Effect of weed interference on Zea mays: Growth analysis

In order to investigate the effect of weed competition on corn, growth trials were conducted in Shushtar, Iran, using a comparative growth analysis. In this study, two sets of treatments were imposed, based on the phenological stages of corn development, using a randomized complete block design with three replicates. The results showed that barnyardgrass and redroot pigweed were the most dominant weeds in these trials. Increasing the duration of weed interference reduced the corn leaf area index gradually. The reduction in the corn leaf area index led to a decline in the crop growth rate as a result of a reduction in the ability of corn to capture light and its photosynthetic ability. The total dry matter and relative growth rate of corn were decreased when the weeds were removed later as a result of a reduction in the leaf area index. According to these results, the leaf area index has a critical role in weed–crop competition.     

Soil microbial biomass, activity and community composition in adjacent native and plantation forests of subtropical Australia

Purpose

Soil nitrogen (N) availability is a critical determinant of plantation productivity in subtropical Australia and is influenced by the soil microbial community. The size, structure and function of the soil microbial community can be impacted by land-use change and residue management. The objectives of this study were to examine the impact of land-use change from (1) native forest (NF) to first rotation (1R) hoop pine plantation and (2) 1R hoop pine plantation to second rotation (2R) hoop pine plantation on the soil microbial community. The impact of residue management on the soil microbial community was also investigated in the 2R forest, where soil microbial parameters were measured in tree rows (2R-T) and windrows (2R-W). In addition, relationships between soil microbial parameters and soil N parameters were investigated.

Materials and methods

Each of the four treatments (NF, 1R, 2R-T and 2R-W) had five 24-m² replicate plots from which 15 soil cores were collected and bulked at three depths (0–10, 10–20, 20–30 cm). Microbial biomass carbon (MBC) and N (MBN) and soil respiration were measured on field moist soils. In addition, carbon (C) source utilisation patterns were assessed using the whole soil MicroResp? technique (Campbell et al. 2003).

Results and discussion

Results indicate that the land-use change from NF to 1R hoop pine plantation significantly reduced MBC, respiration rate, soil total C and total N. Furthermore, the land-use change appeared to have a significant impact on the soil microbial community composition measured using MicroResp? profiles. Land-use change from 1R to 2R hoop pine plantation resulted in a decline in total C and MBN and a shift in microbial community composition. When compared to the 2R-T soils, the 2R-W soils tended to have a greater microbial biomass and respiration rate. Residue management also influenced the microbial community composition measured in the MicroResp? profiles.

Conclusions

Results indicate that land-use change had a significant impact on the soil microbial community, which was likely to be related to shifts in the quality and quantity of organic inputs associated with the change in land use. This may have significant implications for the long-term productivity of the soil resource. Further studies are required to confirm a difference in microbial community composition associated with residue management. In addition, long-term experiments in subtropical Australia are necessary to verify the results of this snapshot study and to improve our understanding of the impact of single-species plantation forestry and residue management on the soil microbial community, soil N dynamics and ultimately the long-term sustainability of the soil resource.     

High performance fibers production process using Taguchi experimental design

In this research, results of an experimental interaction effect of operating parameters on tensile strength carbon fibers from a commercial PAN-based precursor are investigated. Ten parameters at two and four levels (L₃₂=2¹×4⁹) were investigated: stabilization temperature at first stage (STFIS), stabilization duration time at first stage (SDTFIS), stabilization temperature at second stage (STSS), stabilization duration time at second stage (SDTSS), stabilization temperature at third stage (STTS), stabilization duration time at third stage (SDTTS), stabilization temperature at fourth stage (STFOS), stabilization duration time at fourth stage (SDTFOS), carbonization temperature (CT), and carbonization duration time (CDT). In this study, Taguchi method was used initially to plan a minimum number of experiments. Statistical analysis, analysis of variance (ANOVA), was also employed to determine the relationship between experimental conditions and yield levels. ANOVA was applied to calculate sum of square, variance, ratio of factor variance to error variance and contribution percentage of each factor on response. The results show that increasing all of parameters improves tensile strength performance. The optimum levels of influential factors, determined for tensile strength are STFIS 200 °C, SDTFIS 120 min, STSS 225 °C, SDTSS 120 min, STTS 240 °C, SDTTS 120 min, STFOS 260 °C, SDTFOS 60 min, CT 1400 °C and CDT 10 min. The results showed that CT and ODTFIS are the most and the less effective factors on response, respectively.     

Optimization of an artificial neural network topology using coupled response surface methodology and genetic algorithm for fluidized bed drying

In this study, an integrated response surface methodology (RSM) and genetic algorithm (GA) are recommended for developing artificial neural networks (ANNs) with great chances to be an optimal one. A multi-layer feed forward (MLFF) ANN was applied to correlate the outputs (energy and exergy) to the four exogenous inputs (drying time, drying air temperature, carrot cubes size, and bed depth). The RSM was used to build the relationship between the input parameters and output responses, and used as the fitness function to measure the fitness value of the GA approach. In the relationship building, five variables were used (number of neurons, momentum coefficient and step size in the hidden layer, number of epochs and number of training times). A polynomial model was developed from training results to mean square error (MSE) of 50 developed ANNs to generate 3D response surfaces and contour plots. Finally, GA was applied to find the optimal topology of ANN. The ANN topology had minimum MSE when the number of neurons in the hidden layer, momentum coefficient, step size, number of training epochs and training times were 28, 0.66, 0.35, 2877 and 3, respectively. The energy and exergy of carrot cubes during fluidized bed drying were predicted with R² values of greater than 0.97 using optimal ANN topology.     

Identifying Soil and Plant Nutrition Factors Affecting Yield in Irrigated Mature Pistachio Orchards

The main objective of this study was to evaluate the potential use of a hybrid Genetic Algorithm-Artificial Neural Network (GA–ANN) method for predicting pistachio yield and for identifying the determinant factors affecting pistachio yield in Rafsanjan region, Iran. A total of 142 pistachio orchards were selected randomly and soil samples were taken at three depths. Besides, water samples and leaves from branches without fruit were taken in each sampling point. Management information and pistachio yields were achieved by completing a questionnaire. Primarily, 58 variables affecting pistachio yield were measured, and then 26 out of them were selected by minimizing mean square error (MSE) using a feature selection (FS) method. The results showed that the accuracy of the method was acceptable. Furthermore, the sensitivity analysis showed that the main determinant features affecting the pistachio yield were the irrigation water amount, leaf phosphorus, soil soluble magnesium, electrical conductivity (EC), and leaf nitrogen.     

Iron and/or acid foliar spray versus soil application of Fe-EDDHA for prevention of iron deficiency in Valencia orange grown on a calcareous soil

A two-year experiment was conducted in an iron(Fe)-deficient orchard with calcareous soil to find out an alternate method for soil application of Fe ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid) (Fe-EDDHA) in orange trees. Foliar sprays of Fe-EDDHA (5 g l^?1, pH = 7.8), sulfuric acid (pH = 3), citric acid (5 g l^?1, pH = 2.4), Fe (II) sulfate solutions (250, 500, and 750 mg Fe l^?1) with their initial pH (6.5, 6.35, and 6.12) and reduced ones to pH of 3 were compared with soil applied (75 g tree^?1) Fe-EDDHA and a control test. Although optimum chlorophyll content, leaf Fe concentration, fruit quantitative and qualitative attributes were resulted from soil application of Fe-EDDHA, repeated sprays of Fe-EDDHA or acidified Fe solutions created suitable results. Acidification of Fe solutions made them more effective in alleviation of leaf Fe concentration and Fe chlorosis, probably due to remobilization of inactive Fe within the plant and prevention of Fe oxidation and precipitation in foliar solutions.     

Effects of different levels of sanguinarine on antioxidant indices,immunological responses,ileal microbial counts and jejunal morphology of laying hens fed diets with different levels of crude protein

This study was carried out to assess the effects of different levels of sanguinarine on antioxidant indices, immunological responses, serum biochemical parameters, ileal microbial counts and jejunal morphology of laying hens fed on diets with different levels of crude protein (CP). A total of 180 laying hens were subjected into nine dietary treatments with four cages of five birds each. Experimental treatments consisted of three levels of CP (85.0, 92.5 and 100% of Hy‐Line W36 manual recommendation) and three levels of sanguinarine (0.00, 3.75 and 7.50 mg/kg) as a 3 × 3 factorial arrangement of laying hens which fed during a 70‐day feeding trial. The in vitro study showed that sanguinarine exhibited sevenfold and threefold decreased antioxidant activities to inhibit 2‐2‐diphenyl‐1‐picric hydrazyl free radical as well as ferric ion reducing rather than butylated hydroxyl toluene. Although using the decremental levels of CP caused the increase in heterophil‐to‐lymphocyte ratio (p < 0.01), dietary administration of sanguinarine could suppress the serum cholesterol and malondialdehyde concentrations as well as heterophil‐to‐lymphocyte ratio (p < 0.05). Additionally, decreasing CP content resulted in the decreased percentage of albumin (p < 0.05); however, it had no negative effects on humoral immunity. Nonetheless, feeding of at least 3.75 mg/kg sanguinarine led to the remarkable increases in serum gamma globulin concentration (p < 0.01) and secondary (p < 0.05) antibody titres against sheep red blood cells. Moreover, a decline in dietary CP content led to higher villi height and crypt depth (p < 0.05; p < 0.001) and consequently decreased villi height‐to‐crypt depth ratio (p < 0.001) than the optimum level (100% CP). In spite of the effects of sanguinarine on the suppression of Escherichia coli and Salmonella counts (p < 0.05), it markedly enhanced villi height‐to‐crypt depth ratio as well as lamina propria lymphatic follicles extent, simultaneously (p < 0.001). Therefore, in spite of the detrimental effects of feeding low‐CP diets on lymphocytes and serum albumin percentages, and villi height‐to‐crypt depth ratio, the administration of incremental levels of sanguinarine could improve cellular and humoral immunity, decrease ileal microbial counts and in turn improve the intestinal health indices in laying hens.     

Effects of physical form of starter and forage provision to young calves on blood metabolites,liver composition and intestinal morphology

This study evaluated the effects of physical form of starter feed and forage provision on the performance, blood metabolites, liver composition and intestinal morphology of dairy calves. Individually housed calves (n = 52; body weight = 41.5 ± 2.5 kg) were randomly allocated (n = 13 per treatment) to one of the following four treatments: (i) ground starter feed (GS; mean particle size = 0.72 mm in diameter), (ii) textured starter feed (TS; mean particle size = 3.61 mm in diameter, including steam‐flaked corn and barley), (iii) pelleted starter feed (PS; mean particle size = 4.53 mm in diameter) and (iv) ground starter feed with chopped alfalfa hay (GS + AH; mean particle size = 1.02 mm in diameter). The calves fed GS + AH diets had greater (p < 0.01) starter intake, final body weight and average daily gain compared with the other groups, while GS and TS groups both had greater (p < 0.01) starter intake than the PS group. Feed efficiency was found to be better (p < 0.05) in the TS group than in the GS or PS group, but not different from the GS + AH one. Compared with the other groups, the GS + AH group had the highest (p < 0.01), while the PS one had the lowest (p < 0.01) concentrations of blood glucose and triglyceride. The calves fed GS + AH had the highest blood concentrations of total protein, globulin, triiodothyronine (T3), thyroxin (T4), T3 : T4 ratio (p < 0.05) and levels of fat and glycogen in the liver (p < 0.01) compared with the other groups. The highest (p < 0.05) liver glycogen contents were observed in the GS + AH and TS groups. The duodenum, ileum and jejunum in the calves fed GS + AH exhibited a greater muscle layer thickness (p < 0.05) compared with the other groups. Based on the results obtained, the addition of dietary forage to starter diets positively influenced performance, liver composition and intestinal morphology in developing calves.     

The Use of Coal Gangue as a Cultivation Bed Conditioner in Forage Maize Inoculated with Arbuscular Mycorrhizal Fungi

A greenhouse pot experiment was conducted to investigate the effect of application of coal gangue (CG) at different rates (0, 5, 10, 20, and 50%) and inoculation with two arbuscular mycorrhizal (AM) fungi Glomus intraradices and Glomus mosseae, as mediating plant adaptation to soil amended with CG, on the nutrient content of forage maize. The results showed CG amendment at all levels and both AM fungi significantly improved the nutrient content of the plant as compared to control. In general, the highest shoot dry weight and nutrient phosphorus, iron, and zinc (P, Fe, and Zn) were obtained with 10% CG and G. intraradice treatments, which were 49.68, 30.49, 16.72, and 75.71% higher than those of the control plants, respectively. Therefore, 10% dose of CG may be considered as a suitable dose for amendment in the corn cultivation bed in terms of providing nutrient contents for this plant as well as AM fungi root colonization.     

Synthesis of highly intercalated urea-clay nanocomposite via domestic montmorillonite as eco-friendly slow-release fertilizer

The present study describes the preparation and characterization of montmorillonite-urea nanocomposites (Mt-Ur) using aqueous suspension technique at various stirring times and different ratio of montmorillonite to urea (Mt/Ur) via an impure and domestic montmorillonite (Mt), without the application of any chemical reagents and high-energy-demand process (environmentally friendly). The intercalation of urea into Mt interlayer was clearly demonstrated by a significant expansion of d₀₀₁ spacing (interlayer space of Mt) from 1.23 to 1.71 nm which has not yet been reported by aqueous suspension technique. Analyses performed by Fourier transform-infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA) and X-ray diffraction (XRD) also confirmed the effectiveness of this simple process to intercalate the urea into clay lamella. The release pattern demonstrated that the nanocomposite had a slow-release behaviour for urea dissolution. The results also suggested that the Mt type applied in the current study, in a 1:20 Mt/Ur ratio and stirred for 1 h, possessed desirable ecological and economic efficiency in the production of slow-release urea fertilizer due to the application of the impure and domestic clay which is of very low-cost and eco-friendly. Nevertheless, urea was fully intercalated into the interlayer of clay by a simple technique and with a good slow-release behaviour.