Showing papers by "William B. Miller published in 2010"

Residual Effects of Ethylene on Tulip Growth and Flowering

Abstract: Ethylene effects were investigated on two tulip (Tulipa gesneriana L.) cultivars, Markant and Carreria. Pre-cooled bulbs were treated with ethylene (flow-through) for 1 week at 0, 0.1, 1.0, or 10 mLL -1 (± 10%) in a modified hydroponic system. After ethylene exposure, plants were either destructively harvested for root measurements or forced in a greenhouse for flower measurements. Ethylene exposure at concentrations as low as 1 mLL -1 duringthefirstweekofgrowthreducedshootandrootelongationandsubsequently increased flower bud abortion. At 10 mLL -1 , root growth was essentially eliminated. In a second experiment, bulbs were treated overnight with 1-methylcyclopropene (1-MCP) before a 7-day exposure to 1 mLL -1 ethylene. 1-MCP pretreatment eliminated the harmful effects of ethylene on root and shoot growth. This study illustrates the effects of ethylene exposure during hydroponic tulip production and demonstrates a potential benefit to treating bulbs with 1-MCP before planting. Tulip (Tulipa gesneriana L.) is an orna- mental geophyte prized for centuries as a cut flower, potted plant, and garden favorite. Tulip bulbs are grown in fields and sold to specialized producers who ''force'' the plants into flower after a cold treatment of 12 or more weeks. In cut flower tulip production, bulbs are often forced in hydroponic systems that facilitate flower harvesting. With hydroponic forcing, tulip bulbs are given 80% to 85% of their required cold duration before ''planting'' in water or a dilute nutrient solution and then further cooled 1 to 3 weeks to complete the cold requirement (De Hertogh, 1996). This process allows a minimal level of root establishment before forcing at warmer tem- peratures. During tulip bulb development and storage before cooling, ethylene can cause a number of physiological and morphological disorders, including gummosis (excretion of polysaccha- rides), flower bud abortion, shortened leaves or flowers, reduced or eliminated roots, deformed anthers, abnormal growth habit, loss of fresh weight during storage, and excessive growth of daughter bulbs (splitting) (Kamerbeek and de Munk, 1976). The degree of ethylene dam- age depends on a number of factors, includ- ing concentration, duration (De Munk, 1972), temperature during exposure (De Munk,