Evaluation of irrigation frequency on pineapple plants grown in greenhouse conditions

Abstract

The objectives of this work are to evaluate the water status and growth variables of pineapple plants under different frequencies of irrigation to optimize the water productivity irrigation in greenhouse conditions in the subtropics. The experiment was conducted during the vegetative cycle for nine months, comparing three frequencies of irrigation: irrigation every three days (High frequency-T1), every seven days (Medium frequency-T2), and every 15 days (Low frequency-T3). The water status was measured using destructive indicators: Relative Water Content (RWC) and non-destructive indicators: Normalized Difference Vegetation Index (NDVI), Stress Degree Day (SDD), and Leaf Chlorophyll Index (LCI). Water productivity indicators (Irrigated water productivity, crop water productivity) and growth variables (plant height, maximum diameter, plant biomass, assimilate partitioning) were also measured. The environmental conditions monitored were temperature, humidity, and incident radiation. The soil moisture depletion and daily depletion rate were also registered and calculated. Destructive indicators of water status did not detect differences between irrigation treatments in this study, while non-destructive indicators statistically differentiated T1 from T3. T2 was the most appropriate irrigation treatment during the cold season. These results suggest that in greenhouse conditions in subtropical environments, a combination of high frequencies in warm seasons and medium frequencies in cold seasons would adjust irrigation management according to the pineapple crop needs, optimizing irrigation water productivity.