Effects of different irrigation programs on yield and quality parameters of eggplant (Solanum melongena L.) under greenhouse conditions

Abstract

This study was carried out to determine the effects of different irrigation programs on yield and quality parameters of 
eggplant under greenhouse conditions, using Class A pan evaporation calculations and different plant-pan 
coefficients. Irrigation water was applied through drip irrigation method twice a week during the growing period. 
Irrigation treatments consisted of five plant-pan coefficients (S1: kcp = non-irrigation, S2: kcp = 0.50, S3: kcp = 0.75, S4: 
kcp = 1.00 and S5: kcp = 1.25). The amount of irrigation water ranged between 95.2 and 238.7 mm among the 
treatments. Evapotranspiration (ET) values varied from 93.1 to 466.3 mm for the treatments. The highest yield was 
obtained from the S3 and S4 treatments. A significant polynomial correlation was obtained between the yield and 
irrigation water, and between the yield and ET (P < 0.01). This indicated that when irrigation water and ET increased, 
yield also increased to a certain point. However, when the amount of irrigation water exceeded the plant water 
requirement, eggplant yield decreased. Yield response factor (Ky) was determined as 0.81. Since Ky < 1, eggplants 
were not sensitive to water deficiency. In addition, the highest water use efficiency (WUE) and irrigation water use 
efficiency (IWUE) values were calculated in the S3 (12.9 kgm-3) and S2 (44.2 kgm-3) treatments, while the lowest WUE 
and IWUE values were calculated in the S5 (7.9 and 15.5 kgm-3) treatment to which the highest irrigation water was 
applied. This finding indicated that WUE and IWUE values decreased with the increasing irrigation water and ET. 
These results suggested that S3 (kcp = 0.75) treatment can be the most appropriate irrigation program for eggplant 
with higher yield and WUE under greenhouse conditions.