Optimization of inter-seasonal nitrogen allocation increases yield and resource-use efficiency in a water-limited wheat-maize cropping system in the North China Plain

Winter wheat–summer maize cropping system in the North China Plain often experiences droughtinduced yield reduction in the wheat season and rainwater and nitrogen(N)fertilizer losses in the maize season.This study aimed to identify an optimal interseasonal water-and N-management strategy to alleviate these losses.Four ratios of allocation of 360 kg N ha^(-1)between the wheat and maize seasons under one-time presowing root-zone irrigation(W0)and additional jointing and anthesis irrigation(W2)in wheat and one irrigation after maize sowing were set as follows:N1(120:240),N2(180:180),N3(240:120)and N4(300:60).The results showed that under W0,the N3 treatment produced the highest annual yield,crop water productivity(WPC),and nitrogen partial factor productivity(PFPN).Increased N allocation in wheat under W0 improved wheat yield without affecting maize yield,as surplus nitrate after wheat harvest was retained in the topsoil layers and available for the subsequent maize.Under W2,annual yield was largest in the N2 treatment.The risk of nitrate leaching increased in W2 when N application rate in wheat exceeded that of the N2 treatment,especially in the wet year.Compared to W2N2,the W0N3 maintained 95.2%grain yield over two years.The WPCwas higher in the W0 treatment than in the W2 treatment.Therefore,following limited total N rate,an appropriate fertilizer N transfer from maize to wheat season had the potential of a“triple win”for high annual yield,WPCand PFPN in a water-limited wheat–maize cropping system.

Yield sustainability of winter wheat under three limited-irrigation schemes based on a 28-year field experiment

Sustainable intensification is an agricultural development direction internationally.However,little is known about the yield sustainability of winter wheat(Triticum aestivum L.)under limited irrigation schemes on the North China Plain(NCP).A 28-year field experiment from 1991 to 2018 at Wuqiao Experimental Station was used to characterize long-term yield,evapotranspiration(ET),and water use efficiency(WUE)trends under three irrigation treatments(W1,irrigation just before sowing;W2,irrigation before sowing and at jointing stage;W3,irrigation before sowing,at jointing stage,and at anthesis).Yield gaps and the effects of genetic improvement,climate change,and climate variables on wheat yield and key phenological stages were estimated using the Agricultural Production Systems Simulator(APSIM)model.Grain yield and WUE of winter wheat increased during the 28 years under the three irrigation treatments,and the upward trend of WUE followed a saturation curve pattern.ET increased slightly.Simulation results showed that genetic improvement dramatically prolonged the phenological stages of vegetative growth period and contributed to yield increase by 0.03%-15.6%.The rapid increase in yield with lower water use was associated mainly with an increase in biomass with genetic improvement and partly with an increase in harvest index.A curvilinear relationship between WUE and yield emphasized the importance of obtaining high yields for high WUE.The yield gaps between potential yield and yield under W1 treatment increased from 1991 to 2018 but were relatively constant for the W2 and W3 treatments.Elevated atmospheric CO_(2) concentration offset the negative effects of temperature increase on yield,leading to minor(-2.3%to 0.3%)changes in yield under climate change.Thus,genetic improvement played a dominant role in yield increase,and limited-irrigation schemes(W2 and W3)can increase wheat yield and promote sustainability of crop production on the NCP.

Prevention and Control of Iodine Deficiency Disorders—China,1995–2020

Basic Information about Iodine Deficiency Disorders Iodine is an essential micronutrient for the human body and an important raw material for the synthesis of thyroid hormones.Thyroid hormones maintain the basic activities of the body and have different effects on almost all systems of the body by promoting growth and development,participating in brain development,regulating metabolism,and impacting most organs and system functions.

Praziquantel decreases fecundity in Schistosoma mansoni adult worms that survive treatment:evidence from a laboratory life-history trade-offs selection study

Background:Mass drug administration of praziquantel is the World Health Organization’s endorsed control strategy for schistosomiasis.A decade of annual treatments across sub-Saharan Africa has resulted in significant reductions of infection prevalence and intensity levels,although‘hotspots’remain.Repeated drug treatments place strong selective pressures on parasites,which may affect life-history traits that impact transmission dynamics.Understanding drug treatment responses and the evolution of such traits can help inform on how to minimise the risk of drug resistance developing,maximise sustainable control programme success,and improve diagnostic protocols.Methods:We performed a four-generation Schistosoma mansoni praziquantel selection experiment in mice and snails.We used three S.mansoni lines:a praziquantel-resistant isolate(R),a praziquantel-susceptible isolate(S),and a coinfected line(RS),under three treatment regimens:untreated,25 mg/kg praziquantel,or 50 mg/kg praziquantel.Lifehistory traits,including parasite adult-worm establishment,survival,reproduction(fecundity),and associated morbidity,were recorded in mice across all four generations.Predictor variables were tested in a series of generalized linear mixed effects models to determine which factors had a significant influence on parasite life-history traits in definitive hosts under different selection regimes.Results:Praziquantel pressure significantly reduced adult-worm burdens across all generations and isolates,including within R-lines.However,previous drug treatment resulted in an increase in adult-worm establishment with increasing generation from P1 to F3.The highest worm numbers were in the co-infected RS line.Praziquantel treatment decreased adult-worm burden,but had a larger negative impact on the mean daily number of miracidia,a proxy for fecundity,across all three parasite isolates.Conclusions:Our predicted cost of resistance was not supported by the traits we measured within the murine host.We did not find evidence for negative adult worm density-dependent effects on fecundity.In contrast,of the adult worms that survived treatment,even low doses of praziquantel significantly reduced adult-worm fecundity.Such reductions in worm fecundity post treatment suggest that egg-based measures of drug efficacy,such as Kato-Katz,may overestimate the short-term effect of praziquantel on adult-worm burdens.These findings have important implications for S.mansoni transmission control,diagnostic protocols,and the potential for undetected selection toward drug resistance.