مجله چغندر قند
سال بیستم شماره 1 (بهار و تابستان 1383)

To determine the effects of steckling weight and planting density on seed quantitative and qualitative characteristics of monogerm sugar beet c.v. 9597, this experiment was carried out in Ardabil Agricultural Research Station in two years (1998-99). In this study, steckling weight with three different sizes(including <100, 100-200, and 200-300g) as main-plot, and planting density with three levels (including 40, 50 and 60 cm) as sub-plot were used in a split-plot experiment based on the RCBD with five replications. In this experiment morphological and qualitative (rate and uniformity of germination) characters, seed size distribution, and monogerm seed percentage were measured. According to the results, effect of planting density on the axillary branches number and seed yield was significant at 1% probability level. Seed yield increased by 43%, as planting density was increased from 40 to 60 cm. Increasement of steckling weight led to increasement of standard seed portion (with 3.5-4.5mm in diameter), germinable standard seed yield (11%) and reduction of germination rate and germination uniformity; and increasement of planting density was accompanied by increasing of >4.5 mm seed portion, velocity and unifomity of germination and decreasing of germinable standard seed yield. Eventually, the highest crude (1208 kg/ha) and germinable standard (229.16 kg/ha) seed yield were obtained by using steckling weight of 200-300 g and planting density of 60cm.

Saline and drought stress conditions are the most important factors in yield reduction of crops in the world. Breeding of cultivars with high tolerance to these stresses and satisfactory yielding are considerable. The aim of this study was to compare the means of selected generations in saline and drought stress conditions in order to calculate response to selection. In this study two populations (8001 and 7233) and their successive generations which were selected based on tolerance to salinity, as well as two breeding materials (BP-Karaj and BP-Mashad) and their generations which were selected for tolerance to drought stress were evaluated under stress conditions. The results showed that response to selection in 8001 sequential generation was higher than that of 7233 in saline condition and selection has increased the root and sugar yield. Also, selection for drought tolerance in BP-karaj and BP-Mashad has increased the tolerance. It seems that, this method of selection was useful for the improvement of these populations in stress conditions.

Water stress decrease water content and water potential between soil and root. Therefore, water potential of plant declines and plant faces with water stress. Water stress in different stages of growth can be useful in different aspects. Water stress can be practiced from two point of view, increasing water use efficiency (WUE) and improving cultural practices. No irrigation in insensitive stages of growth for water stress helps us to save water which could be used for other crops. In this research, the effect of irrigation scheduling at different stages of growth on quality and quantity of sugar beet was studied, in Khoy Agricultural Research station in two years (1999 and 2001). The experimental design was a randomized complete block design with three replications and seven irrigation treatments; as I1:Full irrigation at all stages of growth, I2: No irrigation at sowing until germination, I3: No irrigation at germination until the beginning of growth; I4: No irrigation at sowing till germination and again no irrigation at growth season, I5: No irrigation at sowing till germination and no irrigation at the end of season, I6: No irrigation at the germination till constant growth and one irrigation during constant growth, I7: No irrigation at germination till constant growth and no irrigation at the end of season. According to the results, irrigation treatments influenced the root and sugar yield significantly. Lack of irrigation in the initial increased stage sugar yield 13.3% and decreased irrigation water amount 16.5% as compared to the control treatment (I1, full irrigation). WUE was 1.7 and 1.25 kg/m3 in I2 and I1 treatments, respectively. Omitling irrigation in the initial and in the last stage of growth decreased the irrigation water amount 21.2%, increased available sugar 11% and improved WUE from 1.25 (control treatment) to 1.76. Irrigation treatments had significant effect on sugar content and Na (impurities) and no significant effect on other qualitative characers. No irrigation in initial and last stages of growth caused the most highest increase in sugar content of compared to the control treatment. Accordingly, sugar content increased from 12.74% to 16.09%.

In the present study, vegetative compatibility groups (VCG) of 27 isolates of Fusarium solani collected from root and crown of sugar beets of different provinces in Iran were determined using nitrate non– utilizing (nit) mutants. Totally, 222 nit mutants were generated from 27 isolates using PDC medium. Based on the weak growth on basal medium containing one of four nitrogen sources the phenotypic classes of nit mutants were determined. Among them, 44%, 36% and 20% of nit mutants were belong to phenotypic classes nit1, nit3 and nitM, respectively. To determine VCGs and complementation tests, pairing were made between all nitM and nit1 or nit3. In a compatible reaction between nit M and the two other mutants, a dense growth at the line of contact between two colonies was formed which was more than those between nit1 and nit3. All isolates belonged to 14 VCGs, of which ten were single member and four were multi member. No corelation was observed between VCGs and the geographic origin of isolates and also between the VCGs and the type of disease symptoms.

Experiments were conducted in 1998 and 1999 to study the effects of different levels of potassium and irrigation intervals on yield and water use efficiency of two genotypes of sugar beet (A37.1 and 12681) in Khorasan Agricultural Research Center (Torogh, Iran). Potassium levels were; no potassium application, increasing potassium to 5% of soil cation exchange capacity (CEC) and second treatment plus plant requirment to potassium. Irrigation interval were 9, 12, 15 and 18 days. In 1998, the amount of water in each irrigation was based on local farmer usage (that is 739 mm). In 1999, for increasing water stress, the amount of water decreased 25% as compared to the previous year. Root yield and white sugar yield in two years and water use efficiency in first year were significantly affected by irrigation amount (P<0.01). Among different irrigation intervals, white sugar yield was the highest in 12 and 9 days irrigation frequencies in 1998 and 1999, respectively. In 1998, root yield, white sugar yield and water use efficiency increased when the potassium of soil increased to 5% CEC in different irrigation intervals. Accordingly, for white sugar yield in 9,12,15 and 18 days irrigation frequencies were 11.5%, 7%, 9% and 10%, respectively. In 1999, applying potassium caused reduction in white sugar yield in 12, 15, and 18 days irrigation intervals, which might be due to the decrease in the amount of irrigation water. However, white sugar yield increased in the 9days irrigation interval. According to the results, potassium application had positive effects on yield and water use efficiency only in normal or moderately water stressed conditions.

To study the critical period of weeds competition with sugar beet and determine the duration that the crop can tolerate the weeds, a field experiment was carried out at Esfahan Agicultural Research Center, in Kabotarabad-Esfahan during 1999-2000. The experiment conducted in RCB Design with 14 treatments and four replications. The treatments included control throughout the growth season (as a check), till and after 4, 6, 8, 10, 12 and 14 weeks from crop emergence together with no weed control during the whole growing season. The result showed that the weeding until four weeks after planting had a positive effect on root yield and sugar yield. The results also indicated that there was a critical period for weed control between 4-21 weeks after planting (WAP).There was a significant interaction between the plant density and establishment with the period of weed control. There was no critical period for sugar content, Na, K and NO3. This study showed that the best period for weed control in Baran(Esfahan) would be 4-21 WAP.

It is so far that, experimental scientific researchers have considered modeling because it explains experimental process by simple mathematic relations so they would be more understandable. Modeling is finding relation between logic and related process and producing a dynamic system by which we can predict system changes and prepare conditions for stimulating crop growth and production and increasing model factor in a specific location and also give a best program to improve crop production. We can reduce repeated experiments and research costs without any problem to results by using model. Also modeling can be used to introduce new crop for special region, improve factors affected crop growth, investigate crop yield changes in different climate and deliver production to market on time which would be more profit. So we should use different science such as physiology, computer, mathematic and statistics, irrigation, system engineering, climatology, agronomy and pedology to design a perfect model especially a crop model. As a result model designing is very complicated and needs group working. Beside this matter, model calibration faintness and finalization requires exact basic information and accurate analysis and programming in collection of information which are produced by different researchers in farms laboratories and climatology stations. These data with climate information will be used in models. There are different crop models (Mastrorilli et al 2000,…) which are based on SUCROS mechanistic model in which growth expression is depend on main reaction such as co2 assimilation, respiration and environmental effects. This model uses FST software for simulation, and estimates potential crop growth in sufficient water and nutrition environment without any insect, disease and weed (Nasiri Mahalati,2000) that the crop is only affected by climatic and physiological factors in this environment. One of the model designed for sugar beet is INTERCOM which is based on SUCROS and simulates the competition between sugar beet and Chenopodium album (Kropff and Vanlaar 1993). Climate, soil and sugar beet physiological data are needed to calibrate this model in special region. There are limited collections of these data with cross relations in places of our country. For example although a little sugar beet physiological and morphological data are existed in some regions, other specified data aren’t measured in these places or accessibility to climate data in the form which is profit for models would be difficult so it was observed that INTERCOM model couldn’t desirably simulate LAI changes (one of the most growth parameters) but by many changes in some parameters, it was fit with dry matter information by using the data collected from Kermanshah in 1991 (figure 1). So it is necessary to measure some of model physiological parameters directly in order to use correct and precise value for model simulation. Model calibration needs basic data which will be given to the modeling group only by researcher and won’t be found in analyzed and statistical information of reports and articles. So co-working of expert people and complete information of crop and climate will be needed to improve modeling and it's calibration in places with different climate and management.