Effect of soil moisture on water use and appearance of green eggplant in greenhouse conditions

With rapid economic development and improved living standard, the Chinese have shifted their attention to food quality and safety. Also with increasing water shortage, water-saving irrigation technologies such as drip irrigation have been increasingly used in greenhouse vegetable production. On this basis, the effects of soil moisture at different growth stages on water uptake, yield, water use efficiency, and appearance quality of green eggplant were studied in plot experiments under drip irrigation in greenhouse conditions. The experiment was conducted in 2009 at the experimental station for water requirement of the Institute of Farmland Irrigation Research. Green eggplants were transplanted in wide and narrow rows. The experiment was divided into three growth stages (seedling, flowering/fruit-setting and fruit maturation stages) based on the growth characteristics of eggplants. In the experiment, four different irrigation rates (with soil water content to be kept at 50%, 60%, 70% and 80% of field capacity) were applied at each growth stage. Furthermore, adequate water treatment (with soil water content to be kept at 80% of field capacity) was designed as the control of the experiment. This study was important for high efficiencies in water and fertilizer utilization, and significant environmental and economic benefits. Results showed that water deficit at any growth stage reduced water uptake by green eggplants. Fruit size, number and yield dropped with increasing water deficit. A quadratic parabola correlation existed among yield, water use efficiency and water consumption; with an optimal water consumption of 307.12~339.59 mm. Fruit count, total yield and water use efficiency were higher when the lower limit soil moisture content was kept at 60%~70% of field capacity at seedling stage, 70% of field capacity at flowering/fruit-setting stage and at fruit maturation stage. This was recommended as the optimum soil moisture index for drip irrigation management in green eggplants under greenhouse conditions.