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United States Department of Agriculture

Agricultural Research Service

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Research Project: Improved Production Methods: North South Initiative (University of Minnesota)

Location: Application Technology Research

2009 Annual Report

1a. Objectives (from AD-416)
The objective of this unified research effort is to improve the efficiency of plant production through a multi-disciplinary team approach that focuses on scheduling, the environment, energy, nutrient, water, and chemical growth regulator resources.

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
This congressionally mandated Specific Cooperative Project works in concert with four other projects for improvements in the efficient production of bedding plants. This aspect of the project focuses on the physiology of young and mature plants in response to light, temperature, and CO2 in order to maximize their growth and quality. Photosynthesis was characterized in 13 crops in “normal” and short-term high temperature stress conditions. This data can be integrated to the plant growth component for Virtual Grower software from the parent USDA-ARS project. A second project investigated petunia variation in their photoperiod requirement for flowering. 28 petunia varieties were grown under 10.5 to 14-h photoperiods to identify short- and long-critical photoperiods. Those species that have a short critical photoperiod would best be grown for flowering early in spring in the south and west. In contrast, those petunias that have a long critical photoperiod should be grown last in those same areas or in unlighted greenhouses in the north. A third project investigating the feasibility of growing bedding plants for short periods of time in cool temperatures to reduce production costs. Five commonly grown bedding plants were grown in growth chambers simulating conditions in a heated greenhouse producing a spring bedding plant crop, but moved to a low light and cold growth chamber for 1, 2, 3, or 4 days per week until flowering to simulate the impact of dropping temperatures when natural light levels are low to save energy. A fourth project involves evaluation of the time to flower for vegetatively propagated bedding plants in response to temperature. Twenty vegetatively propagated bedding plants were received from commercial growers, were potted, pinched and were placed in growth chambers varying in temperature (leaf temperatures of 10, 15, 20, 25, 30oC). This data will be integrated into Virtual Grower software. A fifth project is investigating the Kalanchoe genus for new candidate crops. After evaluating 28 Kalanchoe species grown under a variety of conditions, five species were identified with potential as new commercial ornamental crops. Several studies on growth regulator efficacy were conducted including determining the efficacy of a number of cytokinins (5 types) on inducing branching of cacti, succulents, and seed-propagated bedding plant species, and determining the efficacy of seven commercial growth retardants on limiting stem elongation of 28 Kalanchoe species. The final study area investigated tank mixes of insecticides, fungicides and plant growth regulators applied to liners and seedlings, to eliminate a drench in the finished container in the greenhouse or field. This could eliminate pests before introducing them into a greenhouse or field, reduce field losses to disease, and eliminate potential disease vectors by using this technique. Progress of this cooperative project was monitored through monthly electronic (email) communication, shared participation in industry-related educational courses, and twice annual face-to-face communication at national meetings.

4. Accomplishments

Last Modified: 2/23/2016
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