Water-Yield Relationships in Deficit Irrigated Onion

Abstract

This trial was realized in the greenhouses of Uludağ University Yenişehir Vocational School between 2009 and 2010 to investigate effects of water deficit on yield and quality parameters of onion during four crop growth stages. In this trial, fourteen irrigation treatments in four growth periods (establishment, vegetative, yield formation and ripening) of onion (Allium cepa L E.T Grano.502) were constituted and the yield and quality parameters found from these treatments were evaluated. The layout of the experiment was a completely randomized block design with three replications for each of the fourteen irrigation treatments tested. According to the content of the treatments, the irrigation amount water applied to the plants varied between 0 and 436 mm in the first year, and between 0 and 448 mm in the second year. Water consumption of onion in the first year ranged between 205 and 496 mm and in the second year ranged between 210 and 502 mm. Yield, bulb weight, diameter, height and dry matter ratio were determined statistically significant. In 2009 and 2010 years, the maximum yield were found as 52.2 t ha-1 and 52.4 t ha-1 in E100V100Y100R100 treatments, while the minimum yield were found as 0.8 t ha-1 and 0.5 t ha-1 in the E0V0Y0R0 treatments, respectively. Water- yield relationship factors (ky) in 2009 and 2010 years were found as 1.03 and 1.04, respectively. The maximum WUE and IWUE values were obtained from establishment and ripening periods. Establishment and ripening periods may be suggested as the maximum efficient irrigation periods for the onion applied with drip irrigation under unheated greenhouse conditions.