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United States Department of Agriculture

Agricultural Research Service

Research Project: Improved Production Methods: North South Initiative (North Carolina State University)

Location: Application Technology Research Unit

2010 Annual Report


1a.Objectives (from AD-416)
The objective of this research will focus on research to optimize nutrition and irrigation rates during different stages in floriculture crop development taking into account stock plant, propagation, and finishing environments.


1b.Approach (from AD-416)
Develop protocols to flower plants at a specified plant size for the retail environment, and extending the marketing season by producing early- or late-flowering plants for different locations in the U.S. A single product or tank mix growth retardant applications for new crops that reduce elongation most without delaying flowering and whether innovative practices such as rewetting of foliage increases efficiency of growth regulators. Identify the crops and stages of development in which lighting is most effective. In addition, photoperiodic lighting is increasingly being used to induce earlier flowering during the winter and spring. Determine how photoperiodic lighting can be maximized by investigating how light quantity, quality, and duration (including cyclic lighting) impact flowering of a range of popular garden plants. Potential energy savings will be quantified by optimizing light and temperature to produce crops in the most efficient and cost-effective manner for different locations in the U.S. Develop tools and techniques that allow growers to more precisely control and manipulate flowering of greenhouse crops. Techniques will be developed for producing 'programmed' liners that have the branching, height potential, and flower bud development necessary so that the liner can be simply transplanted and quickly finished. "Bud meters" will be developed for important floriculture crops so that growers can manage greenhouse environments in order to properly time flowering on finished crops or to possibly reduce greenhouse temperatures to save fuel costs while still hitting the targeted market dates. Determine optimal fertilziation rates and tissue nutrient levels to maximize growth of flowering plants and characterize the symptoms of nutritional disorders. Measure nutrient uptake through leaves, stems, and roots at different stages of rooting under greenhouse and controlled hydroponic conditions to match fertilizer supply with demand. Quantify the interaction of applied water and fertilizer rates on leaching of different forms of nutrients from propagation media. Identify the fertigation strategies that reduce nutrient leaching while maintaining crop health.


3.Progress Report

The primary focus of the current research project is to investigate methods for improving the quality of rooted cuttings and young plants. Factors being examined include storage conditions, rooting environment, stock plant nutrition, and young plant nutrition during establishment.

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.


Last Modified: 8/2/2014
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