مجله چغندر قند
سال بیست و هفتم شماره 1 (بهار و تابستان 1390)

The crown wart disease caused by Urophelyctis leproides on sugar beet is very important in the growing areas of North Khuzestan influencing quantity and quality of the crop. The objectives of our research were to estimate general combining ability (GCA) and specific combining ability (SCA) of sugar beet lines as well as the gene action governing resistance to this disease. A randomized complete block design with three replications was used to evaluate six parents and their 15 F1 crosses. The method 2 and model 1 of Griffing and also Hayman method were used to estimate variance components. Resistance indices of the disease, ratio of gal weight to root weight and gal weight were measured on these genotypes.. The genotypic effects were significant for the disease indices. GCA and SCA were also significant indicating the importance of both additive and non-additive gene effects in controlling the disease resistance. The results from Hayman analysis showed complete-dominance for the traits under study and resistant genes appeared to be recessive. A recurrent selection program with new recombination in each generation for pyramiding valuable genes in inbred lines is suggested before selecting useful hybrid combinations.

In this research, the effect of crops such as corn, wheat, sugar beet and clover as previous crop on incidence of leaf and crown wart disease of sugar beet was studied. In the first year, corn, wheat, clover and sugar beet were planted as previous crop in a randomized complete block design with four replications. The amounts of turnover of nitrogen to the soil due to crop residue and their effects on soil C/N ratio were measured. In the second year, sugar beet was planted on the previous year’s experiment site and two treatments of 35 kg additional nitrogen and no nitrogen application, in addition to previous crop treatments, were added to the experiment. Therefore, in the second year, the intensity of leaf and crown wart disease infection after different crops and applying additional nitrogen was studied as a split plot design in four replications. The second year results showed that intensity of the disease, the quantitative wart characteristics and wart weights neither was affected significantly by the previous crop nor by additional nitrogen application. However, planting sugar beet after sugar beet and corn showed the highest and lowest incidences of infection, respectively. Also, the highest and lowest wart weights resulted from planting sugar beet after clover and wheat with 770 and 349 kg/ha, respectively. It was, therefore, concluded that the previous crop had no effect on the intensity of infection to leaf and crown wart disease.

Four sugar beet genotypes with different reactions to root rot pathogens were evaluated for resistance to important root rot agents including Pythium aphanidermatum, Phytophthora drechsleri, Rhizoctonia solani AG-2-2 and R. solani AG-4. Inoculums for Pythium and Phytophthora were 3-5 day actively growing colony of the pathogens on CMA medium, while for Rhizoctonia isolates were nine infected corn kernels. Evaluation of resistance to the pathogens was carried out in separate experiments as completely randomized design with three replications. Diseases severity index was measured a month after inoculation based on the available scales. The results showed that genotypes SB19-P.16, SB19-P.44 and SB19-P.78 were rather tolerant to Pythium rot. The genotype SB19-P.78 showed the lowest infection symptoms to Phytophthora rot after the resistant cultivar (Dorotea). Evaluation of sugar beet genotypes for Rhizoctonia root rot resistance showed that the genotype SB19-P.16 had a lower infection rate to AG-4 which was very close to Dorotea. Genotypes SB19-P.78, SB19-P.16 and SB19-P.44 were not significanly different from Dorotea with regard to resistance to R. solani AG-2-2. It seems that SB19-P.16, SB19-P.78 and SB19-P.44 genotypes could be included in the breeding programs to increase the resistance of sugar beet varieties. It is recommended to further evaluate these genotypes in additional experiments. In this paper, we are reporting resistant genetic germplasm of sugar beet to P. aphanidermatum and P. drechsleri for the first time in Iran.

The most common pathogenic agent in sunflower is Sclerotinia sclerotiorum which in some cases can be successfully controlled by some antagonistic bacteria. Environmental factors such as carbon sources are effective on antagonistic strains but application of pure carbohydrates for mass production of these agents is expensive. So in most cases agricultural and industrial residues (such as molasses) which are rich of such carbohydrates are used. In this research, the strain UTPF61 was selected out of 47 strains of Pseudomonas fluorescens. Then, the effect of two media containing sugar beet molasses and sugar cane molasses on growth, antagonistic efficacy (in vitro), and antifungal activity of the bacterium on sunflower in greenhouse was investigated. Results showed that there was no significant difference between the two media in terms of growth and antagonistic efficacy of the bacterium in both environmental but they were significantly different from the control treatment. The two media were effective on antagonistic efficiency in greenhouse trials (with 80% and 78% protection against the fungus, respectively). Investigation of sunflower growth paramters in greenhouse trials indicated that sugar beet molasses increased dry weight of sunflower, but no significant difference was observed between these two media for the length of stem, length of root and fresh weight of plant.

In order to study the effect of irrigation water salinity on quality and quantity of sugar beet (Beta vulgaris) at four growth stages, an experiment was conducted in Rudasht Salinity and Drainage Research Center from 2004-2006. In this experiment, 11 different water salinity treatments and three sugar beet cultivars (IC, 7233 & 7233-P29*MSC2) were considered using split plot design based on randomized complete block design with four replications.The results showed that the increase in irrigation water salinity from 4 to 8 and from 8 to 12 ds/m EC caused significant reduction in root yield (RY), sugar yield (SY) and white sugar yield (WSY). The highest belonged to the check treatment. The least reduction in root yield and the highest response to salinity were observed at the 4th and first growth stages, respectively. Irrigation with 8 ds/m EC of water had no significant effect on RY at the third and fourth growth stages, but at the first growth stage it significantly decreased RY. Irrigation water with 12 ds/m EC had no significant effect on RY at fourth growth stage, but at the other growth stages significantly decreased RY. Irrigation with 8 and 12 ds/m EC decreased RY about 24, 33 percent as compared to the check at all growth stages, respectively. By increasing the irrigation water salinity from 8 to 12 ds/m, RY was dramatically decreased from the second growth stage afterwards. It can be concludedthat the first and second growth stages have the highest sensitivity to salinity and that the increased soil salinity results in increased sensitivity of sugar beet to salinity.

The study was conducted during 2002- 2007 in the first and last stage of a four-year rotation (sugar beet, forage maize, onion, wheat and sugar beet) at Research Station of Irrigation and Drainage Rudasht. In each year, four treatments of organic fertilizers (25 and 50 t/ha urban compost and 15 and 30 t/ha sewage sludge) with a control (no organic fertilizer) were studied in a randomized complete block design with three replications. It was revealed that the maximum organic carbon content, available potassium and lead in the soil was observed in the 50 t/ha urban compost, treatment whereas the maximum available phosphorous and copper in the soil was associated with the application of 30 t/ha sewage sludge. As time elapsed, the available zinc in the soil was enhanced significantly by application of urban compost. Utilization of urban compost as well as sewage sludge significantly enhanced the sugar beet root yield. However, the sugar content was decreased. The decrease in sugar content was greater for the sewage sludge treatment than for the urban compost treatment. In the last year of the rotation, the effect of application of the organic fertilizer on sugar yield was not significant. However, due to the increase in the root impurities resulted from the application of urban compost as well as sewage sludge, the white sugar yield in the last year showed a significant decrease in comparison with that of the first year of the rotation. It follows that continuous application of the types of organic fertilizers, particularly the sewage sludge, to the Rudasht district of Esfahan as well as regions with a fine textured soil is not recommended.

Urea is the most common form of nitrogen fertilizer used in sugar beet cultivation. Urea has a high solubility and its losses are high and consequently its efficiency is low. It is supposed that urea solubility can be limited and its efficiency can be increased by using slow-release nitrogen fertilizers. By conducting an experiment in three important sugar beet cultivation areas of Khorasan Province, the effects of Urea (soluble form of N-fertilizer) and Urea formaldehyde (slow-release N-fertilizer) application in sugar beet cultivation were investigated. In each area, by using a randomized complete block design replicated three times, effects of six fertilizer treatments including three levels of 75, 100 and 125 percent of nitrogen requirement calculated based on soil test from two sources of Urea and Urea formaldehyde were evaluated. Soil samples were taken before cultivation and three times during the growing season and their NO3-N and NH4-N content were determined. During the growing season, leaf samples were taken three times and their NO3-N content was determined. In addition, the quantity and quality of roots were determined after harvesting. The results showed that application of 250 kg N.ha-1 from Urea formaldehyde (equal to 650 kg. ha-1 Urea formaldehyde), with mean root and white sugar yields of 48.836 and 6.544 t.ha -1 respectively, improved the root and white sugar yields for 1500 and 300 kg.ha -1 respectively as compared with the control treatment. Application of Urea formaldehyde as compared with urea increased the NO3-N and NH4-N content of the soils. In two out of the three sites, the increase in white sugar yield due to this treatment was more than one ton per hectare. This finding necessitates more research concerning the application of Urea formaldehyde in sugar beet production.

In order to study the reason for the prominent increase of the average of sugar content in sugar beet produced in Iran in 2007 and finding the relation of this increase with climatic parameters, Chenaran sugar factory district was chosen. Due to precise and reliable statistical data of sugar factory during the campaign and weather data, Chenaran sugar factory was chosen for this investigation. The most important climatic parameters affecting the sugar content of sugar beet (temperature, precipitation, relative humidity, sunshine hours and wind speed) as well as their changes in 2007 in comparison with the previous years were investigated. Regression analysis on the final number representing the sugar content of sugar beet produced in the factory during 2001- 2007 as dependent variable and monthly climatic parameters as the independent variables was conducted. Furthermore, the effect of climatic parameters on soil tare and sugar content of sugar beet during the campaign was analyzed. The daily data of soil tare and sugar content in Darzab district during the campaign of the sugar factory in 2007 were arranged in the form of 10-day averages which were fitted against the 10-day averages of sugar beet soil tare and sugar content and subsequently linear correlation coefficients were calculated. By using the stepwise method, the most important factors were determined. The results showed that among the climatic parameters, the most significant factor affecting sugar content was the minimum temperature in August. The decrease of minimum temperature on August is justifiable by considering the plant physiological changes. The number of days with a temperature of -4°C or less (freezing days) and relative humidity, respectively, had the highest correlation with the soil tare and sugar content in 2007. Therefore, the climatic parameters, especially the minimum temperature in August and in case of the severe increase of temperature, proper and well-timed irrigation has significant effect on sugar content. Proper planning of harvesting and delivering the sugar beet during Autumn regarding to meteorological forecasting in each zone can play a substantial role in decreasing the soil tare and increasing the sugar content of sugar beet.