Dennis R. Decoteau
A one-credit course, Writing in Horticulture, was developed and taught to graduate students in the Dept. of Horticulture at Clemson Univ. The course focused on discussion and explanation of the philosophies and methods of writing in the horticulture field. Discussions included a review of writing mechanics, types of writing and audiences, examples of exemplary writings, editing and reviewing, and examples and methods of professional correspondence. Real-life writing experiences were emphasized. Hands-on activities included writing and reviewing peer manuscripts and grant proposals. Three original written works were completed by the end of the semester: 1) a popular press article, 2) a grant proposal (maximum three pages long), and 3) an abstract for a manuscript published previously in a scientific journal.
Dennis R. Decoteau
The influence of polyethylene (plastic) mulch surface color (white versus black) on leaf area distribution of tomato (Lycopersicon esculentum) was investigated in simulated planting beds at two sampling periods: an early sampling with relatively young plants that had been in the mulch treatment for 22 days and a late sampling with relatively mature plants that had been in the mulch treatments for 50 days. At the early sampling period, tomato plants grown with white mulch had more axillary leaves than plants in the black mulch, resulting in a greater axillary:main leaf area ratio for the plants with white mulch. Leaf area for total leaves (main + axillary) and plant biomass was unaffected by mulch surface color at the early sampling period. Tomato plants grown in black mulch at the early sampling period had significantly more area of main leaves partitioned to node 3, whereas plants grown in white mulch had more area of main leaves in nodes 8 and 9. Plants grown in the white mulch treatment had significantly more axillary leaf area at nodes 1, 2, and 3, whereas plants in black mulch had more axillary leaf area at node 6. At the later sampling period, most of the leaf area from both mulch treatments was recorded in the axillary leaves and there was no effect of mulch surface color on the amount of total leaf area partitioned to main, axillary, or total leaves; to the amount of biomass of the measured top growth; or to the nodal distribution of leaf area among main leaves or axillary leaves. Tomato plants in white mulch had significantly more fruit on plants at the later sampling period than plants in the black mulch. Mulch surface color also affected the plant light environment and soil temperatures. These results suggest that the polyethylene mulch surface color can induce changes in the plant microclimate and affect leaf area distribution of young tomato plants (as recorded at the early sampling) and fruiting of relatively more mature plants (as recorded at the later sampling).
Dennis R. Decoteau
The influence of leaf removal and decapitation (removal of apical bud and top two nodes) of determinate tomato (Lycopersicon esculentum Mill cv. Mountain Pride) plants on canopy development was investigated. Leaf removal and decapitation influenced subsequent leaf development and distribution, and early fruiting of greenhouse-grown tomato plants. `Removal of young axillary leaves increased the size of main (true) leaves in the middle and upper nodes, increased the number of nodes, and increased the number of early fruit produced. Removal of main leaves reduced axillary leaf development at nodes 5 and 9. Decapitation increased axillary leaf development in the middle and upper nodes and delayed early fruit production. These results suggest that cultural practices of tomatoes that remove leaves or apical buds to influence fruiting also affect canopy leaf development and distribution.
Dennis R. Decoteau
The Teaching Portfolio is a factual description of a professor's strengths and accomplishments. It includes documents and materials that collectively suggest the scope and quality of a professor's teaching performance. The Teaching Portfolio is a living, breathing document that changes over time. Items in a Teaching Portfolio include a statement of teaching responsibilities, description of steps to improve teaching, instructional innovations, student and teaching evaluations, awards and honors, and a record of students who have succeeded. I will discuss the steps taken at Clemson University to use the Teaching Portfolio.
Roger Francis and Dennis R. Decoteau
Southernpea and sweet corn can be intercropped effectively. When simultaneously planted, sweet corn appears to be the dominant crop in the mixture, with intercropped southernpea producing a supplemental yield to intercropped sweet corn. Increasing intercrop plant densities increased the amount of sweet corn yield and reduced the amount of southernpea yield. The reduction in light intercepted by southernpea and sweet corn in the intercrop situation probably contributed to the reduction in yield by these component crops as compared to the yield of these crops as monocrops. The total system LER (LERsouthernpea + LERsweetcorn) for the high-population intercropping system, where plant densities for each crop were comparable to the densities of these crops as monocrops, was 1.26. This suggests that intercropping southernpea and sweet corn at this density gave a yield advantage of 26%, or that 26% more land planted in equal proportion of each component crop would be required to produce the same yield as the intercrop. A N application rate of 125 lb/acre (140 kg·ha-1) was optimum for intercropped sweet corn, and there was no advantage of a 2-week delayed planting of sweet corn in this intercrop system.
Sandra L. Barbour and Dennis R. Decoteau
Similarities exist between the effects of phytochrome and cytokinins on plant growth and development (e.g., chloroplast development. amaranthin synthesis, seed germination, photomorphogenesis). It is unclear. however, if and how these two systems interact.
To determine the effects of phytochrome activity on cytokinin synthesis and ultracellular plant development, we utilized tobacco transformed with the Agrobacterium tumefaciens isopentenyl transferase (ipt) gene. This gene encodes for isopentenyl transferase (iptase) which is an enzyme active in cytokinin biosysthesis.
Ipt-transgenic tobacco cultures were treated with end-of-day red or far-red light for 15 minutes. After 15-30 days of treatment, the plant tissue was harvested and ipt expression was verified by SDS-PAGE and western blot analysis. Polyclonal antibodies specific to iptase were used as a primary antibody. Colloidal gold conjugated to goat. anti-rabbit antiserum served as an electron dense, secondary antibody and a probe to light-influenced iptase synthesis and distribution within the cell.
A Hitachi 600AB transmission electron microscope was used to determine the influence of phytochrome/light treatments on the ultrastructure of ipr-transgenic cells.
Heather H. Friend and Dennis R. Decoteau
The effect of planting density on yield and pod distribution of cayenne pepper (Capsicun annuum var. annuum L. cv. Carolina Cayenne) was investigated in a two year study. In 1988, planting density was adjusted by altering the in-row spacing of single row beds, while in 1989 planting density was adjusted by altering both in-row spacing and number of rows per bed. In-row spacings evaluated in 1988 were 60, 45, 30, and 15 cm, while in-row spacings of 60, 30, and 15 cm in single and double rows were evaluated in 1989. In 1988, pepper plants grown in the highest density (15 cm in-row spacing) produced less fruit per plant, but more fruit per hectare than those grown in lower densities. In 1989, greatest yields per hectare were recorded with either 15 cm in-row spacings with single rows per bed or 30 cm in-row spacings with double rows per bed, In general, greater percentages of fruits were located in the upper part of the plant canopy when planted in higher plant densities.
Charles D. Johnson and Dennis R. Decoteau
The influence of N and K rates in Hoagland's nutrient solution on Jalapeño pepper (Capsicum annuum L.) plant growth and pod production was determined on greenhouse-grown plants in sand culture. Varying the rates of N (1 to 30 mm) and K (1 to 12 mm) in Hoagland's solution identified optimum concentrations for Jalapeño plant growth and pod production. Two experiments were conducted to determine Jalapeño pepper sensitivity to differential fertilization. In the experiment seeded in April, nutrient treatments began at transplanting, and in the one seeded in May, treatments began after all plants had flower buds and half had flowered. Biomass and pod production per plant responded curvilinearly to N rate in both experiments. Optimum N rate for pod yield was 15 mm. Nitrogen rate affected pungency of pods only in the first experiment, with 1 mm N reducing capsaicin levels in fruit compared to other N rates. Biomass, fruit count, and fruit weight per plant increased linearly with increasing K rate in the first experiment and curvilinearly with K rate in the second experiment. The optimum K rate for pod yield was 6 mm. Potassium rates did not affect pod pungency. Jalapeño peppers grown in sand culture required 15 mm N and at least 3 mm K for optimum pod production.
N.K. Damayanthi Ranwala and Dennis R. Decoteau
End-of-day (EOD) red (R) or far-red (FR) light treatments were used to study phytochrome-regulated growth and dry matter distribution in 2-week-old watermelon plants. Plants were exposed to low-intensity R or FR light for 15 min at the end of photoperiod for 9 consecutive days. End-of-day FR increased the petiole elongation in the first two leaves, which was accompanied by higher dry matter partitioning to the petioles after 3 days of treatments. However, total plant dry mass (above ground) in FR-treated plants increased significantly after 6 days of treatments. This indicates EOD FR regulated dry matter compensation among plant parts at the early stages of EOD light treatments, allowing plants to better adapt to the environment. Net CO2 assimilation rate in the second leaf of FR-treated plants also increased. Phytochrome involvement in these processes is suggested, since growth and dry matter distribution patterns were reversible when plants were treated with FR immediately followed by R.