Water productivity and water use efficiency indexes of Sugar beet under different levels of water and nitrogen fertilizer

Considering limited water resources in arid and semi-arid climate of Iran, deficit irrigation is one of the strategies for efficient use of water, increasing water productivity and water use efficiency in agricultural district. Regulated Deficit Irrigation (RDI) and Partial Root Drying (PRD) are among deficit irrigation methods aiming to limit using of irrigation water. PRD is a new approach for irrigation management due to increasing water use efficiency and non-significant decreasing yield. The objective of this study was to investigate the effect of different levels of irrigation water and nitrogen fertilizer on water productivity and water use efficiency of Sugar beet.
This research was conducted in the agricultural land of Karafs plain on Hamadan province, at latitude 35° 18̍ N, longitude 49° 20̍ E and altitude 1915 m above sea level. This study was conducted in a split block with a randomized complete block design. In the main blocks Irrigation levels included: Conventional irrigation (CI), three levels of partial root drying: 85 (PRD85), 75 (PRD75) and 65 percent (PRD65) and regulated deficit irrigation at three levels: 85 (RDI85), 75 (RDI75) and 65 percent of the crop water requirement (RD 65). Also, in the sub blocks two fertilizer levels were applied: 100 (f100) and 75 percent of fertilizer requirement (f75).
The results showed that the impact of irrigation treatments on water productivity and water use efficiency of all studied traits were significant at one percent level (P The results showed that water productivity and water use efficiency indexes of root and sugar yield of PRD85 irrigation treatment was more than other irrigation treatments. Due to the non- significant differences between the PRD85 with CI treatment in terms of root and sugar yield and also saving 15 percent of water irrigation in PRD85 treatment, under such study conditions, applying PRD85 treatment is recommended. Also, f100 fertilizer treatment was root yield, sugar yield, water productivity and water use efficiency indexes of biomass, root and sugar yield more than f75 treatment. Therefore, PRD85 and f100 were selected as the best treatments.