Ethephon Foliar Sprays Are Influenced by Carrier Water Alkalinity and Ambient Air Temperature at Application

Abstract

Additional index words. bedding plants, calcium carbonate, ethylene, PGR, water quality Abstract. The plant growth regulator (PGR) ethephon [(2-chloroethyl) phosphonic acid; ETH] can be sprayed on floriculture crops to inhibit internode elongation, hinder apical dominance, increase lateral branching, and abort flower buds and flowers. However, the efficacy of ETH can be reduced as the pH of the carrier water used to mix the spray solution or temperature increase. Therefore, our objective was to quantify how the efficacy of ethephon sprays is influenced by carrier water alkalinity (CaCO 3 ; ALK) and the air temperature at application (TEMP). Young plants of verbena (Verbena peruviana) 'Aztec Blue Velvet', ivy geranium (Pelargonium 3peltatum) 'Precision Pink', and petunia (Petunia 3hybrida) 'Easy Wave Neon Rose' were transplanted into 11-cmdiameter containers and grown in a greenhouse with an average daily air temperature (ADT) set point of 21 8C. Before the ETH spray application(s), the ADT in each greenhouse compartment was changed from a set point of 21 8C to 14, 17, 20, 23, or 26 8C for ' '24 hours. Plants were sprayed with 0, 250, 500, or 750 mg · L L1 ETH mixed with carrier water containing ' '50, 150, or 300 mg · L L1 CaCO 3 2 and 3 weeks (Expt. 1) or 1 or 2 weeks (Expt. 2) after transplant. Generally, high ALK had a negative effect on spray

Increasing Stock Production of Two Herbaceous Perennials with the Application of Plant Growth Regulators

“…Ethephon (200 and 400 ppm) resulted in similar growth to the control group with small increases in the number of cuttings harvested. The inclusion of ethephon in this study was based on previous research that plants treated with ethephon would maintain vegetative growth and induce abscission of flower buds (Walters and Lopez, 2018). No flowering was observed throughout the Table 2.…”

Using ethephon for seedhead suppression of ‘KSUZ 0802’ (Innovation) zoysiagrass

“…This could possibly translate to zoysiagrass as well, where tank mixing ethephon with mineral oil could produce more consistent results in seedhead suppression in KSUZ 0802 zoysiagrass. Furthermore, considering the fact that the metabolism of ethephon is related to air temperature (Lougheed & Franklin, 1972; Walters & Lopez, 2018), the efficacy of ethephon could be more consistent when applied based on environmental parameters such as average air temperature, cooling degree days, growing degree days, photoperiod, etc., during autumn.…”