Effect of Irrigation Regimes on Crop Water Use Efficiency of Autumn Sugar Beets Grown on the Mashhad Plain

Autumn sowing of sugar beets for harvesting the root yield the following spring is possible in some regions of Iran. Autumnal beets effectively conserve irrigation water because they make use of precipitation during the autumn and winter months and do not grow during the warm summer periodn. The presents study determined the water-use efficiency of autumn-sown sugar beets and investigated the best irrigation scheduling for the Mashhad plain. Testing was carried out during the 2013-2014 growing season at the Agricultural Research Center of KhorasaneRazavi province using a randomized complete block design with a split plot arrangement and four replications. This experiment examined with three irrigation intervals (7, 10 and 14 d) as the main plot and four irrigation levels (50%, 75%, 100%, and 125% of water content of field capacity) as subplots. The results showed that the yields of roots, dry matter, sugar, and white sugar showed no significant difference for irrigation interval, but that irrigation level hadsignificant effect on yield at the 1% level. The best irrigation water-use efficiency for the yield of conversion to white sugar as the final economic product of sugar beet cultivation was achieved at the 75% and 100% irrigation levels using the 14 d irrigation interval. The results of this project for the Mashhad plain under similar climatic conditions indicates that autumn-sown sugar beets should be irrigated every 14 d at 75% to 100% of field capacity. This irrigation schedule decreased irrigation costs (33%), conserved irrigation water (18%), and achieved maximum irrigation water-use efficiency compared with the 7 d irrigation interval.