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A survey to determine teaching methodologies for plant material courses was conducted. A total of 120 surveys was sent to horticulture programs at U.S. universities and colleges. Thirty-nine, 22, and 8 respondents taught a woody plant (W), a herbaceous perennial (HP)/annual (A) course, and a foliage plant course, respectively; 21 respondents taught a combination of theses courses. The following similarities were noted for W and HP/A: 1) about 190 species per Semester were presented usually in a taxonomic order using slides as the primary teaching medium for lecture, 2) the most common student complaint was too much work and memorization, 3) the most common student compliment was the practical and useful nature of the subject matter, 4) in order of importance, plant identification, landscape value, and plant cultural aspects were emphasized. For W and HP/A, 93% and 65% of plants, respectively, were presented as landscape and arboreta specimens. Seventy percent of W courses used Dirr's Manual of Woody Landscape Plants; 58% and 10% of HP/A courses used Still's Manual of Herbaceous Ornamental Plants and Taylor's Guides, respectively.
Ilex crenata `Helleri' rooted cuttings were container grown for one summer with Osmocote 18N-2.6P-7.6K which was reapplied at different times. Beginning in April and every month thereafter until October, five plants were harvested and separated into roots and shoots for dry weight and nitrogen (N) analysis. Plants that had received a reapplication of Osmocote in June or July were larger in October than those that received no supplemental fertilizer. If reapplication occurred in August or September, no influence on growth was realized. Plants that were not supplemented had lower percent tissue and medium solution N. These data demonstrate that tissue nutrient analysis as well as the medium nutrient levels extracted with the pour-through procedure can be used to determine when reapplication of a slow-release fertilizer is necessary to promote optimal growth.
The relationship between medium nutrient levels extracted with the pour-through (PT) and the saturated medium extract (SME) procedures was investigated. These procedures were used as indicators of plant nutrient uptake and growth of poinsettia, Euphorbia pulcherrima Wind. ex. Klotzch. The medium nutrient levels and electrical conductivity associated with optimal plant growth were about two times greater for PT than for SME. The pH values were similar for both procedures. Regression analysis of the relationship between applied and extracted nutrient levels gave higher R 2 values for the SME, although the relationship for PT was acceptable. Both procedures provided an acceptable and similar correlation between the level of NO3-N extracted and the level of N absorbed by the plants. The results demonstrate the utility of both PT and SME as indicators of the nutritional status of a greenhouse medium.
Pine bark (PB), either unamended or amended with sand (S) at 9 PB: 1 S or 5 PB:1 S (v/v), was fertilized with solutions of 100,200, or 300 mg N/liter solution and tested for N concentration using the pour-through method (PT). PB, 9 PB: 1 S, and 5 PB: 1 S had porosities of 84%, 75%, and 66%, respectively. PT NO3-N concentrations, obtained via PT, of the 5 PB:1 S substrate were 43%,28%, and 15% higher than PB NO3-N values for the 100,200, and 300 mg·liter-1 treatments, respectively. Differences in N concentration obtained with PT can be attributed to substrate physical characteristics. Based on the results, data for PT should be interpreted with regard to substrate porosity.