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United States Department of Agriculture

Agricultural Research Service

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

Location: Application Technology Research Unit

2013 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 fertilization 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 is the final report for this project. Experiments were performed to quantify effects of temperature on crop timing and plant quality attributes on 18 different annual bedding plant crops of commercial importance. Seed-propagated Antirrhinum, Calendula, Diascia, Gerbera, Gomphrena, Heliotropium, Impatiens, Matthiola, Nemesia, Nicotiana, Nierembergia, Osteospermum, Pelargonium, Petunia, Tagetes, and Torenia were grown in five greenhouse compartments maintained at 14 to 26 °C under a 16-hour photoperiod. As mean daily temperature increased from 14 to 26 °C, days to flower decreased for all crops except Impatiens walleriana. The effect of temperature on node number before flowering varied among species, with four, four, and eight species showing an increase, a decrease, or no difference in node number at flowering as mean daily temperature increased. Flower or inflorescence number increased with an increase in mean daily temperature from 14 to 26 ºC for 14 of the 18 species studied. Shoot dry mass at flowering was inversely related with temperature in many of the crops studied. In contrast, in one species of Impatiens, Tagetes, and Torenia, shoot weight first increased with an increase in temperature and then decreased. Among the nine species in which root mass was measured, the correlation between temperature and root mass was negative in Antirrhinum, Calendula, Matthiola, Nemesia, Nicotiana, Pelargonium, and Petunia, and positive in Torenia. Flower or inflorescence diameter increased as temperature decreased in 9 of the 18 crops studied.

In a separate experiment, Antirrhinum, Gerbera, Osteospermum, Pelargonium, and Tagetes were grown in greenhouses to quantify how temperature and transplant size influenced flowering time and quality parameters. This information was then used to estimate the net profit per pot and per square meter week for each species. Flowering time decreased as average daily temperature increased in all five species. Antirrhinum, Pelargonium, and Tagetes flowered earlier when grown from a larger compared to a smaller transplant, whereas transplant size did not influence flowering time in Gerbera or Osteospermum. Inflorescence number and diameter was greater at 17 than 23 ºC in three and four species, respectively, whereas transplant size had little or no influence on these parameters. Estimated net profit per pot was greater at 23 ºC and with the smaller transplant size in all five species. Therefore, transplanting a larger transplant or lowering the greenhouse temperature to save on heating costs is not necessarily a profitable strategy.

This project relates to two sub-objectives of the parent project. Sub-objective 1a: Elucidate the optimal tissue concentration of P and B in different light environments for major production species and how their susceptibility to foliar and root pathogens are influenced by nutrient status and light; and sub-objective 2b: Improve the Virtual Grower software model to enable growers to optimize their production systems by making more informed economic decisions about energy use, plant growth, and scheduling to meet premium market windows. Each 12-month milestone adds 6 to 8 new species, and this project will assist in meeting that goal. Additionally, features such as supplemental lighting, water use, nutrient use, can be added and improved, and additional model validation will be accomplished.


Last Modified: 8/22/2014
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