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United States Department of Agriculture

Agricultural Research Service

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

Location: Application Technology Research Unit

2011 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 project has involved studies of the effects of temperature, light, and high temperature stress on plant photosynthesis. We have collected this data primarily in growth chambers, but have also collected data in commercial greenhouses both in Minnesota as well as in California. Data are collected by directly measuring environmental effects on photosynthesis utilizing a portable photosynthesis meter. These data are being utilized to set standards for shade cloth, high-pressure sodium lighting, and temperature management in greenhouses, and have been presented at a variety of meetings and in the trade press. Research has involved the determination of light levels of different species reach their maximum photosynthetic capacity and has been identified so we do not ‘over-light’ plants unnecessarily. Collaboration with researchers at University of Florida involved integration of these data into Excel spreadsheets for growers to easily identify the impact of lighting or temperature changes on dry weight gain (photosynthesis of approx. 10 species). In addition, these data are being utilized to integrate into USDA-ARS Virtual Grower software. Standards developed from the existing research are being used to.
1)identify when plastic needs to be replaced, when ‘white wash’ needs to be applied and at what concentration, and.
3)when shading systems should be closed. A variety of species have been studied to identify how temperatures affect development and photosynthetic rate. These groups enable growers to separate species and place them in the optimal temperature environment to reduce production times and heating costs. Our previous work identified that pesticide/fungicide/plant growth regulator efficacy was maximized when spray applications occurred when humidity levels were high – such as the beginning of the day. Subsequent work has identified tank mix combinations that are applied in the seedling and liner stage to maximize efficacy while minimizing quantity used. This technique has several advantages identified thus far: .
1)any existing diseases and pests are often eradicated in a holding area before plant material is transplanted and placed in the finishing area,.
2)field losses in the finishing area (often due to root rots after transplant) have been reduced significantly, and.
3)chemical costs have been reduced by eliminating at least one large field application. Taken together, losses are reduced, introduction of pests and diseases are reduced, and direct chemical and associated labor costs, and environmental impacts are reduced. This research relates to the ARS parent project Sub-objective 2a: evaluate the use of non-destructive sensor technology to measure and predict the impact of biotic and abiotic stresses in ornamental crops. The project was monitored through periodic reports and phone conferences.


Last Modified: 12/27/2014
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