In vitro binding of germanium to proteins of rice shoots

The possibility of in vitro binding between proteins of rice shoots and germanium (Ge) was investigated. The proteins in mixtures of aqueous extracts of rice shoots and radioactive germanium (⁶⁸GeO₂) were fractionated. The binding of radioactivity to the proteins was observed even after 5 successive fractionation steps from the original mixtures. At the final fractionation step using polyacrylamide gel electrophoresis, a constant proportionality between protein concentration and associated radioactivity was found in most samples although not all. These results indicate that the binding of ⁸⁸Ge to proteins is not due to the simple adsorption by proteins.     

Effect of calcium and magnesium on 65zinc absorption and translocation in rice seedlings

Effect of calcium and magnesium on zinc absorption by 21‐day‐old rice seedlings and its translocation within the plants was studied in the nutrient solution culture using radioactive zinc. The concentrations of the elements in the nutrient solution were 0.5, 1.0 and 2.0 μM zinc and 0, 10 and 20 mM calcium and magnesium. Absorption of ⁶⁵zinc was studied for 30, 60 and 90 minutes and translocation for 24 hours. Zinc absorption increased with time and increased zinc concentration in the nutrient solutions. Addition of calcium and magnesium reduced zinc absorption by rice seedlings by about 60 and 90% respectively at a concentration of 20 mM. The nature of inhibition of both calcium and magnesium on zinc was non‐competitive as indicated by Michaelis constants. A large fraction of zinc absorbed remained in roots and only 5.3% was translocated to shoots even at 2.0 #GMM zinc concentrations in solution. The effect of cations on translocation of ⁶⁵zinc within rice seedlings was more at lower( 0.5 μM zinc) than at higher (2.0 μM zinc) concentrations.     

Endogenous Action of Cysteine Endopeptidase and Three Carboxypeptidases on Triticale Prolamins

Quantitative and qualitative changes occurring in the prolamin fraction in the starchy endosperm of triticale grains were analyzed by SDS‐PAGE on consecutive days of germination. The most intensive hydrolysis of prolamins was observed after the second day of the process. The high molecular weight fractions of prolamins were degraded with the highest rate. Endopeptidase EP8 was capable of hydrolyzing all fractions of prolamins isolated from dry triticale grains, but the high molecular weight fractions were the most rapidly degraded by the enzyme. Carboxypeptidases I, II, and III isolated from triticale grains hydrolyzed prolamins proteolytically modified by endopeptidase EP8, whereas intact prolamins were degraded slightly. Differences in the activity of the studied carboxypeptidases against crude prolamins indicate that carboxypeptidase II may be involved in the initiation of the hydrolysis process and, together with carboxypeptidases I and III, participates in the later stages of degradation of prolamins to amino acids. Experiments with exogenous GA₃ demonstrated that the synthesis of EP8 is induced by this hormone and takes place in the aleurone layer. Mass spectrometry analysis showed the enzyme to be a homologue of barley endopeptidase EP‐A. Both enzymes belong to the cysteine class endopeptidases.     

Changes in total protein profiles of barley cultivars in response to toxic boron concentration

In this study, ten‐day‐old seedlings of barley {Hordeum vulgare L. cultivar Anadolu [boron (B)‐tolerant] and Hamidiye (B‐sensitive)} were used. Boron‐treated plants were grown on H₃BO₃ solution (final concentration of 10 mM) for five days. Control plants received no B treatment during this period. Total protein patterns were obtained by analysis of total protein extract from root and leaf tissues of control and B‐treated plants using two‐dimensional gel electrophoresis followed by silver staining. The protein profile of B‐treated seedlings of each cultivar was compared to the profile of control (no stress treatment) plants of the same cultivar. Silver‐stained gels showed that B stress caused increases or decreases in a number of proteins in root and leaf tissues. Moreover, as a result of B treatment, one newly synthesized protein with relative molecular weight (M_r) of 35.0 kDa was detected in root profile of the tolerant cultivar. This protein failed to show up in root profile of the B‐treated sensitive cultivar. Three proteins were quantitatively increased in B‐treated root profile of both cultivars. Following B treatment, three proteins were increased in root profile of the tolerant cultivar, but were not changed in the sensitive one. In leaf tissues, however, there were remarkable changes in total protein profiles after B treatment, relative to the control. Following B treatment, in leaf tissues, at least seven proteins were increased in amount in tolerant cultivar but were unchanged in the susceptible one. In tolerant and sensitive cultivars, amounts of two proteins were increased in B‐treated plants, relative to control seedlings. In addition, four proteins (M_r:29, 58, 58, and 22 kDa) were unchanged in control and B‐treated seedlings of the tolerant cultivar. In the susceptible cultivar however, among these four proteins, the first one (M_r:29) was very much reduced and the others (M_r: 58, 58, and 22 kDa) were completely lost in B‐treated seedlings. Moreover, following B treatment, a set of high‐molecular‐weight proteins was quantitatively decreased in the susceptible cultivar but was unchanged in the tolerant cultivar. These results indicate that in barley, certain proteins may be involved in tolerance to B toxicity. In this study, changes in polypeptide composition as a result of B toxic concentration in leaf tissues were more abundant than in roots. Therefore, it is suggested that these changes, especially at shoot level may form the basis of the tolerance mechanism to B toxicity.     

Impact of Cultivar and Environment on Size Characteristics of Wheat Proteins Using Asymmetrical Flow Field‐Flow Fractionation and Multi‐Angle Laser Light Scattering

The use of multi‐angle laser light scattering (MALLS) in conjunction with asymmetrical flow field‐flow fractionation (A‐FFFF) was investigated for the determination of the molecular weight distribution (MWD) of wheat proteins. The wheat flour proteins were dissolved by sonication in 0.1M sodium phosphate (pH 6.9) containing 2% SDS. The results presented make it evident that efficient separation and size characterization of monomeric (M < 10⁵ g/mol) and polymeric protein (10⁵ ≤ M < 10⁸ g/mol) wheat proteins can be achieved with A‐FFFF/MALLS/UV in a single run. Therefore, this method appears to be able to detect significant modifications of MWD of wheat protein, whatever the factor inducing these alterations (i.e., genetic or environmental) and whatever the nature of these alterations (i.e., monomeric‐to‐polymeric ratio or MWD of polymeric protein). In the present study, we have indeed demonstrated that the MWD of wheat proteins can be altered from one cultivar to another in three main ways: by changing the relative amounts of monomeric and polymeric proteins, by changing the MWD of polymeric protein, and then by changing both the monomeric‐to‐polymeric ratio and the MWD of polymeric protein.     

Effects of zinc fertilization and irrigation on grain yield and zinc concentration of various cereals grown in zinc‐deficient calcareous soils

Effects of varied irrigation and zinc (Zn) fertilization (0, 7, 14, 21 kg Zn ha^‐1 as ZnSO₄7.H₂O) on grain yield and concentration and content of Zn were studied in two bread wheat (Triticum aestivum), two durum wheat (Triticum durum), two barley (Hordeum vulgare), two triticale (xTriticosecale Wittmark), one rye (Secale cereale), and one oat (Avena sativa) cultivars grown in a Zn‐deficient soil (DTPA‐extractable Zn: 0.09 mg kg^‐1) under rainfed and irrigated field conditions. Only minor or no yield reduction occurred in rye as a result of Zn deficiency. The highest reduction in plant growth and grain yield due to Zn deficiency was observed in durum wheats, followed by oat, barley, bread wheat and triticale. These decreases in yield due to Zn deficiency became more pronounced under rainfed conditions. Although highly significant differences in grain yield were found between treatments with and without Zn, no significant difference was obtained between the Zn doses applied (7–21 kg ha^‐1), indicating that 7 kg Zn ha^‐1 would be sufficient to overcome Zn deficiency. Increasing doses of Zn application resulted in significant increases in concentration and content of Zn in shoot and grain. The sensitivity of various cereals to Zn deficiency was different and closely related to Zn content in the shoot but not to Zn amount per unit dry weight. Irrigation was effective in increasing both shoot Zn content and Zn efficiency of cultivars. The results demonstrate the existence of a large genotypic variation in Zn efficiency among and within cereals and suggest that plants become more sensitive to Zn deficiency under rainfed than irrigated conditions.     

Distribution and Structural Variation of Nonstarch Polysaccharides in Milling Fractions of Hull‐less Barley with Variable Amylose Content

Three hull‐less barley genotypes containing starches with variable amylose content (23.8% normal, 4.3% waxy, 41.8% high‐amylose barley) were pearled to 10% and then roller‐milled to produce pearling by‐products (PBP), flour, and fiber‐rich fractions (FRF). PBP were enriched in arabinoxylans, protein, and ash and contained small amounts of starch and β‐glucans. FRF were considerably enriched in β‐glucans and arabinoxylans. The solubility of β‐glucans was higher in PBP than in FRF. The solubility of arabinoxylans was higher in FRF than in PBP. Small amounts of arabinogalactans detected in barley were concentrated in the outer portion of the barley kernel. The content and solubility of nonstarch polysaccharides (NSP) in various milling fractions was also dependent on the type of barley. To obtain more detailed information about the content and molecular structure of NSP, each milling fraction was sequentially extracted with water, alkaline [Ba(OH)₂], again with water, and finally with NaOH. These extractions resulted in four sub‐fractions: WE, Ba(OH)₂, Ba(OH)₂/H₂O, and NaOH. β‐Glucans and arabinoxylans exhibited structural heterogeneity derived from differences in their location within the kernel as well as from the genetic origin of barley. The WE arabinoxylans from FRF and flour had a substantially lower degree of branching than those from PBP. The WE arabinoxylans from FRF of high‐amylose and normal barley contained more unsubstituted Xylp residues but fewer doubly‐substituted and singly‐substituted Xylp at O‐2 than their counterparts from PBP. The WE arabinoxylans from FRF of waxy barley had a relatively high content of doubly‐substituted, but very few singly‐substituted Xylp residues. In all three barley genotypes, the ratio of tri‐ to tetrasaccharides in β‐glucans from PBP was higher than from flour and FRF. Substantial differences in the molecular weight of NSP in different milling fractions were also observed.     

Characterization of Protein Fractions of Rice Bran to Devise Effective Methods of Protein Solubilization

Proteins from the defatted brans of representative rice cultivars were fractionated into albumins, globulins, prolamins, and acid-soluble glutelins, accounting for 34, 15, 6, and 11% of the total bran proteins, respectively. The remaining insoluble residue protein, after treatment with 0.1M sodium hydroxide, resulted in the solubilization of 95% of the residue protein, representing 32% of the total bran protein. The relative molecular mass (M_r) values determined by size-exclusion HPLC were 10–100 kDa, 10–150 kDa, 33–150 kDa, and 25–100 kDa for the fully dissociated polypeptides of albumins, globulins, prolamins, and acid-soluble glutelins, respectively. Despite a breakdown of disulfide bonds of the residue protein during sodium hydroxide solubilization, the M_r of the majority of the fully dissociated polypeptides of this fraction ranged from 45 to 150 kDa. Insolubility of residue protein was due mainly to its strong aggregation and extensive disulfide bond cross-linking. Efficient methods may be developed for solubilizing up to 98% of rice bran protein by the use of dissociating and disulfide breaking agents currently in use in the food industry.     

A rapid method of evaluating the zinc status of coastal plain soils

Abstract

A study was made to evaluate Zn removed by extraction with a 0.075 N acid mixture (0.05 N HCl + 0.025 N H₂SO₄). A ratio of soil to extracting solution of 1 to 4 and an extracting time of 15 minutes was selected. Data obtained by the method was significantly correlated with dithizone (0.01%) extraction. The method was found to be acceptable for evaluation of the Zn status of Southern Coastal Plain soils and easily adapted to routine use in soil testing. A significant correlation was obtained between extractable soil Zn and leaf blade content of Zn for Zn‐deficient and non‐deficient corn plants.     

Leaching and plant offtake of N in field pea/cereal cropping sequences with incorporation of 15N-labelled pea harvest residues

Abstract. Field peas (Pisum sativum L.) were grown in sequence with winter wheat (Triticum aestivum L.) or spring barley (Hordeum vulgare L.) in large outdoor lysimeters. The pea crop was harvested either in a green immature state or at physiological maturity and residues returned to the lysimeters after pea harvest. After harvest of the pea crop in 1993, pea crop residues (pods and straw) were replaced with corresponding amounts of ¹⁵N‐labelled pea residues grown in an adjacent field plot. Reference lysimeters grew sequences of cereals (spring barley/spring barley and spring barley/winter wheat) with the straw removed. Leaching and crop offtake of ¹⁵N and total N were measured for the following two years. These treatments were tested on two soils: a coarse sand and a sandy loam. Nitrate concentrations were greatest in percolate from lysimeters with immature peas. Peas harvested at maturity also raised the nitrate concentrations above those recorded for continuous cereal growing. The cumulative nitrate loss was 9–12 g NO₃‐N m^–2 after immature peas and 5–7 g NO₃‐N m^–2 after mature peas. Autumn sown winter wheat did not significantly reduce leaching losses after field peas compared with spring sown barley. ¹⁵N derived from above‐ground pea residues accounted for 18–25% of the total nitrate leaching losses after immature peas and 12–17% after mature peas. When compared with leaching losses from the cereals, the extra leaching loss of N from roots and rhizodeposits of mature peas were estimated to be similar to losses of ¹⁵N from the above‐ground pea residues. Only winter wheat yield on the coarse sand was increased by a previous crop of peas compared to wheat following barley. Differences between barley grown after peas and after barley were not statistically significant. ¹⁵N lost by leaching in the first winter after incorporation accounted for 11–19% of ¹⁵N applied in immature pea residues and 10–15% of ¹⁵N in mature residues. Another 2–5% were lost in the second winter. The ¹⁵N recovery in the two crops succeeding the peas was 3–6% in the first crop and 1–3% in the second crop. The winter wheat did not significantly improve the utilization of ¹⁵N from the pea residues compared with spring barley.     

Nitrogen (total and 15N) uptake by barley and wheat under two irrigation regimes’

Nitrogen (total and ¹⁵N) uptake by barley (Hordeum vulgare L., cv. ‘Walfajr') and wheat (Triticum aestivum L., cv. ‘Karaj I') plants subjected to water stress were studied at the College of Agriculture, University of Tehran Experimental Farm located in the city of Karaj, Iran. The treatments consisted of two irrigation intervals, 7 days (control) and 14 days (stress). The plants were at the reproductive stage of growth at the start of the ¹⁵N treatment. Nitrogen (¹⁵N) was applied to 1m x 1m plots selected at the center of the 2.5m x 2.5m main plots. The ¹⁵N was provided to plants by adding 250 mg ¹³N as (NH₄)₂SO₄ (5.1 Atom % ¹⁵N) dissolved in water to each plot. The ¹⁵N treatment period continued for 48 hours. The plants were harvested at 6‐hour intervals during the ¹⁵N treatment period. After each harvest, the straw and the grains were separated, oven dried at 65°C and dry weights were recorded. Plant materials were ground in a Wiley Mill to pass through a 2mm sieve for chemical analysis. Total N was measured by an Auto‐Analyzer after Kjeldahl digestion, and ¹⁵N was measured using a mass spectrometer.

Nitrogen (total‐N and ¹⁵N) content of both plant species decreased under stress, with wheat appearing more severely affected than barley. However, nitrogen concentration was slightly higher for the stressed plants as compared with the controls. This pattern was essentially similar for both plants.     

Plasticity of high and low nutrient‐adapted grasses to added sulfur and nitrogen

Crop and native plants can be characterized as high and low nutrient‐adapted based on their expected response to native and applied nutrients. Our objective was to compare the plasticity of biomass allocation and tissue nutrient concentrations to added sulfur (S) and nitrogen (N) across a continuum of high and low nutrient‐adapted grasses, represented by barley (Hordeum vulgare), smooth brome (Bromus inermis), bluebunch wheatgrass (Pseudoroegneria spicata), and Idaho fescue (Festuca idahoensis). In our greenhouse study, treatments included two S sources (pyrite and gypsum), at 150 and 300 kg S ha^‐1, N at 50 kg ha^‐1, and a check. Shoot biomass of barley, smooth brome, and bluebunch wheatgrass was enhanced by S plus N. Shoot biomass of barley and smooth brome was greater with pyrite than with gypsum. Root biomass of smooth brome and bluebunch wheatgrass was greater with pyrite than with gypsum. Plant S concentrations of barley and Idaho fescue were enhanced by added S. Plant S concentrations in barley and smooth brome were greater with gypsum than with pyrite. Except for barley, plant S pools (shoot biomass x shoot S concentration) were enhanced with S plus N compared with no added nutrients. Nitrogen pools of barley, smooth brome, and bluebunch wheatgrass were higher with pyrite than with gypsum. Soil sulfate (SO₄) was greater when S or S plus N was added than without any added nutrients. For barley and smooth brome, soil sulfate tended to be lower with pyrite than with gypsum. For all soils, pH was lower with added S or added S plus N compared with unamended soils. While pyrite lowered soil pH, gypsum tended to increase soil pH. Overall, barley and smooth brome were highly plastic in responding to enhanced nutrient levels, bluebunch wheatgrass was relatively responsive, and Idaho fescue was least responsive.     

1H Nuclear Magnetic Resonance (NMR) and Differential Scanning Calorimetry (DSC) Studies of Water Mobility in Dough Systems Containing Barley Flour

This study used ¹H nuclear magnetic resonance (NMR) spin‐spin relaxation time (T₂) and differential scanning calorimetric (DSC) measurements of unfreezable water content (UFW), to assess water behavior in freshly prepared (25°C), refrigerator‐stored (4°C, one day), or freezer‐stored (–35°C, one day) doughs containing 5, 10, or 30% whole grain, air‐classified β‐glucan‐diminished, and air‐classified β‐glucan‐enriched (BGB‐E) barley flours. Three populations of water were detected by NMR, depending on moisture content of dough, namely, tightly (T₂₁, 2–5 msec), less tightly (T₂₂, 20–50 msec), and weakly (T₂₃, 100–200 msec) bound water. T₂₂ peak was always detectable, and T₂₂ peak time linearly correlated to moisture content of dough in a range of 0.7–2.0 g/g db (r = 0.99, P < 0.05). Freezer storage showed less effect on water mobility in dough compared with refrigerator storage, whereas cooking and cool storage of cooked dough significantly decreased the water mobility (P < 0.05). Adding barley flour steadily decreased the water mobility in dough, and the reduction was more significant with adding BGB‐E (P < 0.05). Immobile water content was calculated by extrapolating T₂₂ peak time versus total moisture content in dough and significantly correlated to the UFW content measured by DSC (r = 0.72, P < 0.05).     

Evaluation of anion exchange membranes to estimate bioavailable phosphorus in native grasslands of semi‐arid Northwestern Australia

Abstract

Anion exchange membranes (AEMs) were used to assess the P status of semi‐arid sub‐tropical soils of high P sorption capacity from the Pilbara region in northwestern Australia. We determined the most appropriate procedure for using AEMs in these soils using a factorial of extraction ratios and shaking times and compared the method with extraction by water. Significantly more inorganic P (Pi) was extracted by the membranes (AEM‐Pi) than by water, and the amount extracted increased with extraction time but was generally independent of the extraction ratio. Maximum AEM‐Pi was 3.61 μg g^‐1 after eight hour extraction. The AEM procedure was compared with traditional extraction procedures using 0.5 M sodium bicarbonate (NaHCO₃) and 0.1 M sodium hydroxide (NaOH) to assess ability to detect spatial heterogeneity. The amount of Pi extracted decreased in the order: AEM>NaOH>NaHCO_3* The AEM method detected a significant effect of depth on Pi (P=0.0001), while the NaOH method detected both site and treatment effects (P<0.05). Inorganic P extracted by NaHCO₃ did not vary by site, treatment, or depth. Coefficients of variation were generally least using the AEM method. We recommend that studies of spatial and temporal dynamics of P on highly‐weathered soils in semi‐arid regions include measurement of both AEM‐Pi and NaOH‐extractable Pi.     

Estimation of critical limit for zinc in rice soils

Abstract

Twenty surface soil samples were collected from Nainital Tarai (foothills of Himalya) where “Khaira”; disease (Zn deficiency of rice) is prevalent. Rice (Oryza sativa L. variety IR‐8) was grown in pots for 8 weeks after transplanting. Experiments were conducted to determine the suitability of five soil Zn extractants: dilute acid (HCl + H₂SO₄) mixture; DTPA‐(NH₄) ₂CO₃, pH 7.3; dithizone; NH₄OAc, pH 4.6; and 2N MgCl₂ to predict Zn deficiency. Critical values for soil available Zn were established for rice by the old and new Cate and Nelson procedures¹.

Zinc extracted from the soils with dithizone; NH₄OAc, pH 4.6; 0.2N MgCl₂. and DTPA‐(NH₄) ₂CO₃ pH 7.3 was significantly correlated with the uptake of Zn by the rice plants. The correlation between Zn extracted with the dilute acid (HCl + H₂SO₄) mixture and plant Zn was not statistically significant. The ex‐tractants which extracted greater quantities of Zn gave higher critical values and vice versa. It is concluded that all extracting solutions except the dilute acid (HCl + H₂SO₄) mixture were found to he suitable for predicting available Zn in rice soils of Tarai.     

Detection of Proteins in Starch Granule Channels

Proteins were detected in channels of commercial starches of normal maize, waxy maize, sorghum, and wheat through labeling with a protein‐specific dye and examination using confocal laser scanning microscopy (CLSM). The dye, specifically 3‐(4‐carboxybenzoyl)quinoline‐2‐carboxaldehyde (CBQCA), fluoresces only after it reacts with primary amines in proteins, and CLSM detects fluorescence‐labeled protein distribution in an optical section of a starch granule while it is still in an intact state. Starch granules in thin sections of maize kernels also had channel proteins, indicating that proteins are native to the channels and not artifacts of isolation. Incubation of maize starch with protease (thermolysin) removed channel proteins, showing that channels are open to the external environment. SDS‐PAGE analysis of total protein from gelatinized commercial waxy maize starch revealed two major proteins of about M_r 38,000 and 40,000, both of which disappeared after thermolysin digestion of raw starch. Commercial waxy maize starch granule surface and channel proteins were extracted by SDS‐PAGE sample buffer without gelatinization of the granules. The major M_r 40,000 band was identified by MALDI‐TOF‐MS and N‐terminal sequence analysis as brittle‐1 (bt1) protein.     

Zinc uptake kinetics in the low and high‐affinity systems of two contrasting rice genotypes

Rice (Oryza sativa L.) cultivars differ widely in their susceptibility to zinc (Zn) deficiency. The physiological basis of Zn efficiency (ZE) is not clearly understood. In this study, the effects of Zn‐sufficient and Zn‐deficient pretreatments on the time and concentration‐dependent uptake kinetics of Zn were examined at low (0–160 nM) and high Zn supply levels (0–80 μM) in two contrasting rice genotypes (Zn‐efficient IR36 and Zn‐inefficient IR26). The results show that ⁶⁵Zn²⁺ influx rate was over 10 times greater for the Zn‐deficient pretreatment plants than for the Zn‐sufficient pretreatment plants. At low Zn supply, significant higher ⁶⁵Zn²⁺ influx rates were found for the Zn‐efficient genotype than for the inefficient genotype, with a greater difference (over three‐fold) at Zn supply > 80 nM in the Zn‐deficient pretreatments. At high Zn supply levels, however, a difference (2.5‐fold) in ⁶⁵Zn²⁺ influx rate between the two genotypes was only noted in the Zn‐deficient pretreatments. Similarly, the ⁶⁵Zn²⁺ accumulation in the roots and shoots of Zn‐efficient IR36 pretreated with Zn‐deficiency were sharply increased with time and higher than that in the Zn‐inefficient IR26 with an over four‐fold difference at 2 h absorption time. However, with Zn‐deficient pretreatments, the Zn‐efficient genotype showed a higher shoot : root ⁶⁵Zn ratio at higher Zn supply. Remarkable differences in root and shoot ⁶⁵Zn²⁺ accumulation were noted between the two genotypes in the Zn‐deficiency pretreatment, especially at low Zn level (0.05 μM), with 2–3 times higher values for IR36 than for IR26 at an uptake time of 120 min. There appear to be two separate Zn transport systems mediating the low and high‐affinity Zn influx in the efficient genotype. The low‐affinity system showed apparent Michaelis–Menten rate constant (K_m) values ranging from 10 to 20 nM, while the high‐affinity uptake system showed apparent K_m values ranging from 6 to 20 μM. The V_max value was significantly elevated in IR36 and was 3–4‐fold greater for IR36 than for IR26 at low Zn levels, indicating that the number of root plasma membrane transporters in low‐affinity uptake systems play an important role for the Zn efficiency of rice.     

Fate of nitrogen and sulphur as affected by the rhizosphere of oilseed rape and barley

Abstract

Within plants, sulphur (S), and nitrogen (N) equilibrium is a requisite for their normal development. Pot experiments with oilseed rape and barley fertilized at different N to S ratios were carried out under glasshouse conditions by using the “rhizobag”; technique. The objective was to compare the induced‐influence of rhizosphere and non‐rhizosphere soil on N and S nutrition of the studied plants. Thus, SO₄ ²‐S, NC₃ ^‐‐N and NH₄ ⁺‐N concentrations, and total N and S taken up by the plants were examined. Barley increased the pH of rhizosphere soil whereas no real change of pH was observed with oilseed rape. Both plants took up all the NO₃ ^‐ present in the soil solution, but rapeseed took up greater quantities of NH₄ ⁺‐N and SO₄ ^2‐ ‐S than barley. Moreover, the ratio values of N to S of the aerial parts of the rapeseed were significantly and positively correlated to those of soil available‐N to ‐S ratios while this correlation was significant but negative with barley. This indicated a clear‐cut different influence between the two rhizospheres which oppositely induce the N and S nutrition of the two plant species.     

Oily waste containing natural radionuclides: does it cause stimulation or inhibition of soil bacterial community?

Contamination with oily wastes containing natural radionuclides is a potential hazard for soil health and function. Our study aimed to reveal both structural and functional changes of the microbial community resistant to and able to decompose oily wastes in soil. To do this, we determined CO₂ efflux, microbial biomass (by the extraction‐fumigation method), and community structure (by PCR‐SSCP) for 120 d after application of radioactive oily wastes to the soil at the ratio 1:4. The addition of the waste resulted in an increase of the activity concentration of ²²⁶Ra by 130 times (up to 643 Bq kg^?1) and of ²³²Th by 29 times (up to 254 Bq kg^?1). The calculated weighted dose for the radionuclide ²²⁶Ra was found to be below the values that are known to affect microorganisms. However, the cumulative effect of a repeated deposition of radioactive oily waste may result in an increase of the weighted dose up to an effective level. During the incubation, the hydrocarbon (HC) content of the waste‐treated soil decreased from 156 to 54 g kg^?1 of soil indicating intensive decomposition of added organics by soil microorganisms. The waste application, however, led to an inhibition of soil microbial biomass compared with the control (by 26–47%). Microbial respiration was stimulated in the first month of incubation and then decreased until the end of the incubation period (by up to 74% compared to the control). The qCO₂ was estimated to be 3‐fold higher than the control on day 1 of incubation and equal to the control on day 120 of incubation. The bacterial diversity decreased in the contaminated soil compared with the control soil. The bacterial community structure was altered by domination of new oil degrader species belonging to the genera Dyella, Pseudoxanthomonas, Sinobacter, and Parvibaculum. Thus, disposal of radioactive petroleum waste strongly altered the structure of the microbial community resulting in the selection of resistant species able to decompose pollutants and also affected the community function (inhibition of microbial biomass and stimulation of respiration) which tended to stabilize after long‐term incubation.     

Ingredient Characterization and Hardening of High‐Protein Food Bars: an NMR State Diagram Approach

A second‐degree simplex lattice mixture design was used to study the effects of soy, dairy, and soy‐dairy blends of powdered proteins in three high‐protein food bar models (sugar syrup, polyol syrup, and reduced‐sugar syrup). Overall protein performance was evaluated based on textural changes during accelerated storage, bar integrity, and dough stickiness and was a strong function of the syrup model used (R² = 92.33%). Nuclear magnetic resonance (NMR) relaxometry was used to measure relaxation times (T₂, T₂*, and T₁) at 20°C and to create state diagrams (temperature, T₂* curves) for the individual powdered proteins and syrups over a temperature range of –35 to 50°C. Increases in relaxation times for powdered protein samples were indicative of better overall protein performance, whereas increases in relaxation times for syrup samples were associated with increases in moisture content and concentration of polyols. Increases in water activity (a_w) of the bars during accelerated storage suggested an elevated rate of hardening for polyol‐containing bars that was caused by a decrease in the amount of water capable of acting as a plasticizer in the product. Proteins were separated into four types (A, B, C, and D) based on the shape of the state diagram curve. Predicted to be the most stable, type D proteins (SUPRO 313 and SUPRO 430) offered the most versatility and, when blended with other proteins, often induced synergistic softening effects in the nutrition bars which led to an extended product shelf life. The NMR state diagram technique appears to be a valuable tool for predicting overall performance of powdered proteins in sugar‐, polyol‐, and reduced‐sugar syrup based food bars.