Study of the effects of climatic parameters on changes in sugar content of sugar beets in 2006 and 2007 (A case study Chenaran district)

The Chenaran district was chosen as the best district for the investigation of the prominent increase of the average of sugar content in sugar beets produced in Iran in 2007 in comparison with 2006 and finding an answer if climatic parameters have influenced these changes. This study was accomplished by the use of information registered in the Chenaran Sugar factory and the study of the most important climatic parameters affecting the sugar content of sugar beets: temperature, precipitation, relative humidity, sunshine hour and wind speed. Regression analysis was found from the final number representing the sugar content of sugar beets produced in the factory during the years 2001 to 2007 as dependent variables and monthly climatic parameters are the independent variables that were considered for analyzing the sugar content. Also the effect of climatic parameters on soil tare of sugar beets was analyzed. The daily information of soil tare in Darzab and Mian Velayat (the most important and nearest area for planting sugar beets to a Synoptic station) from the beginning time of utilization of the sugar factory in 2006 and 2007 were arranged in the form of 10-day averages. The 10-day averages of climatic parameters were correlated with the 10-day averages of sugar beet soil tare and linear correlation coefficients that were calculated. Because the 10-day averages of sugar content in the first 3 weeks of November in 2006 and 2007 reached its maximum and then tended to decrease, so to study the effect of climatic influences on this decrease, the 10-day averages of climatic parameters were correlated with the 10-day averages of sugar content and linear correlation coefficients. By using the SPSS software and the stepwise method the most important factors affecting the sugar content and soil tare of sugar beets were determined. The results showed that among climatic parameters, the most significant factor affecting the sugar content was the minimum temperature in August each year. The results of the analysis clarified that the 1.59% increase of sugar content average in 2007 in comparison with 2006 is justifiable by considering the 0.9 °C decrease of the average minimum temperature in August. Regarding the role of climatic causes on the change of sugar content and soil tare during the harvesting period, results showed that the maximum air temperature in 2006 had the highest correlation with the soil tare and sugar content of sugar beets during the 10-day averages. In 2007 the number of days with a temperature of -4°C and less (freezing) and relative humidity, respectively, had the highest correlation with the soil tare and sugar content of sugar beets. Therefore, attention to the climatic parameters during the sugar beet growing season, especially the minimum temperature in August and in case of severe increase of temperature, proper and well timed irrigation has significant effects on the sugar content of sugar beets. Proper planning of harvesting and delivering the sugar beets during Autumn regarding the forecasting of meteorological organization in every zone can play a substantial role in decreasing soil tare and increasing of the sugar content in sugar beets. Keywords: Sugar beet, Sugar content, Soil tare, Maximum temperature, Minimum temperature, Temperature amplitude, Precipitation, Relative humidity, Sun shine hour, Wind speed.