Controlled drainage in the Nile River delta of Egypt:a promising approach for decreasing drainage off-site effects and enhancing yield and water use efficiency of wheat

North Africa is one of the most regions impacted by water shortage.The implementation of controlled drainage(CD)in the northern Nile River delta of Egypt is one strategy to decrease irrigation,thus alleviating the negative impact of water shortage.This study investigated the impacts of CD at different levels on drainage outflow,water table level,nitrate loss,grain yield,and water use efficiency(WUE)of various wheat cultivars.Two levels of CD,i.e.,0.4 m below the soil surface(CD-0.4)and 0.8 m below the soil surface(CD-0.8),were compared with subsurface free drainage(SFD)at 1.2 m below the soil surface(SFD-1.2).Under each drainage treatment,four wheat cultivars were grown for two growing seasons(November 2018–April 2019 and November 2019–April 2020).Compared with SFD-1.2,CD-0.4 and CD-0.8 decreased irrigation water by 42.0%and 19.9%,drainage outflow by 40.3%and 27.3%,and nitrate loss by 35.3%and 20.8%,respectively.Under CD treatments,plants absorbed a significant portion of their evapotranspiration from shallow groundwater(22.0%and 8.0%for CD-0.4 and CD-0.8,respectively).All wheat cultivars positively responded to CD treatments,and the highest grain yield and straw yield were obtained under CD-0.4 treatment.Using the initial soil salinity as a reference,the soil salinity under CD-0.4 treatment increased two-fold by the end of the second growing season without negative impacts on wheat yield.Modifying the drainage system by raising the outlet elevation and considering shallow groundwater contribution to crop evapotranspiration promoted water-saving and WUE.Different responses could be obtained based on the different plant tolerance to salinity and water stress,crop characteristics,and growth stage.Site-specific soil salinity management practices will be required to avoid soil salinization due to the adoption of long-term shallow groundwater in Egypt and other similar agroecosystems.

The Improvement of the Quality of Irrigation Water Contaminated with Heavy Metals in the Borg El Arab, Egypt

The aim of this study is to estimate the effects of the accumulation of harmful heavy metals in the irrigation water resulting from the proximity of the various activities of various water: sewage, artesian wells and industrial activities, particularly Borg El Arab Industrial area and take Nile water l Control (Bahig canal). The concentrations of these heavy metals in samples drawn from different distances from the source of irrigation in summer 2011 that contain the highest concentrations, followed by the winter of 2012. These results have shown that the amount of heavy metals in the samples at a distance of 50 meters is more than quantity of 5000 m by a 30 to 35 twice in water for irrigation, also the amount of heavy metals in the samples at a distance of 50 meters has values less than the permissible limits and disappeares completely at a distance of 5000 meters and that for different sources.

Competitiveness and Profitability of Intercropping Sunflower with Peanut under Different Irrigation Water Levels and Potassium Fertilizer Rates

A two-year study was carried out at Ismailia Agricultural Research Station, Egypt during 2016 and 2017 summer seasons to evaluate competitive effects of intercropping sunflower and peanut under different drip irrigation water amounts and K fertilizer rates for increasing farmer profitability. Three irrigation amounts (70%, 100% and 120% ETo), three K fertilizer levels (57, 86 and 114 K2O kg/ha) and four intercropping patterns of sunflower and peanut (different spatial arrangements) were implemented. The experimental design was strip split plot with three replications. The results showed that there were no significant differences between 100% and 120% ETo on most of yield traits of the intercrops. The highest K fertilizer level had the highest values of most yield traits of the intercrops. The highest values of peanut and sunflower traits were obtained from intercropping sunflower with peanut, where peanut seeds were sown on both sides of all the raised beds, sunflower seeds were sown on one row above the raised beds and the following bed was left without intercropping (P1). Thus, to attain the highest yield of intercrops and water equivalent ratio (WER), the lowest competitive pressure and the highest farmer profitability, 120% ETo, 114 K2O kg/ha and P1 intercropping pattern should be implemented. This research found that the result of competitiveness was consistent with the result of profitability.

Microbial Water Source for the Desert Plants

Finding water resources for the desert plants is one of the important research areas since it enables saving water resources.Bromus inermis plant was noticed to keep 5%of moisture in its rhizosphere zone;therefore,this study aimed to identify this source of water.Thirteen endophytic bacteria were isolated from the root of B.inermis and identified.Their specific respiration rate was determined.Alcaligenes faecalis showed the highest specific respiration rate.It is a facultative chemoautotrophic hydrogen-fixing bacterium that utilizes the hydrogen gas as energy source and the water is produced as an end product.The source of hydrogen gas for this bacterium is not only from air and soil gases but also from the hydrogen-producing bacteria such as Enterobacter spp.,which was among the isolated bacteria.The hydrogenases synthesizing genes(HoxC,HypA and HypB)were detected in most of the isolated bacteria and roots of four wild plants,out from 18 wild plant samples,epically the grains of the wild wheat plant.This result suggests that the hydrogen-fixing and hydrogen-producing bacteria transfer from the root through the plant to inhabit the grain/seeds.This can help the grain/seeds to germinate in drought environment.

Using Environmentally Friendly Hydrogels to Alleviate the Negative Impact of Drought on Plant

The use of natural hydrogels in agriculture provides solutions to many problems without threatening the environment. This study aims to evaluate the potential impact of environmentally friendly hydrogels (pectin, starch and pectin + starch) in reducing the negative effects of drought stress on tomato yield and quality. Two different peels (orange peel and banana peel) are used to prepare environmentally friendly hydrogels. The water retention efficiency of hydrogels has been studied. Greenhouse experiment for tomato under drought stress was conducted during 2019. These hydrogels were used under several level of irrigation (100%, 75%, and 50% FC), soil without hydrogel was used as a control. The results showed that the eco-friendly hydrogels (starch, pectin, and pectin + starch) had capacity retention of water for a long time. The obtained data from the greenhouse experiment showed that the eco-friendly hydrogel showed a positive effect on retention of water and increase the soil moisture content compared to control. The highest increase was observed at pectin + starch treatment. This increase reached to 2.8-, 2.4- and 2.0-fold for 100%, 75% and 50% FC compared to the control. Eco- friendly hydrogel application under different drought conditions led to improve yield and quality of tomato fruits. Moreover, conversion of agricultural wastes to hydrogels and the use of these eco-friendly materials instead of synthetic hydrogels are necessary to utilize the limited natural resources and decrease the harmful impact of agricultural wastes on the environment and pave the way for the transition to a sustainable agriculture system.

Positive and Negative Environmental Effect of Using Zinc Oxide Nanoparticles on Wheat under Drought Stress

Nanoscience is a development concept in the field of agriculture. Water scarcity is one of the most serious stresses that restrict growth of plant. This search was done to value the positive and negative influence of ZnO nanoparticles on wheat plant growth under drought stress. A green synthesis technique was used to produce pollutant-free nano structures. A field experiment was carried out during successive season (2019/2020). NP-Zn-O was applied either by seed-soaking, foliar spraying, or both together applications. The dose of ZnO NPs was 100 mg/l. Data showed that drought stress reduced the grain and shoot wheat yield. The use of different forms of ZnO improved the grain and shoot wheat yield, these increases reached 1.16-, 1.54-fold that control. In addition, one of the other effects of Zn-O-NPs is to increase the levels of chlorophyll and proline antioxidants in plant tissues, as it is a cofactor for enzymes such as superoxide dismutase and catalase. The data suggest that the role of ZnO NPs is not only to improve plant growth and physiological parameters, but also to improve nutrient uptake and plant nutrient levels. In this regard, the use of zinc in the form of ZnO NPs has a positive effect on reducing the adverse effects of drought conditions and improving the nutritional quality of plants.

Evaluation of Cobalt Application Combined with Gypsum and Compost as a Regulator of Cabbage Plant Tolerance to Soil Salinity

In response to the global food crisis and the imperative to address soil degradation, the international agricultural policy is actively working to alleviate the adverse impacts of soil salinity. As part of this initiative, a field trial spanning two consecutive seasons (2019/20-2020/21) was conducted under saline conditions. The primary objective was to evaluate the influence of various compost sources, including vermicompost at a rate of 0.5 ton·fed-1 and plant residues compost at a rate of 5.0 ton·fed-1, as main plots. Subplots were established by applying agricultural gypsum, both in the presence and absence of gypsum requirements. Additionally, sub-subplots were created by externally applying cobalt at a rate of 10.0 mg·L-1, with one sub-subplot receiving foliar cobalt application and the other not. The trial sought to assess the growth performance, chemical composition, enzymatic antioxidants, yield, and quality of cabbage plants (Brassica oleracea var. capitata L.) cultivated in saline soil. According to the findings, cabbage plants exhibited the most favorable response in terms of plant height, chlorophyll content, carotene levels, leaf area, nitrogen (N), phosphorus (P), potassium (K), head yield, vitamin C, and total dissolved solids (TDS) when treated with vermicompost, followed by plant compost. Conversely, plants grown without compost exhibited the least improvement in performance. Cabbage treated with agricultural gypsum requirements showed better performance than those without gypsum amendment. Moreover, plants subjected to cobalt spray demonstrated the highest growth, yield, and quality parameters compared to those without cobalt foliar application. In contrast, the control group (plants without the studied treatments) displayed the highest levels of enzymatic antioxidants, specifically catalase and peroxidase. This indicates that soil salinity stress led to an increase in catalase and peroxidase production in cabbage plants as a defense against the harmful impact of reactive oxygen species (ROS) resulting from soil salinity stress. The applied treatments (compost, gypsum, and cobalt) led to a reduction in the cabbage plant’s inherent production of catalase and peroxidase. Generally, the combined treatment of vermicompost × gypsum requirements × cobalt proved effective in mitigating the detrimental effects of soil salinity on cabbage plants. These findings hold significance for farmers and policymakers aiming to enhance agricultural productivity in regions affected by soil salinity. Additionally, further research can explore the long-term effects of these treatments on soil health and crop sustainability.

Aqueous extracts of microalgae exhibit antioxidant and anticancer activities

Objective:To investigate the antioxidant and anticancer activities of aqueous extracts of nine microalgal species.Methods:Variable percentages of major secondary metabolites(total phenolic content,terpenoids and alkaloids) as well as phycobiliprotein pigments(phycocyanin, allophycocyanin and phycoerythrin) in the aqueous algal extracts were recorded.Antioxidant activity of the algal extracts was performed using 2,2 diphenyl-1-picrylhydrazyl(DPPH) test and 2,2'azino-bis(ethylbenzthiazoline-6-sulfonic acid(ABTS.) radical cation assay.Anticancer efficiency of the algal water extracts was investigated against Ehrlich Ascites Carcinoma cell(EACC) and Human hepatocellular cancer cell line(HepG2).Results:Antioxidant activity of the algal extracts was performed using DPPH test and ABTS.^+ radical cation assays which revealed 30.1-72.4%and 32.0-75.9%respectively.Anticancer efficiency of the algal water extracts was investigated against Ehdich Ascites Carcinoma Cell(EACC) and Human Hepatocellular cancer cell line(HepG2) with an activity ranged 87.25%and 89.4%respectively.Culturing the promising cyanobacteria species;Nostoc muscorum and Oscillatoria sp.under nitrogen stress conditions(increasing and decreasing nitrate content of the normal BG11 medium,1.5 g/L),increased nitrate concentration(3,6 and 9 g/L) led to a remarkable increase in phycobilin pigments followed by an increase in both antioxidant and anticancer activities in both cyanobacterial species.While the decreased nitrate concentration(0.75,0.37 and 0.0 g/L) induced an obvious decrease in phycobilin pigments with complete absence of allophycocyanin in case of Oscillatoria sp.Conclusions:Nitrogen starvation(0.00 g/L nitrate) induced an increase and comparable antioxidant and anticancer activities to those cultured in the highest nitrate content.

Changes in Germination and Seedling Traits of Sesame under Simulated Drought

Drought is considered one of the leading abiotic constraints to agricultural crop production globally.Present study was conducted to assess the effects of different drought treatments(viz.Control,10%PEG,and 20%PEG)on seed germination,germination indices,seedling traits,and drought tolerance indices of sesame.Our results showed that maximum reduction in the studied parameters was observed at higher PEG concentration(i.e.,20%PEG).As compared to control,the drought treatments viz.10%and 20%PEG decreased the values for germination indices,such as germination percentage,coefficient of variation of germination time,germination index,and seedling vigor index.Similarly,for seedling traits,the values were decreased for root length,shoot length,root shoot ratio,root fresh weight,shoot fresh weight,root dry weight and shoot dry weight under 10%and 20%PEG treatments significantly in comparison with control.Furthermore,relative to control,the values for drought tolerance indices,such as germination drought tolerance index,root length drought tolerance index,shoot length drought tolerance index,total seedling length drought tolerance index,root fresh weight drought tolerance index,shoot fresh weight drought tolerance index,total fresh weight drought tolerance index,root dry weight drought tolerance index,shoot dry weight drought tolerance index and total dry weight drought tolerance index were also reduced under 10%and 20%PEG treatments,respectively.Our results confirms that drought impact on seed germination and seedling traits could be quantified by using different indices which can further help to design drought adaptation and mitigation strategies.Based on these results it can be concluded that germination indices,seedling traits,and drought tolerance indices have great potential to simulate drought stress impacts on different crop traits thus they should be used in all kinds of stress related studies.

An evaluation of the bioavailability and bioaccumulation of selected metalso ccurring in a wetland area on the volcanic island of Guam,Western Pacific Ocean

This initial research examined the presence, distribution and bioavailability of Cu, Cr, Ni, Mn and Fe in a wetland area of southern Guam. The research sites are within an area covered with saporite, a soil type derived from volcanic deposits on the island. Leaf tissue of Pandanus tectorius was extracted and analysed to determine the bioaccumulation of the target metals. Metal accumulation at sites considered aerobic and anaerobic was investigated together with an attempt to correlate actual accumulation of the target metals in the plant tissue with a recognised bioavailability indicator, in this case, three step sequential extraction scheme. Manganese was found to be accumulated in relatively high concentrations and to a lesser extent Cu was also accumulated. Chromium, Ni and Fe however exhibited very low accumulation factors. Accumulation of Mn in particular was significantly affected by aerobic conditions whereas the converse effect was experienced by Cu. Significant correlation between various steps of a Sequential Extraction Scheme and actual accumulation was not achieved although the degree of aerobic conditions at each site and soil pH did affect concentrations of metals extracted by differing steps of SES. Results obtained suggest that further research in the area should be undertaken using different plant species and tissues.

Preliminary Study on Wetland Resources and Management in China

China is rich in wetland resources.It is an important way to improve the ecological environment and realize the sustainable development strategy by strengthening the protection and sustainable utilization of wetland resources.In this paper,based on the analysis of the current situation of wetland resources and management,it is proposed that wetland management should be included in the social and economic system as well as land and water system management.

Fungal assembly of L-asparaginase using solid-state fermentation:a review

Because of its antitumor therapeutic-activity,as well as its application in food industries to improve the quality,L-asparaginase has attracted considerable attention from several investigators.In recent years,fungi have occupied advanced rank among microorganisms in the production process of the enzyme.This review is spotting the light on the advantages of fungal enzyme and its applications in the food industry and medications.The solid-state fermentation was discussed as the wide alternative and most accepted biosynthesis technique.However,some lights were also spotted to the statistical experimental design of the fermentation process,mainly on the methodology of the response surface for L-asparaginase biosynthesis by fungi.Finally,the immobilization of the enzyme and the features of the widely used solid substrates for the maximization of the production process were explored.

Nanoparticles induce the biosynthesis and activity of the new possible therapeutic proteinase source,Talaromyces purpureogenus KJ584844

The need for the bacterial proteinase is rapidly growing,urging to catch a lowcost medium for the microbial fermentation,nanoparticles can play a vital role in this respect.The proteinase of Talaromyces purpureogenus was produced on the tubers of Helianthus tuberosus that also operated as solid support for the fermentation process.The interface amongst nitrogen sources(NH_(4)Cl and yeast extract)was investigated,applying the statistical modeling of central composite design under solid-state fermentation.The optimum medium for proteinase secretion was stimulated by 979.82 mg NH_(4)Cl and 437.68 mg yeast extract per 100 g substrate,yielding 108.15 U/g tubers.Using Plackett-Burman experimental design,the nanoparticles Co,Ni and Fe were assessed as inducers for proteinase stimulants.Co nanoparticles(5 ppm)were the greatest in both proteinase production by the fungus as well as an inducer of the proteolysis process by the enzyme when using faba bean straw as a proteinaceous substrate in the reaction mixture,liberating the extreme quantity of amino acids,compared with the lack of the nanoparticles.The findings suggest the incorporation of Co nanoparticles in both the proteinase fabrication process and during the degradation of proteinaceous materials induce proteinase catalyst.This approach could be extended to modulate the productivity and activity of similar biomolecules.

Exendin-4 inhibits the survival and invasiveness of two colorectal cancer cell lines via suppressing GS3Kβ/β-catenin/NF-κB axis through activating SIRT1

This study examined if the anti-tumorigenesis effect of Exendin-4 in HT29 and HCT116 colorectal cancer(CRC)involves modulation of SIRT1 and Akt/GSR3K/β-catenin/NF-κB axis.HT29 and HCT116 cells were treated either with increasing levels of Exendin-4(0.0-200μM)or with Exendin-4(at its IC50)in the presence or absence of EX-527(10μM/a selective SIRT1 inhibitor)or Exendin-4(9-39)amide(E(9-39)A)(1μM/an Exendin-4 antagonist).In a dose-dependent manner,Exendin-4 inhibited cell survival,but enhanced levels of lactate dehydrogenase(LDH)and single-stranded DNA(ssDNA)in both HT29 and HCT116.In both cell lines and at it has an IC50(45μM for HT29 and 35μM for HCT1165),Exendin-4 also significantly reduced cell survival,migration,and invasion of both cell types,with no effect on the expression GLP-1 receptors(GLPRs)nor of the activity of Akt.At these doses,Exendin-4 also increased the expression of SIRT1 but reduced the acetylation of NF-κB and the expression of Bax and cleaved caspase-3 and in both cell lines.Concomitantly,protein levels of p-GS3Kβ(Ser9),total and acetylatedβ-catenin,and Anix2 were significantly decreased,but levels of p-GS3Kβ(Ser9)and p-β-catenin(Ser33/37/Thr41)were significantly increased in both HT29 and HCT116-exendin-4 treated cells.All the effects exerted by Exendin-4 were completely prevented by Ex527 or E(9-39)A.In conclusion,Exendin-4 suppresses the tumorigenesis of HT29 and HCT116 CRC cell activation of GS3Kβ-induced inhibition ofβ-catenin and NF-κβin a SIRT1-dependent mechanism.

The use of Phanerochaete chrysosporium,Trichoderma harzianum and Trichoderma viride for biogas production

The expanding cost of ordinary fuel in urban zones requires the investigation of other vitality sources.The exploitation of agricultural wastes for biogas production could protect our environment and can also solve emerging energy crises problems.Phanerochaete chrysosporium,Trichoderma virdie and Trichoderma harzianum were used to ferment rice straw and cattle dung for production of compost and biogas.Biogas yield was determined using displacement technique,using acidified water(1 N H_(2)SO_(4))to prevent solubilization of carbon dioxide contained in the biogas.Current results showed that the highest rate of biogas and methane were recorded with treated rice straw mixed with cattle dung where the amount of production from the total gas was 51.84 of biogas and 37.86 of methane per Liter(L)/Kilogram(Kg)of fermented material.Also,the results showed that the consumed biogas and methane related to volatile solids gave the highest amount with untreated rice straw(86.32 and 56.72 L/Kg respectively)followed by treated rice straw and untreated and treated mixtures of rice straw and cattle dung respectively.The results also showed that the highest bacterial count was obtained from fungi treated rice straw mixed with cattle dung(125×10^(3)cells/g)followed by treated rice straw(32×10^(3)cells/g).This study confirms that P.chrysosporium,T.virdie and T.harzianum significantly speed up the process of aerobic and anaerobic fermentation of rice straw in respect to biogas and methane production.

Secondary antiviral metabolites from fungi with special reference to coronaviruses

Profound inspection of the life forms on the earth teaches how to be the complexity of interrelationships among the various systems.Because of the emergence of novel viruses all the time and the inadequate of vaccines and antivirals,viral contagions are amongst the most causative diseases affecting people worldwide.Fungi exemplify a massive source of bioactive molecules as,many fungal secondary metabolities like Oxoglyantrypine,Carneic acid F,Scedapin C,Asteltoxin E,Phomanolide,Norquinadoline A and Quinadoline B have antiviral activity.This review deals with how secondary metabolites of fungi can help in the war against viruses in general and especially Coronaviruses moreover several pieces of literature pointed out that many clusters of fungi in different biotopes are waiting to be exploited.

Climate change impact and adaptation on wheat yield, water use and water use efficiency at North Nile Delta

Investigation of climate change impacts on food security has become a global hot spot.Even so,efforts to mitigate these issues in arid regions have been insufficient.Thus,in this paper,further research is discussed based on data obtained from various crop and climate models.Two DSSATcrop models(CMs)(CERESWheat and N-Wheat)were calibrated with two wheat cultivars(Gemiza9 and Misr1).A baseline simulation(1981-2010)was compared with different scenarios of simulations using three Global Climate Models(GCMs)for the 2030s,2050s and 2080s.Probable impacts of climate change were assessed using the GCMs and CMs under the high emission Representative Concentration Pathway(RCP8.5).Results predicted decreased wheat grain yields by a mean of 8.7%,11.4%and 13.2%in the 2030s,2050s and 2080s,respectively,relative to the baseline yield.Negative impacts of climatic change are probable,despite some uncertainties within the GCMs(i.e.,2.1%,5.0%and 8.0%)and CMs(i.e.,2.2%,6.0%and 9.2%).Changing the planting date with a scenario of plus or minus 5 or 10 days from the common practice was assessed as a potentially effective adaptation option,which may partially offset the negative impacts of climate change.Delaying the sowing date by 10 days(from 20 November to 30 November)proved the optimum scenario and decreased further reduction in wheat yields resulting from climate change to 5.2%,6.8%and 8.5%in the 2030s,2050s and 2080s,respectively,compared with the 20 November scenario.The planting 5-days earlier scenario showed a decreased impact on climate change adaptation.However,the 10-days early planting scenario increased yield reduction under projected climate change.The cultivar Misr1 was more resistant to rising temperature than Gemiza9.Despite the negative impacts of projected climate change on wheat production,water use efficiency would slightly increase.The ensemble of multi-model estimated impacts and adaptation uncertainties of climate change can assist decision-makers in planning climate adaptation strategies.

Using quantile regression to analyze the stressor–response relationships between nutrient levels and algal biomass in three shallow lakes of the Lake Taihu Basin, China

Understanding the stressor–response relationship between nutrient levels and algal biomass is a prerequisite for the management of eutrophication in lakes. In this study, a quantile regression(QR) approach was used to interpret the stressor–response relationships between nutrient(e.g., phosphorus, nitrogen) concentrations and algal biomass as measured by chlorophyll-a(Chl-a) levels. QR results indicated that Lake Dianshan and Lake Changdang,which are both heavily eutrophicated, were P-limited only.In contrast, Lake Kuilei, which has significantly lower nutrient levels and algal biomass than the other two lakes,was P- and N-limited. Moreover, in Lake Kuilei, N and P levels had significant interaction effects on the algal biomass at the upper quantiles(s [ 0.68). The degree to which the lakes were P-limited increased with rises in the mean total P concentration in the lakes. QR has many advantages over ordinary least squares regression for discriminating limiting factors and, in particular, allows us to estimate changes near the upper extremes of distributions associated with limiting factors. QR is adapted to more specialized risk management problems, such as early warnings of the risk of algal blooms.The probable value-at-risk of harmful algal blooms for Lake Kuilei, Lake Dianshan and Lake Changdang is s = 0.76(Chl-a = 9 mg/m3), s = 0.87(Chl-a = 24 mg/m3) and s = 0.72(Chl-a = 35 mg/m3), respectively. Given the results of the stressor–response relationship analysis, we conclude that reductions in P input represent the most feasible and least costly approach for managing eutrophication in the shallow lakes of the Lake Taihu Basin. To control the magnitude and duration of algal blooms in shallow lakes,reductions in P and N inputs are required. The 95 % CI bounds of slopes indicated that the interactions of nonnutrient factors with nutrients had strong impacts on the algal biomass in lightly eutrophicated Lake Kuilei. It is suggested that, in addition to reductions in nutrient loads,several ecological measures, such as an increase in the biomass of submerged macrophytes and the reduction of hydraulic retention time by flushing, could represent important components of an integrated approach to eutrophication management in the Lake Taihu Basin.

Influence of potassium fertilization and foliar application of zinc and phosphorus on growth,yield components,yield and fiber properties of Egyptian cotton(Gossypium barbadense L.)

Aims Supplying optimal quantities of mineral nutrients to growing crop plants is one way to improve crop yields.Nutrients need to be used rationally in order to avoid a negative ecological impact and undesirable effects on the sustainability of agricultural production systems.Excessive application of nutrients also affects the farmer’s economy.In order to calculate the amount of fertilizer to be applied to crops,it is necessary to develop recommendation programmers that adjust nutrient rates to crop requirements.Methods Experiments in two successive seasons were conducted to investigate the effect of K fertilization and foliar application of Zn and P on yield and fiber properties of cotton cv.Giza 86.Potassium(0.0 and 47.4 kg of K ha^(-1))was soil applied,while chelated zinc(0.0 and 57.6 g of Zn ha^(-1),applied twice at 70 and 85 days after sowing‘DAS’)and phosphorus(0.0,576,1152 and 1728 g of P ha^(-1),applied twice at 80 and 95 DAS)were applied to the foliage.Important findings Dry matter yield,total chlorophyll concentration,K,Zn and P uptake per plant,number of opened bolls per plant,boll weight,seed index,lint index,seed cotton yield per plant,seed cotton and lint yield ha^(-1) and earliness of harvest increased with the application of K,Zn and P.Treatments generally had no significant effect on lint percentage and fiber properties,with exceptions,for micronaire reading and flat bundle strength,and uniformity ratio,where the mean values of these characters were significantly increased over the untreated control by applying K,and for the micronaire reading in the first season,when applying P at 1728 g ha^(-1),and uniformity ratio in the second season,when applying Pat 1152 and 1728 g ha^(-1),where the mean values of these characters were significantly increased over the untreated control by applying P.Under the conditions of this study,applying K fertilization at 47.4 kg ha^(-1) combined with spraying cotton plants with zinc at 57.6 g ha^(-1) and also with P at 1728 g ha^(-1) improved growth and yield of Egyptian cotton.

Occurrence, polarity and bioavailability of dissolved organic matter in the Huangpu River,China

Dissolved organic matter （DOM） plays an important role in biogeochemical cycles in aquatic ecosystem. To investigate the characteristics of DOM in Huangpu River {the last tributary of the Yangtze River）, surface water samples were collected along the river from December 2011 to June, 2013. The concentrations of dissolved organic carbon （DOC）, the absorbance and fluorescence spectrum of DOM in water samples were measured. Fluorescent DOM in the Huangpu River was decomposed into four components by the parallel factor analysis （PARAFAC）, including one humic-like substance and three protein-like substances. It showed that high spatial variability of DOC concentration was observed in the upstream water compared to the downstream water, and so did the absorbance coefficients of chromophoric dissolved organic matter and the total fluorescence intensities of different PARAFAC components of DOM. Furthermore, there was a large difference between the polarity and bioavailability of DOM in the Huangpu River. Polar compounds dominated tyrosine-like component of fluorescent DOM in all seasons. Tryptophan-like and humic-like substances had more polar fraction in summer and autumn than those in winter, while aromatic protein-like materials had the highest polar fraction in winter. Almost all of fluorescent DOM components were refractory in spring, while less than 20% of fluorescent DOM in average were biodegradable within 4 weeks in other seasons. We concluded that the spatial variation in the abundance of DOM in the Huangpu River is mainly affected by the water discharges from the Hangjiahu Plain and the seasonal difference in polarity and bioavailability of DOM is largely determined by its origins.