Salt sensitivity of wheat at various growth stages

Summary The relative salt tolerance of two wheat species (Triticum aestivum L., cv. Probred and Triticum turgidum L., Durum Group, cv. Aldura) at different stages of growth was determined in a greenhouse experiment. Plants were grown in sand cultures that were irrigated four times daily with modified Hoagland's solution. Salinization with NaCl and CaCl₂ (2:1 molar ratio) provided seven treatment solutions with osmotic potentials ( _s ) ranging from –0.05 to –1.25 MPa (electrical conductivities of 1.4 to 28 dS/m). Salt stress was imposed for 45 days beginning at either 10, 56, or 101 days after planting. The three 45-day stages are referred to here as the vegetative, reproductive, and maturation stages although the first stage included spikelet differentiation. In a separate experiment, seedling growth was measured after 21 days of salt stress ( _s = –0.05 to –0.85 MPa) initiated at 0, 7, 11, and 16 days after planting. Salt stress ( _s = –0.65 MPa) delayed germination by 4 days for both wheats but full emergence occurred. Relative growth response curves of the seedlings were alike regardless of whether salt stress was imposed at planting or at the 1st, 2nd, or 3rd-leaf stage of growth. Salt stress also retarded leaf development and tillering but hastened plant maturity. Grain yields from plants stressed during either the vegetative, reproductive, or maturation stages indicated that both species became less sensitive to salinity the later plants were stressed. Grain yield was reduced 50% at _s = –0.76, –1.53, and –1.58 MPa for Probred and –0.65, –1.08, and –1.34 MPa for Aldura when salinized during stages 1, 2, and 3, respectively. Salinity reduced grain yield by reducing seed number more than seed weight indicating that salt stress during stage 1 affected spikelet differentiation. Straw yield was significantly reduced by salt stress only during stage 1. Leaf mineral analyses revealed that Aldura readily accumulated Na whereas Probred did not. Both species accumulated Cl but the concentrations were much higher in Aldura. K uptake was severely inhibited by salt stress imposed during the first stage but not when imposed the second stage.     

Salinity sensitivity of sorghum at three growth stages

Summary The relative salt tolerance of two sorghum cultivars [Sorghum bicolor (L.) Moench., cvs. Northrup King 265 and Asgrow Double TX] at three different stages of growth was determined in a greenhouse experiment. Plants were grown in sand cultures irrigated four times daily with modified Hoagland's solution. A nonsaline solution and six solutions salinized with NaCl and CaCl₂ (2: 1 molar ratio) provided treatments with osmotic potentials (_s) ranging from –0.05 to –1.05 MPa. The saline treatments were imposed for 30 days beginning at either Stage 1, 4, or 7 as defined by Vanderlip and Reeves (Agron J. 64:13, 1972). The 30-day stages are referred to here as the vegetative, reproductive and maturation stages although the first stage may have included initial panicle differentiation. Both cultivars were most sensitive to salinity during the vegetative stage and least sensitive during maturation. Based on a nonlinear least-squares analysis, grain yield reductions of 50% were predicted at _s=–0.68, –1.02, and –1.14 MPa for NK265 and at –0.62, –1.00, and –1.10 MPa for Double TX when salinized during the vegetative, reproductive, and maturation stages, respectively. Although salinity had no significant effect on mean kernel weights, significant growth stage effects and interaction indicated that kernels were heaviest for plants salinized during the vegetative stage. Stover yields were significantly reduced by salination during the vegetative stage but were unaffected when plants were salinized during the maturation stage. Salination during the reproductive stage also decreased stover yield of Double TX but the effect was smaller than that during the first stage. Stover yield of NK265 was unaffected by salinity at this stage.Mineral analysis of the first leaf below the flag leaf at harvest indicated that both cultivars tended to exclude Na from the upper leaves. Ca and Cl concentrations increased with increased salinity in plants salinized during the maturation stage but salination in earlier stages decreased Ca concentration of this upper leaf at harvest and had no effect on the final Cl concentration. Phosphate and K concentrations decreased when plants were salinized during the third stage but increased when plants were salinized during the vegetative and reproductive stages. Mg was unaffected by salinization during the first and last stage but decreased when plants were salinized,during the reproductive stage. An extensive data base now exists which describes the salt tolerances of many different crops (Maas and Hoffman 1977; Maas 1986). These data express yield responses as a function of the average salt concentration in the rootzone. Generally, these data apply only if salinity is fairly uniform from the seedling stage to maturity. Except for germination, little information exists on the tolerances of crops at different stages of growth. Such information could be invaluable to optimize the use of limited water resources. Knowledge that crops are more tolerant during some stages of growth will improve new strategies for utilizing saline drainage waters (Rhoades 1984).Several studies indicate that tolerances do change as the crop develops and matures, but none of these studies completely separated the effects of duration of treatment from the stage of growth that the crop was treated (Ayers et al. 1952; Kaddah and Ghowail 1964; Kovalskaia 1958; Lunin et al. 1961 a, 1961 b; Maas et al. 1983; Ogo and Sasai 1955; Piruzyan 1959; Verma and Bains 1974). Comparisons of sensitivity during specific phenological stages are confounded when treatment periods are of unequal duration.This study was initiated to determine the sensitivity of grain sorghum [Sorghum bicolor (L.) Moench] to salinity during three 30-day periods of growth. Francois et al. (1984) recently reported that sorghum is a moderately salt-tolerant crop. In field plot tests, grain yields of two cultivars decreased 16% per unit increase in salinity (electrical conductivity of saturated soil extracts from the rootzone) above 6.8 dS/m. They further reported that both cultivars were significantly more tolerant at germination than at later stages of growth. Soil water salinities above 8.2 dS/m delayed germination but full germination occurred within 10 days at salinities up to 22 dS/m. Treatments in the present study were designed to assess plant growth and yield responses to 30-day exposures to salinity beginning at either the 2-leaf stage, at the beginning of rapid culm elongation, or after anthesis.     

Nanotribology and Nanofabrication of MoO3 Structures by Atomic Force Microscopy

Atomic force microscopy was used to characterize the sliding of molybdenum oxide (MoO3) nanocrystals on single-crystal molybdenum disulfide (MoS2) surfaces. Highly anisotropic friction was observed whereby MoO3 nanocrystals moved only along specific directions of the MoS2 surface lattice. The energy per unit area to move the MoO3 nanocrystals along their preferred sliding direction was an order of magnitude less than required to slide macroscopic MoS2-bearing contacts. This extreme friction anisotropy was exploited to fabricate multicomponent MoO3 nanostructures. These reversibly interlocking structures could serve as the basis for devices such as mechanical logic gates.     

Characteristics of Actinomyces pyogenes involved in lameness of male turkeys in north-central United States

A new condition of clinical lameness in 20 male turkey flocks of North-Central United States, associated with isolation of gram-positive rod bacteria from lesions of osteomyelitis, is characterized. The characterization confirmed the randomly selected isolates as Actinomyces pyogenes based on macroscopic and microscopic observations and 17 biochemical tests. The disease was reproduced within 3 weeks in all male turkeys, following an intravenous challenge at 15 weeks of age. The agar gel precipitin test and immunoblotting confirmed the antigenic similarity of the isolates recovered from the osteomyelitis lesions of lame birds.     

An In Vitro Biomechanical Study of a Multiplanar Circular External Fixator Applied to Equine Third Metacarpal Bones

The biomechanical characteristics of a 4-ring circular multiplanar fixator applied to equine third metacarpal bones with a 5 mm mid-diaphyseal osteotomy gap were studied. Smooth Steinmann pins, either 1/8 inch, 3/16 inch, or 1/4 inch, were driven through pilot holes in the bone in a crossed configuration and full pin fashion and fastened to the fixator rings using cannulated fixation bolts. The third metacarpal bone fixator constructs were tested in three different modes (cranial-caudal four-point bending, axial compression, and torsion). Loads of 2,000 N were applied in bending and axial compression tests and a load of 50 N ± m was applied during testing in torsion. Fixator stiffness was determined by the slope of the load displacement curves. Three constructs for each pin size were tested in each mode. Comparisons between axial stiffness, bending stiffness, and torsional stiffness for each of the three different pin sizes were made using one-way analysis of variance. There was no visually apparent deformation or permanent damage to the fixator frame, and no third metacarpal bone failure in any of the tests. Plastic deformation occurred in the 1/8 inch pins during bending, compression, and torsion testing. The 3/16 inch and 1/4 inch pins elastically deformed in all testing modes. Mean (±SE) axial compressive stiffness for the 1/8 inch, 3/16 inch, and 1/4 inch pin fixator constructs was: 182 ± 16 N/mm, 397 ± 21 N/mm, and 566 ± 8.7 N/mm; bending stiffness was 106 ± 3.3 N/mm, 410 ± 21 N/mm, and 548 ± 12 N/mm; and torsional stiffness was 6.15 ± 0.82 N.m/degree, 7.14 ± 0.0 N±m/degree, and 11.9 ± 1.0 N.m/degree respectively. For statically applied loads our results would indicate that a 4-ring fixator using two 1/4 inch pins per ring may not be stiff enough for repair of an unstable third metacarpal bone fracture in a 450 kg horse.     

Intermediate Filament Proteins Expression and Carbohydrate Moieties in Trophoblast and Decidual Cells of Mature Cat Placenta

The aim of this study was to characterize cytoskeletal intermediate filament proteins and glycoconjugates of syncytiotrophoblast, cytotrophoblast and decidual cells of feline endotheliochorial placenta. Samples from 12 normal pregnant female cats, after 45 ± 5 days of gestation, were obtained removing the uterine horns by hysterectomy. Sections were processed for routine observation and for immunohistochemistry using anticytokeratin, antivimentin and antidesmin antibodies. In addition, lectin histochemistry was performed using a panel of several biotinylated lectins to characterize glycosides expression profile. Cytotrophoblast and syncytiotrophoblast showed immunoreactivity only with acidic and basic cytokeratins. Decidual cells were only positive to vimentin, consistent with their origin from endometrial fibroblasts. Trophoblast expressed a broad population of glycans, highly exposing terminal N‐acetyl glucosamine residues and non‐sialylated galactose and N‐acetyl galactosamine oligomers. Oligosaccharides bound by Phaseolus vulgaris erythroagglutinin were the only highly branched N‐linked residues evidenced in cats, and they were restricted to the syncytium. Unlike results reported on humans, mice and rats on lectin affinity of decidual cells, sialid acids and complex N‐linked oligosaccharides were not demonstrated in cats. Glycosylation of proteins determines many of their final properties, thus becoming essential for the embryo‐maternal dialogue during implantation and placentation. Changes in glycosylation pattern have been related to pathological pregnancies in other species. Hence, the knowledge about glycosylation profile of the normal cat placenta may lead to a better understanding of both normal and pathological reproductive events.     

Resistance to synthetic pyrethroids in South Australian populations of sheep lice (Bovicola ovis)

SUMMARY Lice were collected from 71 flocks detected as Infested at market Inspection in 1990 and 1991, from 16 flocks where resistance was suspected and from 31 flocks from Kangaroo Island. Susceptibility to cypermethrin was measured by a treated surface technique and survival of lice at 5 ppm or greater was taken as an indication of resistance. The prevalence of resistance was 34% in louse populations from the market inspection sample, 50% in flocks in which resistance was suspected and 68% in flocks from Kangaroo Island. Most resistance factors were in the range 1 to 20 although one louse population with a resistance factor of 91 was found on Kangaroo Island.     

Reproductive Performance of Ewes after 5-Day Treatment with Intravaginal Inserts Containing Progesterone in Combination with Injection of Prostaglandin F2α

Three experiments were conducted with a total of 1579 ewes to examine reproductive performance in response to synchronization of oestrus during the breeding season, using controlled internal drug releasing (CIDR-G) inserts in regimens designed to provide high concentrations of circulating progesterone. In experiment 1, treatment with two CIDR-G inserts for 12 days produced conception rate (79%) and prolificacy (1.9) to first service equivalent to breeding at natural oestrus (56% and 2.0, respectively). Pregnancy rates to two service periods were 90 and 79%, respectively. In experiments 2 and 3, progesterone was delivered by a single CIDR-G insert for 5 days in combination with prostaglandin F2alpha (PGF2alpha; 5 mg i.m., twice, 3 h apart) the day before (experiment 2), or at insert removal (experiment 3). The combined treatments improved rates of synchronization of oestrus (p<0.01) by 23 and 20% points, respectively, and pregnancy rates to the first service period by 19 (p<0.05) and 13 (p<0.01) percentage points, respectively, compared to treatment with PGF2alpha alone. It is concluded that the combination of treatment for 5 days with a CIDR-G insert and two injections of 5 mg PGF2alpha, the day before, or the day of insert removal, were effective treatments to obtain high fertility at synchronized oestrus in ewes during the breeding season.