Journal of Agricultural Science and Technology
Volume:16 Issue: 6, Nov 2014

The parasitoid Trichogramma brassicae Bezdenko is used for inundative releases in biological control programs against lepidopteran pests in agro-ecosystems. Age-specific functional responses of T. brassicae to different egg densities (5, 10, 20, 30, 40, 60, and 80) of sterilized eggs of Ephestia kuehniella at 23±1°C, 60±5% RH, and 16:8 h (L:D photoperiod) were studied. E. kuehniella densities were separately presented to a single mated female of T. brassicae (1-day-old). The egg densities were replaced every day until the parasitoid died and each density was replicated 20 times. A type III functional response was obtained for the one-day-old females and a type II for two- to nine-day-old ones. Results show that parasitoid age influences searching efficiency and handling time. Searching efficiency (a´) varied as adult parasitoids aged. In contrast, handling time increased with age. The lowest and highest values were obtained in days 1 and 9 of the parasitoid''s life, respectively. The maximum rate of parasitism (T/Th) decreased significantly with an increase in parasitoid age. It was concluded that T. brassicae females were most efficient at early ages of their life and might be capable of efficiently suppressing lepidopteran pest populations.

The beet armyworm (Spodoptera exigua Hübner) is an important pest of many agricultural crops all over the world. Most of the sugar beet growing regions in Iran are infested. In this study, the acute lethal effects of Pyriproxyfen, Spinosad, and Indoxacarb as well as sublethal effects of Pyriproxyfen on the 1st instar S. exigua were assessed by leaf dip bioassay method. Mortality was recorded 48 hours after treatment. LC50 and LC90 values for Spinosad were 0.096 and 0.252 mg ai l-1, respectively, and for Indoxacarb, they were 2.510 and 38.828 mg ai l-1, respectively. The LC50 value for Spinosad was 26 times lower than that of Indoxacarb. Preliminary experiments revealed that Pyriproxyfen did not cause acutely lethal effects on the beet armyworm larvae even following exposure at recommended doses. Pyriproxyfen, however, did show considerable delayed effects against this pest. Significant differences in biological, reproductive, and population growth parameters were found in Pyriproxyfen treated insects in comparison with the control insects. Population growth parameters including net reproduction rate (R0), gross reproduction rate (GRR), intrinsic rate of population increase (rm), and finite rate of population increase (λ) were reduced by 14.7-, 6.63-, 2.33-, and 1.09-fold, respectively, following Pyriproxyfen exposure. Additionally, mean generation time (T) and doubling time (DT) of the population were increased by 1.12- and 2.3-fold, respectively.

Application of chemical pesticides has increased significantly worldwide and has raised serious concerns about environmental pollutions. One of the encouraging trends to minimize pesticide risk is production of resistant plants containing toxic proteins against insect pests. Considering the importance of purification and characterization of digestive enzymes in the production of resistant plants, in this study an α-glucosidase from the Naranga aenescens Moore''s midgut was purified by ammonium sulfate precipitation, ion exchange chromatography on DEAE-sepharose, and concentrating through ultrafiltration. The apparent molecular mass of the enzyme was 48 kDa determined by SDS-PAGE. The optimum pH and temperature of the enzyme were 6.0 and 45°C, respectively. The irreversible thermoinactivation of the enzyme showed that it was highly stable at 35ºC but moderately stable at 40 and 45ºC. Zn2+, Hg2+, Co2+ at 10 and 20 mM, and Ba+2only in 20 mM strongly inhibited the α-glucosidase activity. Ba2+ and Ca2+ only at 10 mM, EDTA and Hg22+ only at 20 mM and Mg2+ at 10 and 20 mM significantly increased the enzyme activity. The Km and Kcat values for the α-glucosidase were 0.54 mM and 3.62 min-1, respectively, when p-Nitrophenyl-α-D-glucopyranoside (pNαG) was used as a substrate.

To estimate population density of the cabbage aphid, Brevicoryne brassicae (L.), a stratified random sampling was conducted in two unsprayed canola fields in Isfahan (central Iran) during 2011-2012. Population density was determined for apterous, and alates, as well as the total population, at two plant growth phases (PGP1: From plant emergence to the end of rosette, and PGP2: From the beginning of stem elongation to ripening) on the whole plant as the sampling unit. Sources of variation in the sampling procedure were analyzed with a nested analysis of variance (NANOVA). In PGP2, aphid density in upper (10-15 cm upper part of stem) and lower (the rest of stem) parts were compared using Student’s t-test. Temporal changes in spatial pattern during the growth season were evaluated using 1/k (aggregation index) and Lloyd’s Patchiness Index. Results showed that differences among fields accounted for the majority of total variation observed in aphid densities and the aphids significantly preferred upper parts of canola plants. Among different indices used for analyzing spatial distribution of the aphid, Taylor’s Power Law (TPL) described well the relationship between variance and mean of the population. In both PGPs spatial patterns of apterous, alates, and total population were aggregated, random, and aggregated, respectively. Estimates of 1/k and changes in the value of patchiness index revealed that the aphid population was aggregated at the beginning of rosette stage and became more dispersed with time.

The extensive use of traditional irrigation systems has led to overexploitation of groundwater and overuse of surface water in theUrmia Lake Catchment (ULC) area ofIran. The purpose of this study was to model the adoption process of drip irrigation system (DIS) by apple orchardists (AOs) using the five stages of Roger’s model for Innovation Decision Process (IDP). Survey method of applying questionnaire and interview technique was used to collect data from 136 AOs. The results of the study indicated that, first, AOs’ knowledge level was “relatively low” and the majority of them were in the early stages of IDP. Secondly, applying an ordinal logistic regression, up to 36.3% of knowledge level variability, could be explained by variables consisting of: the contact level with extension agents, educational level, rural-urban commuting and information sources. Thirdly, using binary logistic regression, up to 74.1% of probability of adoption, could be explained by variables consisting of source of irrigation, knowledge scores, and orchard size. Fourthly, the main barriers for adoption were high costs, lack of license for semi deep wells, need to grow alfalfa, poor knowledge, and low surface area, respectively. Fifthly, about 0.5% of AOs had already implemented DIS. These findings were instrumental for localizing a model and developing the needed policy and institutional interventions falfa, poor knowledge, and low surface area, respectively. Fifthly, about 0.5% of AOs had already implemented DIS. These findings were instrumental for localizing a model and developing the needed policy and institutional interventions.

Since women hold a small share in Iranian agricultural extension administration, it is necessary to seriously facilitate women''s participation in development programs and improve the policy of job opportunities and educational equity. The purpose of this study was to identify the challenges of women''s career advancement in Iranian Agricultural Extension Organization (AEO). Survey study was applied as the methodology of research. The statistical sample consisted of 135 female agricultural field officers in AEO. Statistical sample was selected through stratified random sampling technique. A structured questionnaire was used as the research instrument. The face validity of the instrument was confirmed by a panel of specialists. Questionnaire reliability was estimated by calculating Cronbach''s Alpha (α= 0. 92). The results showed that: «giving key positions to men», «offering routine and simple tasks to women», «limited willingness of male colleagues toward women career advancement», «administrators’ weak belief in female experts'' competencies», and «limitation to visit villages» were recognized as the first five preventive variables by respondents. Also, based on factor analysis, attitudinal aspects, male-dominated organizational structure, time limitation, and adaptive factors were recognized. Under a collection of preventative challenges such as managerial discrimination, negative attitudes and norms regarding women’s role and abilities, severe conflict between work and family duties and personal willing, the female experts have low share in managerial positions in AEO. Therefore, the empowering plans must be focused on these areas.

Rapeseed is the most widely used oil crop in Europe and it is an ideal raw material for the production of biodiesel. Because of a high nutritional value and a relatively high omega-3 fatty acids content, rapeseed cake can be used in poultry nutrition for the enrichment of meat and eggs. Therefore, the aim of this study was to determine the possibility of using rapeseed cake in diets for turkeys for the purpose of enriching turkey meat with omega-3 fatty acids. In the study, 120 male day-old Nicholas 700 turkeys were used and randomly divided into 3 groups, each group with 4 replications (n= 10). The control groups of turkeys were fed on compound feed without rapeseed cake and the experimental groups were fed with 5 or 10% share of rapeseed cake in compound feed. Based on the results obtained, we can conclude that the share of rapeseed cake of 5 or 10% in the compound feed did not cause any adverse impact on the performance of turkeys. Also, we established that there was an increase of the amount of omega-3 fatty acids with increased share of rapeseed cake and there was a positive trend of a decrease of the ratio of omega-6/omega-3 polyunsaturated fatty acids. Positive financial effect of fattening can be expected, because rapeseed cake is a cheaper source of protein in comparison with the commonly used soybean meal. Therefore, rapeseed cake can be recommended in fattening of hybrid turkeys, with a share up to 10% in the compound feed.

Commercial utilization of black mouth croaker (Atrobucca nibe) is in progress in Iran. This study was carried out to assess the physicochemical and sensory evaluation of minced fish and surimi prepared from small size of A. nibe, which is not common for human consumption. The surimi proximate composition contains protein (14.77±0.506%), lipid (0.94±0.081%), ash (0.58±0.007%) contents and yield rate (36.56±0.732%) were significantly lower than the mince, while the moisture content was higher in the surimi (79.58±0.729%) as compared to the mince (78.49±0.687%) (P< 0.05). Total volatile bases and thiobarbituric acid values of black mouth croaker surimi were 4.76±0.594 mg N 100 g-1, and 0.40±0.018 mg malondialdehyde kg-1, which, respectively, were significantly lower than those found for the minced fish (P< 0.05). Minced fish delivered significantly lower water holding capacity and pH value than the surimi (P< 0.05). Higher whiteness index was obtained in the surimi (66.23±0.029%) compared to the mince (51.68±0.020%) (P< 0.05). Total lipids of surimi contained more polyunsaturated fatty acids (36.32±0.257 g 100 g-1 total lipids) than other fatty acids of the minced fish (P< 0.05). Fish fingers prepared from the surimi obtained a higher mean score of all attributes (8.71±0.366) than the minced fish (7.47±0.326) (P< 0.05). It was concluded that this white-fleshed fish species was an appropriate raw material for surimi production. Further trials are needed to evaluate the surimi gel characteristics.

Chitosan is a polysaccharide derived from chitin by N-deacetilation, which has the property of gel formation. The objective was to develop a chocolate milk beverage using modified (hydrogel) chitosan as a thickening agent, and to make a sensory and rheological evaluation of this beverage. In the sensory evaluation an acceptability and comparative test with 50 local consumers was carried out, with the developed beverage and samples from the Brazilian market, with the attributes overall acceptability and viscosity. The hybrid hedonic scale was used. The rheological evaluation was carried out with a rotational rheometer (Rheotest) with the H1 probe. A controlled rate test – ramp (0- 500, and 500-0 L s-1, 120 seconds, up and down), at 25ºC was used. There was no difference (P> 0.05) among the beverages in the overall acceptability. In spite of that, the developed beverage had a better score (7.12) in comparison with a market beverage (6.4). The beverages differed in viscosity (P< 0.05); the score of the developed beverage was 7.06 and the score of the market beverage was 5.87. The market beverage fitted to the Ostwald-de-Waele, Bingham, and Casson models, and the developed beverage fitted better to the Ostwald-de-Waele model. The consistence index (K) of the market beverage was 0.150 Pa sn, while that of the developed beverage was 1.590 Pa sn, showing a high difference in the consistence characteristic of the samples. The flow index (n) of the market beverage was 0.625 and that of the developed beverage was 0.435. All market beverages showed thixotropic behavior. The hydrogel chitosan was effective as a thickening agent and furnished a good acceptability of the beverage.

Guar gum and whey proteins concentrate (WPC-35) were used as functional additives to improve the functional characteristics (hardness and meltability) of the Na-caseinate-based imitation cheese. Also, the alterations in the composition, sensory acceptance, color, and texture caused by these ingredients were evaluated. Imitation cheeses were formulated with three levels each of WPC (0, 1.5, and 3%) and guar gum (0, 0.3 and 0.6%) w/w in cheese formulation. Cheeses with higher guar and lower WPC were softer and melted to a greater degree. Use of the two food additives at increasing levels reduced the amount of protein significantly (P< 0.05). Unlike guar, WPC increased pH values. Color of the cheese was affected positively by guar and negatively by WPC (P< 0.05). The overall acceptability of the cheese was not affected by the levels of WPC, but it did improve with increasing level of guar used in the formulation. Taking into consideration the adverse impact of WPC on color and meltability and slight adverse effect of guar on the hardness of imitation cheese, use of WPC at 1.5% and guar at 0.3% level in the formulation of imitation cheese is recommended.

The antifungal potential of essential oils of thyme (Thymus vulgaris L.), rosemary (Rosmarinus officinalis L.), and laurel (Laurus nobilis L.) was determined. To establish this antifungal potential, two molds related to feed spoilage, namely, Aspergillus flavus and Aspergillus parasiticus, were selected. The agar dilution method was employed for the determination of antifungal activities. The investigated essential oils exhibited inhibitory effects on both molds tested. Thyme oil showed the highest inhibition of mold growth, followed by rosemary and laurel. Thyme essential oil was a stronger inhibitor against A. parasiticus than against A. flavus.The finding of the present study suggests that thyme essential oil inhibits the growth of fungi attacking stored feed and strengthens the possibility of using it as the alternative to potassium sorbate as effective inhibitor of biodegrading and storage contaminating fungi.

The objective of this work was to study the responses of two baby lettuce (Lactuca sativa L.) cultivars, namely, green Paris Island and red Sanguine, to different NaCl concentrations (0, 5, 10, and 20 mM). The study was conducted in a floating system and plants were harvested at the stage of 5-6 leaves, outside leaf 6-10 cm in length (25 and 31 days after sowing for green and red lettuce, respectively). Photosynthetic parameters (photosynthesis rate, stomatal conductance, transpiration rate, and intercellular CO2 concentration) and yield (leaf fresh weight) as well as color [L* (lightness), C* (saturation), Hº (object’s color)], pigments (Chla, Chlb, total chlorophyll, carotenoids and anthocyanins) and quality indices (appearance, freshness, taste and texture) were determined. The results indicated that, in both cultivars, leaf fresh weight was reduced at 20 mM NaCl; the reduction depended on the limited water accessibility and photosynthetic rate was suppressed in high salt concentration through stomatal limitations aiming at the retention of water but resulting in restricted availability of CO2. Nevertheless, no limitations were observed in photosynthetic pigments and, thus, stomatal closure was the dominant factor limiting photosynthesis. On the other hand, salinity improved anthocyanin content and coloration in red lettuce and enhanced freshness in green lettuce.

Welsh onion (Allium fistulosum L.) is one of the important vegetable crops in China. However, the seeds of this crop are short-lived and their vitality tends to be easily lost in the course of storage. The present study was conducted to elucidate the effects of welsh onion seed priming with potassium nitrate (KNO3) on seed vigor and on other such related mechanisms during twelve months of storage. The priming treatment improved the germination rate and vigor index of welsh onion. Membrane deterioration of welsh onion seeds was significantly alleviated by the priming treatments, as assayed by using soluble sugar content and electrical conductivity of the seed leachates. The accumulation of hydrogen peroxide (H2O2) and malondialdehyde (MDA) in primed seeds was reduced compared with non-primed seeds. The increased activities of antioxidant enzymes, such as dehydrogenase, superoxide dismutase (SOD), and catalase (CAT) in primed seeds correlated with seed vigor and lipid peroxidation. This study provided the theoretical basis for improving the initial quality of welsh onion seeds using KNO3 priming.

Taxus chinensis var. mairei is a rare and endangered medicinal plant species distributed in China. In order to promote fast propagation and preserve the natural resources, conditions for in vitro germination and seedling development of embryos of T. chinensis var. mairei from Anhui or Zhejiang were investigated. Results showed that in vitro germination rate of excised embryos cultured under 14 hours photoperiod was higher than that in darkness. But, nearly all embryos germinated under 14 hours photoperiod failed to develop into seedlings. Comparatively, 23.3 and 36.3% of embryos from Anhui and Zhejiang, respectively, which germinated in darkness, developed into full seedlings. Addition of plant growth regulators [gibberellic acid(GA3), indole-3-acetic acid (IAA), 6-benzylaminopurine (BA)] and organic additives (casein hydrolysate and yeast extract) in mediums promoted germination and seedling development. (Woody plant medium) WPM medium supplemented with 0.5 mg L-1 GA3, 0.5 mg L-1 IAA, 0.5 mg L-1 BA and 1 g L-1 activated charcoal was optimal for the culture of embryos from Anhui, while WPM medium supplemented with 0.5 mg L-1 GA3, 500 mg L-1 casein hydrolysate and 1 g L-1 activated charcoal was optimum for embryos from Zhejiang. Moreover, the germination and seedling survival rate of embryos of T. chinensis var. mairei decreased with increasing maturity of the seeds. In conclusion, darkness during germination is necessary for subsequent seedling development and immature seeds are optimal for embryo culture of this species.

Fennel (Foeniculum vulgare Mill.) is an industrial medicinal plant with different pharmaceutical and food applications. In this study, the leaf essential oil composition of 12 Iranian accessions of fennel collected from different geographical regions was assessed. The essential oil yield of fennel leaves ranged from 0.65% (Varamin accession) to 2.03% (Tabriz accession). Trans-anethole, fenchone and limonene were highly abundant in all of the examined oils. Trans-anethole ranged from 41.19% in Shiravan to 56.6% in Shiraz accessions and had negative correlation with most of the constituents. According to the major compounds, two chemotypes were defined in which group 1 was considered as the high trans-anethole (> 50%) and group 2 was a high limonene group. The correlation of essential oil yield and trans-anethol with climatic conditions and some morphological characters were also assessed. Higher temperatures and essential oil yield had negative Pearson correlation (r= -0.371), while trans-anethol and high temperature showed positive correlation (r= 0.459) in fennel. Furthermore, the studied accessions had different flowering time and height. The early flowering and dwarf accessions had higher essential oil yield, while the late flowering ones had higher trans-anethol in their leaves.

Subsurface drainage systems are used to control the depth of the water table and to reduce or prevent soil salinity. Water flow in these systems is described by the Boussinesq Equation، and the Advection-Dispersion Equation coupled with the Boussinesq Equation is used to study the solute transport. The objective of this study was to propose a finite difference solution of the Advection-Dispersion Equation using a lineal radiation condition in the drains. The equations’ parameters were estimated from a methodology based on the granulometric curve and inverse problems. The algorithm needs the water flow values، which were calculated with the Boussinesq Equation، where a fractal radiation condition and variable drainable porosity were applied. To evaluate the solution descriptive capacity، a laboratory drainage experiment was used. In the experiment، the pH، temperature، and electric conductivity of drainage water were measured to find the salt’s concentration. The salts concentration evolution was reproduced using the finite difference solution of the Advection-Dispersion Equation، and the dispersivity parameter was found by inverse modelling. The numerical solution was used to simulate the leaching of saline soil. The result showed that this solution could be used as a new tool for the design of agricultural drainage systems، enabling the optimal development of crops according to their water needs and the degree of tolerance to salinity.

Exploitation of the full potential of any hybrid requires the possessing of genetically high-purity seeds. Commercial soybean hybrids have been developed using a cytoplasmic male sterility (CMS) system. In order to avoid reduction in yield caused by using low-purity seeds, development of a simple, rapid, and accurate method for hybrid purity assessment is of great essence and significance. Therefore, the parental lines of HybSoy 1 to 5 were screened using 160 Simple Sequence Repeat (SSR) makers, of which 8 markers exhibited polymorphism. A PCR-based assay with these markers detected both alleles of the parental lines in pure hybrids, proving their heterozygosity, whereas impurities were identified by the presence of only one parental allele. The confirmation of hybrid purity indicated that a single polymorphic marker was sufficient for detection of contaminations of these hybrids from their parents. It was also found that if a hybrid seed lot was contaminated by another hybrid or its parental lines, two or more appropriate markers could be used to easily detect such contamination. This method could accurately and effectively identify the hybrid purity in a predetermined sample of soybean hybrids constituted by deliberately mixing seeds of parental lines. This is the first report that demonstrates the utility of SSR markers for assessment of genetic purity of soybean hybrids.

Eight pollinators (as pollen parents) and four CMS lines (as seed parents) differing in salinity and drought tolerance were evaluated using agro-morphological traits and microsatellite markers. Root yield, leaf weight, sugar content, sodium content (Na+), potassium content (K+), a-amino nitrogen content, alkalinity coefficient, molasses sugar, white sugar content, extraction coefficient of sugar, dry matter, sugar yield, and white sugar yield were evaluated. The genetic diversity of 14 individual plants within each parent (a total of 168 genotypes) was also assessed using 18 microsatellite (SSR) markers. The results showed that 43 and 32.6% of the total variation in agro-morphological traits could be explained by the first 2 principal components, which could discriminate salinity and drought tolerant parents. Based on SSR analysis, a total number of 104 alleles were detected with an average number of 5.7 alleles per primer pair and an average polymorphism information content (PIC) of 0.64 with the highest PIC belonging to EST-SSR FDSB502. Cluster analysis based on SSR markers clearly discriminated 112 plants belonging to pollen parents from 56 plants of seed parents. In conclusion, the SSR markers have been shown to be efficient and reliable for assessing genetic diversity in sugar beet crossing parents.

Salinity stress is a major limitation in wheat production. The lack of economically viable methods for screening salinity tolerance in field is an obstacle to breeders. In this study a population of 254 recombinant inbred lines (RILs), derived from a cross between Roshan × Sabalan was assessed in glasshouse during the seedling phase in order to identify quantitative trait loci (QTLs) for salinity related traits. A genetic linkage map was constructed from 239 markers, namely, 225 Diversity Arrays Technology markers (DArTs) and 14 simple sequence repeats (SSRs) which spanned a total of 1,099.7cM. A total of 31 QTLs for salinity tolerance were identified on 13 chromosomes, contributing more than 50% of the total phenotypic variation. The frequency of Roshan and Sabalan alleles were high at loci on different homeologous groups. Most of the detected QTLs were located on chromosomes 3B, 5B among the 13 chromosomes. Two QTL related fresh weight and height of shoot were detected on 1A and 3A which explained 18% and 12.9% of the total phenotypic variation respectively. Roshan (salt tolerance) alleles were associated with an increase in all traits under both control and stress conditions. SSR markers gwm626 and gwm540 (on chromosomes 6B and 5B, respectively) were tightly linked with different QTLs under control and stress conditions, and explained 21.1% and 8.1% of the total phenotypic variance, respectively. Some of these QTL mapped to genomic regions previously associated with salt tolerance in wheat.

The objectives of the present study were to evaluate spring wheat recombinant inbred lines (RILs) of diverse origin by estimating genetic parameters viz., variability, character association, cluster analysis, and principal component analysis (PCA) for spot blotch resistance and yield components at BHU Agricultural Research Farm during 2010-2011. Grain yield per plot was significantly and positively associated with biomass, 1,000-grain weight, harvest index, chlorophyll content, and grains per spike at genotypic level. The line 65 exhibited lowest mean of AUDPC value (632) indicating its potential as resistant parent. Cluster analysis grouped all the 324 spring wheat lines into 19 clusters using Ward’s method. Extreme divergence was observed among clusters. By using D2-statistics, the highest inter cluster distance (584.72) was found between Clusters VIII and XIX. Cluster VIII recorded highest mean values for chlorophyll content, peduncle length, bio-mass, grains per spike, 1000-grain weight and grain yield. The major contributing trait towards genetic divergence was found to be AUDPC (60.36%). First 5 principal components (PC1, PC2, PC3, PC4 and PC5) accounted for proportionate values of 20.66, 17.96, 15.07, 8.28, and 7.38%, respectively, contributing 69.35% of the total variability. The second PCs had high positive PC value for plant height, biomass, and 1,000-grain weight. The breeding objectives of the present experiment was to identify genetically diverse wheat spot blotch resistant RILs for developing high yielding spot blotch resistant cultivars especially adopted to south Asia in future breeding programs.

Mass generation of bagasse wastes from every 100 kg of sago starch pith being processed are likely to pollute the water when they are discarded into rivers. The increase of livestock production increases manure production and improper management of these manures will pollute the soil and environment, and causing diseases outbreak. Co-composting of sago bagasse and chicken manure could serve as a viable alternative of managing these wastes. In order to reduce pollution, the objective of this study was to co-compost sago bagasse and chicken manure slurry to obtain a high quality organic fertilizer. The sago bagasse was thoroughly mixed with chicken manure slurry, chicken feed, and molasses in polystyrene boxes. Co-compost temperature readings were taken 3 times daily. Nitrogen and P concentrations increased (1.46 and 0.12%, respectively), whereas C content decreased (48.6%) throughout the co-composting. The CEC increased from 45.7 to 68.3 cmol kg-1 indicating humified organic material. By the end of co-composting, humic acid and ash contents also increased from 7.3 to 10.0% and 7.1 to 11.6%, respectively. The pH of the co-compost increased from 4.78 to 7.21. The final co-compost had no foul odour, but it had low heavy metals content, and a desired amount of nutrients. Seed germination indices of phytotoxicity test were above 80% of final co-compost. Co-compost product with balanced nutrients content can be produced by co-composting sago bagasse and chicken manure slurry.

Soil erosion by water is the main factor of land degradation, particularly in semi-arid regions where soil productivity is usually low and lowering soil quality can severely decrease crops yields. This study was done in an area of 900 km2 in the semi-arid agricultural region of Hashtroud in northwestern Iran to determine the relationship between soil productivity and soil erodibility. Wheat grain yield (WGY) and soil erodibility factor (K) were measured separately at 108 plots in 36 dry-farming lands under natural rainfall conditions for a two-year period from March 2005 to March 2007. Based on the results, significant differences were observed among the lands in WGY (P< 0.001) and K (P< 0.001). These differences were attributed to variations of soil properties among the lands. There was a negative relationship between WGY and K (R2= 0.77). Multiple regression analysis indicated that both WGY and K were significantly related to aggregate stability and infiltration rate, with a determination coefficient (R2) of 0.74 and 0.90, respectively. Organic matter and calcium carbonate equivalent were the most effective soil properties that enhanced both aggregate stability and infiltration rate. The study revealed that soils with a lower percentage of water-stable aggregates and a lower infiltration rate also tended to have a higher susceptibility to erosion and a lower potential for crop production.