Investigating Verticillium wilt occurrence in cotton and its risk management by the direct return of cotton plants infected with Verticillium dahliae to the field.

Verticillium wilt is one of the most crucial diseases caused by Verticillium dahliae that threatens the cotton industry. Statistical results showed that the return of cotton plants infected with V. dahliae to the field might be an essential cause of the continuous aggravation of cotton Verticillium wilt. The correlation among the cotton plants infected with V. dahliae returning to the field, the occurrence of Verticillium wilt, and the number of microsclerotia in rhizosphere soil need further investigation. A potted experiment was carried out to explore the effects of the direct return of cotton plants infected with Verticillium dahliae to the field on the subsequent growth and Verticillium wilt occurrence in cotton. As a risk response plan, we investigated the feasibility of returning dung-sand (i.e., insect excreta) to the field, the dung-sand was from the larvae of Protaetia brevitarsis (Coleoptera: Cetoniidea) that were fed with the V. dahliae-infected cotton plants. The results demonstrated that the return of the entire cotton plants to the field presented a promotional effect on the growth and development of cotton, whereas the return of a single root stubble or cotton stalks had an inhibitive effect. The return of cotton stalks and root stubble infected with V. dahliae increased the risk and degree of Verticillium wilt occurrence. The disease index of Verticillium wilt occurrence in cotton was positively correlated with the number of microsclerotia in the rhizosphere soil. The disease index increased by 20.00%, and the number of soil microsclerotia increased by 8.37 fold in the treatment of returning root stubble infected with V. dahliae to the field. No Verticillium wilt microsclerotia were detected in the feed prepared from cotton stalks and root stubble fermented for more than 5 days or in the transformed dung-sand. There was no risk of inoculation with Verticillium wilt microsclerotia when the dung-sand was returned to the field. The indirect return of cotton plants infected with V. dahliae to the field by microorganism-insect systems is worthy of further exploration plan of the green prevention and control for Verticillium wilt and the sustainable development of the cotton industry.

Food-water-land-ecosystem nexus in typical Chinese dryland under different future scenarios.

Healthy coupling of the food-water-land-ecosystem (FWLE) nexus is the basis for achieving sustainable development (SD), and FWLE in drylands is frontier scientific issues in the study of coupled human land systems. To comprehensively safeguard the future food, water, and ecological security of drylands, this study examined the implications for FWLE linkages in a typical Chinese dryland from the perspective of future land-use change. First, four different land-use scenarios were proposed using a land-use simulation model with a gray multi-objective algorithm, including an SD scenario. Then, the variation of three ecosystem services was explored: water yield, food production, and habitat quality. Finally, redundancy analysis was used to derive the future drivers of FWLE and explore their causes. The following results were obtained. In the future in Xinjiang, under the business as usual scenario, urbanization will continue, forest area will decrease, and water production will decline by 371 million m3. In contrast, in the SD scenario, this negative impact will be substantially offset, water scarcity will be alleviated, and food production will increase by 1.05 million tons. In terms of drivers, the anthropogenic drivers will moderate the future urbanization of Xinjiang to some extent, with natural drivers dominating the sustainable development scenario by 2030 and a potential 22 % increase in the drivers of precipitation. This study shows how spatial optimization can help protect the sustainability of the FWLE nexus in drylands and simultaneously provides clear policy recommendations for regional development.

The Effects of Oil and Gas Produced Water on Soil Bacterial Community Structure in the Arid Desert Area.

The safe utilization and risk assessment of produced water (PW) from oil and gas fields for desert irrigation have received increasing attention in recent years. In this context, this study aimed to analyze structural changes in soil bacterial community, and assess the environmental impact of PW discharge and irrigation over time. High-throughput sequencing technology was employed to examine the structure of the soil bacterial community in the constructed wetland and its surrounding desert vegetation irrigation region where PW was released for a considerable amount of time (30 years). The results revealed that long-term discharge of PW and irrigation significantly reduced the abundance of the soil bacterial community but did not significantly alter the richness and diversity of the soil bacterial community. Proteobacteria was the dominant bacterial phyla in soil, but in irrigated and drained areas, the dominant bacterial phyla changed from Alphaproteobacteria to Gammaproteobacteria, the Firmicutes abundance was significantly reduced.

Effects of mulching film on soil microbial diversity and community of cotton.

Different types of mulching film could variously influence soil properties and plant growth. Yet, surprisingly few studies have investigated the effects of mulching film upon soil microbial diversity and community structure. In this research, two kinds of mulching film, a traditional PE (polyethylene) mulching film and a degradable PBAT ((Poly [butyleneadipate-co-terephthalate])) mulching film, were applied to cotton (Gossypium spp.) plants grown in Xinjiang Province, China. The respective influence of the two mulching films on the cotton's soil microbial (bacteria and fungi) diversity and community were investigated. The results showed that applying the PBAT mulching film could significantly alter the diversity of non-rhizosphere soil fungi when compared to using the PE mulching film. However, neither the PE nor PBAT mulching film had any significant influence on the diversity of soil bacteria and rhizosphere soil fungi. Nevertheless, soil microbial community composition differed under the PBAT mulching film treatment vis-à-vis the PE mulching film treatment. The abundance of Gibellulopsis was higher under the PBAT than PE mulching film treatment. Our study's findings provided an empirical basis for the further application of degradable PBAT mulching film for the sustainable development of cotton crops.

The Mechanisms Responsible for N Deficiency in Well-Watered Wheat Under Elevated CO2.

Elevated CO2 concentration [e(CO2)] often promotes plant growth with a decrease in tissue N concentration. In this study, three experiments, two under hydroponic and one in well-watered soil, including various levels or patterns of CO2, humidity, and N supply were conducted on wheat (Triticum aestivum L.) to explore the mechanisms of e[CO2]-induced N deficiency (ECIND). Under hydroponic conditions, N uptake remained constant even as transpiration was limited 40% by raising air relative humidity and only was reduced about 20% by supplying N during nighttime rather than daytime with a reduction of 85% in transpiration. Compared to ambient CO2 concentration, whether under hydroponic or well-watered soil conditions, and whether transpiration was kept stable or decreased to 12%, e[CO2] consistently led to more N uptake and higher biomass, while lower N concentration was observed in aboveground organs, especially leaves, as long as N supply was insufficient. These results show that, due to compensation caused by active uptake, N uptake can be uncoupled from water uptake under well-watered conditions, and changes in transpiration therefore do not account for ECIND. Similar or lower tissue NO 3 - -N concentration under e[CO2] indicated that NO 3 - assimilation was not limited and could therefore also be eliminated as a major cause of ECIND under our conditions. Active uptake has the potential to bridge the gap between N taken up passively and plant demand, but is limited by the energy required to drive it. Compared to ambient CO2 concentration, the increase in N uptake under e[CO2] failed to match the increase of carbohydrates, leading to N dilution in plant tissues, the apparent dominant mechanism explaining ECIND. Lower N concentration in leaves rather than roots under e[CO2] validated that ECIND was at least partially also related to changes in resource allocation, apparently to maintain root uptake activity and prevent more serious N deficiency.

Element Geochemistry of Lake Sediments from L07-10 in the "Great Ear" Area of Lop Nur and Its Significance for Climate Variation Change with ICP-OES.

Spectral analysis techniques were applied to geochemical element analysis to provide additional environmental data about evolution of salt lakes and climate change. The elements composition of lake sediments from L07-10 in the "Great Ear" Area of Lop Nur was analyzedby using Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES )and from 14 C carbon dating by using the EN accelerator mass spectrometry (AMS).This paper estimated the climate change in this region since 16.34 ka BP. Results demonstrate that the geochemical characteristics of major elements at all sediment levels can indicate environmental change sensitivity, and element composition is more sensitive to climate change. Overall, climate succession since 16.34 ka BP had been: warm-wet, warm-dry, cold-wet and warm-dry. From 8.09~6.34 ka BP，the climate obviously heated up and was warmer and drier, which is consistent with global and regional climate change estimates from other studies. By about 2 ka BP, the climate becomes warmer and drier and the water carrying capacity of this lake was reduced.

[Analysis of chemical speciation of heavy metals in L07-11 profile sediments of "Big Ear" Region of Lop Nor Lake].

As playa is the typical characteristic in "Big Ear" Region of Lop Nor Lake, it is significant for enriching playa heavy metal earth environmental chemical data by analyzing species distribution of heavy metal among this district. In this thesis, heavy metal Cd, Pb, Ni, Cu in L07-11 Profile Sediments of "Big Ears" Region of Lop Nor Lake are considered as research objects. Tessier sequential extraction and Graphite furnace atomic absorption method (GF-990) are used to discuss and analyze five forms of Cd, Pb, Ni, Cu among sediments. The results show that the content of Cd, Pb, Ni and Cu is in the range from 1.10~2.54, 9.18~20.02, 9.88~17.15, 4.43~21.11 mg · kg(-1), respectively. The value of organic matter range from 8.71-54.72 g · kg(-1). The order of the bioavailable state in heavy metals is Cd>Pb>Cu>Ni. Pb and Cd mainly exist in exchangeable form including water-soluble, and that Ni is in residual form, and that Cu is mostly in Fe-Mn oxide bound iron-manganese oxides or in residual form. Among surface sediments, effective content of heavy metal is more than 80%. Except Cu, the content of heavy metal Cd, Pb, Ni in exchangeable form is more than 60%. Heavy metal Cd and Pb has higher secondary release potential. The content of heavy metal and organic material has some correlation.

[Measuring soil water content by using near infrared spectral characteristics of soil].

Different textured soils (sandy loam, silty clay loam and clay) from Manas County, Xinjiang were researched with indoor spectral reflectance, continuum removal was used to process soil spectra curve, and correlation analysis was made about normalized spectral reflectance and water content for modeling. The results show that different textured soils have reflectance in a order that clay>silty clay loam>sandy loam; the critical points of field capacity in sandy loam, silty clay loam and clay were 20.01%, 24.10% and 30.43% respectively, and water content was inversely proportional to spectral reflectance below such critical points while proportional above the points. Within 1390-1623 nm band, the negative correlation coefficients of soil water content and normalized spectra reflectance show better negative correlation and reaching significant levels, R2 of the model established for soil water content prediction exceeded mostly 0.8, and the average relative error of the model was 10%. The model could accurately reflect the soil moisture content, Its advantages such as accuracy, non-destruction and rapidness provide a new approach to measuring soil water content.

Synthesis, characterization, and antifungal activity of novel quaternary chitosan derivatives.

Three novel quaternary chitosan derivatives were successfully synthesized by reaction of chloracetyl chitosan (CACS) with pyridine (PACS), 4-(5-chloro-2-hydroxybenzylideneamino)-pyridine (CHPACS), and 4-(5-bromo-2-hydroxybenzylideneamino)-pyridine (BHPACS). The chemical structure of the prepared chitosan derivatives was confirmed by Fourier transform infrared (FT-IR) and (13)C nuclear magnetic resonance ((13)C NMR) and their antifungal activity against Cladosporium cucumerinum, Monilinia fructicola, Colletotrichum lagenarium, and Fusarium oxysporum was assessed. Comparing with the antifungal activity of chitosan, CACS, and PACS, CHPACS and BHPACS exhibited obviously better inhibitory effects, which should be related to the synergistic reaction of chitosan itself with the grafted 2-[4-(5-chloro-2-hydroxybenzylideneamino)-pyridyl]acetyl and 2-[4-(5-bromo-2-hydroxybenzylideneamino)-pyridyl]acetyl.

The effects of drying following heat shock exposure of the desert moss Syntrichia caninervis.

Desert mosses are components of biological soil crusts (BSCs) and their ecological functions make assessment and protection of these mosses a high-ranking management priority in desert regions. Drying is thought to be useful for desert mosses surviving heat shock. In this study, we investigated the role of drying by monitoring the responses of physiological characters and asexual reproduction in the typical desert moss Syntrichia caninervis. Heat significantly decreased chlorophyll content and weakened rapid recovery of photochemical activity, and increased carotenoid content and membrane permeability. Lethal temperatures significantly destroyed shoot regeneration potential. In comparison with heat alone, drying significantly increased protonema emergence time and depressed protonema emergence area. Drying combined with heat accelerated water loss, followed by a decrease of photosynthetic activity. Drying had different influences on membrane permeability at different temperatures. When moss leaves were subjected to a combined stress of drying and heat shock, photosynthesis was maintained mainly due to the effects of drying on physiological activity although the cellular morphological integrity was affected. Drying caused opposing effects on moss physiological and reproductive characteristics. On the one hand, drying caused a positive synergistic effect with heat shock when the temperature was below 40 degrees C. On the other hand, drying showed antagonism with heat shock when the moss was subjected to temperatures higher than 40 degrees C. These findings may help in understanding the survival mechanism of dessert mosses under heat shock stress which will be helpful for the artificial reconstruction of BSCs.

[Analysis on the dynamics of desert-oasis vegetation in the Sangong River Basin].

Taking the Sangong River Basin as a typical research area, the relationships between the change of landscape pattern of desert-oasis and the dynamics of vegetation were studied in this paper, and the evolution of the landscape pattern of desert-oasis was also discussed. The results showed that the main characteristics of landscape pattern were the dynamics of vegetation. It had the impact on the vegetation by the changes of topography, water resources using, corridor of river and drainage channel. It was shown the great variability for the height, cover and biomass of vegetation with the change of landscape pattern. Taking the corridor of river as the center, it usually showed a zone distribution from inside to outside for the desert-oasis landscape pattern. The vegetation types evolved from the tree-shrub mixed forest, thicket meadow, salinized meadow to desert with the change of the condition of water and heat in the basin. The stability of natural patch was higher than that disturbed by mankind or manmade patch. Usually, the stability of each patch was in order of desert > sandy land > urban > pond > paddy field > grass land > vegetable plot > woodland > residential area > saline-alkali land > wasteland > farming land > orchard. The landscape pattern of desert-oasis in the research area was developed by human activities based on natural oasis.