Hormones and Young Leaves Control Development of Cotyledonary Buds in Tomato Seedlings

Abstract

Hormonal and plant factors regulating the development of the inhibited cotyledonary buds of Lycoperskon escueatum Mill. cv. 'Firebal' seedings were studied. Excision of the Immature plumular leaves of 5-to 20-milhimeter length significantly stimulated bud development after 2 to 4 days, but excision of leaves exceeding 20-millimeter length was without effect. Apial application of 20 microliters of 5 milmolar abscisic acid significantly promoted development of the cotyledonary buds after 6 days. A subapical ring of 0.1 mim r concentration of 2,3,5-triodobenzoic acid (TIBA) in lanoln slgllatiy promoted cotyledonary bud development after 11 days. Twenty microliters of 0.1 mllimolar 6-benzylaminopurine (BAP) applie directly to the cotyledonary bud loci significantly promoted bud develmt, but I mkromolar pberelln A4/7 was ineffective. Applicaion of 0.1 i BAP in lanolin to the petiole or hypocotyl was ineffective. However, applcation of 0.1 milmoar TIBA as a ring around the petoles of the cotyledons or 1-centimeter on the hypocotyl below the cotyledons significanty promoted cotyledonary bud development.The growth of lateral buds in plants and their correlative inhibition by the apical bud have been investigated by a number of investigators (1,8,15,16,19). In Lycopersicon esculentum Mill., understanding the nature and control of lateral bud development is of special interest because: (a) its morphology exhibits an initial phase of monopodial growth followed by a sympodial growth habit (3); and (b) manual or chemical removal of unwanted lateral buds or lateral shoots poses certain physiological problems such as disease and chemical injury in addition to being a laborrequiring and costly operation in tomato production (22,25,26).In IAA-treated decapitated stumps of tomato plants, exogenous application of a combination of gibberellin A3 and kinetin in lanolin paste stimulated lateral bud development, but the treatment effect was inconsistent on intact plants (7). Tucker (23,24) found that the far red light suppression of the development of lateral buds of tomato was associated with an increase in endogenous levels of auxins and ABA, while stimulation of lateral bud development was associated with increased levels of endogenous gibberellins and cytokinins. The vigorous lateral bud situated immediately below the first main inflorescence was not inhibited by the far red light exposure following the 16-hr photoperiod. Aung (3) indicated that the factors controlling the development of the lateral bud located immediately below the first main inflorescence emanated from the inflorescence itself and from the roots.Heretofore, studies on the development of the lateral buds of tomato have been concerned primarily with the buds subtended between the first inflorescence ofthe main stem and the cotyledons (3, [22][23][24][25]. There is little information on the inhibition of the cotyledonary axillary buds during the ontogenetic development of the tomato plant. In an earlier study on the effects of gibberellins and cytokinin on ...

Tomato Leaf Development and Distribution as Influenced by Leaf Removal and Decapitation

“…Axillary leaf initiation and growth in tomato is precocious (Tucker, 1977), and the factors involved in axillary shoot outgrowth are not well understood. Removal of the apical bud (Tucker, 1977) and leaf removal or loss can increase budbreak and shoot formation (Aung and Byrne, 1978;Aung and Kelly, 1966).…”