مجله چغندر قند
سال سی و پنجم شماره 2 (پاییز و زمستان 1398)

In the present study, the resistance of 30 common commercial sugar beet cultivars against root rot caused by Rhizoctonia solani and Fusarium oxysporum was evaluated in West Azerbaijan province during 2017 and 2018. Cultivars were inoculated in pots under controlled greenhouse conditions. The experiment was conducted in completely randomized design with 15 replications and 5 controls for each treatment. Ranking based on root rot intensity caused by inoculation of R. solani was done eight weeks after inoculation with a scale of 1-9. Harvest Index was also calculated for each treatment. Ranking based on leaves color yellowing and root rot caused by F. oxyporum were recorded weekly from the second week after inoculation with 0-5 index. The mean of area under disease progress curve (AUDPC) was calculated for the disease development comparison among cultivars. Also, in order to compare the cultivars damping off under normal condition, a field experiment was conducted in a randomized complete block design. Missing or dying plants were counted three time after thinning and weeding. Dying plants were identified and transferred to the laboratory for diagnosis of the disease. The results of AUDPC calculation were obtained under field conditions and resistant cultivars were identified. The white sugar yield of cultivars per unit area was calculated. The results obtained from the cultivars resistance in the field and greenhouse with the genetic characteristics of the cultivars introduced by the sugar beet seeds companies were compared and resistant cultivars with high yield were introduced. The BTS233, Flores, Delta, and Murialle showed relative resistance to both pathogens and showed significant yield per hectare and are recommended in fields with contamination.

Soil salinity is one of the most important factors in reducing crop yield around the world, especially in arid and semi-arid regions. Therefore, development of salt-tolerant cultivars such as sugar beet that can grow under stress condition and have economic yield, is one of the most important breeding goals. For this purpose, salinity tolerance evaluation of different sugar beet populations and hybrids based on some physiological, morphological, and biochemical traits was performed in greenhouse and field conditions to select high yield populations and and determining the suitable traits for selection. Two greenhouse environments were used to study physiological, morphological and biochemical traits during establishment and field environment to study physiological traits, yield and its components. Five hybrids and four breeding populations along with three tolerant and susceptible control cultivars were evaluated at two salinity levels of 0 (control) and 16 ds/m in a factorial design based on completely randomized design in greenhouse and in a randomized complete block design in the field in normal (1.2 ds/m) and saline (17.34 ds/m) at Miandoab Research Station, Iran. Several characteristics such as fresh and dry weight of shoot, relative water content of leaves, relative leaf water reduction, specific leaf weight, and proline and nutrients (Na and K) in leaves, root yield and sugar yield, sugar content, Na and K in root were measured in both stress and normal conditions. Under stress condition in greenhouse, proline, dry matter, leaf sodium content and root length increased significantly compared with normal condition, but the values ​​of K, leaf area, relative leaf water content, leaf water reduction and root dry matter decreased. In the field, salinity stress increased the sugar content and potassium and decreased root yield and sugar yield compared with normal condition. In this study, Msc2*FS7 hybrid and FS2 population were found to be superior to other populations in terms of root yield, sugar content, and white sugar yield. Susceptible cultivar Shirin had the lowest ​​ root yield under stress ondition. Based on the results, proline and dry matter traits can be used as criteria for cultivars or populations selection under salinity stress.

There is ample evidence to illustrate the role of triazoles and silicon in mitigating the effects of abiotic stresses. However, the potential of nano-silicon and tebuconazole and their possible interactions in ameliorating the effects of drought stress and related mechanisms in sugar beet have not been investigated so far. Therefore, a split-plot factorial experiment based on randomized complete block design with four replications was carried out at Motahari Research Station of Sugar Beet Seed Institute (SBSI), Karaj, Iran over two seasons, 2016 and 2017. Three irrigation treatments including 100, 75, and 50% of plant evapotranspiration (normal, mild stress, and severe stress, respectively) were assigned to the main plots. Subplots were composed of a factorial combination of three nano-silicon doses of 0, 1 and 2 mM and two tebuconazole doses of 0 and 25 mg l-1. The results showed that under severe drought stress, the effect of nano-silicon on the studied traits was dose-dependent, so that the application of nano-silicon with 1mM concentration improved growth parameters as well as physiological traits and increased white sugar yield and the maximum dry matter by 20 % and 17%, respectively compared with severe drought stress treatment. Under severe drought stress condition (irrigation at 50% of plant evapotranspiration), the highest leaf area index, chlorophyll and relative water content were observed in 1 mM nano-silicon treatment. Under severe drought stress, foliar application of 2 mM nano silicon had an adverse effect on sugar yield. The combined application of nano-silicon and tebuconazole improved dry matter production and sugar yield by maintaining plant greenness and preventing leaf aging which may indicate an interaction between these two compounds. These results indicate that nano-silicon and tebuconazole can be used as a suitable tool to mitigate the effects of drought stress on sugar beet.

This study was conducted to evaluate the effect of transplanting on water use efficiency of autumn-sown sugar beet in Mehran, Ilam province. The experiment was carried out as factorial split-split plot based on randomized complete block design with four replication in two grwoing season 2015-16 and 2016-17. Sowing date (late September, early October, early November and late November) and cultivar (Sharif and Spartak) laid out in main plots, planting method (direct seed planting & transplanting) in sub-plots and harvest time (late April, mid-May and early June) as sub-sub-plots (split at time). The results of ANOVA based on expected mean of squares showed that effect of year on root yield, sugar content, sugar yield, and white sugar yield was significant. However, it had no effect on the water use efficiency based on sugar yield. The effect of planting time on root yield, sugar yield, and white sugar yield was significant. The effect of harvest time on root yield and sugar yield was significant. Water use efficiency based on white sugar yield in transplanting method was 1.60 kg/m3 which was 50% more than seed planting method. Root yield in transplanting method was 101 t/ha (54% increase compared with seed planting method). The highest white sugar with 14.08 t/ha was observed in transplanting, late September sowing, and at early June harvest (28% increase compared with seed planting). Considering the non-economic performance of seed planting method in autumn sugar beet sowing in the province, reduction of water resource , damage of migratory birds, and limitations of growing season, it seems that sugar beet transplanting can be a proper way to increase sugar production and water use efficiency which can be considered as a reliable method to replace seeding by completing mechanization facilities. According to the study results, Mehran city can also be considered as a region prone to the extension of autumn sugar beet sowing.

The widespread use of herbicides in crops can often contaminate aquatic ecosystems. Aquatic macrophytes such as duckweed (Lemna minor L.) are used as a suitable group to evaluate the environmental changes caused by herbicides. To evaluate the toxicity of six commercial herbicides including desmedipham, phenmedipham, desmedipham+phenmedipham+ethofumesate, clopyralid, quizalofop‑P‑ethyl and technical substance of chloridazon used in sugar beet fields of Iran using standard phytotoxicity test of Duckweed (Lemna minor L.), an experiment was carried out in a complete randomized design with four replications at Lorestan University in 2017. For all herbicides used, eight different concentrations of the active ingredient of each of the above-mentioned herbicides were considered as dose-response with control treatment. Toxicity evaluation was based on inhibition of relative growth rate (RGR) of duckweed after seven days. The results of the experiment showed that all the herbicides used affected the growth of duckweed. The EC50 values which derived from the log-logistic fitted curves, showed that the desmedipham+phenmedipham+ethofumesate is more toxic compared with other herbicides used in sugar beet field (EC50 = 1.04 μg/L) and caused a significant decrease in the relative growth rate of duckweed at a much lower herbicide concentration than other herbicides. Clopyralid was made less toxicity effects on duckweed than other herbicides (EC50 = 71.93 μg/L). The order of phytotoxicity of the herbicides applicable to sugar beet can be as follows: desmedipham+phenmedipham+ethofumesate > chloridazon > phenmedipham > desmedipham > quizalofop‑P‑ethyl > clopyralid. Therefore, when using these herbicides, the threshold of aquatic species tolerance such as duckweed which are vital for the formation of food chains and the functioning of aquatic ecosystems should be considered as not to reduce or destroy them.

The purpose of this study was to estimate the demand for Iranian sugar imports considering the two countries of Brazil and the United Arab Emirates as the major importers of sugar to Iran. It should be noted that the UAE acts as a re-exporter and is not a sugar producer. Therefore, time series data from 1992-2016 and Auto-Regressive Distributed lag (ARDL) was used. The results of long-term estimates show that 1% increase in GDP increases the demand for sugar imports by 4.73%, and 1% increase in relative prices and exchange rate reduces the demand for sugar imports by 28%. Also, if the Brazilian export rate increases by one unit, the demand for Iranian sugar imports from Brazil would increase by 0.8% unit compared with the UAE. The Error Correction Model (ECM) in the sugar import demand function also shows that the rate of 0.68% deviation of sugar import from its long-term path is corrected by pattern variables in the next period. Finally, policymakers should consider the exchange rate variable as one of the most important factors influencing foreign trade, especially sugar.

Activity in agricultural sector is considered as a risky job due to its high reliance on nature and its dependence on climatic and environmental factors. Agricultural insurance as a means of risk transfer is of great importance. On the other hand, sugar beet is one of the important crops in the crop rotation of Qazvin plain that every year a large part of its production is damaged due to natural, human and intentional hazards. The purpose of this study was to identify and rank the factors affecting the extension of sugar beet crop insurance among sugar beet growers in Qazvin plain with emphasis on economic components. The present study is based on descriptive-correlation method. Data collection tool was a questionnaire and the statistical population consisted of 250 sugar beets and simple random sampling was performed using Cochran's formula 172 farmers. Data were analyzed using Pearson correlation coefficient and regression analysis by SPSS 23 software. Friedman rank test was also used to rank each of the factors affecting the extension of sugar beet crop insurance. The results showed that economic, social, promotional-educational factors, knowledge, farmers' satisfaction, farmers' attitude towards crop insurance, the amount of damage caused by natural factors in the study area and farmers' risk have a positive and significant effect on the extension of sugar beet crop insurance. Farmers' satisfaction with sugar beet crop insurance had the highest predictive power (Beta = 0.845) and economic factor had the first rank of effect on sugar beet insurance expansion. Given that the economic factor was recognized as the first factor in the extension of sugar beet insurance, it is recommended that the amount of compensation paid be revised and the compensation specified in the contract be paid to growers in a timely manner.

Soil salinity is affecting plant production, including sugar beet growing, especially in Al-Fayoum Governorate, Egypt. Screening for salinity tolerant varieties is one of the most often methods used by breeders in sugar beet. The present study was carried out at Al-Fayoum Governorate, (29°17ˋ N; 30°53ˋ E), Egypt, during 2017/2018 and 2018/2019 growing seasons. The objective was to evaluate the effect of saline soil of three locations (villages) S1, 3.57 dSm-1 (Monshat Sinnuris), S2, 8.6 dSm-1 (Monshat bani Othman), and S3, 11.84 dSm-1 (Monshat Tantawy) on plant growth, quality and yield traits of ten multigerm sugar beet varieties. The experimental design was a randomized complete block design with three replications. Results showed that root yield and sugar yield, as well as root dimensions were significantly decreased by increasing soil salinity levels as compared with the control treatment. Under severe soil salinity, Florima variety was superior in root and sugar yields [13.71 and 1.82 ton/fed (fed=0.42 ha)]; on the other hand, Euklid variety recorded the lowest values (11.38 and 1.39 ton/fed), respectively. As for the interaction between soil salinity levels and sugar beet varieties, the highest values for root and sugar yields were recorded by the varieties Florima, Toro, Cleopatra, and Tarbelli, under severe soil salinity (11.84 dSm-1). The results recommended the above four varieties to be cultivated by farmers under saline soil; these varieties are tolerant to soil salinity and they can produce stable root and sugar yields in the stressed soil. High broad-sense heritability estimates were obtained by extractable sugar (94.9%), root length (93.36%), and root weight (92.05 %). Heritability of metric traits is of great significance to the breeders as its magnitude indicates the accuracy with which a variety can be recognized by its phenotypic expression. Results showed that four varieties (Florima, Toro, Cleopatra and Tarbell (had a salinity susceptibility index (SSI) based on root and sugar yields of <1 and were relatively tolerant to salinity stress.