T. Takakura
The concept of on-line process control has been applied to plant assimilation which can be considered one of the main dynamic processes in plant growth. The optimisation of the process is effected directly without recourse to any mathematical model, assuming CO2 uptake by plants is unimodel. In order to get the maximum value of CO2 uptake, air temperature, relative humidity and CO2 concentration in the plant growing chamber are changed during the light period either by the method of steepest ascent or by the complex method.

Process simulation without using actual plants has indicated adequate values of step size and direction in each method as well as the pattern for pursuing the time-dependent optimum (Fig. 3).

The results with leaf lettuces grown for five days under a constant light intensity confirms the basic pattern which Heath, (1969) suggested. The optimum condition for maximum CO2 uptake changes considerably with time and its daily course is not consistent.

Takakura, T. (1975). PLANT GROWTH OPTIMISATION USING A SMALL COMPUTER. Acta Hortic. 46, 147-156
DOI: 10.17660/ActaHortic.1975.46.13