2. TRANSFERABILITY OF RESULTS IN GROWTH CHAMBERS - TRANSFERABILITY OF RESULTS OBTAINED IN GROWTH ROOMS TO GREENHOUSE AND FIELD CONDITIONS

Fig. 1 summarizes schematically primary effects of environmental factors on plants. Plant performance is a function of such primary reactions of plants to the environment and of the succeeding chains of complicated biochemical and byiophysical processes.

Transferability of experimental results obtained in growth rooms to greenhouse and field conditions is limited for several reasons. Fig. 1 shows, qualitatively, that in most cases it is impossible to establish the effect of a factor on the plant. In addition to air humidity, for example, several other factors determine the water potential in plants. Hence, the effect of air humidity depends strongly on the other parameters, affecting water potential as well. The relative importance of various environmental factors will be quantitatively discussed.

Growth rooms offer great possibilities for horticultural research, when control of environmental factors is used to induce primary plant reactions over ranges of rates to be expected in the greenhouse or in the field. Potential possibilities will be discussed.

Finally, attention will be paid to various methods for the measurement of environmental parameters and to mainly non-destructive methods for the measurement of daily courses of plant performance.