Evaluation of sugar beet .-esl)onses to cut of irrigation at different stages of growth in khoy region.

Water stress cause decreasing water content and water potential among soil and root. In this reason water potential of plan declines and plant involve wKh water stress. Water stress on different stages of growth has divers of effects and sometimes it is useful for improving quality of yield. Water strees can be exercise for two main aim, increasing water use efficiency for optimal use of water resources and improving cultivation methods. Cut of irrigation in insensitive stages of growth for water stress helps us to save water and manage it for other crops. In this research, in order to evaluate the effects of cut of irrigation at different stages of growth on quality and quantity of sugar beet, a farm in Khoy Agricultural Research station was considered for execution of research plan in2 years(1999 and 2001). The project was carried Ollt, using randomized complete blocks design with 7 irrigation treatments(cut ofirrigation at different stages of growth) .in 3 replications. The analysis of two years results indicated that there was a significant effect (I % significant level). Lack of irrigation in initial stage(using rainfall for providing water needed of plant) caused available sugar increased 13.3% and reduction water used was 16.5% compared with control treatment (full irrigation). W.U.E obtained 1.7 and 1.25 kilograms of sugar per one cubic meter of water applied in this treatment and control respeCtively. Lack of irrlgatiO"ri iri iilhiarstage and ignoring last irrigation in late season cause water used decreased up 21.2%, available sugar increased 11 % and W.U.E enhanced fr0111 ~:25 to 1.76 compared with control treatment. Treatments had : .... significant effect on sugar 'content, white sugar contellt and Na(impurities) aJ1d had any significant effect on other quality of sugar beet characteristics. Cut of irrigation in initial and last stage of gro\\\\'th cause the most sugar content and white sugar content c.ompared with control treatment. In this way, sugar content increased from 12.74 to 16.09 and white sugar content increased from .12.74 to 16.09.