AN EVALUATION OF PLANT GROWTH REGULATORS ON GROWTH OF HERBACEOUS PERENNIALS

Abstract

Growing perennials from plugs in warm greenhouses for early spring sale sometimes yields poor quality plants that possess elongated stems and leaf petioles. The objective of this study was to establish concentration ranges necessary to control the subsequent growth of pre-cooled plugs. Plugs of Iberis, Lobelia, and Aquilegia, and corms of Liatris were established in 10-cm pots. Five plant growth regulators, Bonzi (paclobutrazol), Royal Slo-Gro (maleic hydrazide). Cutless (flurprimidol), Atrimmec (dikegulac sodium) and B-Nine (daminozide), were applied at five rates at 5 wk after transplant. Iberis stem length was reduced linearly with increasing concentration concentration by Royal Slo-Gro (0-1200 ppm), and Atrimmec (0-800 ppm). Atrimmec increased branching of Iberis. Growth of Lobelia treated with Royal Slo-Gro was reduced linearly with increasing concentration of Royal Slo-Gro (0-1200 ppm) or B-Nine (0-10,000 ppm). Bonzi and Cutless reduced Lobelia stem growth linearly with increasing concentration (0-40 ppm). Liatris stem growth was reduced linearly with increasing concentration of Royal Slo-Gro (0 to 1200 ppm). B-Nine, Bonzi and Cutless were also effective on Lobelia: however, a refinement of the concentration ranges used might provide better Lobelia growth management.