Effects of Irrigation Water Salinity on Evapotranspiration and Spinach (Spinacia oleracea L. Matador) Plant Parameters in Greenhouse Indoor and Outdoor Conditions

Abstract

Response of spinach to irrigation water salinity under greenhouse indoor and outdoor conditions was investigated in this study to reveal different weather conditions on salinity tolerance of the plant. For this purpose, saline waters at six different salinities (0.65, 2.0, 3.0, 4.0, 5.0 and 7.0 dS m-1) were applied to spinach (Spinacia oleracea L. Matador) grown in pots. Soil salinity increased linearly with increasing salinity of irrigation water. Threshold salinity is 2.35 dS m-1 and yield lost slope after this threshold is 3.51% for indoor and threshold salinity is 2.83 dS m-1 and yield lost slope is 3.3% for outdoor. Salinity harmful effect on spinach yield is higher for indoor conditions than for outdoor conditions because of higher indoor temperatures. These results apparently showed that spinach salinity response could change with changing weather conditions especially for temperature. Yield response factors (k<inf>y</inf>), which is the ratio of relative evapotranspiration decrease to relative yield decrease, were close in the cases of irrigation water salinity in greenhouse outdoor and indoor (k<inf>y</inf> = 2.4 and 2.1), respectively. Considerable water consumption decreases because of salinity were determined. Every 1 dS m-1 increment in soil salinity caused about 1.35% water consumption decrease for spinach. Therefore, depressing effect of salinity on water consumption should be considered in irrigation and salinity management to prevent excess saline water application and to protect environment. © 2017, Eesti Pollumajandusulikool. All rights reserved.