Responses of photosynthetic characteristics and leaf senescence in summer maize to simultaneous stresses of waterlogging and shading

A field experiment was performed to investigate the physiological mechanism of the simultaneous stresses of waterlogging and shading on leaf photosynthetic and senescence during three growth stages of summer maize.The responses of leaf gas exchange parameters and antioxidant enzyme activities of the summer maize hybrids Denghai 605(DH605)to waterlogging(W),shading(S),and their combination(W+S)for 6 days at the third leaf stage(V3),the sixth leaf stage(V6),and the tasseling stage(VT)were recorded.Shading,waterlogging,and their combination disturbed the activities of protective enzymes and increased the contents of H2O2and O-2,accelerating leaf senescence and disordering photosynthetic characteristics.Under waterlogging,shading and their combination,leaf Pn,the photo-assimilates and grain yield was decreased.The greatest reduction for waterlogging and the combined stresses occurred at V3 and that for shading stress occurred at VT.The individual and combined stresses reduced the activities of protective enzymes and inhibited photosynthesis,reducing the accumulation of photosynthetic compounds and thereby yield.Waterlogging and the combined stresses at the V3 stage showed the greatest effect on leaf photosynthetic and senescence,followed by the V6 and VT stages.The greatest effect for shading stress occurred at VT,followed by the V6 and V3 stages,and the combined influence of shading and waterlogging was greater than that of either single stress.

Effect of Fatigue Loading on the Mechanical Properties and Resistance of High-strength Straight-hole Recycled Pervious Concrete to Rainstorm-based Waterlogging

A novel high-strength straight-hole recycled pervious concrete(HSRPC)for the secondary highway pavement was prepared in this paper.This study aimed to investigate the effect of porosity(0.126%,0.502%,and 1.13%),vehicle loading stress level(0.5 and 0.8)and service life on the resistance to rainstormbased waterlogging of HSRPC under fatigue loading.The mechanical properties of HSRPC in terms of flexural strength and dynamic elastic modulus were studied.The waterlogging resistance of HSRPC was described by surface water depth and drainage time.The microstructure of HSRPC were observed with scanning electron microscopy(SEM).Results showed that although the dynamic elastic modulus and flexural strength of HSRPC decreased with the increasing number of fatigue loading,the flexural strength of HSRPC was still greater than5 MPa after design service life of 20 years.After 2.5×10^(5)times of fatigue loading,the permeability coefficient of HSRPC with a porosity of 0.502%and 1.13%increased by 18.4%and 22.9%,respectively;while the permeability coefficient of HSRPC with 0.126%porosity dropped to 0.35 mm/s.The maximum surface water depth of HSRPC with a porosity of 0.126%,0.502%,and 1.13%were 8,5 and 4 mm,respectively.SEM results showed that fatigue loading expanded the number and width of cracks around the tiny pores in HSRPC.

Pore Characteristic Design Method of High-strength Pervious Concrete Based on the Mechanical Properties and Rainstorm Waterlogging Resistance

High-strength pervious concrete(HSPC) with porosity ranging from 0.08% to 2.011% was prepared. The mechanical properties and rainstorm waterlogging resistance of HSPC were evaluated,and a design method of HSPC pore characteristics(porosity and pore diameter) based on the mechanical properties and rainstorm waterlogging resistance was proposed. The results showed that the reduction of effective cross-sectional area caused by artificial channels was the main factor affecting flexural strength but had limited influence on compressive strength. Compared with the concrete matrix without artificial channels,the compressive strength of HSPC with porosity of 2.011% decreased by 7.4%, while the flexural strength decreased by 48.3%. The permeability coefficient of HSPC can reach 16.35 mm/s even at low porosity(2.011%).HSPC can meet the requirements of no rainstorm waterlogging, even if exposed to 100-year rainstorms. When the mechanical properties and rainstorm waterlogging resistance are compromised, the recommended porosity ranges from 1.1% to 3.5%, and the recommended pore diameter ranges from 0.8 to 2.7 mm.

Identification of stable quantitative trait loci underlying waterlogging tolerance post-anthesis in common wheat(Triticum aestivum)

Waterlogging is a growing threat to wheat production in high-rainfall areas.In this study,a doubled haploid(DH) population developed from a cross between Yangmai 16(waterlogging-tolerant) and Zhongmai895(waterlogging-sensitive) was used to map quantitative trait loci(QTL) for waterlogging tolerance using a high-density 660K single-nucleotide polymorphism(SNP) array.Two experimental designs,waterlogging concrete tank(CT) and waterlogging plastic tank(PT),were used to simulate waterlogging during anthesis in five environments across three growing seasons.Waterlogging significantly decreased thousand-kernel weight(TKW) relative to non-waterlogged controls,although the degree varied across lines.Three QTL for waterlogging tolerance were identified on chromosomes 4AL,5AS,and 7DL in at least two environments.All favorable alleles were contributed by the waterlogging-tolerant parent Yangmai16.QWTC.caas-4AL exhibited pleiotropic effects on both enhancing waterlogging tolerance and decreasing plant height.Six high-confidence genes were annotated within the QTL interval.The combined effects of QWTC.caas-4AL and QWTC.caas-5AS greatly improved waterlogging tolerance,while the combined effects of all three identified QTL(QWTC.caas-4AL,QWTC.caas-5AS,and QWTC.caas-7DL) exhibited the most significant effect on waterlogging tolerance.Breeder-friendly kompetitive allele-specific PCR(KASP) markers(K_AX_111523809,K_AX_108971224,and K_AX_110553316) flanking the interval of QWTC.caas-4AL,QWTC.caas-5AS,and QWTC.caas-7DL were produced.These markers were tested in a collection of 240 wheat accessions,and three superior polymorphisms of the markers distributed over 67elite cultivars in the test population,from the Chinese provinces of Jiangsu,Anhui,and Hubei.The three KASP markers could be used for marker-assisted selection(MAS) to improve waterlogging tolerance in wheat.

Enhancing waterlogging tolerance in cotton through agronomic practices

Recent publications have highlighted significant progress in utilizing agronomic interventions to alleviate waterlogging stress in cotton production.Based on these advancements,we provide a concise comment on the effects and underlying mechanisms of various strategies such as utilizing stress-tolerant cotton varieties,applying nitric oxide(NO),and implementing ridge intertillage.Finally,we recommend a combination of measures to enhance cotton’s ability to withstand waterlogging and reduce yield losses.

Changes of Physiological Characters of Wheat After Water-logging at Booting and Relations Between Physiological Characters and Waterlogging Tolerance

Effects of waterlogging on some physiological characters and relationship between waterlogging tolerance and some characters of their own were studied by using 12 varieties of wheat. Results showed waterlogging made the content of malondialdehyde in flag leaf increase, made the root vigor, the content of chlorophyll, the net photosynthesis rate, the nitrate reductase activity, the relative water content of flag leaf decrease, the content of organic matter change obviously, and then the yield per plant declined. The correlations between waterlogging tolerance and the water conservation ability of flag leaf, the content of free amino acids and starch in secondary root at booting, the percentage of stem yield in yield per plant, the content of malondialdehyde and water in flag leaf, the content of free amino acids in leaves were significant or highly significant.

Preliminary Study on the Waterlogging Tolerance of 116 Corn Materials

Maize is one of the most important food crops in the world.With the global warming,waterlogging stress has become an important abiotic stress factor that affects crop growth,including maize.Waterlogging seriously affects 10%of the arable land and can lead to a 15%-80%reduction in crop yield[1].In this study,115 inbred line materials commonly used in spring maize planting areas in the Jianghan Plain,Hubei,and maize inbred line B73 with complete genome information,were collected and stressed by waterlogging for two weeks in the seven-leaf and one-heart stage,and the survival rate was statistically compared and analyzed,aiming to screen germplasms with strong waterlogging tolerance for the genetic improvement of waterlogging tolerance of Hubei maize lines.

Comparison of transcriptomes undergoing waterlogging at the seedling stage between tolerant and sensitive varieties of Brassica napus L.

RNA sequencing of the sensitive GH01 variety of Brassica napus L. seedling roots under 12 h of waterlogging was compared with previously published data of the ZS9 tolerant variety to unravel genetic mechanisms of waterlogging tolerance beyond natural variation. A total of 2 977 genes with similar expression patterns and 17 genes with opposite expression patterns were identified in the transcription profiles of ZS9 and GH01. An additional 1 438 genes in ZS9 and 1 861 genes in GH01 showed strain specific regulation. Analysis of the overlapped genes between ZS9 and GH01 revealed that waterlogging tolerance is determined by ability to regulate genes with similar expression patterns. Moreover, differences in both gene expression profiles and abscisic acid(ABA) contents between the two varieties suggest that ABA may play some role in waterlogging tolerance. This study identifies a subset of candidate genes for further functional analysis.

Waterlogging stress in cotton:Damage, adaptability, alleviation strategies, and mechanisms

Over the last few decades,waterlogging stress has increasingly threatened global cotton production.Waterlogging results in reduced soil oxygen,impairing the growth and development of this valuable crop and often resulting in severe yield loss or crop failure.However,as cotton has an indeterminate growth habit,it is able to adapt to waterlogging stress by activating three mechanisms:the escape,quiescence,and self-regulating compensation mechanisms.The escape mechanism includes accelerated growth,formation of adventitious roots,and production of aerenchyma.The quiescence mechanism involves reduced biomass accumulation and energy dissipation via physiological,biochemical,and molecular events.The self-regulation compensation mechanism allows plants to exploit their indeterminate growth habit and compensatory growth ability by accelerating growth and development following relief from waterlogging stress.We review how the growth and development of cotton is impaired by waterlogging,focusing on the three strategies associated with tolerance and adaptation to the stress.We discuss agronomic measures and prospects for mitigating the adverse effects of waterlogging stress.

Differences in Chlorophyll Fluorescence Parameters, Yield and Its Components Between Different Genotypes of Wheat Under Waterlogging Conditions at Anthesis

Waterlogging is one of the most factors limiting wheat production in the middle and lower reaches of the Yangtze River Plain of China,especially in the middle and late stages of wheat.Wheat varieties‘Jingmai102’(JM102)and‘Yangmai158’(YM158)were planted to study the dynamic changes of photosynthetic characteristics in flag leaf and the influence of waterlogging at anthesis on the yield and components and dry matter accumulation and remobilization of winter wheat in above ground.The results showed that the SPAD values slightly increased at 1 day after anthesis(d),and then kept decreasing with the increase of waterlogging time.The decrease in SPAD value was more remarkably in YM158 than that in JM102.As for the chlorophyll fluorescence parameters,the photochemical efficiency(Fv/Fm),potential activity(Fv/Fo)of photosystem II,and electronic transmission(Fm/Fo)on photosystem II increased first and then decreased with the increase of waterlogging days after anthesis.The quantum ratio of heat dissipation(Fo/Fm)had a tendency opposite to that of Fv/Fm,and the change range of JM102 was lower than that of YM158.For the grain yield and components,waterlogging at anthesis decreased the dry weight of single stem,grain yield,1 000-kernel weight,spikelet per panicle,and harvest index,and the reduction of JM102 was smaller than that of YM158.As for the accumulation and remobilization of dry matter,the accumulation of dry matter after anthesis decreased significantly under waterlogging condition(WL),and the reduction of JM102 was smaller than that of YM158.In conclusion,waterlogging at anthesis significantly affected the photosynthetic characteristics,yield and components in both varieties,but different varieties exhibited different tolerances to waterlogging stress and YM158 was more sensitive to water stress than JM102.

Waterlogging risk assessment based on self-organizing map(SOM)artificial neural networks:a case study of an urban storm in Beijing

Due to rapid urbanization, waterlogging induced by torrential rainfall has become a global concern and a potential risk affecting urban habitant's safety. Widespread waterlogging disasters haveoccurred almost annuallyinthe urban area of Beijing, the capital of China. Based on a selforganizing map(SOM) artificial neural network(ANN), a graded waterlogging risk assessment was conducted on 56 low-lying points in Beijing, China. Social risk factors, such as Gross domestic product(GDP), population density, and traffic congestion, were utilized as input datasets in this study. The results indicate that SOM-ANNis suitable for automatically and quantitatively assessing risks associated with waterlogging. The greatest advantage of SOM-ANN in the assessment of waterlogging risk is that a priori knowledge about classification categories and assessment indicator weights is not needed. As a result, SOM-ANN can effectively overcome interference from subjective factors,producing classification results that are more objective and accurate. In this paper, the risk level of waterlogging in Beijing was divided into five grades. The points that were assigned risk grades of IV or Vwere located mainly in the districts of Chaoyang, Haidian, Xicheng, and Dongcheng.

THE STUDIES ON WATERLOGGING DAMAGE IN JIANGHAN PLAIN USING DEM

The waterlogging damage is the pit to agriculture in plain and lake region. This damage is related to the groundwater, ancient lakes, soil, land use and negative landforms, the conventional technique is adopted to the study of this damage. In this paper, we suggest a new technical method, the technique is based on DEM, to study this problem. The DEM is developed on the ECLIPSE MV/ 10000 AOS/ VS system, and the estimation model of waterlogging loss is built on the historical data of the test region in Jianghan Plain. and then, the rice waterlogging loss of test region is estimated by them.

Poor development of spike differentiation triggered by lower photosynthesis and carbon partitioning reduces summer maize yield after waterlogging

Stable yield of staple grains must be ensured to satisfy food demands for daily dietary energy requirements against the backdrop of global climate change. Summer maize, a staple crop, suffers severe yield losses due to extreme rainfall events, threatening food security. A randomized block experiment with four treatments: control, no water stress(CK);waterlogging for 6 days at the third leaf, sixth leaf stage,and 10 th day after tasseling, was conducted to investigate the mechanism of waterlogging-induced yield losses of summer maize. Waterlogging delayed plant growth and impaired tassel and ear differentiation,leading to high grain yield losses of Denghai 605(DH605). Waterlogging at third leaf(V3) stage reduced the photosynthesis of DH605, reducing total dry matter weight. Waterlogging at V3 stage reduced sucrose-cleaving enzymes activities in spike nodes and ears, reducing the carbon partitioned to ears(–53.1%), shanks(–46.5%), and ear nodes(–71.5%) but increasing the carbon partitioned to ear leaves(9.6%) and tassels(43.9%) in comparison with CK. The reductions in total carbon assimilate together with the reduced carbon partitioning to ears resulted in poor development of spikes(with respectively 15.2%and 20.6% reductions in total florets and fertilized florets) and lengthened the anthesis–silking interval by around 1 day, leading to high yield losses.

Unraveling waterlogging tolerance-related traits with QTL analysis in reciprocal intervarietal introgression lines using genotyping by sequencing in rapeseed(Brassica napus L.)

Soil waterlogging is a major environmental stress that suppresses the growth and productivity of rapeseed(Brassica napus L.).Natural genetic variations in waterlogging tolerance(WT)were observed but no QTL mapping has been done for WT related traits in rapeseed.In this study,QTL associated with three WT related traits including relative root length(RRL),relative hypocotyl length(RHL)and relative fresh weight(RFW)were dissected using a set of reciprocal introgression lines(ILs)derived from the cross GH01×ZS9,which showed significant difference in WT.Genotyping-by-sequencing(GBS)of the populations were performed,totally 1468 and 1450 binned SNPs were identified for GIL(GH01 as the recurrent parent)and ZIL(ZS9 as the recurrent parent)population,respectively.A total of 66 distinct QTLs for WT at the seedling establishment stage including 31 for RRL,17 for RHL and 18 for RFW were detected.Among the 66 QTLs,20(29.4%)QTLs were detected in both genetic backgrounds and then they were integrated into six QTL clusters,which can be targeted in rapeseed breeding for improvement of WT through marker-assisted selection(MAS).Based on the physical positions of SNPs and the functional annotation of the Arabidopsis thaliana genome,56 genes within the six QTL cluster regions were selected as preliminary candidate genes,then the resequencing and transcriptome information about parents were applied to narrow the extent of candidate genes.Twelve genes were determined as candidates for the six QTL clusters,some of them involved in RNA/protein degradation,most of them involved in oxidation-reduction process.These findings provided genetic resources,candidate genes to address the urgent demand of improving WT in rapeseed breeding.

Application of Internet of Things in Urban Waterlogging Prevention Management System

This paper aims to realize the extensive application of Internet of things technology in urban waterlogging prevention management system, and has analyzed the security requirement and security architecture of Internet of things technology, and discussed the demand of urban waterlogging prevention management system in combination with the key technology of Internet of things technology, to do the overall design and functional design well during designing of urban waterlogging prevention management system. Finally, the application process of the Internet of things technology in Chongqing waterlogging prevention management system is summarized. The application result shows that the flood control and drainage function of Chongqing is gradually improved with smooth drainage facilities;the inspection and maintenance management is gradually standardized;operation monitoring and early warning management is fully strengthened. There is visual management for emergency command and dispatch, and at the same time, the drainage pipe network assessment management can be conducted correctly.

Foliar K application delays leaf senescence of winter rapeseed(Brassica napus L.) under waterlogging

To better understand waterlogging effect on leaf senescence in winter rapseed (Brassica napus L.) during flowering stage, experiments were designed to explore foliar K application influences on adverse effects of waterlogging stress. Winter rapeseed was sprayed with K after waterlogging at initial flowering stage. Results indicated that waterlogging significantly decreased leaf net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci) and transpiration rate (Tr). It also declined maximum quantum yield of PS II (Fv/Fm), quantum yield of electron transport (ΦPS II) and photochemical quenching (qP), but increased leaf non-photochemical quenching (NPQ) and minimal fluorescence (Fo). Interestingly, exogenous application of K significantly alleviated waterlogging-induced photosynthesis inhibition. Foliar K application increased RuBisCO activation, chlorophyll and soluble protein contents, while significantly decreased MDA content under waterlogging stress. Moreover, K supplementation improved accumulation of K+, Ca2+, Mg2+, N, Zn2+, Mn2+, Fe2+ in leaves. In general, foliar K application is effective inalleviating deleterious effects of waterlogging stress and delays leaf senescence of winter rapeseed.

PRIMARY ANALYSIS OF DROUGHT AND WATERLOGGING LAW IN NORTH CHINA

According to the drought and waterlogging disaster statistics over the last 30 years (1950-1979), the annual average area suffering from drought was about 300 million mu (1 mu= 1/ 15 ha) in the whole country, among which about 100 million mu were disastrous areas where the output reduced more than 30%. and the annual lost grains totalled about 5 billion kg. The waterlogging disaster was less than drought disaster. The area suffering from waterlogging was about 100 million mu, among which 60 million mu were disastrous. Drought and waterlogging disasters affect directly the development of the national economy. So it is important to study drought and waterlogging variations, especially the drought and waterlogging variation laws of the areas where the disasters frequently occur.The historical literatures and recent observation data reveal the fact that there existed drought and waterlogging variations. For example, the occurrence frequency of the outstanding and severe drought years in north China is

Progress in recent study of drought,flood and waterlogging damages in China

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Mechanism for controlling drought and salinity/waterlogging in Northwest Shandong Province

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Genetic gains with genomic versus phenotypic selection for drought and waterlogging tolerance in tropical maize(Zea mays L.)

Erratic rainfall often results in intermittent drought and/or waterlogging and limits maize(Zea mays L.)productivity in many parts of the Asian tropics.Developing climate-resilient maize germplasm possessing tolerance to these key abiotic stresses without a yield penalty under optimal growing conditions is a challenge for breeders working in stress-vulnerable agro-ecologies in the region.Breeding stress-resilient maize for rainfed stress-prone ecologies is identified as one of the priority areas for CIMMYT-Asia maize program.We applied rapid cycle genomic selection(RCGS)on two multiparent yellow synthetic populations(MYS-1 and MYS-2)to improve grain yield simultaneously under drought and waterlogging conditions using genomic-estimated breeding values(GEBVs).Also,the populations were simultaneously advanced using recurrent phenotypic selection(PS)by exposing them to managed drought and waterlogging and intermating tolerant plants from the two selection environments.Selection cycles per se(C1,C2,and C3)of the two populations developed using RCGS and PS approach and their test-cross progenies were evaluated separately in multilocation trials under managed drought,waterlogging,and optimal moisture conditions.Significant genetic gains were observed with both GS and PS,except with PS in MYS-2 under drought and with GS in MYS-1 under waterlogging.Realized genetic gains from GS were relatively higher under drought conditions(110 and 135 kg ha^(-1) year^(-1))compared to waterlogging(38 and 113 kg ha^(-1) year^(-1))in both MYS-1 and MYS-2,respectively.However,under waterlogging stress PS showed at par or better than GS as gain per year with PS was 80 and 90 kg ha^(-1),whereas with GS it was 90 and 43 kg ha^(-1) for MYS-1 and MYS-2,respectively.Our findings suggested that careful constitution of a multiparent population by involving trait donors for targeted stresses,along with elite highyielding parents from diverse genetic background,and its improvement using RCGS is an effective breeding approach to build multiple stress tolerance without compromising yield when tested under optimal conditions.