The Control of Lateral Root Development in Cultured Pea Seedlings. I. The Role of Seedling Organs and Plant Growth Regulators

Abstract

Experiments were conducted to determine the influence of seedling organs on lateral root development in Pisum sativum `Alaska.' The cotyledons, root tip, and epicotyl were excised from seedlings containing roots of less than 3 cm. In some cases, plant growth regulators or nutritional factors were substituted for the excised organs. The number of emerged and initiated lateral roots was counted after 7 days. Cotyledon removal completely inhibited lateral root emergence and reduced the total number of initiated laterals by 40%. Cotyledon removal did not alter the number of laterals initiated per cm of primary root. Epicotyl removal reduced the number of emerged lateral roots but not the total number initiated. Root tip removal slightly increased the total number of lateral roots formed and emerged from the root region remaining after tip excision. Sucrose, nicotinic acid, pyridoxine, and thiamine did not promote lateral root emergence when provided as cotyledon substitutes. Growth regulator substitutions for...