Irrigation with brackish water under desert conditions I. Problems and solutions in production of onions ( Allium cepa L.)

Abstract

To identify the problems and suggest solutions for onion production under brackish water irrigation in a desert environment, a series of trials with brackish water (electrical conductivity, EC i = 4.4 dS/m) and fresh water (EC i = 1.2 dS/m) was conducted, using both sprinkler and drip irrigation systems. Under sprinkler irrigation with brackish water the mean electrical conductivity of the saturated soil extract ( EC e) was about 6.0 dS/m and the yield reduction was 60%. With drip irrigation, the EC e under the drippers was about 5.0 dS/m and the yield reduction was 30%. Sprinkler irrigation affected yield through a reduction in both bulb size and bulb number per unit area. Drip irrigation affected the bulb number only. In the latter system seedling death occurred during the first 40 days following field emergence. Yield reduction was completely prevented by germinating and establishing the field with freshwater irrigation before transferring to brackish water irrigation, 45 days after sowing. With the sprinkler system, onion yield with brackish water irrigation could be increased by either increasing the sowing density or by alternating between brackish and fresh water irrigation.