Location: Application Technology Research Unit
2010 Annual Report
Studies have been completed to determine how the optimum propagation environment varies with species and with cutting storage duration. Four propagation environments were tested, including contact-spun woven polyester cloth laid directly on cutting and misted periodically, humidity tent with cuttings misted periodically, mist, and fog. Three simulated shipping durations (0, 2, and 4 days) at 20°C were used to determine the effect on rooting of zonal geranium (Pelargonium x hortorum) ‘Charleston’, ‘Designer Red Dark’, ‘Rocky Mountain Violet’, and ‘Tango Dark Red’, New Guinea impatiens (Impatiens hawkeri) ‘Fanfare Orchid’, ‘Sonic Hot Rose on Gold ’, ‘Super Sonic Red’, and ‘Super Sonic White’, and poinsettia (Euphorbia pulcherrima) ‘Prestige Red’ and ‘Whitestar’ cuttings. Rooting, cutting quality, color, chlorophyll content, and cutting survival were evaluated.
For geraniums, increasing storage duration reduced rooting and cutting quality. Cutting quality was not affected by the propagation environment. All four propagation methods worked equally well if cuttings were harvested on site and not stored. If cuttings were stored, then mist was the preferred method of propagation based on improved root counts and higher shoot dry weights for three out of four cultivars. Substantial cultivar differences were noted in rooting ability, with ‘Rocky Mountain Violet’ producing the fewest roots and ‘Tango Dark Red’ the most. Providing adequate rehydration to stored or shipped cutting appears to be the key in proper rooting after cuttings are stored or shipped.
For New Guinea impatiens, the four propagation methods worked equally for both stored and nonstored cuttings. New Guinea impatiens were tolerant to a wide range of propagation environments. Other species that are easy to propagate would likely be adaptable to a wide range of propagation conditions, but this has not been tested.
For poinsettias, mist and fog provided better results than tents and the polyester cloth. Cuttings tolerated 2 and 4 day storage and ‘Prestige Red’ had higher cutting survival and rooting than ‘Whitestar’.
Appropriate stock plant nitrogen nutrition is being evaluated to determine their effects on the subsequent rooting of excised cuttings. Various ratios of NO3- and NH4+ and N concentrations are being tested for their effects on rooting, carbohydrate status, and cutting survival with and without simulated shipping in zonal geranium and New Guinea impatiens.
Project was monitored by frequent email communication, and four face-to-face meetings at annual meetings of various organizations.