Journal of Sugar Beet
Year:2010 | Volume:25 | Issue:2|Papers Count:10

This experiment was conducted to evaluate eight new sugar beet genotypes with different drought tolerance responses to three irrigation schemes (including normal irrigation and early season and continuous stressed) in Motahari Research Station of Sugar Beet Seed Institute (SBSI), Karaj, Iran during 2005-2006. The study was accomplished in a split plot design (irrigation schemes and genotypes as main and sub-plots, respectively) based on randomized complete blocks design with four replications. Results showed that the normal irrigation (irrigation after 80 mm evaporation from class A pan) and early season stress (three times irrigation for plant establishment, no irrigation until 500 mm evaporation from class A pan, and then regular irrigation up to the end of growth period) were in the same statistical group for root yield, white sugar yield and root/shoot ratio. But, early season stress increased water use efficiency (WUE) by 35 % compared with the normal irrigation. Maximum sugar content, white sugar yield, WUE and stress tolerance index (STI) were obtained for 7112, BP Karaj and RS003 genotypes and minimum values for 7221-II. Compared with 7221-II, 7221-II*I13 had higher sugar content, white sugar yield, WUE and STI about 22, 49, 62 and 187 percent, respectively, and better yield stability than other genotypes under stress conditions. Our study results indicate that fodder beet germplasm with a high root production potential in drought conditions could be used in sugar beet breeding programs. Transfer of fodder beet root production character to sugar beet in drought conditions is likely to increase the efficiency of sugar beet breeding programs for drought tolerance.

The root pulling force as well as the amount of transferred soil has not been reported quantitatively for various sugar beet types. This study was designed to measure the amounts of transferred soil from farm and estimate the root pulling force among sugar beets populations with different root shapes at harvest time. The experiment was conducted as a split plot with a randomized complete block design with four replications at Motahari Research Station, Karaj in 2002 and 2003. Main plots were allocated to soil moisture contents at harvest time and subplots to 7 sugar beet populations with smooth elliptic, conical and grooved conical root (normal beet) forms. Sugar beets were compared at 40% soil water depletion in 2002 and at field capacity as well as 40 percents water depletion in 2003. Broken roots were 8, 10 and 13% for smooth elliptic, conical and normal conical forms, respectively. Percentages of broken roots in smooth elliptic and conical forms were 38 and 23% less than the normal types, respectively. Pulling forces in these forms were 59 and 52% less than normal sugar beet, respectively. There were no significant differences for root and white sugar yield among different forms. However, lower losses, soil tare and pulling force of smooth conical roots makes them more preferable than the normal roots, for breeding purposes.

Planting pattern can be adjusted by changing row spacing and row width, one row and two- row planting and plant interval on rows. In order to obtain the optimum planting pattern of a monogerm hybrid cultivar and its effect on the quantitative and qualitative characteristics of this cultivar, an experiment was conducted in two years (2001-2002) in Zarghan area of Fars province. The measured characters were as follows: root yield, sucrose content, percentage of the extractable white sugar, juice purity and impurities (a- amino N, sodium and potassium). The experiment consisted of five treatments replicated four times in a randomized complete block design. The treatments included: 1) Row spacing of 60 cm, cultivated in one row. 2) Row spacing of 50 cm, cultivated in one row. 3) Row spacing of 60 cm, row width of 40 cm and cultivated in two rows. 4) Row spacing of 50 cm, row width of 50 cm and cultivated in two rows. 5) Row spacing of 40 cm, row width of 60 cm and cultivated in two rows. Each plot consisted of four rows with 10 meters length which were planted by planter. During the growth period, numbers of existing and missing plants were recorded. Analysis of variance was done with MSTATC and the means were compared by Duncan’s Multiple Range Test. The overall results of the two years showed that the effect of treatment on root yield was significant at 5% probability level. The maximum root yield was obtained in the second treatment (row spacing of 50 cm cultivated on one row) with the amount of 78.93. Although, the sugar content of the second treatment was low (14.09%) but due to increased root yield, the amount of white sugar yield was higher (7.59 t/ha). The effect of cultivation pattern on the impurities (potassium and a-amino N) was significant, but not significant for sugar content, percentage of extractable white sugar, percentage of sugar extraction, and white sugar yield.

Irrigation requirement equals the difference between water requirement and effective rainfall which can be estimated by considering the water application efficiency. The values of water requirement and irrigation requirement of sugar beet have been reported using NETWAT program in different regions of Iran. However, the mean values were used in this program; therefore the values of water and irrigation requirements have the probability level of 50 percent. In the current study, the values of sugar beet irrigation requirement in the probability levels of 10, 20, 30, 40, 50, 60, 70, 80 and 90 percentage and critical conditions (high evapotranspiration and low rainfall) were determined in some regions of Fars province such as Abadeh, Eghlid, Darab, Dorodzan Dam, Zarghan, Shiraz and Fasa by using long- term weather data. The results showed that the critical irrigation requirement of sugarbeet was equal to its irrigation requirement in the probability level of 90 percent, and the reported values of sugar beet irrigation requirement by NETWAT program were equal to 92 percent of its critical irrigation requirement, in Fars province. Also, it is possible to estimate sugar beet irrigation requirement in different probability levels and critical condition by using the obtained regression equations in Fars province.

In order to improve the efficiency of irrigation systems and investigate their impact on the pest population levels, furrow and sprinkler irrigation systems were compared in sugar beet fields. In this study, three different fields were chosen and irrigated by one of the furrow, classic and center pivot irrigation systems. In each field, 20 plots were randomly selected of which 10 plots were marked as untreated control and the rest were sprayed with insecticides. During the growing season, the numbers of insect pests were weekly recorded. Results of the experiments indicated a significant difference between root yield of sugar beet in furrow irrigation and center pivot irrigation with 71.31 t/ha and 61.36 t/ha, respectively, while no significant difference between furrow and classic irrigation systems was observed. Sugar yield in furrow, classic and center pivot irrigation was 7.92 t/ha, 8.96 t/ha, and 7.39 t/ha, respectively. There was also a significant difference at 5% level between classic and furrow irrigation but the difference between center pivot system and classic irrigation was not significant. The rate of sugar beet infestation by cutworms (Agrotis spp.) and armyworm (Spodoptera exigua) in furrow irrigation was 1.146% and 2.033%, respectively which was significantly different from classic irrigation (0.858% and 1.69%) and center pivot system (0.872% and 1.692%). In classic irrigation, the larval population of S. litorallis was 0.932 per plant which was significantly different from furrow irrigation with 0.825 larvae/plant. Treated and untreated plots were not significantly affected by the pests in furrow and center pivot irrigation systems, but there was significant difference between root yield of sugar beet in treated plots (71.99 t/ha) and untreated plots (66.92 t/ha) in classic irrigation.

Biological control of sugar beet damping-off of Rhizoctonia solani AG-4 by two native Streptomyces isolates (S2 and C) was evaluated in green house and field conditions. In dual culture, two Streptomyces isolates inhibited mycelial growth of R. solani AG-4. Besides, volatile components of S2 and C inhibited R. solani mycelial growth for 72 and 74 percentages, respectively. Soil treatment either with isolate S2 or C inhibited Rhizoctonia damping off in sterilized soil inoculated with the fungal pathogen. Isolate C increased plant stand for 76 percentages and was more effective than S2. To elucidate the mode of antagonism, chitinase activity and siderophore production were evaluated. Both isolates showed chitinase activity on medium containing colloidal chitin and biosynthesis of siderophore was detectable for both isolates. A three- year study (2005- 2007) was conducted to evaluate the effectiveness of S2 and C on control of sugar beet Rhizoctonia solani damping off under field conditions. Streptomyces seed treatments significantly (p£0.05) reduced seedling damping off compared to untreated control in naturally (2005) and artificially (2006 and 2007) infested soils. There was no significant difference between the isolates in disease control. Seed treatment with Streptomyces isolates reduced root rot significantly (p<0.05). In 2006 and 2007, the bacterial isolates increased healthy beets up to 80% and 95%, respectively.

In order to find the plant extracts with antifungal activity, 18 plant species were screened. In this study, distilled water, methanol, chloroform, aceton and ethanol were employed to obtain crude extract from plant samples. The extracts were tested against sugar beet root rot agents, Rhizoctonia solani and Phytophthora drechsleri. The inhibitory effect of different extracts was investigated by paper disc method. The most effective antifungal compounds belonged to Carum copticum, Zataria multiflora and Pinus halepensis extracts, so that they showed high inhibitory activity in 1 mg/paper disc. The results of this research revealed the high potential of using natural plant extracts for controlling of plant pathogens.

In order to investigate the impact of government policies on supply, cropping area and yield of sugar beet during 1981-2003, nominal rate of protection (NRP) was applied as a variable to persuade government’s policies in this study. Results showed that despite of its negative impacts on cropping area, the NRP has positive effects on supply and yield of sugar beet in Iran. Moreover, real price of sugar beet has no significant effect on supply, cropping area and yield of sugar beet. The elasticity of supply, cropping area and yield functions with respect to the NRP was found to be 0.2, -0.029 and 0.25, respectively, indicating that the government supports can lead to yield and supply improvement.