Abstract
Papaya (Carico papaya L.) water relations, growth, yield, and water use under drip irrigation at different evaporation-replenishment rates (20, 40, 60, 80, 100, and 120% of United States Weather Bureau Class A Pan evaporation) with subsurface drip (at 250 mm depth in the soil) and surface drip irrigation were investigated at Bangalore, India. Increasing the evaporation-replenishment rates from 20 to 120% increased the relative water content (13.2%), transpiration rate (18.8%), plant height (21.9%), stem girth (12.5%), fruit number (88.3%), and yield of papaya (34.6%). Fruit yield differences above 60% evaporation-replenishment rates were not significant. The water use from 0 to 36 months after planting increased with an increase in evaporation-replenishment rates. It was 1651 mm and 4208 mm at the 20% and 120% replenishment rates. Water-use efficiency (WUE) over this period decreased from 58.6 to 30.9 kg ha·1 mm·1 at the 20% and 120% replenishment rates, respectively. Subsurface drip irrigation recorded significantly higher fruit yield (121.4 compared to 110.6 t ha·1) and WUE (40.6 compared to 37 .2 kg ha·1 mm·1) than surface drip irrigation.
