Location: Application Technology Research2009 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 has sought to minimize water on the foliage during propagation of vegetative cuttings since this creates opportunities for growth of pathogens, leaching of nutrients, and excess use of water resources. Thus, we are aiming to apply just enough water to avoid stress yet allow for photosynthesis and adventitious root formation. The first experiments have focused on 1) stomatal functioning from the harvest of cuttings on the stock plant through the postharvest environment and in the first days or weeks of propagation (before root initiation) using poinsettia as the model crop and 2) quantifying water uptake potential through severed stem tissue. These experiments examine the factors affecting initial water status of the cutting when first stuck and the rate of water uptake through the severed stem tissue, which can inform a baseline for water uptake models or simulations. An example application of this information is that if evaporative demand exceeds this predicted rate of water use, then mist is required to reduce evaporative demand and to supply water through the leaf blade. Concurrently, we are conducting practical problem-solving experiments to evaluate and solve apparent mist-related issues. For example, vinca are very susceptible to leaf yellowing in propagation. This has been demonstrated to result from the leaching of nutrients from leaf tissue due to misting. Plastic tents that eliminate the need for misting solve this problem as do high rates of fertilization during the initial weeks in propagation. Petunia and Calibrachoa develop distorted shoot tips in propagation that appear to be related to excessive water on the foliage inducing a boron deficiency. However, initial experiments with various mist frequencies were not successful in simulating the symptoms observed in commercial facilities. Further work is planned. Information related to water use by young plants is being consolidated for input into Virtual Grower software from the parent USDA-ARS project in order to expand the software’s predictive capacity. 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.