Towards the development of a management information system for glasshouse tomato growers : A thesis submitted in partial fulfilment of the requirements for the degree of Master of Horticultural Science

Abstract

Since the early seventies, glasshouse tomato growers have faced severe cost-price pressures due mainly to the sharply increased cost of heating oil. If growers are to maintain or improve their profitability, on-property changes need to take place to increase yield and returns and/or reduce costs. Formal management information systems (MISs) are interpreted as a basis for assisting growers in their decision making, including the evaluation of alternative strategies. The development and use of MISs was considered using an interdisciplinary approach and drawing upon the experiences of non-agricultural firms and MISs that have been successfully developed for glasshouse cropping firms. Key factors to success were identified. A computer based "mail in" MIS was developed with a group of Auckland glasshouse tomato growers selected for their economic motivation and common information requirements. The MIS was developed closely with growers to determine their information requirements, the scope of the system, the recording of data and input/output form design. A horticultural advisory officer (HAO) from the Ministry of Agriculture and Fisheries (MAF) collected grower data for processing and helped growers interpret and effectively use the new information in their decision making. After two seasons operation, the MIS was evaluated by the growers and the HAO. The MIS project was successful from a number of aspects. Improvements were also suggested, particularly in relation to the design of the output form and the role performed by the HAO. If the HAO had carried out more timely and frequent data collection and interpretation, it was likely that growers would have seen a greater use within the season for information provided by the MIS. The evaluation also highlighted growers' limited perception of the systems over which they have control. seen as an area for discussion between the HAO and the grower. To meet the likely demand for formal planning models within the MIS in the future, an assessment was made of the feasibility of developing a bio-technical simulation model of the glasshouse tomato production system. Temperature was identified as the main factor influencing tomato plant response in New Zealand. A glasshouse climate sub-model based on regression equations was developed to predict daily glasshouse minimum and maximum temperatures using external weather data as input to the model. A glasshouse tomato crop sub-model was developed to predict the date of harvest onset, the pattern of yield throughout the season and total yield using temperature data as input to the model. Ontario heat units were used as a time course for the model and as an indicator of tomato plant response. A harvest threshold of 2206 Ontario units was more effective than calendar days in predicting harvest onset. The model was validated. Crop yield was successfully modelled using Ontario units and regression analysis. The model was validated. However this basic model was only applicable to well managed crops. Factors reducing the yield potential need to be incorporated into the model to broaden its applicability. Other suggestions are made to improve the usefulness of the model. The simulation model can be used by itself or linked with an economic model to compare alternative strategies between seasons or to predict crop development and production part-way through a season using actual weather data, likely future weather and details of any factors reducing yield potential. The future development and use of MISs are discussed.