Concentration and timing of exogenous foliar spray of benzyladenine and ethephon influence crown bud formation in three hosta taxa

Abstract

This study was conducted to determine the effect of benzyladenine (BA) and ethephon application on crown bud formation in two Hosta taxa native to Korea and one cultivar. Hosta yingeri, H. minor f. alba, and H. ‘White Edge’ were divided into uniform single-bud divisions from mother plants on April 8, 2017. BA and ethephon were applied individually as a foliar spray at either an early growth stage (May 29, 2017) 50 days after transplanting, or a late growth stage (September 1, 2017) 145 days after transplanting. BA was applied at concentrations of 500, 1,000, 2,000, or 3,000 mg·L-1, whereas ethephon was applied at concentrations of 50, 100, 500, or 1,000 mg·L-1. In the early growth-stage treatments, there were no significant differences in plant height and width in the three Hosta species. However, in H. yingeri, when 2,000 or 3,000 mg·L-1 BA was applied, the number of leaves was higher (15.4 and 14.5 on average, respectively) than in the untreated plants (9.7 on average). Likewise, there were no significant differences in plant height and width in H. yingeri and H. ‘White Edge’ at the late growth-stage treatments. BA treatments increased the number of leaves regardless of the concentration compared with untreated plants in H. yingeri and H. minor f. alba. In the case of H. ‘White Edge’, only 1,000 or 2,000 mg·L-1 BA increased the number of leaves compared to the untreated plants. The BA treatments had a greater influence on crown bud formation than did the ethephon treatments. When 1,000 or 3,000 mg·L-1 BA was applied at the late growth stage, crown bud formation of H. yingeri and H. minor f. alba was 4.8-and 2.8-times higher than that in the untreated plants, respectively. In the case of H. ‘White Edge,’ the number of crown buds increased after BA application at both the early and late growth stages.