Pregnancy rate following transfer of in vitro produced lamb derived embryos in two embryonic stages

Ovine embryos were produced by maturation, fertilization and in vitro culture (IVM/IVF/IVC) of oocytes collected from slaughtered prepubertal ewes. At 24 h post IVM, oocytes were fertilized with fresh semen collected from Lori-Bakhtiari breed at a concentration of 1.0 x l0(6) sperm mL(-1). The presumptive ova/embryos were transferred into the embryo culture medium at 22-24 h post IVF. Following 4 to 7 day in culture, embryos (at morula and blastocyst stage, respectively) were transferred surgically to the uterine horn of synchronized recipients. Pregnancy was diagnosed at day 30 by hormonal assay and at days 55 and 140 of gestation by ultrasonography and pregnancies were allowed to go to term. A total of nine ewes received 27 embryos (3 embryos/ewe). Five ewes received 15 embryos at morula stage and four ewes received 12 embryos at blastocyst stage. From those received morula stage embryos one was pregnant on day 30 (20%), though no pregnancy was diagnosed on each of days 55 and 140. While from those received blastocyst stage embryos, three ewes were pregnant on day 30 (75%) and two ewes (50%) remained pregnant on each of days 55 and 140. In conclusion, day 4 IVM-IVF morula stage embryos had a lower survival rate than did day 7 IVM-IVF blastocysts embryos, following transfer to the synchronized recipient ewes.     

Experimental study on compressive,flexural and fatigue behavior of warp-knitted spacer fabrics reinforced polyurethane cast elastomer composites

This paper reports an experimental study on compressive, flexural and fatigue behavior of polyurethane cast elastomers (PCE) reinforced with warp-knitted spacer fabrics (WKSF). It aims to investigate new applications for these fabrics as the reinforcements for elastomeric parts such as shoe soles, rubber floor coverings, vibration dampening and shock absorbing pads, etc. A series of polyester WKSF with different thickness, structure of outer layer fabric and spacer yarns density was prepared and converted to PCE reinforced WKSF using the hand molding method. All the samples, including the neat PCE, were subjected to static compression, flat and spherical compression, three-point bending and flexural fatigue tests. The results showed that reinforcing PCE with WKSF, considerably enhances its spherical compressive strength (concentrated loading), flexural strength and fatigue resistance. However, it deteriorates flat compressive strength (distributed loading) and recovery behavior after static compression loading. The effect of fiber weight fraction, thickness, structure of outer layer fabric and spacer yarns density on the mentioned properties of the composites was discussed in the paper.     

Genome-wide association mapping for root cone angle in rice

Background

Plant root systems play a major role in anchoring and in water and nutrient uptake from the soil. The root cone angle is an important parameter of the root system architecture because, combined with root depth, it helps to determine the volume of soil explored by the plant. Two genes, DRO1 and SOR1, and several QTLs for root cone angle have been discovered in the last 5 years.

Results

To find other QTLs linked to root cone angle, a genome-wide association mapping study was conducted on two panels of 162 indica and 169 japonica rice accessions genotyped with two sets of SNP markers (genotyping-by-sequencing set with approximately 16,000 markers and high-density-rice-array set with approximately 300,000 markers). The root cone angle of all accessions was measured using a screen protractor on images taken after 1 month of plant growth in the Rhizoscope phenotyping system. The distribution of the root cone angle in the indica panel was Gaussian, but several accessions of the japonica panel (all the bulus from Indonesia and three temperate japonicas from Nepal or India) appeared as outliers with a very wide root cone angle. The data were submitted to association mapping using a mixed model with control of structure and kinship. A total of 15 QTLs for the indica panel and 40 QTLs for the japonica panel were detected. Genes underlying these QTLs (+/?50 kb from the significant markers) were analyzed. We focused our analysis on auxin-related genes, kinases, and genes involved in root developmental processes and identified 8 particularly interesting genes.

Conclusions

The present study identifies new sources of wide root cone angle in rice, proposes ways to bypass some drawbacks of association mapping to further understand the genetics of the trait and identifies candidate genes deserving further investigation.

     

Dynamic simulation of the performance of an inflatable greenhouse in the southern part of Alberta III. Effects of cloudiness factor

Several numerical simulations are carried out to investigate the effect of cloudiness on the climatic conditions of plastic covered greenhouses. The special cases of a fully sunny day, partially cloudy day and highly cloudy day are treated in detail and the results presented in graphical form.     

Fingerprinting sediment sources in the outlet reservoir of a hilly cultivated catchment in Tunisia

Purpose

Approximately 74 % of agricultural soils in Tunisia are affected by water erosion, leading to the siltation of numerous human-made reservoirs and therefore a loss of water storage capacity. The objective of this study was to propose a methodology for estimating the relative contributions of gully/channel bank erosion and surface topsoil erosion to the sediment accumulated in small reservoirs.

Materials and methods

We tested an approach based on the sediment fingerprinting technique for sediments collected from a reservoir (which has been in operation since 1994) at the outlet of a catchment (Kamech, 2.63 km²). Sampling concentrated on the soil surface (in both cropland and grassland), gullies and channel banks. A total of 17 sediment cores were collected along a longitudinal transect of the Kamech reservoir to investigate the origin of the sediment throughout the reservoir. Radionuclides (particularly caesium-137, ¹³⁷Cs) and nutrients (total phosphorus, total nitrogen and total organic carbon (TOC)) were analysed as potential tracers.

Results and discussion

The applications of a mixing model with ¹³⁷Cs alone or ¹³⁷Cs and TOC provided very similar results: The dominant source of sediment was surface erosion, which was responsible for 80 % of the total erosion within the Kamech catchment. Additionally, we showed that the analysis of a single composite core provided information on the sediment origin that was consistent with the analysis of all sediment layers in the core. We demonstrated the importance of the core sampling location within the reservoir for obtaining reliable information regarding sediment sources and the dominant erosion processes.

Conclusions

The dominance of surface erosion processes indicates that conservation farming practices are required to mitigate erosion in the agricultural Kamech catchment. Based on the results from 17 sediment cores, guidelines regarding the number and location of sampling cores to be collected for sediment fingerprinting are proposed. We showed that the collection of two cores limited the sediment source apportionment uncertainty due to the core sampling scheme to <10 %.     

Kinetics of phosphorus release from calcareous soils under different land use in Iran

The rate of phosporus (P) release from soils can significantly influence P fertility of soils. The objectives of this study were to investigate the effects of land‐use types on the kinetics of P release under different management practices and the relationship between kinetic parameters and soil physical and chemical properties from calcareous soils. The kinetics of P release in 0.01 M CaCl₂ was studied in surface samples of 30 calcareous soils planted to garlic, garden, pasture, potato, vegetables, and wheat. Trend in P‐release kinetics was similar between land‐use types. Significantly different quantities of P were released under different land use. The maximum amount (average of five soils) (46.4 mg kg^–1) of P was released in soil under potato and the minimum amount (10.4 mg kg^–1) under pasture. The kinetics of P release from soils can be described as an initial rapid rate followed by a slower rate. Different models were used to describe P release. In general, parabolic diffusion and power equation were found to be appropriate for modeling P release. The P‐release rate for the soils was estimated by parabolic equation for the studied land‐use types. The constant b was lower for pasture and wheat than for garlic and potato. The relationship between the rate of P release with Olsen‐P was linear, while it was curved with respect to the CaCl₂‐P, indicating that release of P was diffusion‐controlled. When the kinetic parameters of models were regressed on soil properties, CaCl₂‐P and CaCO₃ appeared to be the most important soil properties influencing P‐release rates in these soils.     

Antioxidants and glycine can improve the developmental competence of vitrified/warmed ovine immature oocytes

Despite the numerous potential applications of oocyte cryopreservation, the poor success rate has limited its practical applications. In livestock, particularly in ovine, the oocytes have low developmental competence following vitrification/warming process. Considering the occurrence of osmotic and oxidative stresses during the vitrification/warming process, the application of antioxidants and osmolytes may improve the developmental competence of vitrified/warmed oocytes. In the present study, we aimed to evaluate the effects of the addition of ascorbic acid (AA) and N‐acetyl cysteine (NAC) as antioxidants and glycine as an organic osmolyte either to the vitrification/warming solutions (VWS) or to the IVM medium on the developmental competence of vitrified/warmed ovine germinal vesicle stage oocytes. The survival rate in the vitrified groups was significantly lower than fresh ones. In vitrified/warmed oocytes, there was no significant difference in survival rate between supplemented and non‐supplemented groups. The addition of AA and/or NAC to the VWS or IVM medium and adding glycine to the IVM medium reduced the proportion of apoptotic oocytes and fragmented embryos, which was reflected as an increase in the proportions of metaphase II stage oocytes and blastocyst production. The best result was achieved by supplementing the IVM medium with NAC. In our study condition, antioxidants and glycine could improve the developmental competence of vitrified/warmed ovine immature oocytes, especially when added during IVM.     

Site selection for constructing groundwater dams through Boolean logic and AHP method (case study: watershed of Imamzadeh Jafar Gachsaran)

Paddy and Water Environment - In dry and semidry regions, changes in precipitation in terms of time and level have significant fluctuations, which make management of water resources in these...     

Water Relations and Transpiration of Quinoa (Chenopodium quinoa Willd.) Under Salinity and Soil Drying

Drought and salinity are the two major factors limiting crop growth and production in arid and semi‐arid regions. The separate and combined effects of salinity and progressive drought in quinoa (Chenopodium quinoa Willd.) were studied in a greenhouse experiment. Stomatal conductance (g_s), leaf water potential (Ψ_l), shoot and root abscisic acid concentration ([ABA]) and transpiration rate were measured in full irrigation (FI; around 95 % of water holding capacity (WHC)) and progressive drought (PD) treatments using the irrigation water with five salinity levels (0, 10, 20, 30 and 40 dS m^?1); the treatments are referred to as FI₀, FI₁₀, FI₂₀, FI₃₀, FI₄₀; PD₀, PD₁₀, PD₂₀, PD₃₀, PD₄₀, respectively. The measurements were carried out over 9 days of continuous drought. The results showed that increasing salinity levels decreased the total soil water potential (Ψ_T) and consequently decreased g_s and Ψ_l values in both FI and PD. During the drought period, the xylem [ABA] extracted from the shoots increased faster than that extracted from the roots. A reduction in Ψ_T, caused by salinity and soil drying, reduced transpiration and increased apparent root resistance (R) to water uptake, especially in PD₀ and PD₄₀ during the last days of the drought period. The reasons for the increase in apparent root resistance are discussed. At the end of the drought period, the minimum value of relative available soil water (RAW) was reached in PD₀. Under non‐saline conditions, Ψ_l decreased sharply when RAW reached 0.42 or lower, but under the saline conditions of PD₁₀ and PD₂₀, the threshold values of RAW were 0.67 and 0.96, respectively. In conclusion, due to the additive effect of osmotic and matric potential during soil drying on soil water availability, quinoa should be re‐irrigated at higher RAW in salt‐affected soils, i.e. before the soil water content reaches the critical threshold level causing the drop in Ψ_l resulting in stomatal closure.     

The effect of water salinity on growth and physiological stages of eight Canola (Brassica napus) cultivars

Laboratory/greenhouse and field experiments were conducted to evaluate the effects of salinity levels ranging from 1 to 12 dS/m on germination rate, 8 leaf seedling dry matter, seed yield, and seed oil content of the 8 Canola (Brassica napus) cultivars: ACSN1, Falcon, Shirali, Ceres, Tower, Cobra, Global, and Oyerka. Statistical results revealed that the factors: salinity, cultivar, and their interaction had significant (P<0.01) effect on germination rate and 8 leaf seedling dry matter. Based on statistical analysis seed yield was significantly influenced by both salinity and cultivar at the 5% significance level; while the cultivar factor had a significant effect on seed oil content, salinity did not show any effect on seed oil content. Analytical results, using the well-known sigmoid or S-shape salinity response function gave reliable results for determining tolerant and sensitive cultivars to salinity. Applying an existing model on canola response to salinity levels in different growth stages, the values of C ₅₀ and P parameters were developed for local canola cultivars. Results showed that the response of cultivars to salinity levels vary in different growth stages. While a cultivar is tolerant in a growth stage, it may be sensitive to salinity in another growth stage. Based on observed data and ANOVA analysis, we concluded that ACSN1, Shiraly, and Falcon can be ranked as salt-tolerant, and Global and Oyerka as the salt-sensitive cultivars.