The Effect of Defoliation, and Hypocotyl and Root Removal, on the Development and Flowering of Chenopodium rubrum L.

Abstract

Seedlings of Chenopodium rubrum flowered earliest when they had intact cotyledons, and incremental cotyledon pruning delayed flowering. Seedlings with roots removed prior to photoperiodic induction regenerated roots quickly and, although this treatment delayed flowering slightly, the pattern of flowering of such seedlings with incremental cotyledon pruning was similar to that of seedlings with root and cotyledon pruning. Seedlings with hypocotyls and roots removed prior to photoperiodic induction took longest to flower compared with the other two types of seedlings, and time to flower was not linearly correlated with amount of cotyledon pruning. Presence of cotyledons on seedlings without hypocotyls and roots, that is, on excised stem tips, appeared to inhibit epicotyl development in culture. Gibberellic acid (GA3) overcame this inhibition, and earliest flowering was associated with 10-7M GA3. However, GA3 (10-8-10-6M) did not affect the flowering of cultured excised stem tips devoid of cotyledons.