The Effect of different nitrogen and potassium levels on quantitative and qualitative traits of sugar beet under drought stress

In drought stress condition, it is important to estimate the N and K requirement of sugar beet. A drought-tolerant sugar beet genotype, BP Karaj, was evaluated in split plot factorial design based on a randomized complete block design with four replications at Motahari Research Station, Karaj, Iran for three years. Main plots were allocated to irrigation treatments including normal irrigation (control), irrigation with early season drought stress imposition, and irrigation with drought stress imposition during the growing season. Subplots were allocated to four N levels including 0 (control), 50, 100, and 150 kg ha-1 and three N levels including 0 (control), 100, and 200 kg ha-1. The highest root yield (49.43 ha-1) and white sugar yield (5.94 t ha-1) in irrigated condition were obtained in control treatment. Root yield under drought stress imposed early season and during the growing season was 39.84 and 34.85 t ha-1, respectively, which showed 19 and 30% decrease compared with the control irrigation treatment, respectively. The effect of N and K interaction on root yield, sugar yield and white sugar yield was significant (p