Optimum irrigation scheduling under deficit irrigation in sugar beet growth stages.

The research was carried out in order to study the effect of controlled deficit irrigation (CDI) on quality and quantity of sugar beet in Bardsir region of Kerman and Karaj. Different levels of water application and various irrigation periods were studied in a randomized complete block design with 3 replicates. Sugar beet crop was subjected to water stress at 3 groth stages (vegetative development, root swelling and ripening) by tape irrigation system. Finally, quantitative and qualitative properties of sugar beet were determined and statistics analysis was done. To illustrate the relationship between the volume of used water as an independent factor and measured properties as dependent factors, correlation coefficients were determined and regression analysis was done. The results showed that year effect on all properties were significant (P0.01 or 0.05) except for water use efficiency (WUE) on the basis of sugar weight. The region had no significant effect on root and sugar yield, molasses and industrial quality index (IQI) , but were significant (P0.01 or 0.05) for the other. Irrigation treatments had significant effects (P0.01 or 0.05) on all factors except for Potassium, Sodium and ل-amines. Considering the highest root and sugar yield, WUE, sugar content, and IQI, The treatments of T10 and T9 with medium water stress in development stage, without water stress in swelling stage, severe and medium water stress in ripening stage, respectively were recommended. Total applied water was 7298 and 7398 (m3ha-1) in T10 and T9, respectively which was about 23% less than applied water in T1 (control). These treatments were also the best in each region. Correlation coefficients were not significant. The results showed that water stress in root swelling stage was more effective in decrease of root yield than other growth stages. The lowest WUE was observed for the treatments which had no water restriction in early stages of plant growth and so these treatments were not recommended.