Effects of a set of water restrictions on potted ornamental crops grown in greenhouses - influence on New Guinea impatiens quality

E. Chantoiseau, H. Bouhoun Ali, P.E. Bournet, P. Cannavo
Since agriculture is known as the main consumer of water in the world, reducing water inputs to crops appears a real challenge. This is true in particular in greenhouse ornamental systems, where a compromise must be found to reduce water inputs without impacting plant quality. Indeed, it is known that water restriction tends to limit plant height and leaf surface, and the resulting final architecture may not fulfil criteria for commercialization. Water savings must then be balanced with the quality loss. In order to understand the effect of limited irrigation on potted New Guinea impatiens, an experiment was conducted in a 100-m2 greenhouse compartment on plants distributed on four shelves irrigated with different water inputs, 8 weeks after repotting. Irrigation was maintained at 25, 50, 75 and 100% of the effective transpiration of the most-irrigated shelf. Plant growth parameters [leaf area index (LAI), height, fresh and dry weight] were monitored until the 16th week, and the final plant architectures of the shelves were compared. Measurements of stomatal resistance were performed and the water-use efficiency (WUE) was also calculated. Measurements showed that irrigation at a 25% level appeared to be inadequate and led to plant death. However, plants irrigated at 75% displayed similar growth to the 100% shelf, suggesting that a significant water saving could be obtained. Branching was the same for 50, 75 and 100% treatments. Although the plants of the 50% treatment did not die, they were less developed than those supplied with 75 and 100%, particularly concerning accumulated dry matter production and plant height. The WUE of plants in different treatments varied with time because of stomatal resistance regulation of the transpiration, whereas plants irrigated at 100 and 75% had similar WUE.
Chantoiseau, E., Bouhoun Ali, H., Bournet, P.E. and Cannavo, P. (2018). Effects of a set of water restrictions on potted ornamental crops grown in greenhouses - influence on New Guinea impatiens quality. Acta Hortic. 1227, 425-434
DOI: 10.17660/ActaHortic.2018.1227.53
irrigation, deficit irrigation, plant quality, stomatal resistance, water-use efficiency

Acta Horticulturae