SYSTEMS DESIGN METHODOLOGY TO DEVELOP CHRYSANTHEMUM GROWING SYSTEMS

Abstract

When chrysanthemum growers change soil for a soilless growing system they aim for labour cost reduction, quality and yield improvement and reduced emissions of nutrients. Because many attempts to come up with a viable soilless system failed, improvements and systemizations of the design process were examined. The design methodology chosen uses goal setting based on stakeholder engagement, systemised quantification of a set of conditions for the final system, and a systemised choice of competing systems and quantification of the properties of the competing systems. The set of conditions is assembled upon consultation of a wide variety of growers and experts in fields of plant protection, plant physiology, water management, substrate characteristics, economics and nutrition. The conditions and properties correspond to each other to the extent that both are based on the same measuring methods and expressed in the same units. Thus matches between conditions and properties can be scored. After the complete set of conditions and matching properties is scored, the average of the scores is taken as a measure for the suitability of the whole system. Because properties are quantified, the process is based on knowledge, and gaps in knowledge are identified. Favourable combinations of properties may be applied to systems lacking these properties in order to improve them. This design methodology was used to select and improve a set of 11 competing systems. The resulting 4 improved systems were built and used for growing in experiments. Systems included a soil bed, a sand bed, a peat bed and a cassette bed. The soil bed was a 70 cm deep bed of the original soil on a water impermeable foil with a drainage system. The sand bed was a 15 cm layer of coarse sand with a 5-10 cm under layer of coarse clay pellets including a drainage system which also supplied irrigation water i.e. sub irrigation. The peat bed was a 25 cm peat layer on a sub irrigation bench. The cassette bed was a 130×3×15 cm (length × width × height) container filled with peat. The cassettes were hung on a sub irrigation bench. Chrysanthemum press pot plants were planted on soil and sand beds and bare chrysanthemum cuttings were planted in the peat based systems. Chrysanthemums were grown for the first of 6 crop cycles. Results showed a 5-15% increase in dry matter production and 3-5 days shorter growing period in the peat beds and cassette beds. However, the economic performance is still marginally poor. Nevertheless, the systems tested are environmentally sound and comply with plant requirements for optimal growth. The sand bed and cassette bed may be further optimised by respectively EC control and top down irrigation.