Effect of Gibberellic Acid, 2,3,5‐Triiodobenzoic Acid and Indole Acetic Acid on Growth and Development of Impatiens balsamina during Different Photoperiods

Abstract

AbstractThis paper deals with the effect of 100 mg/1 each of GA3 TIBA and IAA singly and in combination with each other on stem elongation, development of lateral branches and floral bud initiation in Impatiens balsamina plants exposed to 8‐, 16‐ and 24‐h photoperiods. GA3 enhances stem elongation, the enhancing effect decreasing with IAA as well as with TIBA during 8‐h but increasing during 16‐ and 24‐h photoperiods. It decreases the number of lateral branches, the decrease being greatest during 16‐, less during 8‐ and the least during 24‐h photoperiods. The time taken for floral buds to initiate with and length of branches during 16‐h photoperiods.During 8‐h photoperiods, IAA delays the initiation of floral buds, while GA3 hastens it when used together with TIBA or IAA or both. GA3 increases the number of floral buds on the main axis but decreases it on lateral branches, while TIBA decreases the number on the main axis but increases it on lateral branches. IAA reduces the number of floral buds on the main axis only when used alone, but on both the main axis as well as on lateral branches when used together with GA3 and TIBA. Floral buds were not produced on lateral branches when plants were treated with GA3, TIBA and IAA all together.GA3 and TIBA induced floral buds even under non‐inductive photoperiods, the number of buds and reproductive nodes being less in TIBA‐ than in GA3‐treated plants during 24‐h photoperiods. The time taken for floral buds to initiate with GA3 and TIBA during noninductive photoperiods is much longer than that during 8‐h inductive photoperiods with or without GA3 or TIBA application. IAA completely inhibits the GA3‐ and TIBA‐caused induction during 24‐h, but only delays it and reduces the number of reproductive nodes and floral buds during 16‐h photoperiods.