مجله چغندر قند
سال بیست و هفتم شماره 2 (پاییز و زمستان 1390)

The current study was carried out to examine sugar beet growth pattern in climatic conditions of Hamedan, Iran and to recognize the factors affecting its quantity and quality as well as the physiological indices. Two sowing date experiments were conducted on the basis of a Randomized Complete Block Design with four replications and 11 harvests. The plots were destructively sampled and the growth was analyzed by regression method on the basis of the variations of leaf area index, leaf dry weight and total dry weight which are the basis of growth analysis. Results revealed that the maximum crop growth rate of the earlier sowing date reached to 20.2 and 23.3 g.m-2.d-1 90 days after planting in 2002 and 2003, respectively. In the second sowing date, maximum crop growth rate reached to 29.5 and 25.0 g.m-2.d-1 110 and 96 days after planting in 2002 and 2003, respectively. Maximum leaf area index of the earlier sowing date was obtained about three months after planting approximately concurrent with the realization of maximum crop growth rate and reached to 2.5 in 2002 and to 2.6 in 2003, but it started to slowly decrease at later growth period. Relative growth rate was the highest at the early growth period and linearly decreased during growth period. Net assimilation rate firstly increased slowly, but as the leaves grew and shaded each other, it started to decrease. The highest root growth rate in the earlier sowing date reached to 10.1 and 20.0 g.m-2.d-1 94 and 92 days after planting in 2002 and 2003, respectively. The highest root growth rate in the second sowing date reached to 14.0 and 17.3 g.m-2.d-1 108 and 95 days after planting in 2002 and 2003, respectively. In total, root potential yield was considerably higher in the earlier than in the delayed sowing date under climatic conditions of Hamedan in both years. The sugar beet growth pattern-related physiological indices were greatly consistent with crop yield potential during growing season. Therefore, given the climate changes and global warming, sugar beet sowing in the earliest possible date in Hamedan is recommended in terms of physiological indices and yield.

In order to further understand the emergence and germination of sugar beet monogerm cultivars under moisture stress, the current study was carried out at three stages. At the first stage, the quality of germination of three monogerm cultivars (Rizofort, Rasoul and Zarghan) were studied under five moisture stress levels (0, -2, -4, -6 and -8 bars) in germinator at 15°C by between-paper method. At this stage, after the onset of the germination, the number of germinated seeds was daily counted and at the end, germination percentage and rate was determined. The second stage was similar to the first one with the difference that at this stage, the percentage of normal and abnormal seedlings was determined 14 days after sowing and then, radicle length, coleoptile length and their ratio as well as radicle and coleoptile dry weight and their ratio were measured for each treatment. At the third stage, the studied cultivars were evaluated in clay soil in growth chamber under moisture stress of 17.5, 20, 22.5 and 25% (control) of soil volumetric moisture. At this stage, when emergence started, the number of emerged seeds was daily counted and then, emergence rate, days to 50% emergence and final emergence percentage were determined for each cultivar and treatment. The statistical design of all stages was a two-factor factorial (the levels of the factors were different at each stage depending on the number of treatments) based on a Randomized Complete Block Design with four replications. The studies were carried out in the laboratories of Agricultural and Natural Resources Research Center of Kermanshah, Iran. Results of the first study showed that moisture stress significantly impacted germination percentage and days to 50% germination, so that as moisture stress was intensified, germination percentage decreased. Also, results revealed that germination percentage of cv. Rizofort was higher than that of Rasoul and Zarghan. Results of the second study indicated that moisture stress significantly affected normal seedlings and ungerminated seeds at 1% probability level. According to the results of the third study too, moisture stress significantly influenced emergence percentage, emergence rate and days to 50% emergence. Results showed that the emergence of sugar beet seeds dramatically decreased at soil volumetric moisture level of lower than 17.5% (-6 bars soil tension) and the emergence percentage of sugar beet seeds did not significantly change with the increase in clay soil volumetric moisture level from 20 to 25% (soil tension of -3 to -0.3 bars).

To determine sugar beet water requirement and the effect of changing the quantity of applied water on some production components, a study was carried out in Ekbatan Agricultural Research Station of Hamedān, Iran in four years (1994-1997) during which optimum water requirement, root and sugar yield, water use efficiency on the basis of root yield, sugar percentage and water use efficiency on the basis of sugar yield under no water and nutrients limitation conditions were measured and compared by water balance method for four growth periods of 130, 134, 152 and 162 days. At the same time, the water requirement of reference crop - poa - was measured by lysimeter in order to study the pattern of the variations of sugar beet crop coefficient. It was found that the amount of applied water for sugar beet was 8427, 7328, 10256 and 9026 m3.ha-1 in the four studied years, respectively with the average amount of 8759 m3.ha-1. Average four-year maximum crop coefficient was 1.04 at mid-growing season and the minimum one was 0.42 at early-growing season. The highest root yield, sugar yield and sugar percentage was obtained from 162-day growth period (116.8 t.ha-1, 20.36 t.ha-1 and 17.43%, respectively). The lowest ones were obtained from 130-day growth period (52.21 t.ha-1, 8.5 t.ha-1 and 16.26%, respectively). Results revealed that in 130-day growth period, root yield decreased and meanwhile, water use efficiency on the basis root yield and sugar yield was decreased to 7.1 and 1.2 kg.m-3 applied water, respectively. In the longer growth period, water use efficiency on the basis of root yield and sugar yield was 11.4 and 2 kg.m-3 applied water, respectively.

Hargraves-Samani method is one of the methods for calculating plant evapotranspiration that needs minimum meteorological data. In order to evaluate ET-HS model in determining sugar beet crop water demand in Isfahan, an experiment was conducted at research field of Department of Agriculture, Khorasgan Branch, Islamic Azad University, Isfahan, Iran in 2005. The study was based a Randomized Complete Block Design with three replications and six irrigation treatments. Irrigation treatments included irrigation to supply 50, 75, 100, 125 and 150% of crop water demand on the basis of ET-HS model and control on the basis of 90 mm evaporation from Class A evaporation pan during growing season. Results showed that the effect of irrigation treatment was significant on total dry matter and root yield. In addition, root yield increased in the treatment of irrigation to supply 150% of crop water demand. But, sugar percentage increased up to irrigation to supply 100% of crop water demand albeit insignificantly, and then started to decrease. White sugar yield significantly increased to 8.7 t.ha-1 up to irrigation to supply 100% of crop water demand and then, started to decrease with further increase in irrigation level. The highest water use efficiency for root yield was obtained from the irrigation to supply 50% of crop water demand. Given the precision of ET-HS model in control treatment, it can be used for irrigating sugar beet in such regions as Isfahan and sugar beet water demand can be determined only on the basis of the daily temperature data without using the data of evapotranspiration or soil water depletion, so that the yield does not decrease and the appropriate white sugar yield is obtained by the application of minimum irrigation level.

The study was carried out in the fields of Department of Agriculture, University of Lorestan, Iran (Lat. 32°18´ N., Long. 45°22´ E.). According to the data gathered in the nearest synoptic meteorological station, the studied region is classified under semi-arid climates. Mean maximum and minimum daily temperatures have been recorded in July and January as 29.5 and 5.5°C, respectively. Mean annual precipitation is 509 mm. Four control profiles were selected out of 30 dug profiles. The soils were in two categories of Inceptisols and Entisols. In total, 4 families and 12 soil field units were recognized. The objective of the current study was to compare the qualitative evaluation of land suitability and radiation-thermal production potential of sugar beet in two regions of Khorramabad and Silakhoor Plain, Iran, by FAO method. Results showed that sugar beet production potential was 67950 kg.ha-1 in Khorramabad and the land suitability classes were determined as S2 and S3 by parametric method, whereas land suitability classes were S2, S3 and Ns in Silakhoor Plain. The main soil constraints included CaCO3, relief and detritus in Khorramabad, while they were drainage, relief, soil texture, detritus, soil reaction and exchangeable Na percentage in Silakhoor. Therefore, farmers can improve the productivity by removing the modifiable limitations and improving management. But, the expenses of physical, chemical and mineralogical analysis of soil samples were low in this study.

Cellulose is a raw material which is extensively used in the manufacture of paints, papers, textiles, agricultural products and cosmetics. The waste of sugar beet pulp after titration is a source of cellulose. The current study was carried out to study the possibility of cellulose production from sugar beet pulp waste at titration stage as a 3×3×2 factorial study on the basis of a Randomized Complete Block Design with three replications. So, firstly the waste of titrated sugar beet pulp was collected, washed, dried and ground. Then, the ground sample was hydrolyzed by hydrochloride acid 0.6 N at 45°C for 48 hours and was mixed with water at 70°C for one hour in order to isolate dissolved pectin and pectic compounds. Then, the remaining waste was washed, dried and treated with soda solution with the ratio of 1 g waste:100 ml soda solution at three levels with the concentrations of 2.5, 5 and 7.5% (w/v) at three lengths of soda impact including 8, 10 and 12 hours and two levels of temperature of soda impact including 24 and 45°C in order to isolate the basic medium-dissolved polysaccharides from cellulose. The measured traits included relative purity, viscosity and cellulose molecular mass. Results showed that the effect of soda concentration and stirring length as well as their interaction was significant on relative purity at 5% probability level. In addition, it was revealed that out of the studied treatments, the cellulose extracted through treating with 5% soda stirred for 12 hours at 45°C had significantly higher quality given that it enjoyed 95.2% relative purity, 15.9 mPa.s-1 viscosity and 255000 kg.mol-1 molecular mass which were significantly higher than those of other treatments. Therefore, this method allows extracting cellulose with 95.2% relative purity from sugar beet waste.

As an industrial crop, sugar beet plays an important role in meeting domestic demand for sugar. Given the higher level of imported sugar in Iran, the application of protectionist policies is an approach for supplying required sugar. One of these policies is technological improvement. In order to study the effect of this policy, sugar beet supply and demand equations in 1971-2008 were fitted by two-stage least squares method and then, the impact of technological improvement on the welfare of producers, customers and finally, on social welfare was examined under three scenarios of 1, 4 and 10% reduction of prices resulting from technological improvement. Results show that price elasticity of demand is -0.02 and of supply is 0.013. Furthermore, we found that this policy provides more protecttion for the consumers under all studied scenarios given the share of consumer's welfare surplus from total social welfare surplus.

A strength of agricultural production cooperatives is improving the technical knowledge of their members which is along with their function in large-scale development. One of the main obstacles to the success of cooperatives is their inability in improving the technical knowledge of their members. The current study evaluates the role of production cooperatives of Fars province, Iran in improving sugar beet growers’ technical knowledge level. Questionnaire was used for information collection. The questionnaire was validated after some revisions following consulting with professionals and experts. To realize the reliability of the questionnaire, Cronbach’s coefficient α was calculated as to be in the range of 0.71-0.82 for different sections of the questionnaire which was a proof of its high reliability. The data were collected from 148 questionnaires filled out by member and non-member sugar beet growers in production cooperatives. The farmers were selected by multi-stage stratified random sampling method. Factorial analysis of variance was used for analyzing the data. Results showed that personal factors including literacy level, age and field size did not impact farmers’ technical knowledge improvement. Furthermore, membership in cooperatives did not by itself affect technical knowledge improvement, whereas the effect of region and the interaction between region and membership in cooperatives were significant on farmers’ technical knowledge level. However, using extension services was not the reason for the superiority of sugar beet growers’ technical knowledge index in different cities. Therefore, the driving force of extension services did not efficiently work in improving technical knowledge level in all cities.