JOURNAL OF AGRICULTURAL SCIENCE AND TECHNOLOGY (JAST)
Year:2013 | Volume:15 | Issue:5|Papers Count:19

The objective of this research was to study the drying characteristics of powdered agricultural residues. Drying experiments of wheat straw (Triticum aestivum) were conducted at four temperatures of 50, 60, 70, and 80oC by a thermogravimetric analyzer. Drying temperature had a significant effect on the moisture change and drying time. There was no constant drying rate period, but a short rising rate period was evident for all drying process due to increasing temperature of the sample at the beginning of drying. Six mathematical models were selected to describe the drying characteristics of wheat straw. The goodness of fit was evaluated by the coefficient of determination (R2), the reduced chi-square ( c2), and the root mean square error (RMSE). Midilli et al. model was found to be the best for modeling the experimental data. The values of effective moisture diffusivity of wheat straw dried at 50, 60, 70, and 80oC were calculated to be 1.13×10-8, 1.48×10-8, 1.66×10-8, and 2.29×10-8 m2 s-1, respectively.

One of the important bottle-necks in production of microalgae based biodiesel is the lack of an efficient method for harvesting of microalgae from the culture medium. In this study, the electroflocculation method was developed for harvesting of microalgae Dunaliella cells from culture medium. The effect of several parameters such as the current density, electrical conductivity of culture medium, time, electrode gap, and electrode type on harvesting efficiency and energy consumption were also determined. The maximum harvesting efficiency of this method was 97.44% at EC=1.35 S m-1 and current density of 90 A m-2 during 3 minutes electroflocculation process in a 300 ml beaker. The maximum efficiency was achieved by aluminum electrodes with 1 cm distance between electrodes and the maximum energy consumption for this practice was 0.621 kW h m-3. It was concluded that electroflocculation is an efficient and cost effective method for microalgae harvesting.

Individual grain weight of wheat kernels differs with their positions on a spike. Cultivation practices (such as fertilizer nitrogen and plant growth regulators application) can be used to improve weight of basal and distal kernels. For this purpose, two experiments based on randomized complete block design were carried out with three replications. The aim of this research was to study the mechanisms related to sink strength as well as the regulatory factors affecting sink activity. One cultivar of a facultative wheat, cv Yangmai15, was used. Treatments of the experiments included application of nitrogen (two levels) and plant growth regulators [abscisic acid (ABA) and Fluridone (inhibitor of ABA synthesis)] in basal and distal kernels, respectively. Results showed that nitrogen application increased grain yield and its components. Grain filling in basal kernels started earlier and its rate was higher than that of the distal kernels. Nitrogen fertilizer increased the individual kernel weight both in basal and distal kernels, and the rate of increment was higher than the control, even in distal kernels. The application of ABA resulted in increase in grain weight, whereas a considerable decrease in grain weight was observed in response to Fluridone compared to the control. Nitrogen application together with ABA application enhanced the activity of SuSase, AGPase, SSS, and SBE in basal and distal kernels and the increment in the activity was higher in distal kernels. It is concluded that simultaneous application of nitrogen and ABA enhanced grain weight by regulating the activity of key enzymes involved in starch synthesis.

A factorial pot experiment based on randomized complete blocks design with four replications was carried out in order to evaluate salt tolerance of four sugar beet cultivars including Madison (British origin) and three Iranian cultivars (7233-P12, 7233-P21 and 7233-P29) using carbon isotope discrimination (D). Plants were grown in sand culture medium in greenhouse conditions. Sugar beet cultivars were irrigated with saline water (tap water as control, 50, 150, 250 and 350 mM of NaCl and CaCl2 in 5: 1 molar ratio) from 4-leaf stage for 16 weeks. Carbon isotope discrimination significantly decreased with increasing salinity. Significant differences of D between shoot and root were observed in all cultivars and all levels of salinity. Madison cv. showed lower D in shoot and root than the other three cultivars at all levels of salinity except the control, but cv. 7233-P29 had significantly higher D values at saline conditions of 150 mM and above. Although the regression of D and Ci/Ca was positive, the slope of regression line was different from the pattern predicted by theory, indicating an underestimation of D in these samples. Relatively higher 13C (lower D) was found in root as compared with shoots.

Arginine (Arg) requirements of male broilers (Ross 308) reared at high altitude (2100 m above sea level) during the 1-to 3-week period was estimated in a graded supplementation method, in which six diets (230 g kg-1 CP and 3200 Kcal ME kg-1) with Arg increments of 1.25 g kg-1 were applied to four pens of fifteen birds each. Dietary Arg content of the experimental groups ranged from 10 g kg-1 (80% of the NRC recommendation) to 16.25 g kg-1 (130% of the NRC recommendation). Body weight gain, feed: gain ratio, and plasma nitric oxide (NO) concentration were determined as response criteria. Arginine requirements for maximal body weight gain and optimal feed: gain during the 21 days under study were estimated to be 15.3, and 15.1 g kg-1 of diet, respectively. The estimated Arg requirement based on the response in plasma NO was 15.6 g kg-1. In conclusion, broilers receiving dietary Arg of 15 g kg-1 had the best performance. Data obtained for the individual factors are by far the highest values reported for Arg requirements.

Effect of methanolic leaf extract of Moringa oleifera for the stabilization of butter oil with modified fatty acid profile at ambient temperature was investigated. Twelve Sahiwal cows of first and early lactation were randomly stratified into two groups in a completely randomized design and fatty acid profile of milk fat was modified by feeding 300 grams calcium salts of fatty acids (per cow per day) to one group (G-1) and the second group was not fed on calcium salts of fatty acids (G-2). Concentration of long chain fatty acids (C18:1 to C18:3) in milk of G-1 was increased from 30.33±0.174b to 35.36±0.14a% as compared to G-2. Milk fat of G-1 was turned into butter oil. Moringa oleifera leaf extract (MOLE) was incorporated into butter oil (from milk of G-1) at three different concentrations: T1= 400, T2= 600, and T3= 800 ppm. All these treatments were compared with a control, without any addition of MOLE. Peroxide value of T2 in Schaal oven test (after 90 days of storage) was 5.35±0.29b as compared to control 16.64±0.42a (meq /kg). panisidine value and induction time (after 90 days of storage at ambient temperature) of T2 and control were 12.45±0.63b, 28.67±1.36a (meq kg-1) and 10.84±0.28a and 3.95±0.14b hours, respectively. It was concluded that Moringa oleifera leaf extract at 600 ppm concentration may be used for the enhancement of oxidative stability of butter oil with modified fatty acid profile at ambient temperature.

The present study evaluated the effect of packaging (air, vacuum) with or without addition of sodium acetate (2% W/V) on shelf-life extension of rainbow trout (Oncorhynchus mykiss) under refrigeration, for a period of 18 days. Four different treatments were tested: CAP: control air pack; SAAP: sodium acetate treated aerobic packaging; VP: vacuum packaging in the absence of sodium acetate; and SAVP, sodium acetate under VP. Trimethylamine nitrogen (TMA-N), free fatty acids (FFA) and peroxide values (PV) of SAVP samples were lower compared to the other treatments during the entire refrigerated storage period. In the present study, the thiobarbituric acid (TBA) level showed fluctuations during storage indicating that TBA values may not reveal the actual rate of lipid oxidation. Total viable counts for fresh rainbow trout stored aerobically exceeded 7 log CFU g-1 after 10-11 days, while treatments SAAP and VP reached the same value on days 12 and 16, respectively. In contrast, SAVP samples did not reach this value throughout the 18-day. Psychrotrophic counts of SAVP samples were significantly (P< 0.05) lower compared to the control samples during storage period. As regards sensory evaluation, shelf-life of trout was longest for SAVP (15-16 days), followed by VP (12-13 days), SAAP (9-10 days), and CAP samples (6-7 days). The results indicated that the combined effect of vacuum packaging and sodium acetate on fish samples preserved their good quality characteristics and extended the shelf-life of the treated samples during refrigerated storage, as supported by the results of microbiological, chemical, and sensory evaluation analyses.

Sour cherry and orange juice were successfully cryoconcentrated. Novel clarification (Electro-Flotation and Ultra-Filtration) improved cryconcentration efficiency. EF-UF clarified sour cherry and orange juices were cryoconcentrated in three stages up to 34.52±0.14, 44.42±0.19, 52.44±0.13 and 28.43±0.16, 40.51±0.15, and 45.42±0.19o Brix at-10oC respectively. Duncan's multiple range test was used to compare mean values of various parameters. At similar total soluble solid, cryoconcentrated samples showed significantly (P<0.05) higher retention of aroma number, ascorbic acid, and TAA compared to those thermally concentrated. Thermal concentration induced formation of hydroxymethylfurfural more than cryoconcentration process used for concentration of orange juice.

An experiment was conducted to evaluate the effects of some technological processes on the residual levels of imidacloprid in strawberry fruits and products. According to their half-life (t1/2) values, strawberry fruits can be safely harvested for human consumption 7.4 days after spraying. The removal ratio of imidacloprid residue in strawberries was in the range of 9.9–30.55% by washing with tap water. The average amount of imidacloprid residue in strawberry fruits, juice, and syrup under cold and hot break greatly decreased compared with those in unwashed strawberry fruits. Moreover, the residue of pesticide decreased more in strawberries syrup under hot break than cold break. Imidacloprid residue was concentrated into jam and increased to higher levels than strawberry juice and syrup under cold and hot break. A change in physical and chemical properties of strawberry fruits and products was related mainly to the processing operations.

Flow characteristics and rheological parameters of “Malas Yazdi” pomegranate (Punica granatum L.) juice were investigated using rotational viscometer at different temperatures (10, 20, 30, 40, 50, 60 and 70oC) and concentrations (12, 22, 32, 42 and 52o Brix). The experimental data had the best fitness with Herschel-Bulkley model and the values of flow behavior index (n) varied between 0.97 and 1.45 at all temperatures and concentrations, revealing the shear thickening nature of pomegranate juice. The activation energy of flow (Ea) calculated with respect to apparent viscosity at 40 rpm increased from 9.07 to 24.05 kJ mol-1 as the juice concentration increased from 12 to 52o Brix. Power equation indicated that consistency coefficient increased non-linearly with concentration increase. A mathematical model was developed to describe the influence of temperature and soluble solids on the consistency coefficient of pomegranate juice for the studied conditions.

This study pursued the molecular identification of fish species from processed products for human consumption which, a priori, belonged to nine species. DNA barcoding using direct sequencing of about 650 bp of the mitochondrial gene cytochrome oxidase subunit I (COI) revealed incorrect labeling in the three Alaska Pollack samples (11% of all samples). Substitution of fish species constitutes serious economic fraud, and our results increase concern regarding the trading of processed fish products in Iran from both health and conservation points of view.

Forest canopy rainfall interception loss (I), canopy water storage (S), and the ratio of mean evaporation to mean rainfall intensity ( E-/R-) are important components of the water balance in arid and semi-arid climate zones. The goal of this project was to quantify I and S and to evaluate the Gash interception model for rainfall interception in a mature semi-arid Pinus eldarica Medw afforestation planted in the Chitgar Forest Park near Tehran city, Iran. Measurements of gross precipitation (PG) and throughfall (TF) were recorded on an event basis from September 2009 to April 2010. For the measurement period, PG totaled 164.8 mm and I totaled 61.2 mm. I was calculated as the difference between PG and TF. On the event scale, the ratio of I:PG ranged between 0.195 and 1, and averaged 0.614. There was a strong logarithmic correlation between I: PG and PG (R2=0.861; P value£0.01). As the size of rainfall events increased, I:PG decreased. The mean method estimated S to be 1.8 mm. The Gash model accurately estimated I to be within 1.1 mm of the total measured value. The results demonstrate that intercepted rainfall represents a considerable portion of PG in P.eldarica afforested regions of the semi-arid climate zone of Iran where soil moisture is a limiting factor for plant growth and productivity.

Using HPLC, the seasonal changes in the phenolic compound content of the leaves of the Gemlik olive cultivar (Olea europaea L) has been investigated with respect to the effects on the alternate bearing of the cultivar. For this purpose, the leaf concentrations of oleuropein, chlorogenic acid, caffeic acid, 3-hydroxycinnamic acid, scopolin and pcoumaric acid were analyzed at 10 day intervals around the years. The quantity and distribution of these phenolics in the leaves showed significant differences in 2008 (off year) and 2009 (on year). In the “on” year, the levels of chlorogenic and p-coumaric acids were high, whereas the abundance of other phenolic compounds was low. In contrast, during the “off” year, the chlorogenic and p-coumaric acid levels were at low levels, whereas the levels of the other phenolics were high. We found a negative relationship between the chlorogenic acid and caffeic acid concentrations in the “on” and “off” years: the amount of caffeic acid in the leaves was high, and the chlorogenic acid level was low. The contents of chlorogenic acid, caffeic acid, 3-hydroxycinnamic acid and p-coumaric acid were significantly different in the “on” and “off” years. These findings indicated that these compounds and the other phenolics examined in this study were related to alternate bearing. Interestingly, the levels of all of the phenolic compounds examined in this study were at their highest during the dormant season.

Molecular characterization of 19 Jatropha accessions that included 15 accessions of J.curcas and 4 different species was carried out using 3 different markers systems. Highest polymorphism (96.67%) was recorded by RAPD followed by DAMD (91.02%) and ISSR (90%). Polymorphism Information Content (PIC) was higher for DAMD (0.873) and almost equal for RAPD (0.863) and ISSR (0.862) markers, whereas Resolving Power (Rp) was found to be higher for RAPD as compared to the other two marker systems. Marker Index (MI) values varied greatly with highest (19.07) in RAPD. Shannon index (i), observed number of alleles (na), effective number of alleles (ne) and Nei’s genetic diversity (h) values were found to be significantly higher for ISSR as compared to RAPD and DAMD markers. Thus, all the markers proved to be equally efficient for diversity studies in Jatropha. Several alleles in all the markers indicated J. gossypiifolia as one of the parents of J. tanjorensis. Dendrograms and PCA plots generated based on RAPD showed three major clusters with J. integerrima and J. podagrica falling in group I, fifteen J. curcas accessions in group II, and J. gossypiifolia as an outlier in group III. DAMD markers also showed similar clustering pattern whereas ISSR showed last cluster of J. gossypiifolia and J. tanjorensis. These results may provide a future base for conservation and characterization of available Jatropha genetic resources.

The major objective of seedless grape breeding program is production of grapes with high quality. Breeding of seedless grapes is difficult because the embryos are aborted after fertilization. Embryo rescue technique is utilized to obtain plants from crosses between seedless cultivars. In the present study, the effect of paternal genotypes and different IAA concentrations in presence of BA applications were investigated on embryo rescue in Askari cultivar in randomized complete block design with three replications. Sprays with BA were performed two times at 18 E-L and 27 E-L stages. Hybrid embryos were produced from the cross between Askari cultivar as a female parent and Ruby Seedless, Bidane Sefid, and Bidane Ghermez as male parents. Forty days after pollination (at 29 E-L stage), ovules were cultured on NN medium with three different concentrations of IAA (1, 1.75, 3 mg L-1). The results showed that male genotypes and different concentrations of IAA on the media had a significant effect on embryo germination. BA treatment did not affect the embryo germination solely. But, the effect of BA and different concentrations of IAA was significant on embryo germination. The best concentration of IAA with BA treatment was 1 mg L-1 and without BA was 3 mg L-1. The highest embryo germination rate was observed in 'Askari×Ruby Seedless' cross that was pretreated with BA and cultured on medium with 1 mg L-1 IAA concentration.

Transgene integration and expression in host plant is quite unpredictable and is considered as the major problem in plant transformation. The variation in transgene copy number in transgenic plants influences the expression level and is one of such complication. In many plant species, the analysis of transgenic plants has shown that independent transgenic plants have one to many copies of transgenes. This study focused on molecular characterization of difference in copy number of transgenes and its impact on expression level on mRNA basis. Four advanced transgenic lines of phytochrome B were analyzed for the integration of the gene. These transgenic lines were taken out on the basis of difference in copy number as determined by Southern blot analysis and Fluorescence in situ hybridization (FISH) for transgene expression. Results taken by both real time PCR and Northern blot analysis determined high expression in Line QCC11 having two copies of transgenes in homozygous condition while the least expression was seen in lines QCC10 showing three copy number in heterozygous condition as multiple copies can be incorporated from one to few insertion sites.

The nitrogen (N) nutrition, crop yield, and responses of wheat to arbuscular mycorrhizal fungi (AMF) were tested in an experimental field under free-air ozone concentration [O3] enrichment (FACE) conditions. The experiment included three treatments: ambient [O3] (Ambient), elevated [O3] (FACE, targeted at ambient [O3]×1.5), and elevated [O3] inoculated with an AMF consortium consisting of several Glomus species (FACE+AMF). AMF inoculation responsiveness of wheat was estimated by comparing plants grown in unsterilized soil inoculated with the exogenous AMF and in untreated soil containing indigenous AMF. Compared with the Ambient, relatively higher N contents but lower shoot biomasses of wheat plants were observed in the FACE treatment without AMF inoculation from the tillering stage in February and heading stage in April, respectively, which significantly (P<0.05) decreased grain yield by 28% at harvest in June. Under the FACE condition, compared with the non-inoculated treatment, AMF inoculation significantly (P<0.05) increased root colonization rates both at the tillering stage and heading stage, and also significantly (P<0.05) increased shoot biomass at the heading stage and, hence, significantly (P<0.05) increased grain yield by 40% at harvest. However, AMF inoculation significantly (P<0.05) decreased total N content in wheat shoots at the tillering stage, suggesting that AMF consortia may enhance plant tolerance to elevated [O3] by elevating root colonization rate rather than plant total N content at early growing stages.

This study investigated the relationship between clay minerals and different soil moisture regimes in gypsiferous soils of Fars Province in southern Iran. The overall climate of the Province is arid and semi-arid and, under this condition, parent material is the most important factor affecting clay minerals distribution. Beside this factor, climate conditions have determining role too. Palygorskite, smectite, chlorite, illite, and kaolinite were identified as the main clay minerals in gypsiferous soils, using XRD, TEM and SEM analyses. Chlorite and illite were inherited largely from parent rocks and their abundance in soils with different moisture regimes was generally uniform. The presence of gypsum and saline and alkaline ground water in some pedons has favoured the neoformation of palygorskite from soil solution. Palygorskite shows an increasing trend with depth that may be related to its authigenic formation in the presence of gypsum. The correlation between palygorskite percentage and gypsum content was estimated (R2=0.56). The highest amount of palygorskite was observed in soils with aridic moisture regimes, and its lowest amount was estimated in soils with xeric moisture regimes. Notably, with increasing moisture, the length of palygorskite fibber decreased. High soil moisture and rainfall and low evaporation are reasons for instability of palygorskite relative to smectite in xeric moisture regime. Large amounts of well-bundled and elongated palygorskite in soils of piedmont plain are related to their authigenic formation; while presence of slight amounts of short palygorskite fibres in lowlands suggest their transformation to smectite. Results of soil and rock samples analyses showed that some palygorskite in all moisture regimes originated from parent materials. Also, results indicated that the smectite/(illite+chlorite) ratio increased with increase in moisture and the largest value (equal to 2.12) was observed in soils with xeric moisture regime.

The purpose of this study was to look for carbon materials for composting with rabbit manure. Rabbit manure was composted with rice straw and mushroom residues. During the composting process, different related parameters were evaluated. Results showed that the rabbit manure could be normally co-composted with rice straw or with mushroom residues. The GI value showed that both composts could help seed growth. By comparing the effects of the two composts, the rabbit manure co-composted with rice straw had a much greater effect on improving seed growth. The results showed that co-composting rabbit manure with rice straw and mushroom residues was a much more efficient method to utilize the material. Rabbit manure mixed with rice straw has also been shown to compost much more efficiently than with mushroom residues.