Journal of Agricultural Sciences and Natural Resources
Year:2003 | Volume:9 | Issue:4|Papers Count:19

The climatic changes especially global warming as a result of use of fossil fuels has taken many attentions during past years. In order to examine climatic change, 40 years weather data (1961-2000) of Gorgan Station were used. Simple linear regression (y=a+bx) was used to determine rate of change (b) in temperature and precipitation variables. The results showed that annual mean maximum and minimum temperatures have not increased (p=0.05) during past 40 years, but mean minimum temperature in May has decreased by 0.04°c per year (p=0.048). The number of days with a maximum temperature greater than 35°C has decreased by 0.05 day per month per year (p=0.019) for May and 0.13 day per month per year for June. Total annual precipitation has significantly decreased by 4.3 mm per year (p=0.008). Total rainfall in March has also declined by 1.3 mm per year. On the other hand, total annual number of days with precipitation less than<10 mm rainfall in December (p=0.009, 0.12 day per month per year) have increased. It was concluded that there is not any significant warming as a result of global environmental change, but precipitation has significantly declined during past 40 years.

Bromus tomentellus Boiss is a perennial grass belonging to the Poaceae, which grows in wide range of distribution in Iran. This plant was important in rangelands, thus phenology, morphology and cytological study was carried out. In this regards the seeds of the plant belonging to the different areas were provided from the Gene bank around the country. The seeds were grown at glasshouse condition and the characters of morphology and phenology were studied during the vegetation growth. The results obtained from the study of morphology indicated: color of Cellolotic Fibril of base sheath, present or absent of hair and its density, number and length and broad of leaf, culm length, number of tillering branch, spikelet length, spikelet number, upper and lower glumes length, lemma length and seed length are preferred characters. Phenology indicated three different growth stages. The first is vegetative growth stage, which takes from March to July. The second is temporary dryness stage, which starts from early autumn to early spring for about 4-5 months. Flowering, seed ripening and seed falling take from April to May, May to June, and June to August, respectively. This research shows that this plant not only hasn't 28 chromosomes but also has 42 chromosomes and it is Hexaploid (2n=42, x=7) and classified into two groups based on the karyotype results. One group was consisted of 36 sub-metacentric and 6 metacentric chromosomes, whereas the other type contained 26 sub-metacentric and 16 metacentric chromosomes. Cluster analysis was performed based on the results obtained using UPGMA method and relevant dendrogram was constructed. The dendrogram showed two main clusters and each cluster containing the samples belonging to the same ecological areas. It was concluded that it is probably possible to identify different ecotypes of the species based on the geographical distribution.

In order to study the effects of planting date and nitrogen rate on yield and yield components in Zabol local lentil, an experiment was carried out in 1997-98 at Zabol university farm. In this experiment four planting dates (Nov. 1816 and Dec. 1816) and four nitrogen levels (0, 18.5, 37 and 55.5 Kg ha-1) were compared in a split –plot experiment as RCBD with four replications. The results showed that plant growth period decreased as planting date was delayed. Seed yield, plant height, number of branches, number of full and empty pods, number of seeds per pod, 100 -seed weight and number of seeds in plant were affected with planting date and their difference was significant (p<0.01). Planting date effect on number of pods in node was significant (p<0.05). Maximum seed yield was obtained with 55.5 Kg ha-1 at first planting date and minimum seed yield with 55.5 Kg ha-1 at fourth planting date.

Wheat cultivars intercropping especially cultivars with different heights may increase yield. This is because of creating wavy canopy and more efficient utilization of environmental resources especially radiation, which increases yield of intercropping, compared to its components in pure stand. In this regard, two wheat cultivars, dwarf MV-17 with height of about 65 centimeters and Alvand variety with the height of 110 centimeters were evaluated in a factorial experiment based on randomized complete block design with three replications. Three densities of lower than optimum, optimum and higher than optimum (450,500 and 550 seed m-2) and six sowing ratios of MV-17 to Alvand (0:100, 20:80, 40:60, 80:20 and 100:0) were used in a row intercropping system. The experiment was conducted in Ardabil Agricultural Research Station in 1998. Maximum yield in pure stand for both cultivars was obtained in optimum density, which was 5800 and 6240 kg/ha for MV-17 and Alvand, respectively. The highest amount of LER (1.12) was observed for the sowing ratio of 40:60 and in density of higher than optimum. Yield of this intercropping treatment was 9.13 percent higher than maximum yield obtained from monoculture of tall Alvand cultivar. Superiority of this combination to other intercropping treatments was also shown for other agronomic and competition indices.

In order to investigate and determine genetical diversity and its relation to geographical and climatic distribution in the Iranian landraces of barley, 208 samples from Iranian cereal collection were grown. Twenty characters including days to flowering, days to physiological maturity, grain filling period, flag leaf length, flag leaf breath, flag leaf area, the length of extrusion, peduncle diameter, the length of own, the ratio of own length to spike length, the length of flag leaf sheath, the length of spike, plant height, kernel weight per spike, the number of kernel per spike, 1000-kernel weight, spiklets per spike, the internode length of spike, kernel length and its breath were investigated. The importance of all traits for dissociation of zones and climates was revealed by analysis of variance and preliminary studies of difference among samples for mentioned traits. The cluster analysis was based on characteristics and put samples climates in two clusters that comparison of these results with clustering from climatic parameters had showed direct relations between genetic and climatic diversity, but indicated that there was not a clear relation between genetical diversity and geographical classification.

The effects of NaCI salinity on growth traits, leaf water potential and proline content were investigated in onion (Allium cepa L. cv. Ghermez Rey and cv. Sefid Tarom Zanjan). Plants were grown by hydroponic under controlled greenhouse conditions and supplied with Hoagland solution with half-strength containing 0-100 mM NaCl. In this study, split plot design on R.C.B.D. base with 3 replications was used for traits analyzing. This pot experiment was done in sand: perlite mixture at 3:1 ratio. The results were showed that with increase in salt concentration levels, there was not found much difference between two cultivars in the values of leaf water potential and morphological characters. The increase salt concentration was caused significantly increase in proline production. Also, the role of this metabolite was high effective on salinity tolerance increasing especially in the Ghermez Rey cultivar.

Flow pattern investigation in a river needs an applicable tool. For this reason, there is an attempt to prepare software such as MOBED2 for two-dimensional unsteady flow. As it is known that river boundaries are curvilinear, Navier-Stokes equation solution has been written in curvilinear coordinates and for the best fitting of flow and boundaries basic equations of mass conservation and flow equation are solved by implicit method. For validity of the model a case study on Karkheh River has been carried out. The comparison between the results of observed velocity and water level with corresponding calculated values in two specified points shows a good agreement.

Ladybirds from the family Coccinellidae were collected from crop plants, orchards and other plants in different parts of Guilan province during two years faunistic survey. A total of 26 species belonging to 17 genera, 8 tribes and 5 subfamilies were identified. Among the species collected one of them was mycophagous and others were predacious, preying on various species of aphids, coccids, whiteflies, psyllids and plant mites. Asterisks beside their names mark the species, which have been recorded for the first time from Guilan. The collected species are as follows: 1-Subfamily CoccinellinaeCoccinella septempunctata, Coccinella undecimpunctata*, Adalia bipunctata, Oenopia conglobata, Propylea quatuordecimpunctata, Hippodamia variegata*, Psyllobora vigintiduopunctata*.2-Subfamily ChilocorinaeChilocorus bipustulatus, Exochomus nigripennis*, Exochomus nigromaculatus*, Bromus octosignatus*.3-Subfamily ScymninaeScymnus apetzi*, Scymnus quadriguttatus*, Scymnus rubromaculatus*, Scymnus araraticus*, Scymnus auritus*, Scymnus syriacus*, Scymnus flavicolis*, Nephus bipunctatus*, Cryptolaemus montrouzieri, Clitostethus arcuatus*, Stethorus gilvifrons*, Stethorus punctillum*.4-Subfamily Sticholotinae Pharoscymnus ovoideus*, Serangium montazerii*.5-Subfamily CoccidulinaeRodalia cardinalis.

During 1997-98 a survey was carried out to collect and identify syrphid flies (Dipt. Syrphidae) from Marand, East Azerbaijan Province of Iran. In this study a total: of five species belonging to two genera Paragus (Lat.) and Eristalis (Rond.) are determined as follows: paragus albifrons, P. tibialis, P.quadrifasciatus, Eristalis arbustorum and E. tenax. Information concerning their morphology, biology and distribution areas was also provided. This article is considered to be the first record of above mentioned species from Iran.

A Bioecological study of the olive psylla was investigated in two olive groves during three successive years and in the laboratory condition. Olive psylla overwintered as adults on the olive trees and mate in mid March and females start to egg laying at first into the buds of old branches, then deposited on the terminal buds, and at ultimately between the calyx and corolla of flower buds. Individual females deposited an average of 51.4±2.7 eggs from late Match up to May. The nymphs started to appear in early April and lasted until mid July, and adults of spring generation emerged in late May. Olive psylla has one generation per year and spring generation adults spent the summer, autumn and winter on the olive trees with a reproductive diapause. The host preference studies showed that there is significantly difference between varieties (P<0.1), and psylla prefer Roughani variety more than others. Sex ratio of males to females was about 1.1:1 in both Roudbar and Loshan regions. Psylla nymphs were parasited by species of Pteromalidae and Encyrtidae. Coccinellid predators, lacewings, hover flies and spiders were observed feeding upon the eggs, nymphs and adults. In addition to, the cold winter might have an effect on the mortality of overwintering adults and reduce the olive psylla population.

Walnut black spot disease (Anthracnose) has been distributed in northwest of Iran especially in Qazvin province. Recent years (from 1998 to 2001), various regions including Quzvin, Zanjan, Hamedan and East Azarbayjan provinces were surveyed. Suspected samples of leaves, fruits and foliage have been collected from studied areas. Then they were cultured in PDA, CMA and NA media after surface sterilization with sodium hypochlorite. Morphological characteristics and asexual reproduction of pathogen showed that the causal agent of this fungal disease was fungi named Marssonina Julandis which isolated from infected samples specially leaves.The disease was severe in all studied areas and when it was rainy, and relative humidity was high (80%) so that the fungal pathogen hadepidemic population, In this case there was main defoliation in some walnut trees. Investigation showed that the collecting and burning of infected leaves and fruits under trees were reduced severity of disease. On the other hand, there was a resistant variety around the Qazvin called "Alamoty" which had not any Anthracnose infection in natural conditions. The result of experimental test by inoculation of different walnut clones by 105 spores suspension in glasshouse conditions has also indicated that the "Alamoty" clone was more resistant than others to Anthracnose disease.

The population dynamics of Pseudomonae under field study showed an epiphytic life cycle of P.s.pv. syringae and P.s.pv. tomato on susceptible and resistant varieties of tomato. The path of P. syringae colonization on all plant life stages beginning from seedling to seed production was investigated. The results showed that level of colonization of the bacteria depends on interaction between bacterial and plant cells. Bacterial colonization inside the fruit was significantly lower than the growth parts of the plant. The level of bacterial colonization on susceptible plants was significantly higher than resistant plant. In the field conditions the results indicated that transferring of P.s.pv. tomato by seed was low. The ASFR (Amplification Selective Fragment Restriction) method for identification precies of P.syringae isolates was recognized suitable in the field condition. From the results obtained by ASFR method it is concluded that the epiphytic colonization of this bacteria depend on prime infestation and migrated bacteria in the air does not have any importance in epiphytic colonization.

Probiotic on the performance of 500 mixed-sex broilers. The experiment consisted of four dietary treatments and five replicates per treatment with 25 broiler chicks per replicate in a complete randomized design. Four dietary treatments were 1) basal diet containing no probiotic; 2) basal diet+ 80% of the recommended level of immunobac probiotic; 3) basal diet+ the recommended level of immunobac probiotic and 4) basal diet+ 120% of the recommended level of immunobac probiotic. The amount of the probiotic in the diets during 1-10 and 16-25 days were 4, 5 and 6 mg/chick/day in diet 2, 3 and 4, respectively. The corresponding values in these diets during 31-45 days were 8, 10 and 12 mg/chick/day. In this experiment immunobac probiotic was removed from the diets during the days 11-15, 26-30 and 41-45. The results showed that feed conversion was significantly (p<0.05) better with the diets containing immunobac than control in whole production period (1-45 days). Weight gain, feed intake, mortality rate, carcass yield, abdominal fat, litter pH and litter moisture showed no significant difference among groups when whole production period (45 days) was considered.

This study was conducted to investigate the effect of different length of lamb suckling on growth traits, feed conversion and feed efficiency of Lori-Bakhtiari male and female lambs. For this purpose, 66 Lori-Bakhtiari male and female lambs that were born at same season randomly selected. They were weaned at 60, 90 and 120 days of age and put in a 6 month feedlot period. A completely random design with factorial method (sex and weaning age) was used. Diets for male and female lambs were isocaloric (2.51 M.EM cal/kg DM) and isonitrogenous (13.07% CP on DM basis). This diet contents 40 percent forage and 60 percent concentrate.The results had showed that there were significant differences between weights was lower for 60 days weaning age (P<0.05). The means of final weight groups were 44.64, 43.01 and 41.30, 1.09 kg. for 60,90 and 120 days of weaning ages respectively and was significantly higher for 60 days weaning age group (P<0.05). Average daily gain was significantly higher (275.18 g) for male lambs than female lambs (210.74 g) (P<0.01).Interaction effects between weaning length and final weight and daily gain male and female lamb were significant (P<0.05). The mean of feed conversion and feed efficiency in differences groups were not significant, but between male and female lambs were significant (P<0.05). It is recommended that, Lori-Bakhtiari male lambs can be weaned at 60 days and put in a 6-months feedlot period.

Four rumen fistulated Balouchi sheep aged six month with a mean live weight of 35 kg were used in a split plot change-over design to examine effects of live yeast (Saccharomyces cerevisiae-1026) supplement on rumen fermentation and blood metabolites. Diets were balanced according to 1.25 times maintenance requirements based on ARC (1995) recommendations. The treatments were H) High fiber diet (% 30 concentrate+ % 70 hay), HY) High fiber diet plus 4 g of yeast per head per day, C) High concentrate diet (% 70 concentrate+ % 30 hay), CY) High concentrate diet plus 4 g of yeast per head per day. During 6 and 8 hours after feeding, blood and rumen liquid samples were collected, respectively and to predict microbial protein, urinary samples were taken at the end of the study, for three days. Yeast increased significantly rumen pH, two hours after feeding CY, (6.22 vs. 6.05). Rumen NH3 concentration significantly decreased from 1 to 4 hours and from 0.5 to 3 hours after feeding HY and CY, respectively. Yeast decreased plasma urea concentration significantly three hours after feeding HY and two hours after feeding CY (10.72 vs. 13.76 and 10.69 vs. 13.74 mg/dl, respectively). Microbial protein mean was higher relatively by HY than other treatments. Results indicated that, yeast increasing feed efficiency by increase use of ammonia and increases microbial protein product.

Three poplar (Populus nigra) trees from Shastkola forest were cut and from them 5-7 cm thick boards were procured. When the board moisture content reached to 13%, they were cut in accordance whit ISO standard to prepare specimens for physical and mechanical tests. Specimens then were impregnated with styrene monomer, which was already mixed with the dye as well as benzoyl peroxide as an initiator. Impregnated specimens then were polymerized using direct heat by placing them in the oven. Physical and mechanical properties of Wood Polymer Composite (WPC) were measured and compared with those of untreated specimens. Results showed that WPC could increase wood density up to 90 percent and reduce tangential shrinkage as well as radial shrinkage up to 50 percent. All mechanical strengths were improved in WPC; among them, the highest rate belonged to the compression strength perpendicular to the grain with 345 percent, and the lowest rate was related to compact with 16 percent.