Controlling seedling height by treating seeds with plant growth regulators
Abstract (Summary)Treating seeds with growth regulators may be a suitable method for controlling plug height of selected ornamental and horticultural plants. Soaking seeds in 50-1000 mg/L paclobutrazol solutions reduced plug growth in verbena (Verbena x hybrida Voss., cv. Quartz White), pansy (Viola wittrockiana, cv. Bingo Yellow Blotch), salvia (Salvia splendens, cv. Vista Red), marigold (Tagetes patula L., cv. Bonanza Gold), dill (Anathemum graveolens, cv. Fernleaf), and cucumber (Cucumis sativus, cv. Poinsett 76SR). When treating seeds with growth regulators, seedling emergence was delayed and reduced in verbena, pansy, salvia, dill, but not cucumber or marigold. Osmopriming or coating verbena seeds with 10-500 mg/L paclobutrazol were associated with 30-93% or 86-100% reduction in seedling emergence, respectively. Storing paclobutrazol-soaked seeds in a cold chamber for 22 months did not affect marigold growth reduction rates and seedling emergence. Soaking celosia (Celosia cristata, cv. New Look) seeds in 50-1000 mg/L paclobutrazol solutions was associated with negligible reduction in seedling growth. Soaking verbena or marigold seeds in 10-500 mg/L paclobutrazol solutions for 5-180 min did not reduce seed viability (tetrazolium test), but did reduce respiration and heat production rates in seeds. Reductions in seedling emergence and reduced respiration rates in paclobutrazol-treated seeds indicate that paclobutrazol imposed dormancy in verbena seeds. Washing restored rates of respiration and heat production in verbena and marigold seeds. Seed coat morphology or hilum size in verbena, celosia, marigold, or cucumber could not be associated with seedling growth response to treating seeds with growth regulators. Paclobutrazol concentration in the seed coats was higher than in the rest of the seed after soaking cucumber seeds in 1000-4000 mg/L paclobutrazol solutions. Total fruit yield and fruit size in cucumber were reduced when fruits were collected on plants grown from seeds soaked in increasing paclobutrazol rates. Paclobutrazol residue was not detected (0.025 g/kg DW detection limit) in cucumber or tomato (Lycopersicon esculentum Mill., cv. Sun 6108) fruits harvested on plants grown from seeds soaked in 1000 mg/L paclobutrazol solution during 180 min. Results of this study could be further used towards the authorization of paclobutrazol usage for controlling plug height in vegetable crops.
School:The Ohio State University
School Location:USA - Ohio
Source Type:Master's Thesis
Date of Publication:01/01/2004