SUBSTRATE QUALITY, IRRIGATION MANAGEMENT AND THE GREENHOUSE PRODUCTION OF HIGH-PERFORMANCE PLANTS

The physical and hydrodynamic properties of a substrate play a key role in irrigation management in horticulture. After irrigation, a high-performance substrate should provide an adequate amount of water and air to a plant to ensure its optimal growth. However, some producers do not pay enough attention to the quality of the substrate. When working with insufficiently aerated, low-quality substrates, they try to adapt irrigation methods in order to produce high-performance plants similar to those produced in well-aerated substrates. As a result, these producers try to adjust the amount of water during irrigation according to the quality of the substrate. The objective of this study is to evaluate the impact of substrate quality on the growth and development of two popular greenhouse species (the New Guinea impatiens and the geranium) with respect to the impact of irrigation management. According to our results, the use of a well aerated substrate combined with an appropriate irrigation method resulted in earlier plant maturity. This method reduces the duration of plant growth and hence decreases energy costs by reducing the greenhouse heating period. The number of heating days saved by using high-quality substrates depends on irriga¬tion management and was about 23 to 25 days for geraniums and 17 to 22 days for New Guinea impatiens. The production of plants in well-aerated substrate improved performances in terms of growth and development parameters, and resulted in high-performance plants.