The Influence of Irrigation Water Salinity and Humic Acid on Nutrient Contents of Onion (Allium cepa L.)

Abstract

Humic acid (HA) efficiently enhances the uptake of nutrients ofplants, especially on saline soil. In this study, some nutrientcontents of onion in response to salinity and HA applicationwere investigated, and effects of HA application on salinityresistance was evaluated. Research plots were established as arandomized factorial design with four replications on alysimeter and each replication included 10 plants. Plants in thelysimeters were irrigated with tap water (control, EC: 0.3 dS m1) and four different doses of salinized water (EC: 2.0, 4.0, 6.0and 8.0 dS m-1). The HA (0 and 1.0 g kg-1) was applied to thesoil and mixed with the soil before planting. Increasing thelevels of irrigation salinity decreased contents of K, Ca, N, P,Mg, Fe, Zn, Cu and B in onion bulbs; increased contents of Na,Cl and Mn. However, the highest content of K, Ca, and N in thebulbs were obtained by HA application under different salinitylevels. Similarly, the soil application of HA positively wasaffected the P, Mg, Fe, Zn, B contents of the bulbs. Whilecontents of Na, Mn, and Cu were not affected by soilapplication, Cl was decreased. The results showed thatapplication of HA could partially reduce the harmful effects ofsalt, so HA can be used as an alternative method to improveproduct performance in saline conditions.