFT. Therefore, Bio film mulching might be environmentally friendly but not highly productive.

Plastic mulching (PM) is regarded as a promising way to increase crop production. However, its reported that plastic mulching may decrease soil organic carbon content and been unfavorable for sustainable agricultural production. Confirmation of the effects of plastic mulching on soil water and organic carbon balances in a long term, including finding efficient ways to improve these balances, is crucial for the sustainability of agricultural production in semiarid rain-fed areas. We conducted field experiment (2010-2019), with spring maize and wheat as tested crops, using four treatments of plastic mulching (PM), plastic mulching with supplementary irrigation (PMI), plastic mulching with organic fertilizer application (PMO) and without mulching (CK). The results of this 10-year field experiment showed that PM with supplementary irrigation and organic fertilizer application not only significantly increased yield and Water productivity (WP) of wheat and maize, but also had a positive effect on soil water budget. The soil water budget of PMI, PMO and PM significantly increased by 120.4%, 96.1% and 105.8% in wheat and by 149.7%, 28.2% and 53.6% in maize, compared with CK, respectively. The improved soil water condition resulted in a significant increment of yield, PMI, PMO and PM increased yield by 122.8%, 89.7% and 67.0% for wheat, by 237.8%, 183.0% and 148.4% for maize, respectively, compared with CK. The 10 years of continuous PM significantly decreased soil organic carbon content (SOC) in 0-10, 10-20, 30-50 and 50-70 cm profiles by 22.5%, 19.1%, 15.6% and 15.3% for wheat, but had no significant effect for maize. The PMO significantly increased soil organic carbon content in 0-30 cm profiles for both wheat and maize, but the soil organic carbon budgets were negative for all four treatments, the PMO accelerated soil organic carbon loss for maize but had little effect for wheat compared with PM and CK. However, PMI, PMO and PM significantly in-creases crop bio-carbon production, resulted in the positive total carbon budget and significantly increased by 25.0, 15.0, 11.5 Mg ha(-1) in wheat and 105.1, 74.1, 74.0 Mg ha(-1) in maize, respectively, as compared with CK. These results suggested that the soil organic carbon budget differed for the two crops, also affected by water or organic carbon supplementation. A more appropriate crop rotation system with organic fertilizer application should be developed, to increase crop production and soil quality under plastic mulched condition in such semiarid rain-fed areas.