مجله چغندر قند
سال بیستم شماره 2 (پاییز و زمستان 1383)

To determine suitable planting date and predicting emergence time in field conditions of Iranian sugar beet cultivars we need some information including base temperature (t base) and heat units (HU). In this research germination tests were conducted on the seed of seven Iranian monogerm sugar beet cultivars at various temperatures (3 to 36 ºC) with 3 ºC intervals. Also field emergence was evaluated in two years (2003-2004) with two planting dates in each year. This study determined optimum temperature and tbase for germination and mean germination time (MGT) at various temperature in laboratory and also mean emergence time and HU requirement in each planting date under field condition. Results showed that t base for germination in different cultivars is varied between 2 to 3 ºC with mean 2.6 ºC. The maximum germination percentage was in temperature between 12 to 27 ºC, but optimum temperature for germination was 24 to 27 ºC that there was maximum rate of germination in this range of temperature. Required HU was 51 ºCd for germination and 154 ºCd for emergence under field condition.

Selected genotypes of sugar beet are often maintained by conventional propagation, but much faster rates of multiplication can be now obtained through micropropagation. On the other hand, plant micropropagation using bioreactors can decrease the cost of production and makes it an economical method. In this research, the possibility of using bioreactor and optimization of the tissue culture procedure in sugar beet micropropagation was studied. A simple periodical bioreactor was made by using a timer, air pump, microfilters (0.2 μ), and air and medium autoclaveable transfer pipes. In vitro stock plantlets from seeds and liquid MS basal medium supplemented with 1.5 mg.l-1 BAP, 0.2 mg.l-1 NAA, 0.5 mg.l-1 GA3, and 3% sucrose were used for inoculation and multiplication in the bioreactors. Periodical nutrition of the explants established for 10 minutes every 6 hours. The same basal medium with 3 mg.l-1 IBA was used for root induction. Bioreactor system was compared with routine in vitro procedure in tissue culture laboratory. Results showed that the bioreactor system multiplication rate, number of shoots, and biomass production was significantly different from routine in vitro culture in 100 ml jars. Rooting percentage in bioreactor was very low and needs more study to optimization.

To study the effect of seed treatment on damage of harmful moths of sugar beet, an experiment was conducted in RCBD with nine treatments in four replications in Karaj for three years (1996-1998). The treatments were applied as follows: T1, check, T2, T3 and T4, sugar beet seeds treated with Imidacloprid, Fibronil and Orten, respectively; T5, pelleted seeds without insecticide; T6, T7 and T8, pelleted seeds with Imidacloprid, Fibronil and Orten, respectively; T9, sprayed traditionally. Each plot consisted of six rows in ten meter long. In T9 Eterimphos 50% with 0.002 dosage was used. Data were taken on harmful moths of sugar beet, including, cut worm (Agrotis spp.) and armyworm (Spodoptera exigua). Percentage of infested plants with each pest (% damaged plants) was determined separately. Statistical analysis of three years data showed no significant difference between treatments for percentage of damaged plants by cut worm, but significant difference for those of armyworm.

For the purposed water resources management, irrigation scheduling, water usage optimization and gaining maximum yield two step FAO method was applied to determine the water requirement (evapotranspiration) of sugar beet. In this paper reference evapotranspiration were computed from recorded meteorological data at 38 weather stations using the hargreaves-samani method; and then through applying proper crop coefficient the amount of sugar beet potential evapotranspiration were calculated. Sugar beet potential evapotranspiration at 3045 points (3300*5200 m) distancing from weather stations were estimated Using three interpolation methods (cokriging, kriging and inverse distance weighted) and based on derived data the spatial distribution maps for sugar beet potential evapotranspiration in Tehran province were developed through geographic information system (GIS). Evaluation of developed maps based on mean square error (MSE) which was computed by cross-validation showed that the map of cokriging interpolation method was the best. In Tehran, the minimum and maximum sugar beet evapotranspiration during July were 5.5 and 10 mm/day respectively, which equals 0.64 and 1.2 lit/sec/hectare. The acquired minimum and maximum sugar beet evapotranspiration at growth period in Tehran province were 600 and 1200 mm, respectively.

A total of 105 isolates of Erysiphe betae from different regions of Iran were investigated. For probable polymorphism of ITS-5.8S regions using PCR-based RFLP, the mentioned fragments were amplified via PCR by ITS1 and ITS4 primers and subjected to 1.5% agarose gel electrophoresis. PCR products were digested by HaeIII, AluI, TaqI, HindIII, CfoI, EcoRI, MspI, SacI and RsaI REs and the digestion products were resolved on 7.5% polyacrylamide. PCR product of all isolates was only one 645 bp fragment. Among nine REs tested AluI, CfoI, MspI and HaeIII had recognition sequences on PCR products. Because of unstability, results for AluI were ignored.Digestion products for CfoI were 280, 185 and 180bp, for MspI, 325, 160, 120 and 40bp and those of HaeIII, 325, 180, 75, 40 and 30bp fragments for all isolates. Electrophoretic patterns of PCR products and digested products were completely similar,thus no polymorphism was discernible between 105 isolates. Based on the results,Iranian populations of E.betae seems to be highly uniform.

Due to the high antagonistic activity of bacterium, Bacillus subtilis (Ehrenberg) Cohn, three isolates (B.s.Ham, 204 and 202) were selected and their efficacy were studied in control of sugar beet damping–off caused by Rhizoctonia solani, in in vitro and in vivo conditions. In dual culture on PDA, all isolates of B.subtilis inhibited mycelial growth of R.solani. Significantly, volatile metabolites of B.subtilis isolates reduced mycelial growth of R.solani. Inhibitory ability of volatile metabolites of B.subtilis isolates were studied in different culture media. In this experiment, isolate B.s.Ham on PDA with inhibition percent of 62.22%, had the best effect in reduction of mycelial growth of R.solani. Inhibitory effect of five concentration (2%-5%-10%-15%-25%) of culture filtrates of bacterial isolates were studied and it was found that isolate B.s.Ham in 25% concentration with 73.70% was the most effective in inhibition of mycelial growth of R.solani. In green house experiments, we found that seed coating or soil drenching by antagonistic agents, 30 days after sowing, had a good effect in mortality and there were significant differences among treatments. Among isolates, B.s.Ham with 64.59% in comparison to the infected control had the best effect on control of this disease. Overall, soil drenching of antagonistic bacteria was more effective than seed coating, in reducing of sugar beet damping-off.