Effect of soil texture on the emission characteristics of porous clay pipe for subsurface irrigation

Laboratory and numerical experiments were carried out to analyze the effect of soil texture on the emission characteristics of porous clay pipe used for subsurface irrigation. Results show that the emission rate of the pipe is linearly related to the applied hydraulic head in the open environment. With the pipe embedded in the soil, the emission rate becomes a function of the soil texture and the applied hydraulic head. For a given soil texture, as the applied hydraulic head in the pipe increases, the moisture content in the vicinity of the pipe becomes higher, and the effect of the capillary forces on the emission rate of the pipe decreases. Under saturated conditions in the vicinity of the pipe, the effect of capillary forces in the flow domain on the emission rate of the pipe is negligible. The study results are useful in designing the lateral spacing and installation depth of the pipelines, irrigation run time and length, and the hydraulic head required for proper operation of porous clay pipe based subsurface irrigation systems.     

Managing crop damage caused by house mice (Mus domesticus) in Australia

A large-scale outbreak of the house mouse populations occurs in grain growing in Australia on average once every four years. High densities of mice cause major yield losses to cereal crops, and low to moderate densities of mice also cause some losses. Several predictive models based on rainfall patterns have been developed to forecast mouse density. These models carry some uncertainty and the economic value of basing management actions on these models is not clear. Baiting is the most commonly used method and zinc phosphide and other rodenticide bait are effective in reducing up to 90% of mouse populations. Ecologically-based best farming practice for controlling mice has recently been developed on the basis of long-term field studies of mouse populations. No effective biological control method has been developed for mice. However, grain growers still cannot make economically rational decisions to implement control because they do not know the pest threshold density (D_T) above which the economic benefits of control exceed the economic costs of control. Applied predator-prey theory suggests that understanding the relationship between mouse density and damage is the basis for determining D_T. Understanding this relationship is the first research priority for managing mouse damage. The other research priority is to develop a reliable method to estimate unbiased mouse density.     

Comparison of population estimators and indices for monitoring house mice in sorghum crops

House mice (Mus musculus domesticus Schwarz & Schwarz, 1943) are monitored in Australia and China to track changes in mouse population densities and forecast their potential damage to cereal crops. The present study compared population indices based on the number of different mice caught and overall trap success from live-trapping with an oil card index (OC) and a tracking index (T) for monitoring mice in sorghum crops immediately before crop maturation. T was measured as the percentage of track board covered with mouse footprints night⁻¹, and OC as the percentage of card removed by mice night⁻¹. The reliability of these abundance indices was quantified by Pearson correlation coefficient with the trappable population size (Ñ), which was estimated by capture–recapture over eight consecutive nights on 175 × 5 trapping grids, in sorghum crops on two properties on the Darling Downs, Queensland. Because of differences among individual mice in capture probability, Model M_h of program MARK was used to account for such heterogeneity and to estimate the size of each mouse population. The number of individual animals caught was more strongly correlated with Ñ than trap success and, therefore, might be a more reliable index; the data suggest that three trapping occasions provide optimal precision for this index. T correlated significantly with Ñ only at sites where the canopy of sorghum plants was closed, and its use should, therefore, be restricted to this habitat. OC did not correlate with Ñ because none or very little of the cards was eaten at low to moderate mouse densities. T and the number of animals caught over three trapping nights are recommended for monitoring mice in sorghum crops immediately prior to crop maturation.     

Impact of integrated management of nitrogen fertilizers on yield and nutritional quality of potato

Abstract

The aim of this study was to investigate the influence of different compositions of nitrogen (N) sources on yield and nutritional quality in potato cultivars (Solanum tuberosum L.). The experiment used a factorial arrangement as two factors in randomized complete block design. Factor (A) was nitrogen sources: control, 75% M?+?25%V, 50% M?+?50%V, 100% M, where M plots received nitrogen from mineral fertilizer and V plots received nitrogen from vermicompost. Factor (B) was potato cultivars (Sante and Savalan). In Sante cultivar, 75% M?+?25%V produced the highest total and marketable yield. In Savalan, cultivar application of vermicompost in 75% M?+?25%V and 50% M?+?50%V increased significantly total and marketable yield as compared with 100% M. Application of vermicompost significantly decreases tuber nitrate content and increases nitrogen-use efficiency. In Savalan, cultivar 50% V?+?50%M and in Sante cultivar 75% V?+?25%M can effectively be used for improving yield and nutritional quality of tuber.     

Development and characterization of MWNTs/Chitosan biocomposite fiber

The Preparation of conductive biocomposite fiber through Carbon nanotubes (CNTs) incorporation into biopolymer matrixes has stimulated much interest for bio-implant applications. The present study focuses on development and characterization of biocomposite fiber composed of chitosan (CHT) as a biopolymer and multiwall carbon nanotubes (MWNTs) as a conductive filler. In term of processing, the most important challenge is to prepare a highly stable dispersion of MWNTs in biopolymer matrix. The hydrodynamic diameter distribution of CNTs in acetic acid solution acquired by dynamic light scattering (DLS).Results demonstrate the supreme stability of CNTs dispersion which is extremely essential for homogenous distribution of CNT in polymeric matrix. Rheological properties of the spinning solution have also been investigated to adjust the viscosity for fiber processing step. A range of viscosity between 2000–8000 cP, has been recorded in different CNT loading. The scanning electron microscopy (SEM) images of the surface and cross sectional area of the fibers reveal the formation of nano-pores after MWNT addition. The tensile strength show a maximum increase of about 33.65 % compared to bare CHT. Also, the measurement of four probe electrical conductivity for different MWNTs loading shows a maximum conductivity of 0.107 S/cm at percolation threshold of 2.89 wt%.     

Genotypic Variation for Water-Deficit Tolerance in Cotton (Gossypiumhirsutum L.) Germination in Southern Iran

To determine the effect of water deficit on growth characteristics of 27 cotton cultivars (Gossypiumhirsutum L.), two separate experiments were performed in laboratory and glasshouse in Fars Province, Zarin-Dasht city (28° 36′ N, 54° 41′ E) in August 2015. In both experiments, which last for 10 days, a completely randomized block design with three replications was used. The main factor was water-deficit levels ((0, ?4, and ?12 MPa in laboratory and (0 and ?8 MPa) in glasshouse experiments), and the subsidiary factor was different cotton cultivars. The sensitivity to water deficit was compared based on factors such as germination rate, shoot and root lengths, fresh and dry weights, seed energy, and seed vigor. The results of both experiments indicated that Oltan, Opal, Pak, Armaghan, Super-Elit Golestan, Super-Elit Bakhteghan, SB-35, Super-Elit Arian, Khandagh, Tabela-18, and Sahel cultivars are more resistant and therefore are suitable candidates to increase plant density and uniformity in the farm.     

Detection and frequency of Stx2 gene in Escherichia coli O157 and O157:H7 strains isolated from sheep carcasses in Shiraz-Iran

Enterohaemorrhagic Escherichia coli constitute a subset of serotypes (E. coli O157 and some other serogroups) of Shiga toxin-producing E. coli firmly associated with severe human illnesses like bloody diarrhoea and haemolytic uraemic syndrome. Escherichia coli O157:H7 is a zoonotic pathogen. They rarely cause disease in animals, live in the intestines of healthy sheep and ruminants are recognized as their main natural reservoir, so they can contaminate meat during slaughtering practices. The purpose of this study was epidemiological survey on the occurrence of E. coli O157:H7 in healthy sheep in Shiraz-Iran. Polymerase Chain Reaction (PCR) assay was developed to detect the Stx2 gene the only bacterial factor that has been associated with more severe disease. During a period of 7 months (December 2005 to June 2006), 153 slaughtered sheep at Shiraz slaughterhouse, were randomly selected and examined for surface carriage of E. coli O157:H7 by conventional plating and Stx2 gene detection by PCR technique. E. coli O157:H7 was found in 6(3.92%) of 153 sheep. The bacteria were isolated from 5(3.34%) of 114 and 1(2.63%) of 38 sheep two or under two and more than 2 years old, respectively (p = 0.5). The contamination rate might vary depending on season, age and infection time. The higher frequency for younger animals may be due to differences in the composition of the gastrointestinal flora resulting from differences in diet. This is the first report of the presence of E. coli O157:H7 in sheep from Iran.     

Hijacking tobacco hairy roots and leaves in order to produce IpaD antigen by means of different signal peptides

IpaA, IpaB, IpaC, and IpaD are Shigella dysenteriae Ipa operon genes which collectively contribute in invasion to the epithelial cells of the human gut. Among them, IpaD has been demonstrated to play the most crucial role in shigellosis. Noteworthy, due to the more efficient, cost-effective and no need for advanced equipment in comparison with traditional systems, plant-based expression systems are considered as a novel strategy for production of recombinant proteins. As an aim of this research, attempts were carried out to examine and compare IpaD antigen production in three different plant-based platforms, including transgenic tobacco hairy roots and leaves as well as a transient based expression. Furthermore, different signal peptides (i.e. Zera® and Extensin) were also employed in order to improve the production level. Based on TAS-ELISA result, the highest yield of IpaD acquired by ER-derived protein bodies (Zera® ) which was more than 1.29-fold higher as compared with apoplastic space based on TSP% in both transgenic tobacco hairy roots and leaves. Furthermore, transgenic tobacco hairy roots were more abundant than transgenic leaves averaging 0.52 ng of IpaD per μg TSP and with a maximum of 0.94 ng IpaD per μg TSP in the best-performing construct of pBI-ZeCIpaD. Totally, the results of quantitative RT-PCR and TAS-ELISA indicated that the best time point for the production of IpaD using agroinfiltration was 72 h post infiltration and during 72 to 96 hpi, expression levels descended rapidly. To the best of our knowledge, this is the first report representing and combining the potential effects of signal peptides and plant-based expression platforms on stably production of IpaD antigen in transgenic tobacco leaves and hairy roots.     

Evaluation of the influence of irrigation methods and water quality on sugar beet yield and water use efficiency

Rapid urbanization and industrialization have increased the pressure on limited existing fresh water to meet the growing needs for food production. Two immediate responses to this challenge are the efficient use of irrigation technology and the use of alternative sources of water. Drip irrigation methods may play an important role in efficient use of water but there is still limited information on their use on sugar beet crops in arid countries such as Iran. An experiment was conducted to evaluate the effects of irrigation method and water quality on sugar beet yield, percentage of sugar content and irrigation water use efficiency (IWUE). The irrigation methods investigated were subsurface drip, surface drip and furrow irrigation. The two waters used were treated municipal effluent (EC = 1.52 dS m⁻¹) and fresh water (EC = 0.509 dS m⁻¹). The experiments used a split plot design and were undertaken over two consecutive growing seasons in Southern Iran. Statistical testing indicated that the irrigation method and water quality had a significant effect (at the 1% level) on sugar beet root yield, sugar yield, and IWUE. The highest root yield (79.7 Mg ha⁻¹) was obtained using surface drip irrigation and effluent and the lowest root yield (41.4 Mg ha⁻¹) was obtained using furrow irrigation and fresh water. The highest IWUE in root yield production (9 kg m⁻³) was obtained using surface drip irrigation with effluent and the lowest value (3.8 kg m⁻³) was obtained using furrow irrigation with fresh water. The highest IWUE of 1.26 kg m⁻³ for sugar was obtained using surface drip irrigation. The corresponding efficiency using effluent was 1.14 kg m⁻³. Irrigation with effluent led to an increase in the net sugar yield due to an increase in the sugar beet root yield. However, there was a slight reduction in the percentage sugar content in the plants. This study also showed that soil water and root depth monitoring can be used in irrigation scheduling to avoid water stress. Such monitoring techniques can also save considerable volumes of irrigation water and can increase yield.