The Effect of Chilling of the Physiological and Simulated Apex of 2‐ and 3‐leaf Plants of Pisum sativum L. cv. Alaska on Lateral Shoot Growth, C‐14 IAA Movement and P‐32 Accumulation

The apex of a 3‐leaf pea plant was chilled in cold chambers maintained at 5–7°C. The lateral shoots 1 through 5 grew, and shoot 5 eventually dominated other lateral shoots. The apex when returned to the ambient temperature did not reimpose apical dominance. The growing lateral shoots competed with the stem apex. The apices of 2‐ and 3‐leaf plants were chilled and P‐32 distribution in these plants was studied in the entire plant, at various intervals of time. Phosphorus‐32 accumulation followed the growth pattern of the plant. The lateral shoots accumulated P‐32 activity and very little activity was accumulated by the apex. The dominating shoots 2 and 5 accumulated the maximum amount of activity in 2‐ and 3‐leaf plants, respectively. Labeled‐IAA moved basipetally through the stem when applied to the cut stump simulating the apex. By cold treatment the translocation of IAA was influenced more than its absorption. The plant seems to metabolize this compound in the later periods of application. The plant now becomes “insensitive” to auxin and the lateral shoots grow.