Effect of Water Quality and Irrigation Management on Sugar Beet Yield and Yield Components

Quality degradation of some water resources in arid- and semi- arid regions of Iran is a major factor limiting plant growth and agricultural production. One imperative response to this challenge is proper use of saline water for agricultural activities. The present experiment was carried out on sugar beet in southeast of Isfahan city, Iran, and comprised a completely randomized block design, with split-split plots and four replications. In this study, three irrigation water quality treatments of 1.6, 8.1 and 12.3 dS m^-1(S₁, S₂ and S₃, respectively) were assigned to the main plots. The sub-plots contained two different water management practices:(1)irrigating with the aforementioned three water qualities during the whole irrigation period and (2)similar the first treatment but  irrigation with fresh water (1.6 dSm^-1) during germination and establishment stages. In the sub-sub-plots, two leaching treatments were applied consisting of no leaching (LR₀) and leaching amounts of 2.6%, 14.1%, and 19.6%, for S₁, S₂ and S₃, respectively (LR₁). The results showed that salinity of irrigation water significantly reduced white sugar yield (WSY) such that S₂ and S₃ treatments reduced WSY, respectively, 6.7 and 10 percent compared to S₁ treatment. Root yield (RY) also decreased with increasing irrigation water salinity. Application of leaching significantly increased RY, WSY, and sugar yield. Statistical analysis indicated that, with higher levels of water salinity, the amounts of Na⁺, K⁺, and α-amino-N were significantly increased. Also, the molasses sugar increased with increasing salinity. Application of fresh water during initial period of growing season reduced the effect of saline water slightly in most of the yield component traits, whereas the effect of leaching application was significant on sugar beet yield components.