2011 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.
In this phase of the project we are examining the durability of callused cuttings. Plant cuttings are shipped at three developmental stages: unrooted, callused, and rooted, each of which have their benefits and drawbacks. Unrooted cuttings are physically easy to ship, but are short-lived and sensitive to their surrounding environment. Callused cuttings typically perform better in the postharvest environment than unrooted cuttings, produce roots more rapidly after receipt and may not require a propagation environment for rooting. Rooted cuttings require much space during shipping and are typically not allowed to be imported from offshore due to pest concerns. This year we finished experiments on two cultivars of New Guinea impatiens examining the temperature and storage ability of callus cuttings. Two cultivars of geranium are still in progress.
Effects of storage at four temperatures (3.9, 7.2, 10, and 14.4°C) for five durations (0, 3, 6, 9, or 12 days) were determined for Impatiens hawkeri ‘SuperSonic White’ and ‘Hot Rose on Gold’ and Pelargonium x hortorum ‘Rocky Mountain Violet’ callused cuttings.
Storage length and temperature interacted to have significant effects on the abscised and yellow/necrotic leaves in the New Guinea impatiens cuttings, with cuttings stored for 12 days at 3.9°C having the most abscised and yellow/necrotic leaves in both cultivars. This treatment also had the lowest percent survival and percent of cuttings rooted at termination – 10% and 10% and 5% and 35% for ‘SuperSonic White’ and ‘Hot Rose on Gold’, respectively. All other impatiens treatments had survival percentages of 95% and above. All impatiens treatments had rooting percentages of 90% and above with the exception of ‘Hot Rose on Gold’ cuttings stored at 3.9°C for 9 and 12 days. Storage length and temperature interacted to affect the days until rooting on impatiens cuttings. Storage temperature had a more significant effect on days until rooting than storage length did, and some cuttings stored at 10 and 14.4°C initialized roots from their callus tissue during storage. ‘SuperSonic White’ cuttings’ weights were significantly affected by storage length, with weights increasing as storage length decreased and the non-stored control having the highest weights. However, storage length did not significantly affect ‘Hot Rose on Gold’ cutting weights.
In summary, callused New Guinea impatiens cuttings were tolerant of 9 days of storage at a broad range of temperatures from 3.9 to 14.4°C. For 12 days of storage, cuttings needed to be held at 7.2 to 14.4°C as cold damage occurred at 3.9°C. At 10°C storage temperature callused cuttings developed roots one day after sticking when stored for 3 days and during storage when stored for 9 or 12 days. In contrast, un-callused cuttings required 11 days to produce the first root.
This project 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.