Rapid Method for determining Numerical Indexes for Time-course Curves

IN reporting experiments with biological processes such as abscission, germination, and dormancy, where results are observed and recorded periodically, most investigators have found it convenient to present the data as time-course curves. While time-course curves such as those shown for abscission in Fig. 1 are useful in indicating the initiation and the total amount of abscission, as well as the slope of the response curves (rate), they cannot readily be compared numerically. For comparison of the results of large numbers of treatments in individual experiments, or of groups of experiments, and for statistical analyses, numerical designations are necessary. The time required for 50 or 100 per cent abscission and the percentage abscission at an arbitrary time after treatment are designations commonly used. Neither of these methods allows a satisfactory comparison of data frequently encountered in research. For example, comparison of the data represented by curves 1, 2, and 3 in Fig. 1 on the basis of the time to 50 or 100 per cent abscission is impossible as not all the curves reach either of these levels by the end of the experiment. This problem is intensified when treatments retard or inhibit abscission. Furthermore, the relationship of the curves changes with time, and thus comparison of the percentage abscission at an arbitrary time represents only a small part of the information in the curve.