مجله چغندر قند
سال سی‌ام شماره 1 (بهار و تابستان 1393)

Pathogenicity and genetic variability of 13 Fusarium oxysporum isolates collected from sugar beet field of six provinces of Iran during 1999- 2008 were evaluated. Pathogenic variability of the isolates was determined using a root-dip assay in spore suspension in test tubes for four- week plants. The isolates were classified into strong and weak pathogenic groups. A total of 15 RAPD primers were used for the isolates genetic diversity evaluation. On this basis, high polymorphism was observed among the isolates. Cluster analysis (UPGMA) of the isolates using the MVSP software package classified them into five groups. There was a relationship between RAPD results and geographical origins of the isolates. However, no relationship was found between RAPD results and pathogenicity. Genomic DNA of isolates was amplified using ITS1 and ITS4 primers. The amplified DNA products of the isolates was digested by three restriction enzymes EcoR1, Taq1 and HaeIII. ITS- RFLP analysis showed similar banding pattern the isolates.

Sugar Beet cultivation is of great importance in Isfahan province. Powdery mildew is a major limiting factor to sugar beet. To evaluate powdery mildew status in sugar beet fields, samples were collected from main sugar beet growing areas including, Isfahan, Semirom, Farydan and Komsheche during 2009-10. In order to determine the disease severity, in each region, samples were taken at six growth stages from 10 fields. Disease severity was measured based on 0 -100 scale. Results showed significant difference among fields in each location in relation to disease severity. The highest rate of disease was found in Isfahan and Semirom with 50.30 and 46.31%, respectively, whereas in Komsheche and Freydan it was 18.94 and 14.44%, respectively. In all studied regions, the disease progress began from first week of August and reached to its maximum level in the first week of September up to first week of October in Isfahan. In Fraydan, Semirom, and Komsheche, the maximum level was recorded in September, early September, and last week of September, respectively. The disease severity continued up to last week of October in almost all regions. The sexual stage was observed as black points (cleistothecium) at the last stages of the growth. Miscroscopic studies confirmed the production of ascospores in the region.

Curly top disease is one of the important diseases of sugar beet. Spatial pattern and population variation of leafhoppers Circulifer haematoceps, and C. tenellus, vectors of sugar beet curly top virus, were studied in Hamadan province, Iran for three years (2007- 2009). Sampling was carried out at the early stage of the plant growth, in accordance with planting date for 9 weeks, in 7- 10 day intervals. For this purpose, four fields of five hectares each with a distance of approximately one kilometer from each other were selected in Asadabad region, Hamedan province. The insect sweep net was considered as sampling unit. By using the data obtained, the RV (a measure of sampling accuracy) factor for the three years was 12.2, 6.52, and 16.65%, respectively. Because of finding C. haematoceps as a vector of the disease in this region, variance to mean ratio () was used for determination of the spatial pattern of C. haematoceps population. The numerical value of Z for the whole year and total of three years was more than 1.96 which indicates the cumulative spatial distribution of the vector. The proportion of C. haematoceps population to total population of other leafhopper species in 2007, 2008, and 2009 was 5.68, 1.97 and 2.43%, respectively. Average of infected sugar beet plants to curly top disease in 2007, 2008, and 2009 was 5.2, 8.6, and 5%, respectively. In 2007, the number and proportion of leafhopper vector population was higher than total population of other species but owing to late planting, infection percentage was low, while in 2008, due to early planting and slow growth of the plants, vectors had more time for distribution. Despite the low number and proportion of leafhopper vector population to total population of other species in 2008, the average of plants infection (8.6%) was higher than two other years. Also, a linear positive and significant relationship was found between leafhopper vector population frequency and the frequency of plants infection throughout the season. The coefficient of determination (R2) for three years were 96, 90 and 94%, respectively, indicating the existence of a strong relation between the curly top occurrence and the vector population in the field.

This study aimed at determining the evapotranspiration and crop coefficient (kc) of sugar beet during the plant growth using drainage lysimeter by using water balance and experimental methods for three years in Shahrekord. After sugar beet planting and out of lysimeter, evapotranspiration was measured weekly and monthly by measuring the factors of the water- balance equation. Results showed that the total evapotranspiration of sugar beet was 1016.6 mm during the growing season and the rate of water drainage and the soil moisture content were 73.9 and 66.1 mm, respectively. The amount of evaporation from class A pan was 1364.5 mm. Evapotranspiration of the reference plant was measured by using drainage lysimeter and estimated by using the experimental methods. Rusults showed that the evapotranspiration rate of the reference plant was 1123.03 mm and among the experimental methods, the Blaney- Criddle FAO24 and Penman-Monteith FAO 56 method had more accuracy. Crop coefficient at early stage, development stage, middle stage, and final stage was 0.72, 0.81, 1.04, and 0.7 with an average of 0.89 for the whole growing period of sugar beet. The average pan evaporation coefficient (Kp) was 0.83, and the average water requirement coefficient (Kc.p) was 0.73 for the growing season of sugar beet. In other words, sugar beet water requirement was 0.73 of the evaporation from the evaporation pan, and by having the amount of evaporation from the pan, one can estimate the under requirement of the crop with an acceptable accuracy. Water use efficiency for root and white sugar was 5.14 and 0.753 kg m-3, respectively.

Determination of chlorophyll content and chlorophyll fluorescence has the potential needed to analyze the efficiency of photosynthesis in plants against environmental stresses, especially salinity, and its simplicity facilitates stress evaluation. In order to study the response of different photosynthetic characters to salinity stress at different sugar beet growth stages, two separate experiments were designed and conducted. Six sugar beet genotypes were evaluated under two treatments including non-stress (control) and salinity with 16 dsm-1 electrical conductivity in the greenhouse and field conditions. Samples were collected at four and eight- leaf (establishment) stages in the greenhouse and at leaf development (16-leaf) and physiological maturity (40- leaf) stages in the field. Photosystem (II) efficiency, evapotranspiration, stomatal conductance, photosynthesis, respiration, and chlorophyll a and b content were measured at sampling stages. The highest impact of salinity on photosynthetic traits at various growth stages was observed at the second growth stage (8- 10- leaf or establishment stage). Leaf transpiration rate, stomatal conductance, and total chlorophyll content had significant correlation with root and sugar yield. During the early stage of sugar beet growth in the salinity treatment, with reduction in initial fluorescence and without influence on maximum fluorescence, the photosystem (II) efficiency increased but during the establishment stage, reduction in all chlorophyll fluorescence parameters resulted in significant decrease in photosystem (II) efficiency which caused damage to photosynthetic system and reduction in total content of chlorophyll a and b. Salinity tolerance of genotype 7219 was accompanied by a decrease in transpiration and stomatal conductance but genotypes BP Karaj and 7233- p.29*MSC2, displayed tolerance to salinity by transpiration reduction and chlorophyll fluorescence increase. Genotype 452 was susceptible to salinity stress and showed no salinity tolerance mechanism. Finally, it was shown that in addition to genotype, different growth stages are effective on salinity stress tolerance. In genotype selection, physiological mechanisms of stress tolerance in various growth stages are also important.

In this study, some seed physical properties of two sugar beet varieties, Shirin and Gadouk (436), were evaluated as a function of moisture content. Physical properties included length, width, thickness, arithmetic and geometric mean diameters, sphericity, thousand seed weight, angle of repose, terminal velocity, true density, bulk density, porosity, and coefficient of friction. Four moisture contents (8.4, 9.8, 11.9, and 14.0%) and two varieties were evaluated in factorial experiment based on completely randomized design. With increase in moisture content, the length, width, and thickness of Shirin seeds increased by 11.37, 15.61, 8.82%, and for Gadouk (436) variety, increased by 5, 4.54, and 6.69%, respectively. Arithmetic and geometric mean diameters, sphericity, thousand seed weight, angle of repose and terminal velocity were found to increase linearly by the increase in moisture content whilst true density, bulk density, and porosity of the seeds decreased. The friction coefficient of the seeds of both varieties increased with moisture content increase on four structural surfaces including rubber, plywood layer, galvanized steel, and aluminum. The maximum and minimum friction coefficient for the seeds of the both varieties was achieved on rubber and galvanized steel surfaces, respectively. The relationship between the physical properties and seed moisture content was obtained as regression equations, and were validated by analysis of variance. Results showed that the obtained equations can be used in prediction of the seed physical properties in other moisture content levels.

In order to study the effects of micronutrients application on some morphological traits associated with seed quantity and quality of sugar beet cultivar Shirin, an experiment was conducted in 2001-02 at Ardabil Agricultural Research Station. Based on soil test results, soil pH was 7.62-7.80 with 0.49- 0.53% organic matter content, and the quantity of absorbable P, total N, and K amounts were found to be at optimum level. Eight treatments including: 1. control (no micronutrient), 2. Fe, 3. Mn, 4. B, 5. Feand Mn, 6. Feand B, 7. Mn and B, and 8. Mn, Fe and B were evaluated in randomized complete block design with three replications. Results indicated that the effect of different treatments on the number of lateral branches, main banch diameter, leaf dry weight, branch dry weight, and total dry weight was significant (P < 0.01). Means comparision showed that the maximum number of lateral branches was obtained in Fe+ treatment and the highest rate of leaf dry weight, branch dry weight, and total dry weight was observed in both Fe and Fe- B treatments. Results also showed that micronutrient application had a significant effect on seed yield, unfilled kernel percentage, vigour percentage, and standard seed size (round 3.5-4.5 mm) percentage. Fe- B treatment resulted in the highest seed yield per hectare with the highest vigour and the lowest unfilled kernel percentage.

This study aimed to determine the prone areas for sugar beet planting with regards to their major effective factors. Climatic data of 1998-2009 period were obtained from the local stations of Khorasan Razavi Meteorological Bureau. The topographic data including altitude, slope, slope direction, and TIN layers were extracted from 1:250000 topographic maps of Cartographic Organization, Iran. The land use and vegetation land cover maps were prepared from 1:250000 maps of National Soil and Water Research Institute. The Geographic Information System (GIS) was used for numerical calculation and map drawing. After the spatial geo-database of the region was developed, the descriptive data of the maps were added to it using the ARCGIS software. Then, with regards to the climate needed by sugar beet and based on the views of the experts, each layer weight and its importance in Analytic Hierarchy Process (AHP) was determined using Expert Choice software. Finally, through overlay analysis in GIS the potential, cultivated areas for sugar beet cultivation were classified. Results of the final zoning maps showed that 59.61% of Torbat- e- Heydarieh area (3745.82 Km-2) has a great potential for sugar beet planting and about 24.49% of the areas were not suitable for planting of the crop. Among agricultural regions, Rokh hill and Kadkan region (north of Torbat- e- Heydarieh) were highly suitable for sugar beet planting followed by Markazi plain.