The duration of G1, S, G2, and mitosis at four different temperatures in Zea mays L. as measured with 3H-thymidine.

Abstract

The effect of different temperatures on the duration of nuclear cycle in Zea mays (single cross hybrid ‘Seneca 60’) root meristem cells, was studied with autoradiographic techniques and it was shown that all component phases of the nuclear cycle are shortened by an increase in temperature from 20 to 35°C. The durations of total nuclear cycle at 20, 25, 30, and 35°C were 16.5, 9.9, 7.0, and 4.4 hours respectively while the durations of mitosis were 2.68, 1.10, 0.83, and 0.43 hours respectively. 85-90 percent of the nuclear cycle is required for interphase, while the remaining 10-15 percent of the cycle is occupied by mitosis. The mean mitotic indices at 20, 25, 30, and 35°C were 9.8, 9.1, 5.3, and 4.9 percent respectively.