Combining the critical nitrogen concentration and machine learning algorithms to estimate nitrogen deficiency in rice from UAV hyperspectral data

Rapid and large area acquisition of nitrogen(N)deficiency status is important for achieving the optimal fertilization of rice.Most existing studies,however,focus on the use of unmanned aerial vehicle(UAV)remote sensing to diagnose N nutrition in rice,while there are fewer studies on the quantitative description of the degree of N deficiency in rice,and the effects of the critical N concentration on the spectral changes in rice have rarely been explored.Therefore,based on the canopy spectral data obtained by remotely-sensed UAV hyperspectral images,the N content in rice was obtained through field sampling.The construction method of the rice curve for the northeastern critical N concentration was studied,and on this basis,N deficiency was determined.Taking the spectrum of the critical N concentration state as the standard spectrum,the spectral reflectivity data were transformed by the ratios and differences,and the feature extraction of the spectral data was carried out by the successive projections algorithm(SPA).Finally,by taking the characteristic band as the input variable and N deficiency as the output variable,a set of multivariate linear regression(MLR),long short-term memory(LSTM)inversion models based on extreme learning machine(ELM),and the nondominated sorting genetic algorithmⅢextreme learning machine(NSGA-Ⅲ-ELM)were constructed.The results showed two key aspects of this system:1)The correlation between the N deficiency data and original spectrum was poor,but the correlation between the N deficiency data and N deficiency could be improved by a difference change and ratio transformation;2)The inversion results based on the ratio spectrum and NSGA-Ⅲ-ELM algorithm were the best,as the R2values of the training set and validation set were 0.852 and 0.810,and the root mean square error(RMSE)values were 0.291 and 0.308,respectively.From the perspective of the spectral data,the inversion accuracy of the ratio spectrum was better than the accuracy of the original spectrum or difference spectrum.At the algorithm level,the model inversion results based on LSTM algorithms showed a serious overfitting phenomenon and poor inversion effect.The inversion accuracy based on the NSGA-Ⅲ-ELM algorithm was better than the accuracy of the MLR algorithm or the ELM algorithm.Therefore,the inversion model based on the ratio spectrum and NSGA-Ⅲ-ELM algorithm could effectively invert the N deficiency in rice and provide critical technical support for accurate topdressing based on the N status in the rice.

A mitochondrial phosphate transporter,McPht gene,confers an acclimation regulation of the transgenic rice to phosphorus deficiency

Phosphate transporters play an important role in promoting the uptake and transport of phosphate in plants. In this study, the McPht gene from the Mesembryanthemum crystallinum, a mitochondrial phosphate transporter, was isolated and constructed onto a constitutive expression vector carrying 35S：：GFP, and the recombinant constructs were transferred into Oryza sativajaponica L. cv. Kitaake to investigate the regulatory role of the McPhtgene under phosphorus deficiency. The McPhtgene encodes a protein of 357 amino acids with six transmembrane domains and is located to the mitochondria, and the mRNAtranscripts of the McPht gene are highly accumulated in the shoots of M. crystallinum in response to phosphorus deficiency. However, more mRNA transcripts of the McPht gene were accumulated in the roots of the transgenic rice under phosphorus deficiency. Measurements showed that the transgenic rice demonstrated an enhanced promotion in the root development, the root activities, and phosphate uptake under phosphorus deficiency. Transcriptome sequencing showed that the transgenic rice exhibited total of 198 differentially expressed genes. Of these, total of 154 differentially expressed genes were up-regulated and total 44 genes were down-regulated comparing to the wild type in response to phosphorus deficiency. The selective six genes of the up-regulated differentially expressed genes showed an enhanced increase in mRNA transcripts in response to phosphorus deficiency, however, the transcripts of the mitochondrial carrier protein transporter in rice, a homologous gene of the McPht, in both the transgenic line and the wild type had no obvious differences. Functional enrichment analyses revealed that the most of the up-regulated genes are involved in the cytoplasmic membrane-bounded vesicle, and most of the down-regulated genes are involved in the mitochondrion and cytoplasmic membrane-bounded vesicle. The differentially expressed genes were highly enriched in plant secondary metabolisms and plant-pathogen interaction. These results indicated that the overexpression of the McPht gene might participate in the physiological adaptive modulation of the transgenic rice to phosphorus deficiency by up- or down-regulating the differentially expressed genes.

Prevalence of Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency in India: A Systematic Review

Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency is the most common enzyme deficiency of human erythrocyte affecting more than 400 million people worldwide. In India, G6PD deficiency was first reported in 1963 and since then various investigations have been conducted across country. The objective of this work was to study the prevalence of G6PD deficiency in different ethnic, caste and linguistic groups of Indian population. A systematic search of published literature was undertaken and the wide variability of G6PD deficiency has been observed ranging from 0% - 30.7% among the different caste, ethnic, and linguistic groups of India. It was observed that the incidence of G6PD deficiency was found to be considerably higher among the tribes (9.86%) as compared to other ethnic groups (7.34%) and significantly higher in males as compared to females.

Feasibility of Rock Phosphate and Other Amendments in Preventing P Deficiency in Barley on a P-Deficient Soil in Northeastern Saskatchewan

In?the Canadian Prairies, many soils on organic farms are low in available P, and the only alternative is to use external sources to prevent P nutrient deficiency on these soils. A 3-year (2012 to 2014) field experiment was established in spring 2012 on a P-deficient soil near Kelvington, Saskatchewan, Canada, to determine the potential of organic amendments (alfalfa pellets, compost manure, thin stillage and distiller grain dry of wheat), inorganic amendments (rock phosphate granular, rock phosphate fine, wood ash and bone meal ash) and microbial inoculants/products (JumpStart®and MYKE®PRO), applied alone or in a combination with N and/or P commercial fertilizers, in preventing P deficiency and increasing seed yield, N and P uptake of barley. Compared to unfertilized control, N only treatment did not result in any significant increase in seed yield, while application of P alone increased seed yield significantly but to a lesser degree than when both N and P fertilizers were applied together in all 3 years. Rock phosphate did not result in any seed yield benefit, even when applied along with N fertilizer. Wood ash fine increased seed yield of barley significantly only in the presence of N fertilizer, with highest seed yield in the presence of both N + P fertilizers. Seed yield of barley increased moderately with alfalfa pellets, significantly with compost manure, and considerably with distiller grain dry of wheat, but highest seed yield was obtained from thin stillage, which was essentially similar to that obtained from the N + P fertilizer combination. There was no yield benefit from JumpStart or MykePro in any year and only slight benefit from bone meal ash in 2013. The addition of N fertilizer to MykePro or bone meal ash treatments increased seed yield, but highest yield was obtained when both N and P fertilizers were added, suggesting a lack of available P for optimum seed yield. With few exceptions, the response trends of total N and P uptake in seed + straw to the amendments studied were generally similar to those of seed yield. In conclusion, the organic amendment “thin stillage” provided balanced nutrition and produced yield and nutrient uptake of barley similar to balanced N + P fertilizer treatment, and it was closely followed by “distiller grain dry of wheat”, with moderate benefit from compost manure and some benefit from alfalfa pellets. In this extremely P-deficient soil, rock phosphate was not found effective in preventing P deficiency in barley, while wood ash and bone meal ash provided moderate increase in barley yield, with little yield benefit from JumpStart and MykePro, when other nutrients were not limiting in the soil.

Thermal decomposition of magnesium ammonium phosphate and adsorption properties of its pyrolysis products toward ammonia nitrogen

High-purity magnesium ammonium phosphate （MAP） was precipitated by controlling pH value of the reaction system of 9.0-9.5. The thermal decomposition behavior of MAP and the adsorption properties of its pyrolysis products toward ammonia-nitrogen were also studied by XRD, SEM, TGA-DTA and FT-IR methods. The results indicated that high-purity MAP was obtained at pH value of 9.0-9.5. Upon heating to 100-120℃ for 120 min, MAP was thermally decomposed, losing water and ammonia concomitantly with a reduction in grain size and crystallinity. The capacity of pyrolysis products for ammonia nitrogen adsorption reached 72.5 mg/g, with a removal rate of up to 95% from an 800 mg/L solution. The characteristic diffraction peaks corresponding to MAP mainly appeared in their XRD patterns after adsorption of ammonia nitrogen. The pyrolysis products of MAP at 100-120 ℃ could be recycling-used as the chemical treatment regents of ammonia nitrogen in the practical application.

Glucose-6-phosphate dehydrogenase(G6PD) deficiency is associated with asymptomatic malaria in a rural community in Burkina Faso

Objective:To investigate 4 combinations of mutations responsible for glucose-6—phosphate dehydrogenase(G6PD) deficiency in a rural community of Burkina Faso,a malaria endemic country.Methods:Two hundred individuals in a rural community were genotyped for the mutations A376 G.G202A,A542 T,G680T and T968 C using TaqMan single nucleotide polymorphism assays and polymerase chain reaction followed by restriction fragment length polymorphism.Results:The prevalence of the G6 PD deficiency was 9.5%,in the study population.It was significantly higher in men compared to women(14.23%vs 6.0%,P=0.049).The 202A/376 G G6PD Awas the only deficient variant detected.Plasmodium falciparum asymptomatic parasitemia was significantly higher among the C6PD-non—deficient persons compared to the G6PD-deficient(P<0.001).The asymptomatic parasitemia was also significantly higher among G(SPI) nondeficient compared to C6PD—heterozygous females(P<0.001).Conclusions:This study showed that the G6 PD A- variant associated with protection against asymptomatic malaria in Burkina Faso is probably the most common deficient variant.

Effects of Nitrogen, Phosphate and Potassium Fertilizers on Soft Rot of Konjac Based on Grey Correlation Analysis

[Objective] The effects of different application amounts of nitrogen, phos-phate and potassium fertilizers on soft rot of konjac were investigated in this study. [Method] The grey correlation analysis was adopted to evaluate the correlation be-tween the application amount of nitrogen, phosphate and potassium fertilizers and the occurrence of soft rot of konjac. [Result] The excessive application of nitrogen fertilizer would induce the occurrence of soft rot of konjac, but the application of potassium fertilizer had a good control effect on soft rot. [Conclusion] The applica-tion amount of nitrogen fertilizer should be control ed reasonably in the planting of konjac, but the application amount of phosphate and potassium fertilizer could be in-creased to some extent, reducing the occurrence of soft rot of konjac.

Total Amount Control Test of Nitrogen Fertilizer and Phosphate Fertilizer on Winter Wheat

[Objective] This study was conducted to optimize the suitable application amounts of nitrogen fertilizer and phosphate fertilizer for winter wheat.[Method] A field experiment was carried out to investigate the effects of the application amounts of nitrogen fertilizer and phosphate fertilizer on the yield of winter wheat.[Result]The quadratic simulation function between the application of nitrogen fertilizer and wheat yield was y =-0.6611x^2＋20.091 x ＋234.85,with a correlation coefficient of0.970 8,and the yield of winter wheat was the highest at the application amount of nitrogen fertilizer of 228.0 kg/hm^2.The quadratic simulation function between the application of phosphate fertilizer and wheat yield was y =-0.572 6x^2＋13.168 x ＋340.4,with a correlation coefficient of 0.921 95,and the yield of winter wheat was the highest at the application amount of phosphate fertilizer of 172.5 kg/hm^2.[Conclusion] This study provides a scientific basis for the rational application of nitrogen fertilizer and phosphate fertilizer on winter wheat.

Influences of nitrification inhibitor 3,4-dimethyl pyrazole phosphate on nitrogen and soil salt-ion leaching

An undisturbed heavy clay soil column experiment was conducted to examine the influence of the new nitrification inhibitor, 3,4- dimethylpyrazole phosphate （DMPP）, on nitrogen and soil salt-ion leaching. Regular urea was selected as the nitrogen source in the soil. The results showed that the cumulative leaching losses of soil nitrate-N under the treatment of urea with DMPP were from 57.5% to 63.3% lower than those of the treatment of urea without DMPP. The use of nitrification inhibitors as nitrate leaching retardants may be a proposal in regulations to prevent groundwater contaminant. However, there were no great difference between urea and urea with DMPP treatments on ammonium-N leaching. Moreover, the soil salt-ion leaching losses of Ca^2＋, Mg^2＋, K^＋, and Na^＋ were reduced from 26.6% to 28.8%, 21.3% to 27.8%, 33.3% to 35.5%, and 21.7% to 32.1%, respectively. So, the leaching losses of soil salt-ion were declined for nitrification inhibitor DMPP addition, being beneficial to shallow groundwater protection and growth of crop. These results indicated the possibility of ammonium or ammonium producing compounds using nitrification inhibitor DMPP to control the nitrate and nutrient cation leaching losses, minimizing the risk of nitrate pollution in shallow groundwater.

Effect of different levels of nitrogen deficiency on switchgrass seedling growth

Switchgrass(Panicum virgatum L.) is a warm-season rhizomatous perennial grass that can tolerate diverse abiotic stresses while yielding relatively high biomass, and is considered a leading biofuel feedstock for marginal lands. Nitrogen(N) is crucial for the growth and development of switchgrass, and its tolerance to low N supply and high N use efficiency are very important for its production under poor conditions. The large-scale planting of switchgrass on marginal lands could be an effective approach to solving the problem of feedstock supply for biomass energy. This study used a hydroponic experiment to evaluate the effect of N deficiency on switchgrass seedlings. Three N treatments(0, 0.15, and 1.50 mmol L-1Hoagland's solution)and six cultivars were used, three of each ecotype(upland and lowland). The results showed that biomass, leaf area, root surface area, net photosynthesis, and total chlorophyll content significantly decreased under low N treatments compared with those in full strength Hoagland's nutrient solution. However, once established, all plants survived extreme N stress(0 mmol L-1) and, to some extent, were productive. Cultivar Kanlow performed best of the six cultivars under stress. Significant interactions between stress treatment and cultivars showed that breeding for cultivars with high yield and superior performance under N deficiency is warranted. The lowland outperformed the upland ecotypes under stress, suggesting that lowland cultivars may survive and be productive under a wider range of stress conditions.However, given the better adaptability of lowland ecotypes to hydroponic cultivation, further study is needed.

Identification of microRNAs involved in crosstalk between nitrogen, phosphorus and potassium under multiple nutrient deficiency in sorghum

Nitrogen(N),phosphorus(P),and potassium(K)are important for plant growth and development.MicroRNAs(miRNAs)play important roles in regulating plant response to nutrient(N,P,and K)deficiencies.Several miRNAs have been identified under nutrient deficiency conditions in many plant species.However,the manner in which miRNAs regulate the interaction between NPK signaling pathways under multiple nutrient deficiency remains largely unknown.We systematically compared and identified microRNAs involved in both single and triple NPK nutrient deficiency responses.We identified 32 shoot and 17 root miRNAs differentially expressed under potassium deficiency.Several NP starvation-associated miRNAs including miR169s and miR399s,were also regulated by K deficiency.Several identified miRNAs including miR5565c,miR5564,and miR1432 have not previously been associated with respectively N,P,and K deficiency(−N,−P,and−K).Expression correlation analysis between miRNAs and their predicted targets showed that miR169,miR172,and miR160 displayed expression trends exactly opposite to those of their corresponding predicted targets.Of 550 predicted novel miRNAs,novel_mir_42 was upregulated in shoots under−K but was downregulated under−N and−P.The effects of combined NPK starvation were not a simple addition of the individual stresses on sorghum seedlings.The identified common and specific differentially expressed miRNAs were observed under single and combined NPK deficiencies.These findings will help to further elucidate the functions of microRNAs and their interactions under multiple nutrient deficiency.

Comparative Proteomic Analysis of Cucumber Fruits Under Nitrogen Deficiency At the Fruiting Stage

Nitrogen deficiency is a major factor that affects the yield and quality of horticultural crops.Differentially expressed proteins were identified in cucumber fruit under nitrogen deficiency treatment,and are expected to be highly useful for dissecting carbon,nitrogen and ascorbate metabolism in cucumber and for improving nitrogen fertilizer utilization.Cucumber plants grown hydroponically in Hoagland solution were transferred to nitrogen-free conditions for 3 or 5 d after the blossom of female flowers.Fruit proteome profiles were assessed using twodimensional electrophoresis.The relative expression of the genes encoding 50 selected differentially expressed proteins and 4 key enzymes in carbon metabolism was analyzed by qRT-PCR.Resulted showed that most of the identified differentially expressed proteins were mainly associated with carbon metabolism,amino acid biosynthesis,ascorbate metabolism,and proteasomes.Glucose phosphorylation was enhanced,while the pentose phosphate pathway was inhibited.Carbon metabolism and the synthesis of most amino acids was affected significantly,and ascorbate might be accumulated under nitrogen deficiency in cucumber fruit.

Effects of Nitrogen Fertilizer with Nitrification Inhibitor DMPP (3,4-Dimethylpyrazole phosphate) on Nitrate Accumulation and Quality of Cabbage(Brassica campastris L.ssp. pekinesis)

To assess the effects of N fertilizer ammonium sulphate nitrate [(NH4)2SO4 plus NH4NO3;ASN] with the new nitrification inhibitor (NI) 3, 4-dimethylpyrazole phosphate (DMPP)(ASN+DMPP) on yield, nitrate accumulation, and quality of cabbage (Brassica campastrisL. ssp. pekinesis), two field trials were carried out under various soil-climaticconditions in Jinhua City and Xinchang County, Zhejiang Province of China in 2002.Results showed that DMPP could increase the mean yield by+2.0tha-1 in Jinhua, +5.5tha-1 inXinchang, decrease NO3--N content by -9.4% in Jinhua, -7.3% in Xinchang and improvenutritional quality by increasing vitamin C (VC), soluble sugar, K, Fe, Zn contentssignificantly.

Effects of temperature,algae biomass and ambient nutrient on the absorption of dissolved nitrogen and phosphate by Rhodophyte Gracilaria asiatica

Gracilaria asiatica, being highly efficient in nutrient absorption, is cultivated in sea cucumber ponds to remove nutrients such as nitrogen and phosphate. It was cultured in a laboratory simulating field conditions, and its nutrient absorption was measured to evaluate effects of environmental conditions. Ammonia nitrogen （AN）, nitrate nitrogen （NN）, total inorganic nitrogen （TIN）, and soluble reactive phosphorus （SRP） uptake rate and removal efficiency were determined in a 4~2 factorial design experiment in water temperatures （T） at 15~C and 25~C, algae biomass （AB） at 0.5 g/L and 1.0 g/L, total inorganic nitrogen （TIN） at 30 ~tmol/L and 60 ~tmol/L, and soluble reactive phosphorus （SRP） at 3 and 6 ~tmol/L. AB and ambient TIN or SRP levels significantly affected uptake rate and removal efficiency of AN, NN, TIN, and SRP （P〈0.001）. G. asiatica in AB of 0.5 g/L showed higher uptake rate and lower removal efficiency relative to that with AB of 1.0 g/L. Nitrogen and phosphorus uptake rate rose with increasing ambient nutrient concentrations; nutrient removal efficiency decreased at higher environmental nutrient concentrations. The algae preferred to absorb AN to NN. Uptake rates of AN, NN, and SRP were significantly affected by temperature （P〈0.001）; uptake rate was higher for the 25~C group than for the 15~C group at the initial experiment stage. Only the removal efficiency of AN and SRP showed a significant difference between the two temperature groups （P〈0.01）. The four factors had significant interactive effects on absorption of N and P, implying that G. asiatica has great bioremedial potential in sea cucumber culture ponds.

Biogeochemical Character of Dissolved Inorganic Nitrogen and Phosphate at Plume Front in the Changjiang River

Biogeochemical character of dissolved inorganic nitrogen and phosphate at plume front is studied based on the data, which were observed in the Changjiang River Estuary in 1988. The results are as follows: The concentrations of nitrate and phosphate change abruptly -2+4at plume front and halocline. The concentrations of NO and NH are very high at 10~25 -33-4m depth. The vertical circumfluence transports NO and PO , which are released from organisms at the bottom to phytoplankton.

Effect of Nitrogen Deficiency and Toxicity in Two Varieties of Tomatoes(Lycopersicum esculentum L.)

Tomato is one of the most important vegetables cultivated in Mexico. Nitrogen-based fertilizers have greatly contributed to the increase in tomato production;however, the excessive application of this fertilizer may affect yield and fruit quality. A greenhouse experiment was conducted to evaluate the effect of increasing in rates of nitrogen from deficiency to toxic levels. Five N-treatments (0, 15, 30, 45 and 60 mM of N) were applied in two tomato varieties, Caballero and Victoria The optimum N doses for leaf growth in both varieties was 30 mM reaching 13.0 and 13.5 cm in Caballero and Victoria respectively. At low toxic levels leaf growth was recovered more easily in Caballero than Victoria. Nitrate concentration for the low toxicity treatment was greater in leaf and stems for Caballero than Victoria;conversely nitrate in fruits was higher in Victoria. Final yield per plant was not statistically different between varieties except at the low toxic treatment where Caballero had a yield of 780 g per plant compared to that of 330 g per plant of Victoria. Tomato quality was also affected by the applied N-doses, where treatment 30 mM reached the maximum fruit firmness in both varieties while high toxic N-levels decreased significantly this parameter. Soluble solids and titratable acidity increased with increased N-Doses. Caballero variety seems to be more tolerant than Victoria at low levels of N-toxicity.

PuHox52 promotes coordinated uptake of nitrate,phosphate, and iron under nitrogen deficiency in Populus ussuriensis

It is of great importance to better understand how trees regulate nitrogen(N) uptake under N deficiency conditions which severely challenge afforestation practices, yet the underlying molecular mechanisms have not been well elucidated. Here,we functionally characterized PuHox52, a Populus ussuriensis HD-ZIP transcription factor, whose overexpression greatly enhanced nutrient uptake and plant growth under N deficiency. We first conducted an RNA sequencing experiment to obtain root transcriptome using PuHox52-overexpression lines of P. ussuriensis under low N treatment. We then performed multiple genetic and phenotypic analyses to identify key target genes of PuHox52 and validated how they acted against N deficiency under PuHox52 regulation.PuHox52 was specifically induced in roots by N deficiency, and overexpression of PuHox52promoted N uptake, plant growth, and root development. We demonstrated that several nitrate-responsive genes(PuNRT1.1, PuNRT2.4,PuCLC-b, PuNIA2, PuNIR1, and PuNLP1),phosphate-responsive genes(PuPHL1A and PuPHL1B), and an iron transporter gene(PuIRT1) were substantiated to be direct targets of PuHox52. Among them, PuNRT1.1, PuPHL1A/B, and PuIRT1 were upregulated to relatively higher levels during PuHox52-mediated responses against N deficiency in PuHox52-overexpression lines compared to WT. Our study revealed a novel regulatory mechanism underlying root adaption to N deficiency where PuHox52 modulated a coordinated uptake of nitrate, phosphate, and iron through 'PuHox52-PuNRT1.1', 'PuHox52-PuPHL1A/PuPHL1B', and'PuHox52-PuIRT1' regulatory relationships in poplar roots.

Respiratory Response of Dormant Nectarine Floral Buds on Chilling Deficiency

Changes in main biochemical respiratory pathways in dormant nectarine floral buds were studied with nectarine trees （Prunus persica.var, nectariana cv. Shuguang） in order to determine the function of respiration in dormancy release. Oxygen-electrode system and respiratory inhibitors were used to measure total respiratory rates and rates of respiratory pathways. Results showed that chilling deficiency blocked the transition of respiratory mode, and made buds stay in a state of high level pentose phosphate pathway （PPP） and low level tricarboxylie acid cycle （TCA）. The decline of PPP and activation of TCA occurred synchronously with the release of dormancy. In addition, the inhibition of PPP stimulated a respiration increase related with TCA. It could be concluded that the function of PPP activation in dormancy release might be limited and PPP declination inducing TCA activation might be part of respiration mode transition mechanism during bud sprouting.

Fertilizer-Induced Advances in Corn Growth Stage and Quantitative Definitions of Nitrogen Deficiencies

Evidence that nitrogen (N) fertilization tends to accelerate maturation as well as increase rates of growth has received little attention when diagnosing N deficiencies in corn (Zea mays L.).Such a tendency could be a potential source of errors when the diagnosis is solely based on comparing plants with different rates of growth.Whether N fertilization could accelerate rates of growth and maturation was tested in a field study with 12 paired plots representing relatively large variability in soil properties and landscape positions.The plots were located under conditions where preplant N fertilization reduced or avoided temporary N shortages for some plants but did not reduce for other plants early in the season.We measured corn heights to the youngest leaf collar,stages of growth and chlorophyll meter readings (CMRs). The added N advanced growth stages as well as increased corn heights and CMRs at any given time.Fertilization effects on corn heights,growth stages and ear weights were statistically significant (P<0.05) despite substantial variability associated with landscape.Reductions in growth due to a temporary shortage of N within a growth stage might be partially offset by longer periods of growth within that stage to physiological maturity.Temporary shortages of N,therefore,may produce symptoms of N deficiency in situations where subsequent additions of N should not be expected to increase yields.Recognition of these two somewhat different effects (i.e.,increase growth rates and advance growth stages) on corn growth could help to define N deficiency more precisely and to improve the accuracy of diagnosing N status in production agriculture.

Facile Fabrication of Fe2O3/Nitrogen Deficient g-C3N4-x Composite Catalysts with Enhanced Photocatalytic Performances

The modification of graphitic carbon nitride can significantly improve the photocatalytic performance of graphitic carbon nitride(g-C3N4).Fe2O3/nitrogen-deficient g-C3N4-x composite catalysts were prepared with dicyandiamide as the precursor and Fe3+doped in this study.The composite catalysts were characterized by XRD,SEM,FT-IR,XPS and photocurrent measurements.Close interaction occurred between Fe2O3 and nitrogen deficient g-C3N4-x,more photogenerated electrons were created and effectively separated from the holes,resulting in a decrease of photocarrier recombination,and thus enhancing the photocurrent.Photocatalytic performance experiments showed that Fe2O3/nitrogen deficient g-C3N4-x could utilize lowenergy visible light more efficiently than pure g-C3N4,and the removal rate was 92%in 60 minutes.