REGULATION OF CROP GROWTH AND DEVELOPMENT BASED ON ENVIRONMENTAL FACTORS

Production of horticultural crops by growers is becoming increasingly difficult as markets write detailed specifications for products both in time of delivery and quality factors such height and flower number. Such specifications require growers perform proper cultural procedures at the proper time. Environmental variation between and among seasons means proper cultural procedures will vary with every crop. All growers, especially those with little experience in a crop, benefit from information that assist in making proper cultural-procedure decisions. Decision-support tools based on environmental, chemical, or biological data can help provide such information. This presentation will describe examples of biological concepts associated with plant growth and developmental processes that especially lend themselves to decision-support. Types of decision-support tools developed from this information will be presented. For example, development of plants is highly temperature dependent. Relationships between temperature and development rate are often useful as they can be described by a linear relationship over a wide temperature range from the base temperature to near the optimum temperature. Degree-day decision-support tools can be developed from such information. Growth retardant chemicals are used widely in commercial production of flowering plants to meet height-control specifications. Simulation models incorporated into decision-support tools may be useful to maximize efficacy of applications as there is increasing pressure to minimize the use of growth retardants. Biological models relating plant morphological development to the environment, e.g., bud length and temperature to time to flower, can also be useful in creating decision-support tools for accurate crop timing.