Journal of Agricultural Sciences and Natural Resources
Year:2002 | Volume:9 | Issue:1|Papers Count:20

Some soil-borne fungi are caused root rot pathogen and decline of Sweet cherry in Larijan region of Amol. In this investigation samples were infected roots tissue of Sweet cherry and for determining physical and chemical characteristics of soil region; five profiles of soil were studied. The results showed that pathogens are related to two species of fungus. Fungus of Rosellinia necatrix was formed from grey calary and thick mycelium ampoule-like at septum region. Also, fungus produced coremium and one cell conidia on dead tissue. This fungus was more frequent than others. Other fungus is Armillaria mellea produced yellowish-orange colonies on the media, and simple mycelia with clamp connection at septum area. Fungus telemorph as honey-coloured mushroom is formed as a group on crown of same trees in autumn. In same isolates fungus that was isolated from crown of trees identified as Fusarium lateritium. This fungus produced white colony which then becomes orange with curved macroconidia by three to seven cells. Results of soil analysis indicated that soil in this area has texture with clay-loam to clay and high moisture. Reaction of soil pH showed the level of neutral to weak alkaline.Ratio of C/N was in balance and this type of soil was evaluated as poor nitrogen level. But, from point of various elements, phosphorus, sodium, calcium and magnesium were in high level and suitable. With attention to high level of pH and nitrogen reductions in soil, trees are highly under environmental stress so that field condition is prepared for disease development.

Glomus species are most common arbuscular mycorrhizal fungi symbiont with roots of field crops and fruit trees. These fungi improve water and nutrient elements absorption; therefore increase growth and yield of plants. In order to collecte and identify these fungi, roots and soils were collected from wheat, barley, corn, sorghum fields and few jujube orchards located in Khorasan, Semnan, Tehran and Khuzestan provinces.Glomus species symbiont with their roots were studied and identified in trap and pure pot cultures. Five Glomus species were identified as follow: Glomus claroideum (in 11% of samples), G. clarum, G. dominikii and G. coronatum (each in 1% of samples) and G.etunicatu, (in 2% of samples). All of these fungi are new for mycoflora of these plants in Iran and two species, which remark with aristics, are new for mycorrhizal flora in Asia.Morphological characteristics, taxonomy, mycorrhizal associations and distribution of these species are illustrated.

Increased growth of wheat resulting from amendment of soil with strains of Trichoderma harzianum was investigated to determine if increased growth could be attributed to a direct effect of these Trichoderma spp. on the plant or a secondary effect due to control of plant pathogens. Three strains of T. harzianum (T.95, T-12B and T-12) and its parent's wild type (WT, isolated from a soil in Fortcollins) were grown on PDA.After 24h. sterile and washed cellophane membrane was placed on the growing mycelium. Seeds of wheat cv. Oslo (dwarf) and Butte (tall) were surface sterilized and placed on the membrane. The percentage of germination of seeds on the cellophane was more than the control (without T. harzianum). This experiment revealed that the exudates of T harziamum stimulated the germination of seeds. In the greenhouse experiments, wheat seed cvs Oslo and Butte treated with suspension of 108 spores per ml. the strains of T. harzianum and type (WT), were sown in the soil infected with P. ultimum (300 CFU).The percentage of the infected root tips of the plants resulted from treated seeds was fewer than those of the control and wild type. The percentage of root pieces colonized by the propagules of the strains was more than the wild type. The fresh and dry weights of plants resulting from the seeds that have been treated with the T. harziamum were higher than the control. These experiments explore the possibility of biocontrol of some soil borne plant pathogenic fungi with strains of T. harziamum and increased growth response.

Biology of a predatory bug, Andrallus spinidens (F.) on hosts of Spodoptera exigua, Ephestia Kuehniella, Chilo supperessalis, Galleria mellonella and a mixture of them (except E. Kuehniella) was studied. Different hosts had significantly different effects on duration of embryonic period, as it varied between a minimum of 7.5 days in G. mellonella to a maximum of 9 days in E. Kuehniella and mixture of them too. These hosts did not have any significant different effect in duration if pre-oviposition and oviposition periods, but they had significantly different effect on duration of postoviposition period.This study revealed that nymphalperiod was varied from a minimum of 18.25 to a maximum of 21.37 days on G. mellonela and S. exigue, respectively. Means of unmated adults longevity, depending on the kind of host, ranged between 31 to 40.25 days for males and 30 to 47.7 days for females, respectively. Matuing of adults had significant effects on their longevity. In all of our observations, males longevity was shorter than females. Mean duration of one generation for A. spinidens was 43.7, 41.5, 39.5 and 46.3 days on S. exigua, E. Kuehnilla, Ch. Supperessalis, G. Mellonella and mixture of them respectively.

Some crops have allelopathic effects. It is important to study their effects on other crop plants, particularly in rotations. A field study was conducted to determine the response of cotton (Gossypium hyrstum L.) to different ages and rates of sunflower (Heliantus annus L.) residues in a randomized complete block design with 7 treatments and 4 replications at College of Agriculture, University of Mazandaran, Sari, Iran.Treatments were 80 grams of 6, 8, and 10 weeks - old residues, 160 grams of 6, 8 and 10 weeks- old residues, and a control treatment (no residue). Measured traits were percent emergence, height, and dry weight of cotton two and six weeks after planting and final height, dry weight, and yield. Results showed that percent emergence, height, dry weight, and yield of cotton were significantly reduced in comparison with control. Increased maturity residue reduced these traits significantly, but residual rate did not cause significant effect. The reduction in percent emergence, height, and dry weight were 62, 59 and 74% two weeks after planting, respectively. In these research residues from older plants were found to be more phytotoxic than residues from younger plants.

Bermudagrass [Cynodon dactylon (L.) Pers.] is a perennial, warm-season and C4 plant of Gramineae (Poaceae) that reproduces by seed, stolon and rhizome. The species is drought resistant and tolerates alkalin soils. Bermudagrass grows on a wide range of soil types. High capability for vegetative reproduction as well as reproductive reproduction causes rapid expansion in short time after establishment and it's eradication is practically difficult. Apart from competing with the crop for growth requirements (e. g. water and nutrients), this weed is considered a potent allelopathic plant, which inhibits crop growth and depresses crop yield.Worldwide, bermudagrass is perhaps one of the most serious weed of the grass family. Also, C. dactylon interferes with producing numerous annual and perennial crops in Iran. It is considered as one the worst weeds in Iran. Therefore, heavy cost is spent for controlling of weed by different methods in fields and gardens, annually. Careful selecting of tillage instruments is very important in mechanical control, because using some instruments (e.g. disk) are resulted in increasing weed population. Successful chemical control is possible by translocated (systemic) herbicides. Finally, although bermudagrass is known as the worst weed in Iran, some genotypes of this species are used as turfgrass or pasture plant, and medicinally applying of this plant has long history in many countries.

This research was performed in order to evaluate five Iranian rice cultivars (cvs. Sange- Tarum, Mahalli- Tarum, Oeilamani- Tarum, Hassani and Hassan saraie) for studying the percent of callus induction and plant regeneration on two culture medium of Murashige and Skoog (MS) and Linesmair and Skoog (LS). After dehusking and sterilization, seeds were cultured on the callus induction medium MS and LS including 2, 2.5 and 3 mg/l 2, 4-D. Then, petri dishes were incubated at 26±1 oC The percent of callus induction and embryogenic callus were compared in different varieties. Then, the embryogenic calli were transferred on LS and MS medium, with different proportion of hormones such as kinetin (1, 2.3 mg/l), BAP (1, 2.3 mg/1) and NAA (05, 1, 2 mg/l). The callus incubated in the dark or under fluorescent light at 26±1 oC for plant regeneration.Results showed that the first group included two cultivars of Oeilamani Tarum and Hassan saraie with average of callus induction 80 and 78.67 percent representatively, second group included two genotypes of Mahalli Tarum and Hassani with average of callus inductuin 70.33 and 73.67 percent, representatively and third group included Sange- Tarum that its average callus induction was 66.33 percent. There were many differences in regeneration between Iranian rices, cv. Oeilamani Tarum had the maximum percent of regeneration between studied cultivars and cvs. Mahalli Tarum, Hassani, Sange- Tarum and Hassan saraie placed after that. The results showed that LS medium was better for callus induction and plant regeneration in the different cultivates.

In this study the effects of salinity, drought, cold, heat and pH on germination of four Iranian wheat cultivars including: Sardary, Sabalan, Alamout and Zarrin were investigated in petridishes using randomized complete block design with three replications. The results revealed that in 5 Co Alamout with 100% germination was the most resistant and Zarrin with 58% germination was the most sensetive cultivar to chilling stress. In-1.22 Mpa Sardary with 75% germination was the most resistant and Zarrin by 0% germination was sensitive cultivar to drought stress. In 10 g/lit or 0.171 M concentration of NaCl Sabalan with 60% germination was the most resistant and Sardary by 40% germination was sensitive to salinity. Germination of wheat cultivars in different levels of pH showed that optimum pH for germination of wheat was between 5- 90.Sardary was appropriate cultivar for acidic soils and Zarrin was sensitive to acidic soils, wheras Alamout showed sensivity to alkaline soils. The study of some chemical compounds in seeds of wheat cultivars showed significant relationship between protein content of seeds and their resistance to drought, cold and heat stress. So, resistant cultivars in comparison with sensitive ones contained higher protein and lower starch percentages.

In order to study the effect of different rate of Nitrogen (N) and Phosphorus (P) on grain yield and essential oil rate of anise an experiment was conducted in pots with 12 treatments, each with different amounts of Nitrogen on urea form in three levels: No (without Nitrogen), N30 (30 Kilogram of N in hectar that equals 0.11 grams of N in the pot) N60 (60 kilograms of N in hectar that equals 0.23 of N in the pot) and some phosphorus in the form of super phosphate triple in four levels: Po(without phosphorus), P30 (30 kgs of P in hectar that equals 0.11 grams of P in the pot), P60 (60kgs of P in hectar that equals 0.23 grams of P in the pot), P90 (90 kgs of P in hectar that equals 0.35 grams of P in the pot) using factorial experiment with completely randomized design with five replications. The result of the experiment indicates that there is a significant difference at 1% statistical level between difference levels of N, P and their interaction with anise grain yield. Also the highest yield is concerned with N60 and P60 treatments.Since there is no statistically significant difference between P60 and P90 treatments, concerning the mean comparison, it can be concluded that the highest yield of anise grain 60kgs of N and P in hectar. The essential, oil obtained, using water distillation method was also measured. The result indicates that adding azote and phosphorus fertilizers has no effect on the essintial oil content obtained and there is no statistically significant difference between the means of different treatments. Regarding the essential oil yield (amount of essential oil in area unit), the result indicates a significant difference at 1% statistical level between different treatments. The highest amount of essential oil obtained, is concerned with N60 and P60 treatments. The comparison of the means of different treatments also showed that there is no statistically significant difference between P60 and P90 treatments.

This study was carried out in two exprimental plots to investigate the effects of Shahinshahr Wastewater Treatment Plant and soil characteristics on yield and characteristics, of corn (Zea mays L.). Irrigation water treatment including well water and wastewater and irrigation system treatment including sprinkler and surface irrigation were used. Using Microsoft CROPWAT model, irrigation intervals were selected to be every 10 days but the amount of water and time of irrigation were different in each cycle.Waster water treatment increased kemal yield, harvest index, plant hight, ear length, ear diameter, row of seed and column of seed corn. Sprinkler system as compared to surface system caused significant increase in above parameters. Wastewater treatment as compared to well water treatment caused significant increase in soil basic intake rate.Also, irrigation system showed significant effect on soil basic intake rate. The wastewater can be used as a source for irrigation water in Shahinshahr region for corn production, and it can be used as a source of nitrogen as it is required by soil.

In order to evaluate and compare the energy requirements in different tillage methods for corn production, three moldboard plow- based tillage systems were compared with a chisel plow-based tillage system, in different soil moisture regimes at Darab Agricultural Research Station during 1998. The experimental design was a randomized complete block design with five replications and four treatments. Ground speed, time used, draft, fuel consumption and the rate of drawbar energy used for primary and secondary tillage operations were measured and used as performance index. Results obtained from the experiment showed that the rate of soil moisture content during primary tillage operation had a significant effect on performance index of implements. Maximum rate of fuel consumption, draft, drawbar power and drawbar energy used, was occurred when primary tillage operation was done by moldboard plow in 8.65% moisture content, and the minimum was occurred when primary operation was done by chisel plow in moisture content of 16 to 18%. Analysis of the data showed that in treatments having moisture content less than 10%,the performance index of disk harrow and leveler were more than in those treatments with moisture content between 16 to 18%.The results also revealed that there are significant differences between fuel requirements, time and drawbar energy used in four corn tillage systems.

In order to study fruit set pattern and effect of apical meristem removing on the percentage of fruit setting of pistillate flowers, length of fruit setting period, rate of fruit growth and length of growth period of the fruit on samsoory cantaloupe, an experiment was carried out in the Research Station of Varamin, Iran. The results indicated that flowering and growth rate corresponded with the proposed pattern of MacGlasson and Harlan. Analysis of variance showed that the effect of apical meristem removing enhances the beginning of fruit set and shortens the growth period of the fruit, but has no effect on the length of the fruit setting period and percentage of fruit set of pistillate flowers. The number of fruit bearing branches was significantly among first to fourth nodes, the second and the third nodes showed maximum number of fruit setting branches.

Soil erosion is a serious problem throughout the world. Wind erosion is due to the increase wind velocity and air turblulent. This phenomenon usually is seen in soft, smooth, bare, dry, disperse and fine soil. It always classifies to two main factors named erodibility and erosivity. The first depends on the physical and chemical properties of soil and the second depends on wind physic and kinetic energy. The goal of the recent research is making the mathematical models which explain the relationship of soil properties with erodibility. The most important factors that affect on erodibility are percent of surface gravel coverage, soil texture, gypsum, electrical conductivity and sodium absorption rate. The rest of measured factors including lime, organic matter, percent of particles greater than 0.84 mm are less important than above mentioned. Soil erodibility was measured by portable wind tunnel (wind erosion-meter) in geomorphologic unit of Yazd - Ardakan plain. Because of the importance of desert pavement (Reg), gypsum and mean diameter of soil particle, these factors were chosen to fit for modeling. A mathematical model was made for part of catchment with erodibility range from zero to 0.50 ton/ ha- hr by statistical software of Excel and Matlab. This model compared with real erodibility and erodibilit index depended on percent of soil particle> 0.84 mm. The results indicated that the model is more efficient than another one.

Tomato concentrated products were diluted up to 12 percent solids to measure their consistency by Bostwich consistometer. The evaluation of the consistency of tomato concentrated with different Brixes showed that the error in consistency measurement of tomato concentrated by Bostwich method increased as the Brix increased. The studies indicated that the drying rate of insoluble solids and the lacking of reconstituting properties of them were caused error in the measurement of paste consistancy (especially at high Brixes). In this research, the effect of variety, tomato concentrated Brix and the temperature of consistency measurement were evaluated to determine the error changes in Bostwich consistometer and to modify it. The results showed that the variety had no effect on the accuracy of consistency measurement by Bostwich method, but Brix and temperature had a very significant effect on the accuracy of this assay and thus the error of Bostwich consistometer increased, especially at high Brixes. It was concluded that heating of diluted tomato concentrated (up to 45 Co) and then cooling it can decrease the error of consistency measurement considerably. Also, the consistency can be estimated accurately by using the regration between Brix, temperature and Bostwich consistency (R2=0.94).

The present research suggests a mathematical model for predicting water table position between two underground drainage ditches and simulates a transient flow regime after a single event recharge due to rainfall or irrigation. This model solves the two dimensional transient flow equations within the anisotropic soils for unsteady State. The Alternating Direct Implicit (ADI) method is also used to solve numerically flow equation.The results of comparison indicated that the model is correlated with one-dimensional flow in which vertical hydraulic conductivity of soil was ignored (kz/kx<<1) (Glover and Dumm). This model was suited to be used for vertical flow condition within the upper and lower line of drainage canal. The results showed that in anisotrope soils in which the vertical hydraulic conductivity is considered (kz/kx>1), the use of analytical equation which only horizontal flow towards ditches does not provide a real water table prediction.The position of water table related to impermeable layer will be overestimated. The position of water table in transient flow using two dimensional flow models has more realistic application than that of analytic procedures.