Plant response to evapotranspiration and soil water sensor irrigation scheduling methods for papaya production in south Florida

An irrigation study was conducted to determine the effects of implementing different irrigation practices on growth and yields of papaya plants in south Florida. Treatments included using automated switching tensiometers based on soil water status, irrigation based on ET calculated from historic weather data and a set schedule irrigation regime. The study consisted of two trials (2006-2007 and 2008-2009). Water volumes applied, plant height and diameter, leaf gas exchange, leaf petiole nutrient levels, fruit yields and fruit total soluble solids were measured throughout the study. For both trials, significantly more water was applied in the set schedule irrigation treatment than in all other treatments; historic ET and soil water based treatments received only about 31-36% of the water applied in the set schedule irrigation. Trunk diameter and plant height per unit water volume applied values for the set schedule treatment were significantly lower than those from all other treatments during both trials. The set schedule treatment in both trials also had the lowest crop production water use efficiency (CP-WUE); CP-WUE values among all other treatments were generally not significantly different from each other. Soil water and historic ET-based irrigation methods were identified as more sustainable practices compared to set schedule irrigation due to the lower water volumes applied while maintaining plant nutrient content, growth, photosynthetic rates, and fruit yields for this production system.