مجله چغندر قند
سال سی و ششم شماره 2 (پاییز و زمستان 1399)

Rhizomania is the most destructive disease in spring sugar beet along with root-knot nematode and are spreading in some parts of Iran. The best control method against these two diseases is using resistant cultivars. Therefore, the aim of this study was to develop and select a high yield hybrid resistant to rhizomania and root knot nematode. Twenty-seven full-sib families (S1) from SB-34 origin which screened with molecular markers for rhizomania and root knot nematode resistance gene, were used to develop double resistant hybrids. In the spring of 2015, vernalized families were crossed to one single cross (7112*SB-36) in separate isolates. In summer, S1/S2 seeds from the paternal plants and three-way cross hybrid seeds from maternal plants were harvested and cleaned. Out of 27 isolates, only 19 isolates had adequate seeds from both parental lines. In autumn of the same year, selected hybrids were planted in greenhouse in Karaj. Seedlings were analyzed by SCAR and SNP markers linked to rhizomania and root knot nematode resistance genes to determine gene frequencies in hybrids. Based on the results of molecular evaluation, 14 hybrids were selected. In the spring of 2016, selected hybrids along with some controls, overall 20 varieties, were planted in two rhizomania-infected areas in Khorasan Razavi and Fars based on randomized complete block design with six replications. Roots were harvested in autumn and qualitative and quantitative characteristics such as root yield, sugar content, and white sugar yield were measured. Data were analyzed using SAS 9.1.3 software. According to the results of field trials and the frequency of rhizomania resistance gene and root node nematode in the laboratory, hybrid SB36*(7112*930620) with 10.92 t/ha white sugar yield to be used.

Estimation of sucrose content in sugar beet through density determination is notable in terms of its non-destructiveness, inexpensive, speed and lack of destructive environmental effects compared with polarimetric method. The aim of this study was to evaluate the effect of sugar beet root weight on sucrose estimation by densitometry compared with polarimetry method. One hundred fifty healthy sugar beet roots cultivated in the field and harvested in Karaj, Iran were randomly selected. Each root was considered as an experimental sample. Brei was prepared from the root samples after weighing and density determination. Qualitative characteristics included sucrose, dry matter, marc, and soluble solids. Identification of outliers’ data was performed by standardization of residues. Samples were divided up into 13 weight classes in 100 g groups and then a linear relationship between density and sucrose was determined for each class. Statistical comparison between slope and intercept of linear relationships was performed in a stepwise manner from the smallest to the highest weight class and if there was no significant difference (P> 0.05) data were placed in a statistical group. Results showed that average sugar content, dry matter, marc, and purity of the samples were 15.10, 23.46, 4.06, and 73.84%, respectively. The coefficient of determination (R2) obtained from the linear relationship between density and sucrose in weight classes decreased with increasing root weight so that R2 = 0.997 for roots smaller than 350 g and R2 = 0.67 for roots larger than 1450 g was obtained. Statistical comparison of slope and intercept width regression coefficients from the origin of linear relationships between density (x) and sucrose (y) in weight classes resulting in three classes with a weight range of <350-750 g (small) including linear relationship y = 43.38x-32.557 and R2 = 0.92, medium weight class with weight range of 751 to 950 g (average) with linear relationship y = 51.55x-41.38 and R2 = 0.89 and weight class of 951 to roots larger than 1450 g (large) with linear relationship y = 58.05 x-48.014 and R2 = 0.77. Therefore, considering the root weight, the linear relationships obtained by density determination can be used instead of polarimetric method to accelerate the estimation of sucrose content.

In order to determine the genetic parameters and heritability of different traits of sugar beet and also the relationship between traits, full-sib and hybrid genotypes were evaluated in separate trials at Miandoab Agricultural Research Station under salinity and normal conditions in 2017. In full-sib trial performed under salinity condition, root yield, sugar yield, white sugar yield, leaf relative water content, root dry weight, and root/shoot ratio, and under normal condition, root yield, sugar yield, root/shoot ratio and specific leaf weight had higher genetic variance than environmental variance and consequently had higher broad-sense heritability. In hybrid trial performed under salinity condition, for white sugar yield, potassium content, potassium/sodium ratio, nitrogen content, and leaf area, and under normal condition, for root yield, sodium content, potassium/sodium ratio and nitrogen content, genetic variance was high and as a result, broad-sense heritability was above 0.5. Therefore, these traits can be considered in breeding and selection programs. Under salinity condition, the narrow-sense heritability ranged from 0.16 to 0.66. The highest narrow-sense heritability was related to molasses sugar with 0.66, nitrogen content with 0.43, sugar yield with 0.38 and leaf relative water content with 0.38, respectively. Therefore, it can be concluded that these traits are partially controlled by additive effects and can be used for selection of different degrees. Under normal condition, the narrow-sense heritability ranged from 0.01 to 0.29 and the relative water content with 0.29 showed the highest heritability. Under salinity stress, heritability of root yield and sugar yield was moderate; so yield could be improved by long-term selection and hybrid production. The results of regression and path analysis showed that under salinity and normal conditions, when the root yield was considered as dependent variable, specific leaf weight, leaf area, and relative water content explained the variation among which the leaf area had the highest positive direct effect on root yield.

Considering the importance of water in agriculture as well as extending ​​autumn-sown sugar beet cultivation area, this study was conducted to evaluate the effect of growth restriction treatments, planting date and cultivar on bolting and other quantitative and qualitative traits of autumn-sown sugar beet in Karaj, Iran during two years (2018-19). The experiment was performed as a factorial split plot in a randomized complete block design with 3 replications. Studied factors included two planting date (22nd September and 22nd October) as the first factor, the growth restriction with four levels including control (without limit), paclobutrazol (300 pp M), Nitrogen fertilizer restriction (50% of the recommended amount), Paclobutrazole + Nitrogen fertilizer restriction as the second factor, and three cultivars including Giada, Eudoro, and one Iranian genotype resistant to bolting as the third factor. Planting date and growth restriction factors were included in main plots and genotype factor in subplots. The studied traits included bolting percentage, root yield, sugar content, molasses sugar, and white sugar yield. Results showed that the effect of the year on bolting percentage was significant. The lowest bolting percentage (50%) was obtained by Eudoro cultivar on the second year of study planted on 22nd October. The highest root yield (79.91 tha-1) was related to the Eudoro cultivar, planted on 22nd September and treated with paclobutrazol (300 ppm). Giada and Eudoro cultivars planted on the 22nd September had the highest white sugar yield of 8.15 and 8.62 t ha-1, respectively with no significant difference between.

Today, one of the practical ways to improve the quantity and quality of sugar beet is to use micronutrients in appropriate proportions and in the form of foliar application. For this purpose, 14 micronutrient fertilizer treatments in four replications were applied on Latatia cultivar in a randomized complete block design in Roshtkhar and Zaveh cities of Khorasan Razavi in 2017. Results showed that fertilizer treatments had a significant (P<0.01) effect on sugar yield, white sugar yield, extraction coefficient of sugar, and sugar content in Roshtkhar field. However, the effect of fertilizer treatment on potassium (P<0.01), molasses sugar percentage (P<0.01), and extraction coefficient of sugar (P<0.05) were also significant in Zaveh field. The highest white sugar yield obtained in Roshtkhar and Zaveh fields was 8.5 (in fertilizer No. 1) and 7.61 t ha-1 (in fertilizer No. 3), respectively. The highest root yield (51.47 tha-1) and the lowest sugar content (18.29%) were obtained in fertilizer treatment No. 1 in Roshtkhar field. In Roshtkhar and Zaveh fields, fertilizer composition number 7 (19.16 %) and number 8 (20.01 %) were resulted in the highest sugar content, respectively. Studies showed that the most effective elements in increasing sugar yield and white sugar yield are molybdenum, boron and manganese and the most effective elements in increasing sugar content, white sugar content, extraction coefficient of sugar, and molasses sugar content are iron, zinc, manganese and magnesium. The most effective elements for extraction coefficient of sugar are magnesium, copper and molybdenum. The general conclusion of this study is that the combination of micro- and macronutrient elements containing less nitrogen had positive and significant effect on production quality and sugar efficiency and the proper combination of iron, manganese, zinc, magnesium and molybdenum with macro elements containing less boron and chlorine percentage have the greatest effect on increasing extraction coefficient of sugar, white sugar yield, and root yield.

In order to evaluate the morphological, quantitative and qualitative traits of different fodder beet cultivars (genotypes) under foliar application of methanol and the glycine betaine amino acid, the present study was conducted in 2018 in Hamedan and Qom. The experiment was designed as a factorial split plot in a randomized complete block with three replications. The studied factors were methanol at three levels of foliar application (control, 15 and 30% by volume of methanol) as the first factor, glycine at two levels (control and 4 gL-1 of methanol consumed) the second factor, and six fodder beet cultivars (SBSI050, SBSI051, SBSI052, Brunium, Jamon, and Kyros) as the third factor. Results showed a significant difference (P<0.01) among locations. The root yield in Hamedan region was 40.59 tha-1 more than Qom region. Methanol foliar application increased root yield by an average of 16.56 t ha-1 and dry matter yield by 2.85 tha-1 compared with control treatment. Glycine foliar application also made a significant difference in quantitative traits thorough the average total yield by 17.47 tha-1. There was no significant difference between different levels of methanol and glycine in qualitative traits including crude protein and root digestibility. A significant difference (P<0.01) was observed among genotypes. Based on the results of interaction between genotype and methanol, kyros treatment in Hamedan with applying 15% methanol concentration recorded 120 tha-1 root yield, 20 tha-1 root dry matter yield, and 142 tha-1 total yield which is recommended as the optimum option.

Sugar as a strategic commodity has always been of interest to governments. This product is obtained from sugarcane and sugar-beet. Therefore, the relationship between sugar beet production and sugar import is considered significant. This study aimed to estimate the relationship between sugar import and sugar beet production in Iran during 2001-21 using a vector autoregressive model. The statistics required for sugar beet production and sugar import were extracted from the information baser of the Ministry of Jihad-e-Agricultural and the Iranian Sugar Factories Association. Results showed that changes in sugar imports are the cause of changes in sugar beet production. Results of vector autoregressive model showed that in short time, one percent increase in sugar import reduced sugar beet production by 0.30%, and in long-term model, one percent increase in sugar import reduced sugar-beet production by 0.19%. Based on the results, it is suggested that the capacity assessment of imports should be done based on the supply and demand gap in the country. The appropriate capacity of the country in sugar beet production and support of processing industries and development of contract agriculture should be considered by policy makers.

Sugar is one of the basic and strategic products that has always been considered and supported by governments. Sugar is an international and strategic commodity that has a special place in the trade, social and economic policies of many countries. Given that part of the country's needs is met through imports, therefore, one of the important issues in the sugar market in the country is the effect of domestic sugar prices on exchange rate fluctuations, which in turn affects the production of sugar beet and sugar. The aim of this study was to evaluate the effect of variation in foreign exchange policies on sugar price using the monthly time series data of 2018-20 and also due to the relationship between imports and sugar beet and sugar production, the indirect effect of this policy on production be analyzed. Monthly data were analyzed to using VAR model. Results showed that change in foreign exchange policy (exchange rate change from 42,000 Rials to the Nima currency) with a two-month break had a direct effect on sugar price. Due to the causal relationship between the variables, it was also observed that variation in foreign exchange policy has also affected the sugar beet production. Considering the results of this study, in order to sustain the effect of this policy in the coming years, it is necessary to pay special attention to the effect of these variables in designing related policies so that from the beginning with the implementation of the policy to other effective factors in this regard, including increase in the productivity of production factors and supporting technology, especially the production of suitable and economical seeds for producers, more attention should be given to the growing trend of production in the country against the import of sugar.

To develop cultivars tolerant to salinity stress, diverse genetic resources are required. This study was performed to evaluate the salinity tolerance of new imported sugar beet genotypes in a factorial design based on completely randomized design with three replications including 15 multi-germ genotypes and two controls as the first factor and two salinity levels (0 and 16 dsm-1) as the second factor at the greenhouse of the Agricultural Research, Education & Extension Organization of Isfahan. Different traits including germination percentage, plant establishment percentage, and salinity tolerance index were recorded. Based on the results, all 15 genotypes were significantly different from the tolerant control 7233-P.29 and among the studied genotypes, genotypes 1, 2, 3, 5, 7, 8, 10, 11, 12 and 14 were identified as tolerant genotypes. Results showed that the most obvious difference between the new genotypes and the tolerant control under stress condition was in final plant establishment percentage so that the average germination percentage of new genotypes compared with tolerant control increased by about 6%. The average plant establishment percentage which is an important trait in salinity tolerance, increased by 53.25% in new genotypes compared with the control.