IRRIGATION OF ROSA HYBRIDA L. ‘KARDINAL’ BASED ON SOIL MOISTURE TENSION INCREASES PRODUCTIVITY AND FLOWER QUALITY

Abstract

An irrigation control system based on soil moisture tension (SMT) for potted plants was able to reduce the amount of water used to produce commercially acceptable crops. This system was adapted for use on plants growing in ground beds for cut flower production. Since this type of system reduces the amount of water applied, the possibility of a detrimental effect on flower quality was tested. The irrigation control system consisted of tensiometers, modified with high flow ceramic tips and pressure transducers, an analog-digital signal converter, a computer, and custom written software. The system continuously monitored the moisture condition of the soil, initiated irrigation when the soil dried to a specific level, and turned off the water when an adequate amount was applied. When the system was installed in a commercial greenhouse of Rosa hybrida L. ‘Kardinal’ plants, water use in the test area was 26% less than the amount applied by the grower. Productivity (stems harvested@m) was 66% greater in the test area. Flowers harvested from the test plants were not lower in quality than those from the grower irrigated controls. In fact, except for the initial harvest, the flowers from the test area were significantly longer (up to 8 cm) than those from the grower’s area. An additional harvest, 71 days after the irrigation control system was removed, showed no differences in stem length. The use of this irrigation control system can reduce both water and fertilizer usage when a liquid feed program is utilized. Increases in productivity and quality can result in significant increases in profitability for commercial producers.