Sulfur Deficiency Research Articles

Diagnosing early disorders in Jatropha curcas to calcium, magnesium and sulfur deficiency

Jatropha is an excellent plant model to evaluate physiological responses involving species tolerance to abiotic stresses, such as low calcium (Ca), magnesium (Mg) and sulfur (S) availability. Moreover, Ca, Mg and S are essential for the establishment of this plant in large areas. Better acknowledgment of appropriate nutrient levels can help with proper fertilization. This study aimed to gain insight during initial growth in Jatropha plants deficient in Ca, Mg and S by measuring leaf gas exchange, nutrient uptake efficiency (UpE), nutrient use efficiency (UtE) and biomass partitioning at plant harvest. Chlorophyll, carotenoid concentration, net photosynthesis rate (A), stomatal conductance (gS), transpiration (E), leaf-scale intrinsic water use efficiency (IWUE) and instantaneous carboxylation efficiency (k) in leaves of Ca-, Mg- and S-deficient plants revealed imbalances prior to visual symptom appearance. Nutrient deficiencies decreased A, which in turn hindered plant growth and biomass partitioning among leaves, stem and roots. However, S-deficient plants maintained values of UtE (at 120 days after S withdrawal), as well as of A, gS, E, k and biomass allocation similar to those of control plants, during all evaluation periods. Jatropha was highly and very sensitive to Ca and Mg deficiency, respectively, with all results were dramatically decreased in contrast to the control. In conclusion, early physiological evaluation of Ca and Mg status in starved young plants with contrasting UtE values may be a reliable tool with which to predict early nutritional deficiencies before visual symptom appearance.

Strigolactones Decrease Leaf Angle in Response to Nutrient Deficiencies in Rice.

Strigolactones (SLs) are a class of plant hormones that are synthesized from β-carotene through sequential reactions catalyzed by DWARF (D) 27, D17, D10, and OsMORE AXILLARY GROWTH (MAX) 1 in rice (Oryza sativa L.). In rice, endogenous SL levels increase in response to deficiency of nitrogen, phosphate, or sulfate (−N, −P, or −S). Rice SL mutants show increased lamina joint (LJ) angle as well as dwarfism, delayed leaf senescence, and enhanced shoot branching. The LJ angle is an important trait that determines plant architecture. To evaluate the effect of endogenous SLs on LJ angle in rice, we measured LJ angle and analyzed the expression of SL-biosynthesis genes under macronutrient deficiencies. In the “Shiokari” background, LJ angle was significantly larger in SL mutants than in the wild-type (WT). In WT and SL-biosynthesis mutants, direct treatment with the SL synthetic analog GR24 decreased the LJ angle. In WT, deficiency of N, P, or S, but not of K, Ca, Mg, or Fe decreased LJ angle. In SL mutants, deficiency of N, P, or S had no such effect. We analyzed the time course of SL-related gene expression in the LJ of WT deficient in N, P, or S, and found that expression of SL-biosynthesis genes increased 2 or 3 days after the onset of deficiency. Expression levels of both the SL-biosynthesis and signaling genes was particularly strongly increased under −P. Rice cultivars “Nipponbare”, “Norin 8”, and “Kasalath” had larger LJ angle than “Shiokari”, interestingly with no significant differences between WT and SL mutants. In “Nipponbare”, endogenous SL levels increased and the LJ angle was decreased under −N and −P. These results indicate that SL levels increased in response to nutrient deficiencies, and that elevated endogenous SLs might negatively regulate leaf angle in rice.

Effect of Sulfur Sources on Megathyrsus Maximus ‘Mombaça’ Grass Cultivated in a Typic Ultisol

ABSTRACTThe deficiency of sulfur (S) in agricultural soils has been aggravated in recent decades, mainly by the application of high concentration fertilizers that are S-free and intensive agricultural activities. This study evaluated forage yield, nutritional status and inorganic sulfate-S in soil when submitted to levels and sources of sulfur, including elemental sulfur, of the ‘Mombaça’ grass in a Typic Ultisol. The experimental design was completely randomized arrangement in a 5 × 4 factorial design, with five S rates (0, 50, 100, 150, and 200 mg kg−1) and four S sources. The sources were elemental sulfur pastilles (ESPA), phosphogypsum (GY), gypsite (GI), and elemental sulfur powder (ESPO). The results showed that the S-use efficiency with the GI, GY and ESPO sources was obtained with the supply of 50 mg kg−1 of S, and was enough to optimize the ‘Mombaça’ grass yield and promote a better quality for the nutritional status of the forage. The ESPA source had an S leaf concentration below the adequate range and resulted in lower yield values in relation to the other S sources evaluated. The SPAD index in the newly expanded leaves was shown to be an indicator of shoot dry weight (SDW) yield and could be used as a pre-diagnosis of the S-efficiency in ‘Mombaça’ grass. The soil processes associated to the availability of S had a great influence on the granulometry, which drove the SDW yield and S use efficiency with the source ESPO in relation to ESPA.

Sulfur Deficiency-Induced Glucosinolate Catabolism Attributed to Two β-Glucosidases, BGLU28 and BGLU30, is Required for Plant Growth Maintenance under Sulfur Deficiency

Sulfur (S) is an essential element for plants, and S deficiency causes severe growth retardation. Although the catabolic process of glucosinolates (GSLs), the major S-containing metabolites specific to Brassicales including Arabidopsis, has been recognized as one of the S deficiency (-S) responses in plants, the physiological function of this metabolic process is not clear. Two β-glucosidases (BGLUs), BGLU28 and BGLU30, are assumed to be responsible for this catabolic process as their transcript levels were highly upregulated by -S. To clarify the physiological function of BGLU28 and BGLU30 and their roles in GSL catabolism, we analyzed the accumulation of GSLs and other S-containing compounds in the single and double mutant lines of BGLU28 and BGLU30 and in wild-type plants under different S conditions. GSL levels were highly increased, while the levels of sulfate, cysteine, glutathione and protein were decreased in the double mutant line of BGLU28 and BGLU30 (bglu28/30) under -S. Furthermore, transcript level of Sulfate Transporter1;2, the main contributor of sulfate uptake from the environment, was increased in bglu28/30 mutants under -S. With these metabolic and transcriptional changes, bglu28/30 mutants displayed obvious growth retardation under -S. Overall, our results indicate that BGLU28 and BGLU30 are required for -S-induced GSL catabolism and contribute to sustained plant growth under -S by recycling sulfate to primary S metabolism.

Autophagy Controls Sulphur Metabolism in the Rosette Leaves of Arabidopsis and Facilitates S Remobilization to the Seeds.

Sulphur deficiency in crops became an agricultural concern several decades ago, due to the decrease of S deposition and the atmospheric sulphur dioxide emissions released by industrial plants. Autophagy, which is a conserved mechanism for nutrient recycling in eukaryotes, is involved in nitrogen, iron, zinc and manganese remobilizations from the rosette to the seeds in Arabidopsis thaliana. Here, we have compared the role of autophagy in sulphur and nitrogen management at the whole plant level, performing concurrent labelling with 34S and 15N isotopes on atg5 mutants and control lines. We show that both 34S and 15N remobilizations from the rosette to the seeds are impaired in the atg5 mutants irrespective of salicylic acid accumulation and of sulphur nutrition. The comparison in each genotype of the partitions of 15N and 34S in the seeds (as % of the whole plant) indicates that the remobilization of 34S to the seeds was twice more efficient than that of 15N in both autophagy mutants and control lines under high S conditions, and also in control lines under low S conditions. This was different in the autophagy mutants grown under low S conditions. Under low S, the partition of 34S to their seeds was indeed not twice as high but similar to that of 15N. Such discrepancy shows that when sulphate availability is scarce, autophagy mutants display stronger defects for 34S remobilization relative to 15N remobilization than under high S conditions. It suggests, moreover, that autophagy mainly affects the transport of N-poor S-containing molecules and possibly sulphate.

Identification of Loci Through Genome-Wide Association Studies to Improve Tolerance to Sulfur Deficiency in Rice.

Sulfur (S) is an essential nutrient for plant growth and development; however, S supply for crop production is decreasing due to reduced inputs from atmospheric deposition and reduced application of S-containing fertilizers. Sulfur deficiency in soil is therefore becoming a widespread cause of reduced grain yield and quality in rice (Oryza sativa L). We therefore assessed the genotypic variation for tolerance to S deficiency in rice and identified loci associated with improved tolerance. Plants were grown in nutrient solution with either low (0.01 mM) or high (1.0 mM) supply of S. Plants grown under low-S treatment showed a reduction in total biomass, mainly due to a marked reduction in shoot biomass, while root biomass and root-to-shoot ratio increased, relative to plants under high-S treatment. Genome-wide association studies (GWAS) identified loci associated with root length (qSUE2-3, qSUE4, and qSUE9), and root (qSUE1, qSUE2-1, and qSUE3-1 and qSUE3-2) or total dry matter (qSUE2, qSUE3-1, and qSUE11). Candidate genes identified at associated loci coded for enzymes involved in secondary S metabolic pathways (sulfotransferases), wherein the sulfated compounds play several roles in plant responses to abiotic stress; cell wall metabolism including wall loosening and modification (carbohydrate hydrolases: beta-glucosidase and beta-gluconase) important for root growth; and cell detoxification (glutathione S-transferase). This study confirmed the existence of genetic variation conferring tolerance to S deficiency among traditional aus rice varieties. The advantageous haplotypes identified could be exploited through marker assisted breeding to improve tolerance to S-deficiency in modern cultivars in order to achieve sustainable crop production and food security.

Fertilizer Source and Rate Affect Sulfur Uptake and Yield Response in Corn

With sulfur deficiencies being found throughout Kansas, the evaluation of sulfur fertilization and plant uptake are vital to optimize corn production. The objective of this study was to evaluate the effect of application rates of sulfur on yield and uptake in corn. Nutrient concentrations in corn biomass and grain were evaluated at the Kansas River Valley Experiment Field at Rossville, KS, in 2019. Five treatments were evalu­ated, including a control with no sulfur and no nitrogen (N), and four fertilizer treat­ments with 180 lb of nitrogen and four rates of sulfur fertilizer (0, 30, 50, and 200 lb S/a). The nitrogen source was urea and balanced for all treatments at 180 lb N/a. The sulfur-containing fertilizer applications were at the time of planting corn. Whole corn plant biomass and grain samples were taken at physiological maturity and analyzed for nitrogen and sulfur concentrations. Results for the study show that sulfur application rates have a significant yield response in corn, likely contributing to increased uptake of nitrogen. Moreover, high yielding environments increased total plant sulfur uptake and removal.

Nutritional status of coriander under fertigation depths and pulse and continuous drip irrigation

ABSTRACT The objective of this study was to evaluate the nutritional status of coriander cultivar Verdão under fertigation depths and pulse and continuous drip irrigation. The experiment was conducted in a protected environment at the Universidade Federal Rural de Pernambuco, Recife, PE, Brazil (8° 1’ 6.50” S, 34° 56’ 46” W and altitude of 6.5 m), in the randomized block design in 2 x 5 factorial scheme, with three repetitions. Treatments consisted of five irrigation depths (40, 60, 80, 100 and 120% of crop evapotranspiration - ETc) and two types of fertigation application (pulse and continuous). At 27 days after sowing, the aerial part of 48 plants per plot was collected for subsequent quantification of nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, copper and zinc concentrations. Pulse fertigation combined with ETc replacement depths below 100% promoted higher leaf concentrations of phosphorus, sulfur, iron and manganese. Continuous fertigation combined with 100% ETc depth induced sulfur deficiency in the crop and, combined with 40% ETc depth, promoted the highest calcium concentration. Regardless of the type of application, ETc replacement depths from 82.7 and 40% provide adequate leaf concentrations of nitrogen and magnesium, respectively. Regardless of the applied depth, pulse fertigation reduced the leaf concentrations of magnesium.

Effect of gypsum applications to nursery seedbed on transplanted rice with symptoms of sulfur deficiency at the downstream of abandoned zinc mine

Effect of gypsum applications to nursery seedbed on transplanted rice with symptoms of sulfur deficiency at the downstream of abandoned zinc mine

Unraveling the complexities underlying sulfur deficiency and starvation in the cyanobacterium Anabaena sp. PCC 7120

The present study focuses to decipher the impact of long-term sulfur deficiency in the cyanobacterium Anabaena sp. PCC 7120. Cell growth parameters (cell biomass and photopigments) were analysed under varying long-term sulfur deficiency showed significant reduction in growth under sulfur limitations. The reminiscent growth of cyanobacterium in the sulfur shortage possibly pertained to minimize cell size and spherical cell shape. Additionally, lower sulfur availability exhibited negative impacts on photopigments, D1 protein (all3572) transcription and PSII efficiency in the cyanobacterium. Furthermore, depletion in protein and corresponding increase in carbohydrate and lipid contents were interpreted as reprogrammed C-allocation. Additionally, enzyme assay of ATP sulfurylase depicted increased activity in the deficient conditions. Moreover, decreased intracellular concentrations of Mg2+, Fe2+, Ca2+, Na+, and K+ at low sulfur supplementations might be a consequence of counter-ion balancing and attributed to lipid peroxidation and electrolyte leakage resulted from increased ROS. In addition, overexpression of desC followed by fatty acid unsaturation and programmed cell death markers were also noticed. Overall, the result suggest that reduced biomass in sulfur limitation is a cumulative outcome of disrupted photosynthesis, reprogrammed C-allocation, reduced electrolyte contents, and subsequent PCD in the cells of Anabaena sp. PCC 7120 reveal S deficiency exerts an adverse impact on cyanobacterial population and reduces primary productivity.

Effects of Y substitution on the electronic structure and charge dynamics of SmS

Evolution of the electronic state by Y doping was explored by optical conductivity covering a wide energy and compositional region deduced from systematic reflectivity measurements of ${\mathrm{Sm}}_{1\ensuremath{-}x}{\mathrm{Y}}_{x}\mathrm{S}$ single crystals. Although electrons doped onto the $5d$ band by Y dopants immediately realize a metallic state, the charge dynamics do not obey a simple Drude response and the spectral intensity is condensed in the mid-infrared region. Contrary to the pressure-induced case, a metallic phase appears in a certain compositional region before reaching the valence transition. The Fermi level is shifted upwards by electron doping. Therefore, the $5d$ band must overlap with the weakly dispersive $4f$ band more deeply than in the pressure-induced case to reach the valence transition, which can explain the stability of the divalent phase up to higher temperatures in the doped system than in the pressure-induced case. The present optical study provides us with a strategy that sulfur deficiency might increase operating temperature of negative thermal expansion in this system.

Adjusting Interfacial Chemistry and Electronic Properties of Photovoltaics Based on a Highly Pure Sb2S3 Absorber by Atomic Layer Deposition.

The combination of oxide and heavier chalcogenide layers in thin film photovoltaics suffers limitations associated with oxygen incorporation and sulfur deficiency in the chalcogenide layer or with a chemical incompatibility which results in dewetting issues and defect states at the interface. Here, we establish atomic layer deposition (ALD) as a tool to overcome these limitations. ALD allows one to obtain highly pure Sb2S3 light absorber layers, and we exploit this technique to generate an additional interfacial layer consisting of 1.5 nm ZnS. This ultrathin layer simultaneously resolves dewetting and passivates defect states at the interface. We demonstrate via transient absorption spectroscopy that interfacial electron recombination is one order of magnitude slower at the ZnS-engineered interface than hole recombination at the Sb2S3/P3HT interface. The comparison of solar cells with and without oxide incorporation in Sb2S3, with and without the ultrathin ZnS interlayer, and with systematically varied Sb2S3 thickness provides a complete picture of the physical processes at work in the devices.

Molybdate toxicity in Chinese cabbage is not the direct consequence of changes in sulphur metabolism.

In polluted areas, plants may be exposed to supra‐optimal levels of the micronutrient molybdenum. The physiological basis of molybdenum phytotoxicity is poorly understood. Plants take up molybdenum as molybdate, which is a structural analogue of sulphate. Therefore, it is presumed that elevated molybdate concentrations may hamper the uptake and subsequent metabolism of sulphate, which may induce sulphur deficiency.In the current research, Chinese cabbage (Brassica pekinensis) seedlings were exposed to 50, 100, 150 and 200 μm Na2MoO4 for 9 days.Leaf chlorosis and a decreased plant growth occurred at concentrations ≥100 μm. Root growth was more affected than shoot growth. At ≥100 μm Na2MoO4, the sulphate uptake rate and capacity were increased, although only when expressed on a root fresh weight basis. When expressed on a whole plant fresh weight basis, which corrects for the impact of molybdate on the shoot‐to‐root ratio, the sulphate uptake rate and capacity remained unaffected. Molybdate concentrations ≥100 μm altered the mineral nutrient composition of plant tissues, although the levels of sulphur metabolites (sulphate, water‐soluble non‐protein thiols and total sulphur) were not altered. Moreover, the levels of nitrogen metabolites (nitrate, amino acids, proteins and total nitrogen), which are generally strongly affected by sulphate deprivation, were not affected. The root water‐soluble non‐protein thiol content was increased, and the tissue nitrate levels decreased, only at 200 μm Na2MoO4.Evidently, molybdenum toxicity in Chinese cabbage was not due to the direct interference of molybdate with the uptake and subsequent metabolism of sulphate.

An Alkane Sulfonate Monooxygenase Is Required for Symbiotic Nitrogen Fixation by Bradyrhizobium diazoefficiens (syn. Bradyrhizobium japonicum) USDA110T.

Sulfur (S)-containing molecules play an important role in symbiotic nitrogen fixation and are critical components of nitrogenase and other iron-S proteins. S deficiency inhibits symbiotic nitrogen fixation by rhizobia. However, despite its importance, little is known about the sources of S that rhizobia utilize during symbiosis. We previously showed that Bradyrhizobium diazoefficiens USDA110T can assimilate both inorganic and organic S and that genes involved in organic S utilization are expressed during symbiosis. Here, we show that a B. diazoefficiens USDA110T mutant with a sulfonate monooxygenase (ssuD) insertion is defective in nitrogen fixation. Microscopy analyses revealed that the ΔssuD mutant was defective in root hair infection and that ΔssuD mutant bacteroids showed degradation compared to the wild-type strain. Moreover, the ΔssuD mutant was significantly more sensitive to hydrogen peroxide-mediated oxidative stress than the wild-type strain. Taken together, these results show that the ability of rhizobia to utilize organic S plays an important role in symbiotic nitrogen fixation. Since nodules have been reported to be an important source of reduced S used during symbiosis and nitrogen fixation, further research will be needed to determine the mechanisms involved in the regulation of S assimilation by rhizobia.IMPORTANCE Rhizobia form symbiotic associations with legumes that lead to the formation of nitrogen-fixing nodules. Sulfur-containing molecules play a crucial role in nitrogen fixation; thus, the rhizobia inside nodules require large amounts of sulfur. Rhizobia can assimilate both inorganic (sulfate) and organic (sulfonates) sources of sulfur. However, very little is known about rhizobial sulfur metabolism during symbiosis. In this report, we show that sulfonate utilization by Bradyrhizobium diazoefficiens is important for symbiotic nitrogen fixation in both soybean and cowpea. The symbiotic defect is probably due to increased sensitivity to oxidative stress from sulfur deficiency in the mutant strain defective for sulfonate utilization. The results of this study can be extended to other rhizobium-legume symbioses, as sulfonate utilization genes are widespread in these bacteria.

Co-limitation and stoichiometry capture the interacting effects of nitrogen and sulfur on maize yield and nutrient use efficiency

Abstract Nitrogen (N) and sulfur (S) deficiencies, individually and in combination, produce gaps between actual and potential yields in maize (Zea mays L.). Our objectives were to evaluate the effect of N and S status and their interaction on yield gap, and nutrient use efficiency (yield per unit of nutrient supply) using frameworks of co-limitation and stoichiometry. Factorial trials were established combining two N (unfertilized, N-fertilized) and two S (unfertilized, S-fertilized) treatments in five site-years. Yield ranged from 6.7 to 15.4 Mg ha−1. In a scale from 0 (no stress) to 1 (maximum stress), N stress varied from 0 to 0.67, and S stress from 0 to 0.66. Yield gap varied from 0 to 10 Mg ha−1, diminished as both N and S stresses reduced, and with higher N-S co-limitation. Both N and S use efficiencies increased with reductions in nutrient stresses and with increases in some of the N-S co-limitation indices. Co-limitation between N and S was maximized with N:S ratio ∼9.6 in shoot biomass and ∼11.2 in grain, indicating the balanced nutrient ratio in each plant organ at maturity. Both co-limitation and stoichiometry frameworks captured the interacting N and S effects on yield and nutrient use efficiency.

To the question of amino acids and whey consumption

The article summarizes, in a concise form, information about the importance of amino acids in the context of solving the problem of fodder protein deficiency. Amino acids, as structural components of proteins, are central to the exchange of nitrogen-containing compounds and are vital for life processes. Essential amino acids are not synthesized by the body of animals and humans, but are prepared as a part of diets. Vegetable proteins are less complete than animal proteins due to the absence of some essential amino acids. Therefore, in feeding, plant feeds are balanced by limiting amino acids, which are obtained by chemical or microbiological synthesis, or combine protein sources, taking into account their amino acid composition. Amino acids are the primary microbial metabolites that are synthesized by microorganisms in the process of life. Due to the large-scale cultivation of microorganisms in industrial conditions, amino acids, proteins, preparations for increasing the productivity of crops and animals are receive. Appropriate types of microorganisms use ammonia oxidation energy to synthesize their own organic matter. Different bacteria for the synthesis of amino acids also use nitrogen, nitrates, urea. The microbiological synthesis and accumulation of metabolites in the substrate depends on the component composition, temperature. Microbial growth is usually limited by the nutrient component. Sulfur deficiency limits the utilization of nitrogen by microorganisms. The introduction of sulfur compounds into the environment stimulates microbial synthesis in general, including sulfur-containing amino acids. As a result of incubation of the biosubstrate for 3 days at a temperature of 18 °C, the synthesis of most amino acids by microbial association was activated. Incubation with sodium sulfate (at a dose of 0.3% by weight of biosubstrate) for 3 days at 25 °C had the best stimulating effect on amino acid biosynthesis. Such a biosubstrate can be used as a source of amino acids in the form of a fertilizer or feed additive. In the XXI century anthropogenic impact causes an imbalance of the ecological situation, one of the manifestations of which is the reduction of soil fertility, which can be restored by the introduction of mineral and organic fertilizers, as well as preparations containing amino acids and stimulate seed germination, increase the yield, fertility, and fertility. Amino acids are used as additives in food production, in the treatment of diseases of different etiologies and for other purposes.

Distribution of “Invisible” Noble Metals between Pyrite and Arsenopyrite Exemplified by Minerals Coexisting in Orogenic Au Deposits of North-Eastern Russia

The study focused on the forms of occurrence and distribution of hidden (“invisible”) noble metals (NMs = Au, Ag, Pt, Pd, Ru) in the coexisting pyrites and arsenopyrites of four samples of mineral associations from three Au deposits in the north-east of Russia. The unique nature of our approach was the combination of methods of local analysis and statistics of the compositions of individual single crystals of different sizes. This allowed us to take into account the contribution of the surface component to the total NM content and to distinguish the structurally bound form of the elements. The following estimates of the distribution coefficients of the structural (str) and surficial (sur) forms of elements were obtained: D ¯ P y / A s p s t r = 2.7 (Au), 2.5 (Pd), 1.6 (Pt), 1.7 (Ru) and D ¯ P y / A s p s u r = 1.6 (Au), 1.1 (Pd), 1.5 (Pt and Ru). The data on Ag in most cases indicated its fractionation into pyrite ( D ¯ P y / A s p s t r = 17). Surface enrichment was considered as a universal factor in “invisible” NM distribution. A number of elements (i.e., Pt, Ru, Ag) tended to increase their content with a decrease in the crystallite size in pyrite and arsenopyrite. This may be due to both the phase size effect and the intracrystalline adsorption of these elements at the interblock boundaries of a dislocation nature. The excess of metal (or the presence of S vacancies) in pyrite increased Ag and Pt content in its structure and, to a lesser extent, the content of Ru, Pd and Au. Arsenopyrite exhibited a clear tendency to increase the content of Pt, Ru and Pd in samples with excess As over S. Sulphur deficiency was a favourable factor for the incorporation of Ag and platinoids into the structures of the mineral associations studied. Perhaps this was due to the lower sulphur fugacity. Pyrite with excess Fe was associated with higher contents of some NMs. The presence of other impurity elements was not an independent factor in NM concentration.

Linear and nonlinear optical response of sulfur-deficient nanocrystallite WS2 thin films

Multilayered-to-bulk-like films were deposited by pulsed laser deposition at various argon gas deposition pressure where a significant amount of sulfur deficiency was observed. All films showed high atomic disorder and corresponding lattice distortion attributed to the large-scale sulfur deficiency. Instead of continuous film, huge sulfur deficiency created a mixed state of metallic tungsten and WS2 nanocrystals of sizes 4–8 nm throughout the films. The as-deposited WS2 films showed a dramatic shift in linear optical response, with the behavior resembling that of quantum dots. A significantly large reverse saturation absorption and positive nonlinear refraction response was observed in all the films, as measured by the open- and closed-aperture Z-scan experiment under He–Ne laser at 632.8 nm. In addition, third-order nonlinear optical susceptibility of the thin films was found to be of the order of 10−2 esu as measured from Z-scan experiment. The anomalously high nonlinear optical response of the film was attributed to the continuous-wave laser-induced thermal nonlinearity dominance over optical nonlinearity. Optical limiting was also observed in the films where optical limiting thresholds were found to increase with an increase in nonlinear absorption coefficient.

Corn Response to Sulfur Fertilizer in the Red River Valley

The recent incidence and severity of sulfur (S) deficiency due to a decrease in atmospheric S deposition and greater S removal by crops requires reevaluating current S recommendation for corn (Zea mays L.). Ten on‐farm field trials were conducted to evaluate corn response to S additions at sites in the Red River Valley of North Dakota and Minnesota between 2016 and 2017. Sulfur rates of 0, 11, 22, 33, 44 kg S ha–1 as granular (NH4)2SO4 were broadcasted and incorporated prior to corn planting using randomized complete block design with four replications. Plant tissue S concentration and N/S ratios were determined at two corn growth stages (V6 and V12 in 2016, V12 and R1 in 2017) and grain yield was measured at harvest. Plant tissue S did not increase with S fertilizer at V6 and V12 stages in 2016 whereas in 2017, tissue S increased with 11 kg S ha–1 at two sites in the V6 growth stage. Yield was not related to both soil S and plant parameters. Corn yield increased with 11 kg S ha–1 fertilizer rate at two of ten locations. Lack of response at the remaining sites suggests that S from organic matter and mineralization was enough for crop growth and hence applied fertilizer S had no effect on yield.Core Ideas Corn grain yield increased with S fertilizer at two of ten sites. No response to S fertilizer occurred due to dry early growing season. Plant tissue tests were not reliable indicators in predicting response.

Contrasting gene expression patterns in grain of high and low asparagine wheat genotypes in response to sulphur supply

BackgroundFree asparagine is the precursor for acrylamide formation during cooking and processing of grains, tubers, beans and other crop products. In wheat grain, free asparagine, free glutamine and total free amino acids accumulate to high levels in response to sulphur deficiency. In this study, RNA-seq data were acquired for the embryo and endosperm of two genotypes of bread wheat, Spark and SR3, growing under conditions of sulphur sufficiency and deficiency, and sampled at 14 and 21 days post anthesis (dpa). The aim was to provide new knowledge and understanding of the genetic control of asparagine accumulation and breakdown in wheat grain.ResultsThere were clear differences in gene expression patterns between the genotypes. Sulphur responses were greater at 21 dpa than 14 dpa, and more evident in SR3 than Spark. TaASN2 was the most highly expressed asparagine synthetase gene in the grain, with expression in the embryo much higher than in the endosperm, and higher in Spark than SR3 during early development. There was a trend for genes encoding enzymes of nitrogen assimilation to be more highly expressed in Spark than SR3 when sulphur was supplied. TaASN2 expression in the embryo of SR3 increased in response to sulphur deficiency at 21 dpa, although this was not observed in Spark. This increase in TaASN2 expression was accompanied by an increase in glutamine synthetase gene expression and a decrease in asparaginase gene expression. Asparagine synthetase and asparaginase gene expression in the endosperm responded in the opposite way. Genes encoding regulatory protein kinases, SnRK1 and GCN2, both implicated in regulating asparagine synthetase gene expression, also responded to sulphur deficiency. Genes encoding bZIP transcription factors, including Opaque2/bZIP9, SPA/bZIP25 and BLZ1/OHP1/bZIP63, all of which contain SnRK1 target sites, were also expressed. Homeologues of many genes showed differential expression patterns and responses, including TaASN2.ConclusionsData on the genetic control of free asparagine accumulation in wheat grain and its response to sulphur supply showed grain asparagine levels to be determined in the embryo, and identified genes encoding signalling and metabolic proteins involved in asparagine metabolism that respond to sulphur availability.