changes in carbohydrates and sugar yield in sugar beet (beta vulgaris l.) under different biofertilizers and irrigation closed time

objective: many agronomic practices may need to be adjusted to maximize yield and quality of sugar beet. thus agronomic package must be always modified. this sutdy was laid out for evaluation of changes in carbohydrates and sugar yield in sugar beet (beta vulgaris l.) under different biofertilizers and irrigation closed time at dorud region of iran, during 2013. methods: the experimental design was factorial based on rcbd with three replications. treatments were three irrigation closed time [oct-6 (a1), oct-13 (a2) and oct -21 (a3)] and three nitrogen biofrtilizers [nitroksin (b1), nitrokara (b2), biozar (b3) and control (b4)]. after treatments 3m2 in each plot harvested for sugar measurement. sugar was determined by betalizer machine in isfahan sugar beet factory. results: the effect of any treatment on root and molasses sugar was not significant but all treatments were significant on sugar yield and white sugar yield. among the all treatment highest sugar yield and white sugar yield was belonged at application of biozar in oct-13 irrigation closed time and minimum sugar yield and white sugar yield was belonged at application of nitrokara in oct-21 irrigation closed time.