Current Trends in Natural Sciences , cilt.5, sa.9, ss.145-151, 2016 (Hakemli Dergi)
This study was carried out in an unheated greenhouse in order to determine effects of different irrigation levels on
lettuce yield (cv. Hazar) grown from December to February in Şanlıurfa, Turkey. Different irrigation water amounts
based on Class-A-Pan evaporation were applied to the plants by drip irrigation system at four irrigation levels (Kp1=
1.0, Kp2=0.75, Kp3=0.50, Kp4=0.25) in one week irrigation interval. Applied irrigation water and evapotranspiration
of Kp1 treatment were 118 and 125 mm, respectively. The highest average lettuce yield of 7.8 ton da-1 was obtained from
the full-irrigation treatment (Kp1). Significant differences were not observed between Kp1 and Kp2 treatments in terms of
lettuce yield. Maximum irrigation water use efficiency and total water use efficiency were obtained from Kp4 treatment
respectively with 0.117 and 0.074 ton da-1
mm
-1. Yield response factor (ky) was found to be 0.88. The research results
showed that a 7 day irrigation interval with Kp2 treatment could be used for irrigating lettuce under the unheated
greenhouse conditions without any significant yield loss but increased water use efficiencies.