Journal of Agricultural Sciences and Natural Resources
Year:2004 | Volume:10 | Issue:4|Papers Count:22

The causal organism was isolated from rotted crown of pepper and was identified as Phytophthora capsid. In this study, 151 bacterial isolates were collected from various plant rhizospheres, 37 isolates belonging to fluorescent Pseudomonads and gramp ositive bacteria showed antagonistic effect on P. capsid among these antagonists, six were studied for their inhibitory effect against pepper damping -off. Baesd on biochemical, physiological and morphological tests, isolates D andH1083 were as Bacillus subtilis. The isolates 1083 and D produced antibiotic as well as volatile metabolites that inhibited mycelial growth of P. capsid in vitro. Isolates 1083 on king B medium produced siderophore, while isolate D did not produce siderophor at different FeC13 concentrations. B. subtilis isolates prevented the mycelial growth through antibiotic and volatile metabolite Production. Among antagonistic isolates, only D and 1083 could produce hydrogen cyanid.

Effect of salinity stress, with four levels 1.7, 4.7, 8.7, and 14.5 dSm-1, on growth and yield of Zagros and Tajan wheat cultivars were evaluated. A factorial experiment was conducted using a randomized complete block design with three replicates. Vegetative and reproductive variables were measured at anthesis and maturity. Leaf area and dry weight and total plant dry weight at anthesis decreased at 8.7 dSm-1 salinity, but the decrease was not significant for Tajan. Salinity treatments of 8.7 and 14.5 dSm-1 caused significant decrease in stem number, stem and leaf dry weight, spike number and weight and total dry weight, but differences between salinities of 1.7 and 4.7 dSm-1 were not significantly different. Seed dry weights of both cultivars were significantly decreased only by salinity of 14".5 dSm-1. Seed number per spikelet of Tajan increased by increasing salinity, but in Zagros the greatest seed number per spike let was observed at 4.7 dSm-1. Salinity, had no effect on harvest index of both cultivars, but increased in Tagen and decreased in Zagros. Salinity of 8.7 and 14.5 dSm-1 significantly decreased Zagros grain yield in comparison to salinity of 1.7 dSm-1. However, Zagros over-yielded 46% compared to Tagen in salinities of 4.7, 8.7 and 14.5 dSm-1

Among different diseases of zucchini squash, virus diseases cause severe damage in this crop every year. Viruses in the potyvirus genus (potyviridae family) are the major viruses infecting zucchini squash. In the spring and summer of 2001, successive sampling accomplished from zucchini plants with symptoms such as mosaic, malformation and color breadking of leaf and fruit blistering at the different stages of growth in Khorasan province (in the main growing areas of zucchini squash). Detection of viruses was based on ELISA tests. Identified potyviruses were watermelon mosaic virus 1 (WMV -1) and watermelon mosaic virus-2 (WMV -2). For determining distribution of these viruses, samples were collected randomly in the fields and were tested by DAS-ELISA. The infected samples with WMV-1 and WMV-2 were 98 and 134 out of 500 collected samples respectively. Some of the samples show infection with these two viruses simultaneously, this shows "that viruses do not crossprotect each other. Host range of WMV-2 was larger than WMV-l. Watermelon mosaic virus-2 (WMV-2) was purified. The purification was confirmed by spectrophotometry and coat protein electrophoresis. The molecular weight ofWMV-2 coat protein was 34047 dalton.

In order to study the effect of drought stress on yield, components of yield and Tesistance indices of five hull-less barley genotypes (Hordeum vulgare L.), a field experiment was carried out with a silty clay loam texured soil at the Chamkhani Agricultural Experimental Station, situated at 15 km of western south of Yasudge, Iran in 2000-2001. The experimental design was split .plot with three replications. Four irrigation levels were allocated to main plots, and five hulls-less barley genotypes (FICC0963, FICC1570, FICC1571, FICC1725, and FICC2712) to sub-plots. The irrigation levels consist of: adequate irrigation untill tillering (23 of the Zadoks code) (I1), stem-elongation (33 of the Zadoks code) (I2), anthesis (6S of the Zadoks code) (I3), and physiological maturity (I4) of hull-less barley genotypes. . The total dry matter, yield and yield components were affected by irrigation levels. Impose of drought stress at anthesis stage did not decrease grain yield significantly. The amount of grain yield for 11 and 12 were 224 and 312 g m.2, respectively. Based on the stress tolerance index, the EICC2712 genotype was identified as the most stable in grain yield.

The effect of irrigation water quality on the yields of barley was studied in a silty soil. This study was carried out in Woshmgir dam in Golestan province, in 1988 - 1999. The experiment included three salinity levels treatments, It. 12 and 13 with .76, 5 and 10 dS/m respectively, which is mixed from non-saline (fresh) and saline (drainage) water. The other factors were imposed with 8 different genotypes of barley. The design of experiment was strip plot with 4 replications. The results showed that the yield of genotypes was decreased due to apply of saline "water, but the grain yield of different genotypes was considerable, except one genotype. The average maximum grain yield was obtained at treatment 11 (4288 kg/ha). The lowest grain yield was obtained at treatment 13 (3859 kg/ha).The analysis of soil samples during 2 years indicated that application of saline water (10 dS/m) increased the soil saturation paste extract (ECe) from 1.4 to 5.3 dS/m in the surface layer (0-30 cm) and from 2.4 to 3 dS/m in the subsurface layer (30-60 cm).

To evaluate the generative growth responses to drought stress, five chickpea lines (accession numbers of 4488, 4283, 4348, 5132 and 5436 selected as promising lines among available 362 lines in collection through previous experiments) were treated by different irrigation gradient systems during generative growth stage. The irrigation gradient treatments were: 5, 10, 15 and 20 percent of reduced water supplies compared to control.(moisture kept at field capacity level) at two-week intervals, from flowering commencement to physiological maturity stages. The treatments were arranged in split plots and were compared in a Complete Block Design with "four replications. Irrigation gradients were assigned to main plots and chickpea lines to subplots. Chickpea lines showed different reactions to irrigation gradient. Accessions No. 4283 and 4488 produced the most biomass and seed yield (respectively) averaged over all irrigation treatments. Accession No. 4283 showed a severe reaction to irrigation gradient compared to other accessions, while accession No. 4488 was more stable/ in biomass and seed production across all irrigation gradients. Pod and seed numbers per plant were the most important components contributing to seed yield.

A pot experiment in randomized complete blocks design with four treatments in four replications was conducted to study the effect of drought stress and determination of some drought resistance indices in basil (Ocimum basilicum). The irrigation treatments for induction of drought stress were: 100%, 85%, 70% and 55% of field capacity. When the plants had reached the 6 to 8 true-leaf stage, the treatments were imposed and different levels of soil water content were kept at constant level by daily weighting and watering of pots. Leaf water potential, relative water content (RWC), leaf temperature, proline and soluble sugars concentration were measured at flowering stage (5 weeks after irrigation treatments were imposed). According to the results of statistical analysis, different levels of soil water content had significant effect on measured characteristics. As the soil water content decreased, leaf water potential and RWC decreased but leaf temperature, proline and soluble sugars concentration increased. The results of this study showed that basil plant could be able to tolerance the water deficit conditions by stomatal closure and increasing of proline and soluble sugars accumulation (osmotic adjustment).

Environmental conditions determine productivity of cotton at a given location. An experiment was conducted at Hashem-Abad Cotton Research Station, Gorgan during 2000 under irrigation condition. The objective of the study was to determine the effect of weather conditions on cotton flower and boil retention. To create different weather conditions during flowering and boIling period, different sowing dates were used. Experimental design was a split plot consisting 4 sowing date (24 April, 9 and 25 May and 9 June) as main factor and 3 cotton cultivars (Sahel, Siokra324 and Deltapine) as sub-factor. The percentage of flower and boIl shedding linearly increased with delay in sowing date in all the cultivars. An inverse linear relationship was observed between flower and boil shedding and yield for all cultivars. Cultivars showed different slope for the relationship and Siokra324 showed the lowest yield reduction as a function of the shedding. Shedding percentage in Sahel was twice greater than the other cultivars. Significant, positive correlations were found between shedding and mean air temperature ana the number of hot days (maximum temperature greater than 30-35°C), but negative, significant correlations were observed for wind speed and relative humidity. Thus, it was concluded that the most important factor is temperature and the effect of other factors (solar radiation, wind speed and relative humidity) is indirect via temperature. The evaluation of the probability of occurrence of hot days showed a high probability of these days during July and especially August. Therefore, it can be recommended that the cotton crops in Gorgan should be sown at first opportunity in spring during April, in order to avoid from high temperature at flowering and bolling stages during August.

In order to study the effects of three plant arrangements (Rectangle 40*40, Square20*20 and diamond 20*20) on growth of safflower, a field experiment was conducted in the experimental farm of University of Agricultural and Natural Resources in Gorgan, Iran, using the line NO10, Darab295, Arak2811 and Zarghan cultivars. The results of the growth analysis revealed that the trend of changes with GDD in the TDM, CGR, RGR, LAI and NAR was similar for the all plant arrangements and under study cultivars. For example, the LAI increased, but subsequently decreased with increasing GDD in the all treatments. The cultivar of Arak2811 possessed higher TDM, CGR, but lower NAR when compared with the other cultivars. The RGR in the rectangle arrangement was lower than in the other two arrangements. After about 900 GDD, the values of the NAR for the rectangle arrangement were to lowest. It was found that the seed yield was under the influence of plant arrangement and the cultivars.Araak2811, significantly, had the highest seed yield (3746 kg/h). Plant arrangement of equal distances between and within plant (rectangle and square) had the highest seed yield.

In order to compare the desi and kabuli types of chickpea cultivars in respect of responses to salinity at heterotrophic stage, a greenhouse pot experiment was conducted in the university of Tabriz, on 1379. In this experiment, 40 seeds of Jam, Hashem (kabuli type), Pirooz and Kaka (desi type) cuftivars were grown in pots containing soils with 0.9 (control), 2.6 and 4.9 dSm-l salinity. The results revealed that at second salt level, the kabuli type cultivars possessed lower K and Ca concentrations, KINa ratio and seedling dry weight (SDW), respectively, but higher Na concentration in the radicle and plomule, when compared with the desi type cultivars. According to SDW, the desi type cultivars showed more salt tolerance than other type, that should be more considered by breeders. In spite of high salt condition, at control, the higher concentrations of some elements in radicle and plomule could not be considered as productivity indices, because the relations of these attributes with SDW were statistically negligible. The grouping of cultivars by cluster analysis with respect to eleven attributes at higher salt intensity yielded two clusters. The first cluster consisted of the desi type cultivars and second one of the kabuli type cultivars. At control, the kabuli type cultivars, Kaka and Pirooz possessed three different clusters. Considering significant positive relation between SDW and concentration of K and Ca at high salt level, it seems that K and Ca could be used as selection indices for screening of more tolerant cultivars at seedling stage. For confirmation of these indices, heritability of these attributes should be evaluated in further studies.

Twenty mature Raeini male goat at the age of 2-2.5 years with body weight of 30-J!-2.5 kg were used to assess the effects of different levels of undegradable protein on the fiber characteristics of this breed. the duration of this trial was 84 days. Four levels of the undergradable protein (2.75, 4.86,5 .91 and 6.97%, DM basis) were used. The diets (n=5) were formulated according to AFRC (1998) in which the ME content of the all diets was similar (10.04 MJ/Kg DM). The cashmere of the animals was sheared at beginning and at the end of the trail. The quantity and the quality of the cashmere produced by animals fed the experimental diets were determined. The data were statistically analyzed using completely randomized design. Mean values for the results for the diets were as follow: unwashed fiber weight 311.4,300.6,302.6,280.6 g; washed fiber weight 221.4,218.6,235.1,215.4 g cashmere weight 131.3, 110.8, 121.7, 111.8 g; cashmere length 22.9, 20.5, 20.1, 21.5 mm. Cashmere diameter 18.6, 1-8.6, 18.6, 18.9 micron. There were no significant differences between the parameters measured in the animals offered the experimental diets. In conclusion, adding the ungedradable protein above the recommended level by AFRC (1998) had no influence on the fiber characteristic of Raeini goat.

During 6 monthes (from August 2001 to January 2002) ovarian development stages were histologically studied in the rearing ponds of South Caspian Sea (Gomishan). The aim of this study was determining of hormonal inducing time for oocyte final maturing. Different stages of oocyte development (nucleus changes, oocyte diameter and forming of yolk vesicle, yolk granules and lipid droplets) were surveyed. According to the results, stage I, n, III and IV of ovary maturation occurred in July, August, September and October, respectively. From November fishes were ready for hormonal induction.

With regard to desired natural regeneration stablisl1rhent that it is the goal of selection systems. The role of tree and group selection silvicultural systems on the quantity and quality of natural regeneration was conducted at four parcels of district no. 1 in Dr. Bahramnia forest, Gorgan (the systems had been executed ten years ago). First, 80 circular sample plots (1000 square meter) has been selected by use of random systematic inventory. Then into the each plots nine micro-plots defined (3 by 3=9 square meter, total nomiro-plots). In the end, collecting of data by counting the seedlings number, height measurements and health evaluation has been done in the micro plots. The results of oneway analysis of variance, multiple ranges Tukey - HSD test and Chi- square test of seedlings showed that there is significanct difference in the level of 0105 between mean of seedlings number, mean of carp in us seedlings number, percent of the bealth, shining, even and vertical seedlings in tree selection and group selection systems. So in the stablishment of natural regeneration the quantity and quality of natural regeneration in tree selection. system is more desireable than group selection system. In the bigger cutting sites the stand comes out of his climax conditions and in the result it will reduce, the stablishment percent of original species regeneration. With regard to the desireable results of tree selection system it is necessary to recommend that tree selection system should be write down in forest management plans descriptions.

A study was carried out to determine the vegetati..n at altitudes between 1350-1500 meters in Eastern Ardebil forests. Using Broun Bhinquet"s R",ldom-Systematic sampling method, necessary samples with an inter nsity of 1.3 percent were collected. The total number of the plots selected sampling was 65. The findings of the phytosociological study shows 136 plant species in the area of which 131 species are Magnolophyta (109 species are Dicotyledon and 22 species are Monocotyledon), 4 species of Polypodiophyta (Ferns), and one species of Bryophyta (Moss). Also there exist 8 species of trees, 22 species of shrub, and 101 herbal species. The results of the study show that altitudes have effect on the diversity and the density in two Associantion of Quercus-Coryletum and Acero-Coryletum Vegetation. However, the slope and the aspect of the selected plots play a significant role in determining the vegetative variation. Furthermore, the study also indicated 3 plant associations in the area as bellow. Quercus-Coryletum Association: Located at altitudes of 1380 1460 meters on different slopes of 5-35 percent, mostly in the southern and the south-western aspects on loam silty soils with coverage, of 75-100 percent. Fageto-Coryletum Association: located at altitudes of 13 70-1500 meters on different slopes of 10-60 percent, mostly in the norhthern and the norhth-western aspects on loam silty soils with coverage of 80-100 percent. Acero-Coryletum Association: located at altitudes of 1440-1500 meters on down slopes of 2-15 percent in the south aspects on loam silty soils with coverage of 75-100 percent.

In this study, the fixation speed of 2% Ce1cure (ACe) preservative in three different temperatures (10,20 and 30.C) in poplar (Populus nigra far. Pyramidalis) wood was examined. The 2 by 2 by 2 cm wood blocks from sapwood and heartwood with 14% moisture content were impregnated with the ce1cure solution. The impregnated blocks then were exposed to different temperatures. In each temerature, the blocks were chosen periodically and squeezed to extract the solution. The extracted solutions were analyzed to determine the concentration of chromium VI using diphenyl carbazide method. The process was continued until 99.8% of chromium is fixed. The results showed that temperature plays an important role in the fixation process. In general, fixation in sapwood was faster than heartwood. The fastest fixation occurred in sapwood at 30.C in 460 hours (19 days) while with the same temperature in heartwood, fixation time was 1132 hours (47 days).

Flood is one of the most important natural hazards, which results in human and financial losses. Annually in Atrak and Gorgan rivers- and their sub watersheds of Golestan province some floods occur. From the economical point of view nonstructural preventions including flood hazard zonation, is considered as a proper method of flood mitigation. This investigation was aimed at determination of the probability of flooding in a part of Mid Atrak river and factors affecting the area of flooding. Moreover, in order to fin4- the suitable method of Manning coefficient, different methods were compared and Chow method was chosen as the suitable method. The annual maximum flood discharge was-estimated for different return period (2-200 years) using Log-Pearson type ill distribution. The area under study was divided into some reaches based on morphological and hydraulical characteristics. Then, plan of the river, longitudinal profile and some cross sections were drowned. Water level in every cross section was calculated using HEC-RAS software and Chow method. After that, the profile of water level was drawn. Flood zone for different return period (2-200 years) was drowned and the flooding areas Were estimated. The results showed that floods with short return periods, may also affect arable lands. The most important reasons for this problem are very low slope (even less than 0.0005) of the river and dens shrubs like tall tamarisk grown beside the river. In spite of lack of flood danger-for residential area in cause of floods less than 100 years return period, risk of water penetration and. building-destruction will still remain due to geological conditions of area (i.e. erodable area covered by loess).

Estimation of an accurate peak discharge at unguaged catchments can be important when the weirs dimension calculates to reduce the flood risk to gain the purpose of engineering and economic projects. The regional model of peak flow estimation is a method that instantaneous peak flow is function of catchment area, but it is also expected that flood discharge depends on the climatic and physiographic factors such as drainage density, form factor, length of catchment, mean precipitation and etc. The purpose of this study is to find the best regional model for the peak flow estimation with return period in sub-basins of Gorgan-river catchment in Golestan Province. As an investigation technique in relation to gauge stations, 20 stations were selected wbich are analyzed in relation to climatic and physiographic factors. The results shown that 93.9 percent of variances of 5 selected variables which are more important than the other variables such as area, drainage density, form factor and bifurcation ratio. The catchment area and drainage density divided as homogenous region in clustering and multiple regression methods and also 5 independed variables identified for two positions in discharge estimation models on different return periods. In different ways; first of all the whole area and then homogenous region were selected for purpose of modeling. Finally it can be concluded that the recommended models for the whole region are more suitable than the-other models. In models with the return periods of 2, 3, 5 and 10 years only the area factor was effective. But in the models with the return periods of 25, 50 and 100 years in addition to the area, elevation of the catchment was also calculated in models which is shown the same results from the other researches.

Since the flow at free overfall is self-calibrated, it has been extensively studied and used for flow measurement by many researchers. Previous investigations were done for different channel geometry, super and subcritical regime, with no lateral inflow along the channel, i.e. there is no variation in the discharge along the channel length. This research was conducted to investigate the discharge-end depth relationship in circular pipes carrying spatially varied flow with increasing discharge. Comparison between manometer reading and direct end depth measurements confirmed the deviation of the pressure distribution from the hydrostatic one. At the brink, nonetheless the data indicated that the end depth ratio in such flow condition is closer to unity than that of constant discharge. Consequently, based on the compiled data a relationship was proposed, which facilitates discharge. measurement with reasonable accuracy.