Plug source and growth retardants affect finish size of bedding plants

Abstract

Eight bedding plant species were grown from plugs obtained from two sources. The plugs were transplanted into jumbo six packs and sprayed with a solution of chlormequat/daminozide with concentrations of 1000/800, 1250/1250, or 1500/5000 mg.L-1 when new growth was ≅5 cm in height or width. Three different species were grown in the fall (Dianthus chinensis L., 'Telstar Mix', Petunia xhybrida Hort. Vilm.-Andr., 'Dreams Red', and Viola xwittrockiana Gains., 'Bingo Blue'), winter [Antirrhinum majus L., 'Tahiti Mix', Matthiola incana (L.) R. Br., 'Midget Red', and P. x hybrida, 'Dreams Mix'], and spring [Catharanthus roseus (L.) G. Don, 'Cooler Pink', Salvia splendens F. Sellow ex Roem. & Schult., 'Empire Red', and Begonia xsemperflorenscultorum Hort., 'Cocktail Mix']. The treatments significantly reduced finished plant size of all species for each season. There was a significant difference in finish size between sources for Dianthus, Antirrhinum, Matthiola, Catharanthus, Salvia, and Begonia. The efficacy of chlormequat/daminozide also differed for each source of Dianthus, Matthiola, and Begonia, but the treatments minimized the differences in finish size between sources for Petunia and Viola. Chemical names used: (2-chlorethyl) trimethylammonium chloride (chlormequat); (N-dimethylaminosuccinamic acid) (daminozide).