Role of mineral nutrients and growth regulators in the apical dominance in Solanum sisymbrifolium.

The lower axillary buds of intact plants of Solanum sisymbrifolium are released from complete inhibition by supplying high doses of potassium to the soil while complete apical dominance is shown by plants grown at low, but not deficiency levels of K. Nitrate and phosphate supplied alone or together are ineffective but when either of them is supplied with K, the effect of the latter on the growth of axillary buds is somewhat enhanced. The buds thus released from inhibition elongate further only when supplied with gibberellin A3 (GA3). Indoleacetic acid (IAA) alone has a considerably weaker effect but when supplied with GA3 the stimulatory effect is greater than is caused by the latter alone. The completely inhibited buds of low-K plants can be released from inhibition by supplying kinetin. In such buds IAA promotes further extension but GA3 does not. The partially inhibited buds of the high-K plants, on the other hand, are not affected by exogenous kinetin.