JOURNAL OF AGRICULTURAL SCIENCE AND SUSTAINABLE PRODUCTION
Year:2007 | Volume:17 | Issue:2|Papers Count:22

Some inputs in agricultural products are quasi-fixed in nature, and there is no defined market for them. These input prices are not determined in the market. So there is not a suitable and efficient price for them. One of these inputs in Iran is water. Water is the limited and important in Iranian agricultural sector that exist no defined market for it. At these times, we can use from non-market methods for determining the economic value (real price) of water. The main objective of this study was to determine the economic value of irrigation water used in some of staple crops (wheat and onion), in the Maragheh- Bonab Plain using flexible production functions approach. The results of this study indicate that the economic value of water used in wheat and onion production are almost 248 and 291 Rials per cubic meter, respectively. The estimated prices are much higher than local prices of these inputs.

An understanding of the main factors influencing microbial diversity in soils is necessary to predict the effects of current land use trends on terrestrial diversity. In this study the effects of land use (high and low input systems) and pasture on microbial biomass and diversity was investigated. Respiration responses to specific substrate can be used to measuring of soil microbial diversity. We measured catabolic evenness and richness of microorganisms as measures of soil microbial diversity. Richness is the number of substrate used by the heterotrophic community, whereas heterotrophic evenness is the variability in substrate use, among the substrate tested. In comparison with agricultural systems, native pasture resulted in an increase in organic matter and microbial biomass. Within three land use types, in the high input system basal respiration was higher than under the other two systems, suggesting the presence of a small but highly metabolically active micro floral community. Analysis of catabolic response profiles demonstrated that there were large differences in the catabolic capability of the soil microbial communities under different land use type. Values for Shanon's and Simpson's diversity indices indicated that greatest catabolic existed under native grassland and least diversity under high input systems. It was attributed to a broad range of organic pool in the pasture. It was concluded that land use has substantial effects on the size, activity and diversity of the soil microbial community and these changes could be broadly related to the changes in soil organic matter content. Although the consequences of losses of microbial diversity are unknown, but diversity may results in greater resilient to stresses or disturbances.

In order to study irrigated wheat nutrient balance, 982 flag leaf samples were collected at pollination stage from wheat pilot projects at East Azarbaijan province, Iran, during 5 years (1999-2004). After preparation of the samples, N, P, K, Fe, Mn, Zn, Cu and B concentrations were measured. At maturity stage, grain yield in all field plots were determined and plant analysis data was interpreted by the correlation coefficient of nutrient ratios with grain yield and path analysis method. The results showed that in order to realize nutrient balance and obtaining yields higher than obtaining six ton/ha in irrigated wheat, it requires to apply phosphorus and zinc fertilizers as compared with other nutrients in East Azarbaijan province. Every factors that limit P and Zn concentrations in plant will probably decrease wheat grain yield. It was also deduced that in order to realize nutrient balance, phosphorus and zinc should be applied concomitant with nitrogen fertilizer in the province.

Subsurface irrigation due to effective decrease in soil evaporation, runoff and deep percolation and to strict control on weeds and soil crusting has obvious advantage over the conventional irrigation systems. To evaluate its suitability for onion production, a field experiment was carried out in a sandy loam soil during two growing seasons at the research experimental station of the University of Tabriz, Iran. The experimental treatments comprised three irrigation tape spacing (0.6, 0.8 and lm) installed at 10cm depth, two irrigation depths equivalent to ETc and 0.8 ETc as predicted from Penman-Montieth ET-model and two methods of fertilizer application (manual and fertigation). Basin irrigation as a control and as a prevailed irrigation method in the onion producing region was also employed. Results indicated that yield difference between various treatment turned to be significant at 1% probability level. Subsurface irrigation with equivalent depth of 0.8 ETc and 0.6m tape spacing, produced maximum yield of 52.73 ton/ha. Fertigation comparing to the conventional fertilizer application led to 20% increase in yield under subsurface irrigation (ETc and 0.8 ETc treatment). Basin irrigation produced 40 ton/ha. Effective fertilizer use, better weed control and aeration in root medium with sufficient soil moisture all apparently attributed to the higher yield under subsurface irrigation. Seasonal water use achieved to 6200 and 4800 m3/ha at equivalent depth of ETc and 0.8 ETc under subsurface and to 6870 m3/ha under basin irrigation, respectively. These figures are 27.7, 44.9 and 19.8 percent lower with respect to the water use figure recorded for the region, implying that there may be saving in seasonal water use as much as 40% by adopting subsurface irrigation to the region, Maximum water use efficiency reached to 10.9 Kg/m3 under subsurface irrigation with 0.6m tape spacing and 0.8ETc indicating high productivity in the region for onion production under subsurface irrigation system is achievable.

Salinity stress through distractive effects would reduce crop growth and yield. Calcium has nutritional and physiological benefits to crop and therefore, may reduce salinity hazards and cause high growth and yield. In order to study these effects, an experiment with two wheat genotypes G12 (salt tolerant) and G3 (salt sensitive), three levels of salinity (control, 100 and 200 mM NaCl), and three levels of calcium (0.5, 5 and 10 mM CaCl2) was conducted in a hydroponic culture media at the glasshouse of Agricultural Biotechnology Research Institute, Iran. Twenty three days after seeding, salinity treatments gradually were imposed and experiment was continued until physiological maturity. Results showed that in 200 mM NaCl treatment, physiological maturity, plant height, number of tillers per plant, number of spiklets per main spike, number of kernel per main spike, kernel 1000 weight, tillers grain yield, main stem grain yield, biomass and grain yield all were reduced as 31%, 33%, 83%, 36%, 33%,46%, 92%, 68%, 82%, 72%, respectively. Raising calcium concentration in root media reduced salinity effects, so salt tolerance was enhanced. For example, in 200 mM NaCl with 10 mM CaCl2 compared to the same treatment of lacking CaCl2, 1000 kernel weight, total grain yield and biomass in sensitive genotype (G3), were increased by 10%, 14% and 33% respectively. For the tolerant genotype (G12) the corresponding increases were 18%, 33%, and 51%, respectively. Tolerant Genotype (G12) through greater growth ability under salinity stress, produced greater numbers of tillers, main stem grain yield stability, higher kernel weight and led to greater grain yield and biomass as compared to G3.

Pre-anthesis stored dry matter in vegetative tissues of barley (Hordeum vulgare L.) are important, because grain filling and yield frequently depend on the remobilization of pre-anthesis assimilates. In this work that was conducted in the University of Tabriz in 2004 and 2005 (pot and field experiments, respectively), the contribution of leaf, stem and sheath in grain filling were determined in two cultivars of barley, Walfajr and Reihan. Influence of three levels of nitrogen (60, 120 and 180 Kgha-1) and drought stress (>80, 55-65 and 35-45 percentage of field capacity) on accumulation and remobilization of assimilates and their contribution in grain filling were investigated. Maximum pre-anthesis stored dry matter (including non structural carbohydrates and nitrogen) increased in high N treatment. Nitrogen and non structural carbohydrates had the highest values in leaf and sheath, respectively. A significant enhancement of remobilization was observed under drought stress particularly in high N.treatment. Under severe drought stress, harvest index was increased 10% in both pot and field experiments. Remobilization efficiency was higher in flag leaf, peduncle, internode 1 and sheath 4. Prean thesis application of high and normal nitrogen in pot and field experiments, respectively, increased contribution of stem internodes and sheath reserves to grain filling especially, when plants were confronted with drought stress. Peduncle with 3.9% and internode beneath peduncle with 6% and their respective sheaths had the highest contribution to grain filling in pot and field experiments respectively, which was related to the length of these parts. Generally, application of controlled water stress during grain filling period causes a higher remobilization from vegetative tissues before onset of water stress at the end of growing season.

Leaf stripe disease caused by Pyrenophora graminea, constitutes a potential threat to the cultivation of barley in all barley growing countries. To identify resistant landraces of barley to leaf stripe in field condition, 17 landraces (four two-rowed black grain and 13 six-rowed white grain barleys) and a cultivar, Zarjow, were tested with two virulent isolates of East Azarbaijan Province in factorial experiment based on randomized complete block design with three replications in the research Station of Faculty of Agriculture, University of Tabriz, Iran, during 2002-2003 growing season. Further more a control experiment was conducted at the same location to evaluate barley landraces under disease free condition. Percentage of infected plants was recorded in both seedling and adult plant stages. Reaction of landraces to disease was different in both stages and landraces categorized from resistant to very susceptible. Interaction between landraces and isolates of leaf stripe fungus was significant, and isolates differed for virulence. Most of the landraces were susceptible and only three landraces (numbers of 1, 8 and 16), in both stages were resistant or partially resistant to both isolates. Cultivar Zarjow was susceptible to both isolates at both stages, but degree of susceptibility of this cultivar was different depending on the virulence of isolates. Two-rowed black grain barleys were less susceptible to stripe disease than six-rowed white grain barleys. Comparison of percentage of infected plants of seedling stage with adult plant stage showed, that at least in some of the landraces the mechanisms of controlling resistance to leaf stripe disease may be different in these stages. In the disease free condition the yield of six-rowed barleys was more then two-rowed barleys, however, in the presence of disease, differences in yield of two-rowed and six-rowed barleys were not significant and yield losses were different depending on the isolates of the pathogen and the barley varieties.

In order to evaluate grain yield potential in bread wheat genotypes and its relationship with quantitative traits and selection of best genotypes for breeding purposes, 64 bread wheat genotypes were planted using alpha-lattice design with two replications in Seed and Plant Improvement Institute of Karaj in 2003. Results of data analysis showed significant differences between genotypes for most of traits. Based on factor analysis via principle component, seven factors explained 77.485 % (using all the traits excluding grain yield) and 79.302% (with elimination of grain yield) of total variance. Also factor analysis showed the importance of relevant traits contributing to grain yield components, height, and early maturity (days to heading and maturity) for selection of appropriate genotypes.

Progress of an effective, genotype-independent regeneration system is crucial to gain any advances in the field of cotton (Gossypium hirsutum L.) gene transfer and biotechnology. The aim of this research was to study regeneration potential of shoot apex explants. Shoot apices from Sahel, Varamin and Coker 312 cultivars were cut and transferred to MS basal medium containing 100 mg/l of myo-inositol and 0.5 mg/l of each of nicotinic acid, pyridoxine and thiamine. Following several subcultures and removal of whitened explants, regenerated shoots were transferred to previous medium (without growth regulators) for root induction. After root development and acclimatization, they were maintained in greenhouse. Results showed that there were no significant differences between three Sahel, Varamin and Coker 312 cultivars concerning survived shoot apex percentage and regenerated plantlets. A total percentage of 53.9 of excised shoot apices belonging to three cultivars were regenerated and survived. Plantlets were successfully established in pots with a mean of 3.9 percent. Frequency of plantlets with abnormal phenotypes was so low (0.69%). No calli were observed at the shooting period and just one unique shoot was developed from each shoot apex explants. According to results, use of shoot apex explants could be so appropriate for tissue culture and genetic engineering of Iranian cotton cultivars.

To evaluate forage yield and quality of sweet corn as affected by plant density and sowing date, a field experiment was conducted at Tarbiat Modarres University in 2004. Experiment was carried out in a split plot design based on RCBD with four replications. In this research four levels of sowing date (May 22th June 10th, July 1st and July 21th) and four plant densities (45, 55, 65 and 75000 plants/ha) were arranged in main and sub-plots, respectively. The results in the first sampling (%50 silking) showed that plant density and sowing date have significant effects on some traits such as leaf and stem weigh (fresh and dry), LAI and leaf/stem ratio. In the second sampling (after ear harvest in soft dough stage) total forage yield, crude protein and mineral nutrients (P, Ca, Na, K, and Mg) were determined. and most of them were affected by plant density and sowing date. Sweet corn which was sown on 10th, June produced the highest forage yield (50ton/ha).

This study was conducted to investigate the effects of different levels of lime treated wheat straw on performance and carcass quality in Ghezel lambs. Sixteen male lambs with initial body weights of 33.36±2.45 kg were used in a completely randomized design with four experimental diets (containing 0, 7, 14 and 21 % DM treated-wheat straw) in four replicates. Treated - wheat straws were prepared by mixing chopped straw with a Ca (OH)2 suspension at 1.34 1/kg DM to supply 100gCa (OH)2 Kg/DM of straw. Treated wheat straws stored three weeks at room temperature. Daily feed intake was not affected by diets containing different levels of treated wheat straws in comparison to the control diet but daily feed intake per metabolic body weight decreased significantly (P<0.05) in diet with-21% treated wheat straw. Final body weight (52.35 kg) and daily weight gain (218.45 g) in diet containing 14% treated -wheat straw were significantly (P<0.05) higher than those in diets with 0 % (48.5 kg and 171.13 g, respectively) and 7 % (48.5 kg and 172.61 g, respectively), 21 % (48 kg and 148.01 g, respectively) lime treated -wheat straw. Feed conversion ratio in the diet with 14% treated-wheat straw was higher than other ones. Dressing percentage based on the average of four experimental diets was 50.60. Leanmeat, rib and leg as percentage of live body weight in lambs fed four experimental diets were on the average 26.7, 13.4 and 7.4, respectively.

One of the immune system genes which has important role in mastitis disease is BoLA-ORB3. Initially, 30 Sarabi cows (from Sarab region and around) and 39 Holstein cows (from several herds of Tehran region) were selected. Then 214 blood samples from Holstein cattle (Mogan Plant Production & Industry Corporation) were provided. Out of these 214 cattle, 150 cattle were susceptible and 64 cattle were resistant to mastitis (within 41 half-sib families). In order to study microsatellite polymorphism in intron 2 of BoLA-DRB gene and to obtain allelic frequency and to compare allelic variability between Sarabi and Holstein cows, all blood samples were randomly collected. In these samples two microsatellite markers ORB3 and DRBP1 were studied (the two microsatellites DRBP1 and ORB3 are located in intron 2 of the corresponding DRB3 gene). In the second stage, microsatellite marker DRB3 was analyzed in 214 of Holstein cows for studying probable linkage between disease and different alleles of BoLA-DRB3 gene. In the Sarabi breed, 9 and 5 different alleles and in Holstein breed 10 and 4 different alleles were observed for DRB3 and DRBP1 microsatellites, respectively. The amount of heterozygosity for two loci in the Sarabi and Holstein breeds were estimated as 0.49 and 0.67, respectively. Association between mastitis and microsatellite DRB3 alleles was studied among 214 Holstein cows. Statistically significant (P<0.05) association between allele 5 of DRB3 microsatellite and mastitis disease was observed. The results of this study demonstrate that DRB3 and DRBP1 microsatellites are highly polymorphic in the Iranian native Sarabi cattle and can be used as genetic markers. In this study, close association was found between one of the several alleles of DRB3 microsatellite and mastitis.

Considering of milk pricing system in Iran, a deterministic model was used to predict economic weights of milk production, fat percentage, protein percentage and herd life for maximum profit, when product input were restricted and variable enterprises costs were used in animal unit. The sensitivity of these coefficients to a 20% change on prices of forage to concentrate, feed costs, non-feed costs, milk base price, milk free-market price, average milk production, fat percentage, protein percentage and herd life were examined, using data simulation and available data from three different dairy herds of Iran. On the basic condition, the economic weights of milk production, fat percentage, protein and herd life in maximum condition were (745, 581.5, 790.5), (460105, 492630, 161877), (424857, 905336, 488234) and (506.7, -16.2, 571.5) in three herds, respectively. Milk production, fat percentage, protein percentage and herd life had the highest sensitivity to change the average milk production, basic milk spice and herd life. Intake changing in forage to concentrate ration had the lowest effect on economic weights. Economic weights changes in contrast to changing on production factors in different systems had variable effects. Changing of production factors causes difference on economic weights of traits and their economic weights should be estimated for each production system.

Effect of various drying temperatures (39, 45, 60, 70, 80, 85 and 90°c) was investigated on the quality of Spaghetti. Spaghetti samples were produced in a semi-continuous industrial extrusion process and subsequent drying stage was done in a laboratory scale cabinet drier with a controlled temperature and relative humidity. The results of cooking experiments showed that increasing drying temperatures decreased cooking loss and increased cooked weight and swelling index of cooked Spaghetti. High temperature drying caused an increase in the pH of dried Spaghetti (up to normal pH of flour). Total organic matter (TOM) was decreased upon high temperature drying process. It was also concluded that - high-temperature drying reduced the number of micro organisms in the final product. Sensory evaluation of high temperature dried spaghetti revealed a significant improvement of sensory characteristics, especially the final quality of product. Spaghetti dried at 85 and 900C had the highest quality scores.

The majority of breeding programs of edible mushrooms are carried out in the button mushroom due to its commercial importance and genetic difficulties. In this research, for the first time in Iran, it was possible to examine intra-hybridization and its effect on both productivity and mycelium morphology as a potential for commercialization. The strains comprised six heterokaryons and four homokaryons from different sources. Twenty five homokaryotic isolates were obtained from six heterokaryon and having 29 homokaryons, 406 diallele crosses were performed from which 145 crosses were compatible. Productivity of compatible crosses was examined in an industrial mushroom farm on a basis of randomized complete block design with two replications. From 145 crosses, nine hybrids which had significantly higher yield than the control, were used in yield trials performed in two industrial mushroom farms on a completely randomized design basis with three replications. The yield of three hybrids was significantly higher than the control. For these hybrids, a strain registration form was prepared. The resulting information showed some interesting points, particularly about the study of pedigree of offspring having high performance than the control, which will be useful in designing the future breeding programs.

Losses in quality and quantity of forage occur during harvest and post-harvest operations. The losses mainly occur in the most useful part of the plant, which is leaf. In the present work, a mat-making unit was designed, fabricated and integrated with a maceration unit developed earlier. Field trials of complete unit were conducted to evaluate the effects of three levels of feed rate and three levels of peripheral speed of the large roller on the moisture removal, specific fuel consumption, and mechanical losses of forage. A 3 x 3 factorial experiment arranged in a completely randomized design with three replications was considered to evaluate the unit. The forage harvested with cutter-bar mover was considered as control. The analysis of data indicated that mat making technique results in a higher moisture removal as compared to control. Comparison of means of forage moisture measured after nine hours revealed no significant difference among retained moisture for various feeding rates whereas different roller speeds resulted in different moisture removal, the lowest speed showed to be the most effective. The analysis also indicated that specific fuel consumption was significantly affected by both factors. Mean comparison indicated that the treatment with feed rate of 4 t h-1 and roller speed of 85 rpm consumed least fuel. The analysis also indicated that there were no differences in mechanical loss between the new technique and control. The experiment also revealed that roller speed is the only factor affecting this index. The treatments with feed rate of 4 t h-1 at roller speed of 85 rpm and 3 t h-1 at roller speed of 127 rpm had the minimum and maximum mechanical loss, respectively.

Artificial drying is one of the most common methods of preservation of agricultural products. Drying conditions can affect physical and mechanical properties of grain. The drying process must be designed and controlled to minimize drying damage. In this study, the thin layer drying kinetics behavior of wheat (tajan) with initial moisture content of 26% (d.b.) in a convective type experimental dryer was investigated and mathematical modeling using four replications of thin layer drying kinetics models from the literature was performed. Drying experiments were carried out at inlet temperatures of 35, 45, 50, 60 and 70°C. Drying time to reach 10.5 % moisture content from the initial moisture content at various drying air temperatures were found to be between 62 and 246 min. Six different thin layer mathematical drying kinetics models were compared according to their correlation coefficient to estimate drying kinetics curves. The effects of drying air temperature on the model constants and coefficients were predicted by regression models. According to the results, the approximation of diffusion model represents the curves of the wheat drying kinetics (r=0.932). Non-linear regression method was used to simulate the drying kinetics as a function of the temperature.