Integrated management strategy for improving the grain yield and nitrogen-use efficiency of winter wheat

Understanding of how combinations of agronomic options can be used to improve the grain yield and nitrogen use efficiency（NUE） of winter wheat is limited. A three-year experiment involving four integrated management strategies was conducted from 2013 to 2015 in Tai＇an, Shandong Province, China, to evaluate changes in grain yield and NUE. The integrated management treatments were as follows： current practice（T1）; improvement of current practice（T2）; high-yield management（T3）, which aimed to maximize grain yield regardless of the cost of resource inputs; and integrated soil and crop system management（T4） with a higher seeding rate, delayed sowing date, and optimized nutrient management. Seeding rates increased by 75 seeds m^-2 with each treatment from T1（225 seeds m^-2） to T4（450 seeds m^-2）. The sowing dates were delayed from T1（5 th Oct.） to T2 and T3（8 th Oct.）, and to T4 treatment（12 th Oct.）. T1, T2, T3, and T4 received 315, 210, 315, and 240 kg N ha^-1, 120, 90, 210 and 120 kg P2O5 ha^-1, 30, 75, 90, and 45 kg K2O ha^-1, respectively. The ratio of basal application to topdressing for T1, T2, T3, and T4 was 6：4, 5：5, 4：6, and 4：6, respectively, with the N topdressing applied at regreening for T1 and at jointing stage for T2, T3, and T4. The P fertilizers in all treatments were applied as basal fertilizer. The K fertilizer for T1 and T2 was applied as basal fertilizer while the ratio of basal application to topdressing（at jointing stage） of K fertilizer for both T3 and T4 was 6：4. T1, T2, T3, and T4 were irrigated five, four, four and three times, respectively. Treatment T3 produced the highest grain yield among all treatments over three years and the average yield was 9 277.96 kg ha^-1. Grain yield averaged across three years with the T4 treatment（8 892.93 kg ha^-1） was 95.85% of that with T3 and was 21.72 and 6.10% higher than that with T1（7 305.95 kg ha^-1） and T2（8 381.41 kg ha^-1）, respectively. Treatment T2 produced the highest NUE of all the integrated treatments. The NUE with T4 was 95.36% of that with T2 and was 51.91 and 25.62% higher than that with T1 and T3, respectively. The N uptake efficiency（UPE） averaged across three years with T4 was 50.75 and 16.62% higher than that with T1and T3, respectively. The N utilization efficiency（UTE） averaged across three years with T4 was 7.74% higher than that with T3. The increased UPE with T4 compared with T3 could be attributed mostly to the lower available N in T4, while the increased UTE with T4 was mainly due to the highest N harvest index and low grain N concentration, which consequently led to improved NUE. The net profit for T4 was the highest among four treatments and was 174.94, 22.27, and 28.10% higher than that for T1, T2, and T3, respectively. Therefore, the T4 treatment should be a recommendable management strategy to obtain high grain yield, high NUE, and high economic benefits in the target region, although further improvements of NUE are required.

Stable oxygen-hydrogen isotopes reveal water use strategies of Tamarix taklamakanensis in the Taklimakan Desert, China

Tamarix taklamakanensis,a dominant species in the Taklimakan Desert of China,plays a crucial role in stabilizing sand dunes and maintaining regional ecosystem stability.This study aimed to determine the water use strategies of T.taklamakanensis in the Taklimakan Desert under a falling groundwater depth.Four typical T.taklamakanensis nabkha habitats(sandy desert of Tazhong site,saline desert-alluvial plain of Qiemo site,desert-oasis ecotone of Qira site and desert-oasis ecotone of Aral site)were selected with different climate,soil,groundwater and plant cover conditions.Stable isotope values of hydrogen and oxygen were measured for plant xylem water,soil water(soil depths within 0–500 cm),snowmelt water and groundwater in the different habitats.Four potential water sources for T.taklamakanensis,defined as shallow,middle and deep soil water,as well as groundwater,were investigated using a Bayesian isotope mixing model.It was found that groundwater in the Taklimakan Desert was not completely recharged by precipitation,but through the river runoff from snowmelt water in the nearby mountain ranges.The surface soil water content was quickly depleted by strong evaporation,groundwater depth was relatively shallow and the height of T.taklamakanensis nabkha was relatively low,thus T.taklamakanensis primarily utilized the middle(23%±1%)and deep(31%±5%)soil water and groundwater(36%±2%)within the sandy desert habitat.T.taklamakanensis mainly used the deep soil water(55%±4%)and a small amount of groundwater(25%±2%)within the saline desert-alluvial plain habitat,where the soil water content was relatively high and the groundwater depth was shallow.In contrast,within the desert-oasis ecotone in the Qira and Aral sites,T.taklamakanensis primarily utilized the deep soil water(35%±1%and 38%±2%,respectively)and may also use groundwater because the height of T.taklamakanensis nabkha was relatively high in these habitats and the soil water content was relatively low,which is associated with the reduced groundwater depth due to excessive water resource exploitation and utilization by surrounding cities.Consequently,T.taklamakanensis showed distinct water use strategies among the different habitats and primarily depended on the relatively stable water sources(deep soil water and groundwater),reflecting its adaptations to the different habitats in the arid desert environment.These findings improve our understanding on determining the water sources and water use strategies of T.taklamakanensis in the Taklimakan Desert.

Nutrient retranslocation strategies associated with dieback of Pinus species in a semiarid sandy region of Northeast China

In the semiarid sandy region of Northeast China,Mongolian pine(Pinus sylvestris var.mongolica)suffers dieback after the age of 35,while Japanese red pine(Pinus densiflora)and Chinese pine(Pinus tabuliformis)stay healthy.Foliar nutrient retranslocation reflects the nutrient conservation and utilization mechanism of plants in response to their habitats.However,the nutrient retranslocation strategies employed by three Pinus tree species to cope with nutrient limitations remain largely unknown.For this study,we investigated the seasonal variations in nitrogen(N)and phosphorus(P)concentrations of Mongolian pine,Japanese red pine,and Chinese pine plantations in terms of the green needles of all ages,senesced needles,and soil.Further,the N retranslocation efficiency(NRE),and P retranslocation efficiency(PRE),and correlations between the N:P ratios of needles and soil were analyzed.The results showed that,except for the spring NRE in 1-year-old needles of Mongolian pine,the spring NRE and PRE in 1-and 2-year-old needles of the three tree species were greater than zero.The autumn PRE was higher than zero for Mongolian pine,but lower than zero for Japanese red pine and Chinese pine.Among the three Pinus species,Mongolian pine showed greater spring PRE in 2-year-old needles,and PRE from 1-to 2-yearold needles,and from 2-year-old needles to litter.However,Japanese red pine had higher P concentrations and lower N:P ratios in senesced needles,while greater PRE was found in Chinese pine litter.Significant relationships between the N:P ratios were found in the current year and 1-year-old needles and soil in the Mongolian pine plantation,while there was an insignificant relationship between the N:P ratios of the needles and soil in the Chinese pine plantation.Thus,for Mongolian pine,the removal of P from needles in autumn,and higher P translocation from older needles under P-deficient soil may have contributed to the tree dieback.In contrast,Japanese red pine and Chinese pine stored P in their needles during autumn.Japanese red pine returned more P to the soil via litter,while Chinese pine maintained N:P homeostasis and increased P withdrawal prior to needle abscission.

An Overview of Language Learning Strategies

As English has become a universal lingua franca at present,more and more learners are anxious to learn it effectively and successfully.Studies show that the use of language learning strategies directly relates to language performance.This article attempts to provide an overview of language learning strategies for researchers' reference,helping them get insights in this field.

Resorption Efficiency of Four Cations in Different Tree Species in a Subtropical Common Garden

High rainfall in subtropical regions can leach cation elements from ecosystems,which may limit plant growth.Plants often develop efficient resorption patterns to recycle elements,but there is relatively little available information on this topic.In February 2012,a common garden was established in a subtropical forest by planting dominant trees from the area.Green and senescent leaves were sampled from 11 tree species.The concentrations of potassium(K),calcium(Ca),sodium(Na)and magnesium(Mg)were determined,and the resorption efficiencies were calculated.The results showed significant K,Na and Mg resorption in most of the investigated tree species,while Ca mainly displayed accumulation.Evergreen coniferous and evergreen broad-leaved trees(such as Cunninghamia lanceolata,Pinus massoniana,Cinnamomum camphora,and Michelia macclurei)exhibited relatively higher resorption efficiencies of K(39.0%-87.5%)and Na(18.3%-50.2%)than deciduous broad-leaved trees.Higher Mg resorption efficiencies(>50%)were detected in Liriodendron chinense,C.lanceolata and P.massoniana than in other trees.Overall,evergreen coniferous and evergreen broad-leaved trees could show higher cation resorption than deciduous broad-leaved trees.K and Mg resorption efficiencies and Ca accumulation decrease with increasing nutrient concentrations in green leaves.Our results emphasize that nutrient resorption patterns largely depend on elements and plant functions,which provides new insights into the nutrient use strategies of subtropical plants and a reference for the selection of suitable tree species in this region.

Application of GIS in Oilfield Power System

This paper discusses the use of GIS in oilfield power system,combined with the basic concept and advantages of GIS,combined with the characteristics of the oilfield power system,put forward the overall design system of the oilfield power system,ensure the stability of the power system operation,give full play to the role of GIS.

Improving social media use for disaster resilience: challenges and strategies

This paper develops a social media-disaster resilience analysis framework by categorizing types of social media use and their challenges to better understand and assess its role in disaster resilience research and management.The framework is derived primarily from several case studies of Twitter use in three hurricane events in the United States-Hurricanes Isaac,Sandy,and Harvey.The paper first outlines four major contributions of social media data for disaster resilience research and management,which include serving as an effective communication platform,providing ground truth information for emergency response and rescue operations,providing information on people's sentiments,and allowing predictive modeling.However,there are four_key challenges to its uses,which include,easy spreading of false information,social and geographical disparities of Twitter use,technical issues on processing and analyzing big and noisy data,especially on improving the locational accuracy of the tweets,and algorithm bias in Al and other types of modeling.Then,the paper proposes twenty strategies that the four sectors of the social media community-organizations,individuals,social media companies,and researchers-could take to improve social media use to increase disaster resilience.

Differential water use strategies among selected rare and endangered species in West Ordos Desert of China

Aims West Ordos Desert(WOD)in Inner Mongolia of China is charac-terized by unique geographical and ecological features to avoid the direct invasion of Quaternary Continental Glaciation,so it hosts many endangered relic species such as Tetraena mongol-ica,Ammopiptanthus mongolicus and Potaninia mongolica from Tertiary.However,how these plants utilize available water sources remains unknown.The objective of this study was to investigate the water utilization strategies of selected rare and endangered plant species in WOD by comparing hydrogen isotope ratios between their xylem water and possible water sources following four rainfall events of varying-intensities.Methods We measured the hydrogen isotope ratios of xylem water from T.mongolica,A.mongolicus and P.mongolica and an accom-panying species Sarcozygium xanthoxylum and potential water sources(including precipitation and soil water in different soil layers from 0 to 150 cm)over 9 days following each of four varying-intensity rainfall events during the summer of 2012.And then calculated the percentage utilization of potential water sources by each species after each rainfall events using the linear mixing model.We also made the measurements of soil moisture and root biomass in favor of interpretation of plant water use strategies.Important Findings Tetraena mongolica,A.mongolicus and S.xanthoxylum primarily relied on deep soil water,whereas P.mongolica depended predomi-nantly on rainwater.These rare and endangered desert plants had differential utilizations of available water sources,so some com-petition for limited water existed among some species.Tetraena mongolica had a competitive relationship in absorption of soil moisture with the same family species S.xanthoxylum,suggesting that T.mongolica and S.xanthoxylum should be restored separately at different areas in the WOD.Overall,this study provides a better understanding of water use strategies of these four plants and scien-tific evidence for protecting rare and endangered plants,maintain-ing regional species diversity,and developing effective vegetation restoration plans in the WOD.

Soil nutrient patchiness affects nutrient use efficiency,though not photosynthesis and growth of parental Glechoma longituba ramets:both patch contrast and direction matter

Aims Most plants are clonal in nature.Clonal ramets can share water,nutrients and photosynthate,especially when they experience patchy resources.Patch contrast(i.e.a difference in resources among patches)and patch direction(i.e.source–sink relations)are among the basic attributes of spatial patchiness.Here,I hypothesize that young established ramets in nutrient-rich patches support old ramets in nutrient-poor patches when ramets are subjected to different patch contrasts and patch directions.Methods In a greenhouse experiment,old and young ramets of Glechoma longituba were grown in four combinations consisting of patch contrast and patch direction.Minus patch direction refers to a patch combination in which parent ramets grow in nutrient-rich patches while connected daughter ramets grow in nutrient-poor ones and plus patch direction is the opposite direction.Imeasured photosynthesis and fluorescence traits,harvested all ramets,took morphological measures,weighed their dry mass and determined their nutrient uptake and use.Important Findings For parental ramets of G.longituba,patch contrast and patch direction and their interactions had no significant effects on net photosynthetic rate,maximal fluorescence yield,photochemical quenching(quenching refers to any process which decreases the fluorescence intensity of a given substance),non-photochemical quenching,nutrient uptake,biomass and stolon weight ratio.Patch direction alone significantly affected root weight ratio.Large patch contrast enhanced N use efficiency(NUE)and P use efficiency(PUE);plus patch direction decreased NUE,but increased PUE;the patch contrast by patch direction interaction affected PUE and K use efficiency(KUE).There were significant interactions between patch direction and patch contrast on PUE and KUE.It is concluded that soil nutrient patchiness may influence nutrient use strategies,but not nutrient uptake,photosynthesis and growth of parent ramets of G.longituba connected to daughter ramets,and that patch contrast and patch direction jointly affect PUE and KUE.

Understanding plant drought resistance in a Mediterranean coastal sand dune ecosystem:differences between native and exotic invasive species

Aims Mediterranean coastal dunes are habitats of great conservation interest,with a distinctive and rich flora.In the last century,Acacia spp.,native from Australia,have been introduced in Portugal,with the objective of stabilizing sand dunes,and since have become dominant in numerous sand dune habitats.This invasion process led to the reduction of native plant species richness,changed soil characteristics and modified habitat’s microclimatic char-acteristics.The aim of this research was to typify and compare,in Mediterranean sand dune ecosystems,the ecophysiological responses to drought of Helichrysum italicum and Corema album,two native species,and Acacia longifolia,an exotic invasive spe-cies.We addressed the following specific objectives:(i)to com-pare water relations and water use efficiencies,(ii)to evaluate water stress,(iii)to assess water use strategies and water sources used by plants and(iv)to evaluate the morphological adaptations at leaf and phyllode level.Methods In order to obtain an integrative view of ecophysiological patterns,water relations and performance measuring methods have been applied:predawn(ψPD)and midday(ψMD)water potential,chloro-phyll a fluorescence,oxygen isotopic composition of xylem,rain and groundwater(δ18O)and leaf carbon isotopic discrimination(Δ13C).The leaf characteristics of the three species,as well as the histochemistry of non-glandular trichome cell walls,were also studied to identify morpho-traits related to drought resistance.Important Findings The results support our initial hypothesis:although A.longifolia clearly possesses a degree of resistance to water stress,such ability is provided by a different water strategy,when compared to native species.Natives relied on morphological adaptations to restrict water loss,whereas the invasive species adjusted the water uptake as a way to balance their limited ability of restricting water loss.We corroborate that woody native species(i)have a conservative water-saving strategy and minor seasonal variations relative to invasive species,(ii)use enriched water sources during drought periods,indicating different water sources and root systems com-paring with invasive species and(iii)present drought leaf morpho-functional adaptations related with limiting water loss.Comparing the physiological performance of invasive and native species can offer causal explanations for the relative success of alien plant invasions on sand dunes ecosystems.

USING LEARNING STRATEGIES TO DEVELOP LISTENING COMPREHENSION—A CASE STUDY

By adopting the research method of case study, this article studies the learning strategies of an adult learner of English in listening comprehension. It is found that the learner can use some learning strategies but only at very elementary level. After an eight-week training course in learning strategies, the learner made noticeable progress in listening, which proves that learning strategies can be trained and contribute positively to language proficiency.

Strategies and Methods for the Treatment of Diabetic Neuropathy Using Integrative Chinese and Western Medicine

Diabetic neuropathy （DN） is the most common metabolic neuropathy in clinics, not only in diabetes patients （〉60%）, but also in pre-diabetic （8%） and normal persons （5%）^（1）. Its pathogenesis has not been fully understood up to now. It is generally believed that it is related to the increase in glycation endoproducts （AGEs） caused by hyperglycemia,

Contrasting responses of legume versus non-legume shrubs to soil water and nutrient shortages in the Mu Us Sandland

Legumes and non-legumes usually differ in using soil water and nutrients.Both water and nutrients are scarce in the semi-arid Mu Us Sandland where legume and/or non-legume shrubs coexist/dominate.Here,we addressed the responses of legume versus nonlegume shrubs to different soil water and nutrient conditions.Methods We conducted an experiment in which a legume(Hedysarum laeve)and a non-legume(Artemisia ordosica)were used,both of which are dominant species in the Mu Us Sandland.Seedlings of these two species were subjected to three water levels(45.0,67.5 and 90.0 ml every 3 days)and three nutrient treatments(0,0.1%and 0.2%nutrient solution every week)during the experiment.Important Findings Interactions between water and nutrients on total biomass,root weight ratio and rain use efficiency(RUE)were detected in A.ordosica but not in H.laeve,suggesting that water effects on A.ordosica but not on H.laeve are dependent on soil nutrients.Nutrient addition alleviated drought stress and increased RUE in A.ordosica.The interspecific differences in response to soil water and nutrients may be linked to the ability of plants to fix nitrogen.In addition,under lowsoil water or nutrient conditions,H.laeve produced more biomass than A.ordosica,and the opposite was the case under high-soil resources.The relationship between relative growth rate(RGR)and RUE[or nutrient use efficiency(NUE)]varied with two species.RGR of A.ordosica was positively correlated with both RUE and NUE while RGR of H.laeve was negatively correlated with NUE.The different responses may be linked to the trade-off between high-growth rate and low-resource use efficiency.