Influence of Seed Priming on Performance and Water Productivity of Direct Seeded Rice in Alternating Wetting and Drying

Direct seeded rice is promising alternative to traditional transplanting, but requires appropriate crop and water management to maintain yield performance and achieve high water productivity. Present study evaluated the effect of seed priming and irrigation on crop establishment, tillering, agronomic traits, paddy yield, grain quality and water productivity of direct seeded rice in alternate wetting and drying （DSR-AWD） in comparison with direct seeded rice at field capacity （DSR- FC）. Seed priming treatments were osmo-priming with KCI （2.2%）, CaCI2 （2.2%） and moringa leaf extracts （MLE, 3.3%） including hydro-priming as control. Among the treatments, seed osmo-primed with MLE emerged earlier and had higher final emergence, followed by osmo-priming with CaCI2. Tillering emergence rate and number of tillers per plant were the highest for seed priming with CaCI2 in DSR- AWD. Total productive and non-productive tillers, panicle length, biological and grain yields, harvest index were highest for seed priming with MLE or CaCI2 in DSR-AWD. Similarly, grain quality, estimated in terms of normal grains, abortive and chalky grains, was also the highest in DSR-AWD with MLE osmo-priming. Benefit cost ratio and water productivity was also the highest in DSR-AWD for seed priming with MLE. In conclusion, seed priming with MLE or CaCI2 can be successfully employed to improve the direct seeded rice performance when practiced with alternate wetting and drying irrigation.

Effect of Phosphorus and Irrigation Levels on Yield,Water Productivity,Phosphorus Use Efficiency and Income of Lowland Rice in Northwest Pakistan

With decreasing availability of water for agriculture and increasing demand for rice production, an optimum use of irrigation water and phosphorus may guarantee sustainable rice production. Field experiments were conducted in 2003 and 2004 to investigate the effect of phosphorus and irrigation levels on yield, water productivity （WP）, phosphorus use efficiency （PUE） and income of low land rice. The experiment was laid out in randomized complete block design with split plot arrangements replicated four times. Main plot consisted of five phosphorus levels, viz. 0 （P0）, 50 （P50）, 100 （P100）, 150 （P15o）, and 200 （P200） kg/hm2, while subplots contained of irrigation times, i.e. 8 （I8）, 10 （I10）, 12 （I12）, and 14 （I14） irrigation levels, each with a water depth of 7.5 cm. Mean values revealed that P150 in combination with I10 produced the highest paddy yield （9.8 t/hm2） and net benefit （1 231.8 US$/hm2） among all the treatments. Phosphorus enhanced WP when applied in appropriate combination with irrigation level. The highest mean WP [13.3 kg/（hm2-mm）] could be achieved at Plso with 18 and decreased with increase in irrigation level, while the highest mean PUE （20.1 kg/kg） could be achieved at P100 with I10 and diminished with higher P levels. The overall results indicate that P150 along with I10 was the best combination for sustainable rice cultivation in silty clay soil.

Responses of water productivity to irrigation and N supply for hybrid maize seed production in an arid region of Northwest China

Water and nitrogen（N） are generally two of the most important factors in determining the crop productivity. Proper water and N managements are prerequisites for agriculture sustainable development in arid areas. Field experiments were conducted to study the responses of water productivity for crop yield（WP_（Y-ET）） and final biomass（WP_（B-ET）） of film-mulched hybrid maize seed production to different irrigation and N treatments in the Hexi Corridor, Northwest China during April to September in 2013 and also during April to September in 2014. Three irrigation levels（70%–65%, 60%–55%, and 50%–45% of the field capacity） combined with three N rates（500, 400, and 300 kg N/hm^2） were tested in 2013. The N treatments were adjusted to 500, 300, and 100 kg N/hm^2 in 2014. Results showed that the responses of WP_（Y-ET） and WP_（B-ET） to different irrigation amounts were different. WP_（Y-ET） was significantly reduced by lowering irrigation amounts while WP_（B-ET） stayed relatively insensitive to irrigation amounts. However, WP_（Y-ET） and WP_（B-ET） behaved consistently when subjected to different N treatments. There was a slight effect of reducing N input from 500 to 300 kg/hm^2 on the WP_（Y-ET） and WP_（B-ET）, however, when reducing N input to 100 kg/hm^2, the values of WP_（Y-ET） and WP_（B-ET） were significantly reduced. Water is the primary factor and N is the secondary factor in determining both yield（Y） and final biomass（B）. Partial factor productivity from applied N（PFP_N） was the maximum under the higher irrigation level and in lower N rate（100–300 kg N/hm^2） in both years（2013 and 2014）. Lowering the irrigation amount significantly reduced evapotranspiration（ET）, but ET did not vary with different N rates（100–500 kg N/hm^2）. Both Y and B had robust linear relationships with ET, but the correlation between B and ET（R^2=0.8588） was much better than that between Y and ET（R^2=0.6062）. When ET increased, WP_（Y-ET） linearly increased and WP_（B-ET） decreased. Taking the indices of Y, B, WP_（Y-ET）, WP_（B-ET） and PFP_N into account, a higher irrigation level（70%–65% of the field capacity） and a lower N rate（100–300 kg N/hm^2） are recommended to be a proper irrigation and N application strategy for plastic film-mulched hybrid maize seed production in arid Northwest China.

Influence of Crop Nutrition on Grain Yield,Seed Quality and Water Productivity under Two Rice Cultivation Systems

The system of rice intensification （SRI） is reported to have advantages like lower seed requirement,less pest attack,shorter crop duration,higher water use efficiency and the ability to withstand higher degree of moisture stress than traditional method of rice cultivation.With this background,SRI was compared with traditional transplanting technique at Indian Agricultural Research Institute,New Delhi,India during two wet seasons （2009-2011）.In the experiment laid out in a factorial randomized block design,two methods of rice cultivation [conventional transplanting （CT） and SRI] and two rice varieties （Pusa Basmati 1 and Pusa 44） were used under seven crop nutrition treatments,viz.T 1,120 kg/hm2 N,26.2 kg/hm2 P and 33 kg/hm2 K;T 2,20 t/hm2 farmyard manure （FYM）;T 3,10 t/hm2 FYM＋ 60 kg/hm2 N;T 4,5 t/hm2 FYM＋ 90 kg/hm2 N;T 5,5 t/hm2 FYM＋ 60 kg/hm2 N＋ 1.5 kg/hm2 blue green algae （BGA）;T 6,5 t/hm2 FYM＋ 60 kg/hm2 N＋ 1.0 t/hm2 Azolla,and T 7,N 0 P 0 K 0 （control,no NPK application） to study the effect on seed quality,yield and water use.In SRI,soil was kept at saturated moisture condition throughout vegetative phase and thin layer of water （2-3 cm） was maintained during the reproductive phase of rice,however,in CT,standing water was maintained in crop growing season.Results revealed that CT and SRI gave statistically at par grain yield but straw yield was significantly higher in CT as compared to SRI.Seed quality was superior in SRI as compared to CT.Integrated nutrient management （INM） resulted in higher plant height with longer leaves than chemical fertilizer alone in both the rice varieties.Grain yield attributes such as number of effective tillers per hill,panicle length and panicle weight of rice in both the varieties were significantly higher in INM as compared to chemical fertilizer alone.Grain yields of both the varieties were the highest in INM followed by the recommended doses of chemical fertilizer.The grain yield and its attributes of Pusa 44 were significantly higher than those of Pusa Basmati 1.The seed quality parameters like germination rate and vigor index as well as N uptake and soil organic carbon content were higher in INM than those in chemical fertilizer alone.CT rice used higher amount of water than SRI,with water saving of 37.6% to 34.5% in SRI.Significantly higher water productivity was recorded in SRI as compared to CT rice.

Spatial and Temporal Variation in Water Productivity and Grain Water Utilization Assessment of Heilongjiang Province,Northeast China

Improving crop water productivity is necessary for ensuring food security. To quantify the water utilization in grain production from multiple perspectives, gross inflow water productivity(WPg), generalized agricultural water productivity(WPa), evapotranspiration water productivity(WPET) and irrigation water productivity(WPI) were examined in this study. This paper calculated and analyzed the temporal and spatial variation in these water productivity(WP) indices in the irrigated land of Heilongjiang Province. The results showed that almost all of the municipal WP indices increased from 2007 to 2015. The four indices showed large differences in scientific connotation and numerical performance, and their degrees of spatial variation were ranked as WPI>WPa>WPg>WPET. The spatial patterns of WP indices in different years were similar; the central and southern regions on the Songnen Plain and the eastern region had high WP values, while those of the northern region were low. Each WP index was used to evaluate the relationship between the input of water resources and the output of grain between different regions. Most cities had the potential to improve WP by reducing the input of irrigation water. Furthermore, the results provided recommendations to decision makers to plan for efficient use of water resources in different cities.

Modeling the Effect of Planting Dates and Nitrogen Application Rates on Potatoes Water Productivity in Jordan Valley

Agricultural sector in Jordan is facing serious challenges in meeting the growing needs of food security because of its low water availability. Maintaining and enhancing agricultural water productivity under such prevailing environmental constraints are hard to achieve. Potatoes water productively in Jordan Valley was modeled using Decision Support System for Agrotechnology Transfer (DSSAT) under six nitrogen applications (0, 60, 80, 100, 120 and 140 kg/ha) and twelve planting dates every two weeks from October 1 to March 15 scenarios. The potatoes yield increased from 0% to 100% nitrogen treatment and then no considerable increase occurred. The potatoes’ crop yield increased from October 1st to January 15 and then decreased after which until the last day of planting date. The seasonal cumulative crop evapotranspiration for potatoes about doubled from 0% to 60% nitrogen treatment and then kept increasing gradually until the last treatment. The growing season cumulative crop evapotranspiration for potatoes increased gradually from October 1 to March 1. The water productivity increased from 0% nitrogen treatment to 100% and then decreased. The potatoes’ water productivity increased from October 1 until November 15 and then decreased to the end. From these results, we recommend that 100% of nitrogen requirements should be applied. The best window for potatoes’ planting date is the last two weeks in November.

Calculating the Yield, Water Utilize Efficiency and Water Productivity for Carrot Crop under Climate Change Effects

The present work analyzed the yield, water utilize efficiency and water productivity for carrot Crop under climate change effects. In this research, river water was used with irrigation ratios with drain water to irrigate the carrots (Daucus carota L.) crop during the winter growing season 2021-2022 in free field and utilizing furrow irrigation method with calculation the water use efficiency and water productivity to three sites. The study was conducted in the three sites in the Babil province in Town of Sadat-AlHindya reached 80 km from Baghdad city. Site 1 was used 33% drain water and 67% river water while site 2 was used 83% drain water and 17% river water but the site 3 was used 100% river water. The reduction of yield in site 1 was 17.3% and in site 2 was 75%. The reducing of WUE in site 1 was 23% and in site 2 was 77%. The decrease of WP in site 1 was 22.98% and in site 2 was 82.28%. The value of water stress coefficient (Ks) because irrigation by water salanity and soil salanty was 0.83, 0.78 and 0.92 in site 1,site 2 and site 3, respectively, water salanity and soil salanty reduction in productivity by 9%, 14% and 7% in production of site 1, site 2 and site 3, respectively in every irrigating.

Evaluation of irrigation water salinity and leaching fraction on the water productivity for crops

In arid and semi-arid irrigated croplands,the excessive accumulation of soluble salts in the root zone is an extensive problem that seriously limits crop yield and water productivity(WP).To avoid affects the yield potential of crops,the application of extra irrigation for leaching of excessive salts from the root zone was required.Quantitative knowledge of effects of the irrigation water salinity and leaching fraction(LF)on the relative yield(RY)and the unit water productivity of crop evapotranspiration(UWPET)and the unit water productivity of irrigation water(UWPI)were becoming gradually important.This article provided theoretical models for estimating the UWPs(UWPET and UWPI)and optimizing leaching fraction according to irrigation water salinity.In the present study,eight levels of irrigation water salinity(ECw=0.25,0.50,0.75,1,2,3,4,and 5 dS/m)and 39 levels of LF values ranging from 0.04 to 0.80 were set and tested to assessing their effects on the RY and UWPs for four typical crops(barley,bean,wheat,and maize)with different salt tolerance levels.Almost every curve determined between the UWPs and LFs for the four crops had an inflection point.It was indicated that the UWPET and UWPI could be maximized by optimizing the LF under different irrigation water salinities.Furthermore,the linear regression relationships were established to estimate the maximum values of UWPs and their corresponding optimal LFs for four crops by using the irrigation water salinity.Moreover,the theoretical models for estimating the UWPs were validated by data of wheat from previous literature,and the models could be suitable with acceptable relative errors when LFs ranging from 0.07 to 0.17.

Effects of different irrigation frequencies and incorporation of rice straw on yield and water productivity of wheat crop

The current rapid increase in irrigation water consumption is considered unsustainable and threatens the world food production.Therefore,it is mandatory to promote modern techniques and to manage existing conventional irrigation methods.The present study was attempted to determine the effects of different irrigation frequencies and rice straw incorporation rates on yield and water productivity of the wheat crop.The experiment was arranged with randomize complete block design involving nine treatments(RS 0 I 7,RS 0 I 15,RS 0 I 22,RS 1 I 7,RS 1 I 15,RS 1 I 22,RS 2 I 7,RS 2 I 15 and RS 2 I 22)under three replications.Results exposed that the incorporation of rice straw with different irrigation frequencies significantly improved physico-chemical properties of soil.Moreover,soil bulk density,infiltration rate,pH,electrical conductivity significantly decreased and soil porosity significantly increased under all treatments.Furthermore,maximum crop yield and crop water productivity of 7706.4 kg/hm 2 and 1.92 kg/m 3 respectively were found under RS 1 I 15 treatment.Based on experimental results it can be concluded that irrigation frequency and incorporation of rice straw had significant effects on the physico-chemical properties of soil,total grain yield and water productivity of the wheat crop.However,this study suggested that the wheat crop yield and water productivity could be increased by incorporating 1 t/hm 2 rice straw with 15 d of irrigation frequency.

Remote sensing monitoring on regional crop water productivity in the Haihe River Basin

Crop water productivity （CWP） agricultural development in water scarcity is one of the important indicators for sustainable area. There is serious conflict between water sup- ply and requirement in the Haihe River Basin. CWP of winter wheat and summer maize from 2003 to 2007 in the Haihe River Basin is estimated based on large-scale evapotranspiration （ET） and crop yield obtained by remote sensing technology. Spatial and temporal distribution of CWP of winter wheat and summer maize is investigated in this study. Results show that CWP of winter wheat in most parts of the study area varies from 1.02 kg/m3 to 1.53 kg/m3, and CWP of summer maize varies from 1.31 kg/m3 to 2.03 kg/m3. Multi-year averaged CWP of winter wheat and summer maize in the study area is about 1.19 kg/m3 and 1.59 kg/m3. CWP results show certain promotion potential to alleviate the water shortage in the Haihe River Basin. Correlation analysis of CWP, crop yield and ET shows that there is great potential for crop yield promotion without the growth in irrigation water. Large-scale CWP estimated by remote sensing technology in this study shows spatial distribution features, which could be used to real-time agricultural water resource management combined with crop yield and ET.

A meta-analysis of global crop water productivity of three leading world crops(wheat,corn,and rice)in the irrigated areas over three decades

The overarching goal of this study was to perform a comprehensive metaanalysis of irrigated agricultural Crop Water Productivity(CWP)of the world’s three leading crops:wheat,corn,and rice based on three decades of remote sensing and non-remote sensing-based studies.Overall,CWP data from 148 crop growing study sites(60 wheat,43 corn,and 45 rice)spread across the world were gathered from published articles spanning 31 different countries.There was overwhelming evidence of a significant increase in CWP with an increase in latitude for predominately northern hemisphere datasets.For example,corn grown in latitude 40–50°had much higher mean CWP(2.45 kg/m^(3))compared to mean CWP of corn grown in other latitudes such as 30–40°(1.67 kg/m^(3))or 20–30°(0.94 kg/m^(3)).The same trend existed for wheat and rice as well.For soils,none of the CWP values,for any of the three crops,were statistically different.However,mean CWP in higher latitudes for the same soil was significantly higher than the mean CWP for the same soil in lower latitudes.This applied for all three crops studied.For wheat,the global CWP categories were low(≤0.75 kg/m^(3)),medium(>0.75 to<1.10 kg/m^(3)),and high CWP(≥1.10 kg/m^(3)).For corn the global CWP categories were low(≤1.25 kg/m^(3)),medium(>1.25 to≤1.75 kg/m^(3)),and high(>1.75 kg/m^(3)).For rice the global CWP categories were low(≤0.70 kg/m^(3)),medium(>0.70 to≤1.25 kg/m^(3)),and high(>1.25 kg/m^(3)).USA and China are the only two countries that have consistently high CWP for wheat,corn,and rice.Australia and India have medium CWP for wheat and rice.India’s corn,however,has low CWP.Egypt,Turkey,Netherlands,Mexico,and Israel have high CWP for wheat.Romania,Argentina,and Hungary have high CWP for corn,and Philippines has high CWP for rice.All other countries have either low or medium CWP for all three crops.Based on data in this study,the highest consumers of water for crop production also have the most potential for water savings.These countries are USA,India,and China for wheat;USA,China,and Brazil for corn;India,China,and Pakistan for rice.For example,even just a 10%increase in CWP of wheat grown in India can save 6974 billion liters of water.This is equivalent to creating 6974 lakes each of 100 m^(3)in volume that leads to many benefits such as acting as‘water banks’for lean season,recreation,and numerous ecological services.This study establishes the volume of water that can be saved for each crop in each country when there is an increase in CWP by 10%,20%,and 30%.

Soil water storage,yield,water productivity and transpiration efficiency of soybeans(Glyxine max L.Merr)as affected by soil surface management in lle-Ife,Nigeria

Rainfed agriculture has a high yield potential if rainfall and land resources are effectively used.In this study,conventional(NC)and six in-situ water conservation practices were used to cultivate Soybean in 2011 and 2012 in Ile-lfe,Nigeria.The conservation practices are:Tied ridge(TR),Soil bund(BD),Mulch(ML),Mulch plus Soil bund(MLBD),Tied ridge plus Mulch(TRML),Tied ridge plus Soil bund(TRBD).The practices were arranged in Randomised Complete Block Design with four replicates.Seasonal rainfall was 539 and 761 mm in 2011 and 2012,respectively.Seasonal soil water storage(SWS)ranged from 485 mm for NC to 517 mm for TRML in the two seasons.ML increased the SWS in the upper 30 cm of the soil by 17% while TR increased the soil water content in the lower 30-60 cm by 22% compared with NC.ML reduced soil temperature in the upper 30 cm between 2.2 and 2.9℃ compared with NC,TR and TRML.Seasonal crop evapotranspiration ranged between 432 mm for NC and 481 mm for BD in the seasons.Grain yield increased by 41.7% and 44.3% for BD and MLBD,respectively compared with NC.Water conservation practices increased water productivity for grain yield by 14.0-41.8% compared with NC.Similarly,it increased average seasonal transpiration efficiency by 15.3-32.5% compared with NC.These findings demonstrate that when there are fluctuations in rainfall,in-situ water conservation practices improve SWS,land,and water productivity and transpiration efficiency of Soybeans.

Quantitative analysis of irrigation water productivity in the middle reaches of Heihe River Basin, Northwest China

With the growing shortage of surface water resources,it is of great significance for improving the irrigation water productivity(IWP)to ensure the water and food security.The contribution of the driving factors of the IWP and the rational regulation of the input factors of agricultural production is required.In this paper,118 and 80 sampling points were selected in Pingchuan and Liaoquan irrigation districts(PLID,the spacing of sampling point is approximately 1 km)and the middle reaches of the Heihe River basin(MHRB,the spacing of sampling point is approximately 10 km),respectively.Soil characteristics and management measures near the sampling points were obtained.Results showed that the average value of the IWP in MHRB was 1.67 kg/m3,with a moderate heterogeneity in the space.The main driving factors of IWP were irrigation,fertilization and planting density.On the PLID,the contribution rates of soil factors and management measures to IWP were 20.6%and 35.2%,respectively,and the contribution of soil factors to IWP increased to 43.8%in the MHRB,while the contribution rate of management measures decreased to 24.8%.It shows that in a small irrigation districts,from the perspective of farmers,the improvement of IWP should be mainly controlled by management measures,while in the large area of watershed scale,the spatial differences in soil factors also need to be considered by the government management departments,when they want to increase IWP through regulating management measures.

Experiences with Rice Grown on Permanent Raised Beds: Effect of Crop Establishment Techniques on Water Use, Productivity, Profitability and Soil Physical Properties

In recent years, conventional rice production technologies have been leading to deterioration of soil health and declining farm profitability due to high inputs of water and labor. Conservation agriculture （CA） based resource-conserving technologies i.e. zero-tillage （ZT）, raised-bed planting and direct-seeded rice （DSR） have shown promise as alternatives to conventional production technologies to overcome these problems. Present study was undertaken during 2009-2012 to establish an understanding of how permanent raised bed cropping system could be practiced to save water at the field application level to improve water productivity and also have the capability to enhance productivity, profitability and soil physical quality. The results showed that among different crop establishment techniques, conventional-tilled puddle transplanted rice （CT-TPR） required 14%-25% more water than other techniques. Compared with the CT-TPR system, zero till direct-seeded rice （ZT-DSR） consumed 6%-10%less water with almost equal system productivity and demonstrated higher water productivity. Wide raised beds saved about 15%-24% water and grain yield decrease of about 8%. Direct-seeded rice after ZT or reduced tillage or on unpuddled soil provided more net income than CT-TPR. The CT-TPR system had higher bulk density and penetration resistance due to compaction caused by the repeated wet tillage in rice. The steady-state infiltration rate and soil aggregation （〉 0.25 mm） were higher under permanent beds and ZT and lower in the CT-TPR system. Under CT-TPR, soil aggregation was static across seasons, whereas it improved under no-till and permanent beds. Similarly, mean weight diameter of aggregates was higher under ZT and permanent beds and increased over time. The study reveals that to sustain the rice productivity, CA-based planting techniques can be more viable options. However, the long-term effects of these alternative technologies need to be studied under varying agro-ecologies in western Uttar Pradesh, India.

LINKING CROP WATER PRODUCTIVITY TO SOIL PHYSICAL,CHEMICAL AND MICROBIAL PROPERTIES

Agriculture uses a large proportion of global and regional water resources.Due to the rapid increase of population in the world,the increasing competition for water resources has led to an urgent need in increasing crop water productivity for agricultural sustainability.As the medium for crop growth,soils and their properties are important in affecting crop water productivity.This review examines the effects of soil physical,chemical,and microbial properties on crop water productivity and the quantitative relationships between them.A comprehensive view of these relationships may provide important insights for soil and water management in arable land for agriculture in the future.

Water productivity for living aquatic resources in floodplains of Northwestern Bangladesh

Objective:To measure the productivity of water on the floodplain land in terms of fisheries and living aquatic resources based on two floodplain beels in Bangladesh.Methods:Among two beels,beel Mail is practicing community based fish culture management,and beel Chandpur is open access and improperly managed.The production and market price data of fish,snail,and aquatic plants were collected by direct observation based on 30 samples fishers in the year 2006-2007.This study also collected production related water quality data,such as water temperature,pH and dissolved oxygen.Results:The water quality data are found within the normal range.Net aggregated water productivity values based on production costs were TK 8016.23 ha^(-1)and TK 3912.9 ha^(-1)and based on all cost TK 7160.97 ha^(-1)and TK 3741.13 ha^(-1)at beel Mail and beel Chandpur,respectively.The contribution of fish,snails and aquatic resources were 96.50%,3.10%,and 0.40%of the gross aggregated water produced in beel Mail and 87.85%,8.38%,and 3.77%in the beel Chandpur.The water productivity values in beel Mail are higher than in beel Chandpur due to the intervention of community based fish culture.Conclusions:The proper management and techniques of harvesting fish through appropriate number of fish fingerlings stocked,good quality of fish fingerlings,size of beel,good fencing and well defined embankment,etc.can help to improve the productivity of water in the beel areas.

Use of sewage in split doses to enhance water productivity for fish culture

The problem of sewage disposal has received great attention worldwide.The raw sewage contains a variety of high inorganic and organic matters that affect natural water environment.To mitigate such problem,sewage may be recycled through aquaculture practice.Sewage recycling in aquaculture enhances water productivity through nutrients input.Proper loading of sewage ensures viable aquaculture;otherwise,fish mortality occurs due to poor water quality.To optimize sewage application,two different experiments were conducted,each with four treatments.In both experiments,three fish species namely rohu(Labeo rohita Hamilton,1822),mrigal(Cirrhinus mrigala Hamilton,1822),and bata(Labeo bata Hamilton,1822)were tested in triplicate in FRP(Fibre-Reinforced Plastic)tanks.Different sewage concentrations(0,25%,50%and 75%)used in first experiment were prepared by mixing freshwater,showing Biochemical Oxygen Demand(BOD)2.0±0.4 mg/L,10.8±1.4 mg/L,19.6±1.5 mg/L and 41.6±2.58 mg/L,respectively.After 30 days rearing,results showed≥75%fish survival in sewage concentrations up to 50%with BOD level 19.6±1.5 mg/L.Less than 50%fish survived in 75%sewage concentration,with BOD level as 41.6±2.58 mg/L.The second experiment was conducted for 90 days considering 50%sewage concentration as basal dose with BOD level as 19.6 mg/L as an acceptable limit for fish survival.Split doses of sewage were applied in T_(1),T_(2) and T_(3) treatments fortnightly,weekly and semi-weekly intervals,while single dose was used in C(control)treatment.Application of split doses resulted better hydro-biological changes,including nutrients recovery,in T_(1),T_(2) and T_(3) than that of single dose in control.Fish growth plotted with net primary productivity(NPP),phytoplankton and zooplankton densities exhibited positive correlations in T_(2)(12 doses)and T_(3)(24 doses),considered as optimal doses to ensure better water productivity for desirable fish production than sewage with single dose or limited doses(6 doses).

Distribution of chlorophyU a and estimation of primary productivity in the eastern waters of Balingtang Channel in summer

Oceanographical features on both sides of Balingtang Channel (17°55′-20°06′N, 122°55′-126°57′E) were comprehensively investigated on board of R/V "Experiment 3" in June. 1984. The pre-sent paper reports the chlorophyll data collected and primary productivity estimated there. Water sam-ples were taken with a glass bottle of Model HQMat the depth of 0, 10. 25, 50, 75, 100 and 150m, separately. Chlorophyll was determined according to the spectrophotometry proposed by UNESCO(1966) and calculated with the trichromatic equations of Jeffrey-Humphrey(1975). Estimations ofprimary productivity were carried out using a simplified equation (Q = 1.5) given by Cadee(1975).

Photothermal-photocatalytic thin-layer flow system for synergistic treatment of wastewater

The integration of the photocatalytic effect into solar steam is highly desirable for addressing freshwater shortages and water pollution.Here,a ternary film structure for the adsorption and photothermal and photocatalytic treatment of wastewater was designed by combining the technique of self-assembled carbon nano paper with a nitrogen composite titanium dioxide(N-TiO_(2))deposited on the surface of carbon nanotubes(CNT)using polyvinylidene fluoride(PVDF)as a substrate.The photogeneration of reactive oxygen species can be promoted by rapid oxygen diffusion at the three-phase interface,whereas the interfacial photothermal effect promotes subsequent free radical reactions for the degradation of rhodamine B(93%).The freshwater evaporation rate is 1.35 kg·m^(-2)·h^(-1)and the solar-to-water evaporation efficiency is 94%.Importantly,the N-TiO_(2)/CNT/PVDF(N-TCP)film not only effectively resists mechanical damage from the environment and maintains structural integrity,but can also be made into a large film for outdoor experiments in a large solar energy conversion device to collect fresh water from polluted water and degrade organic dyes in source water simultaneously,opening the way for applications in energy conversion and storage.