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Kenneth R. Schroeder and Janet E. Schroeder

According to brain-based learning theory, learning is enhanced by challenge and inhibited by threat. Effective learning occurs when students are immersed in the educational experience, challenged yet not threatened, and encouraged to actively process information. All of these components are part of simulation or role-play games. With these basic concepts in mind, we approached the challenge of enhancing student learning in a plant identification course taught in a large class setting. Considering that plant identification requires some basic detective skills, and the popularity of criminal investigation television programming, we designed a role-play exercise involving case files, investigation zones, and detective teams. As a spin-off from the television shows “CSI: Crime Scene Investigation” and “CSI: Miami,” the exercise was coined “CSI: Manhattan, Conifer Site Investigation in Manhattan, Kansas.” It was designed to fit into a 50-minute class period. Throughout the exercise, detective teams (students) needed to collectively locate and identify plants based on previous knowledge and clues within the case files and at the sites. Upon completion, plant specimens were checked in and identification logs discussed in order to provide immediate feedback and reinforcement of learning. Students enjoyed the exercise, offering positive feedback and conversations about the exercise throughout the balance of the semester. Six months later, while walking past one of the investigation sites, students remembered the site, exercises performed, and the plant name. The exercise includes both interactive and experiential learning components. This session will discuss the “CSI” exercise and its value in linking action to information.

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Kenneth R. Schroeder and Dennis P. Stimart

In an effort to reduce chemical usage to prolong postharvest keeping time of cut flowers, a cross was made between a long-lived (vase life, 10.9 days) inbred line of Antirrhinum majus and a short-lived (vase life, 5.0 days) inbred line. The F1 hybrid was backcrossed to the short-lived parent. Sixty plants of the BC1 generation were carried on through three generations of selfing by single-seed descent. Eight replications each of 60 BC1S3 families, the parents, and the F1 hybrid were grown in the greenhouse, harvested with 40-cm stems when five florets opened, and placed in distilled water for vase life evaluation. Stems were discarded when 50% of the florets on a spike wilted, browned, or dried. Three families proved not significantly different from the long-lived inbred parent. Results indicate that inbred backcross breeding shows potential to increase the postharvest keeping time of short-lived Antirrhinum majus inbred lines.

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Kenneth R. Schroeder and Dennis P. Stimart

Gibberellic acid (GA3) and photoperiod were used in combination in an effort to reduce generation time of Antirrhinum majus L. Four commercial inbred lines of A. majus were started from seed and grown in a glasshouse in winter 1993-94. GA3 was applied as a foliar spray every 2 weeks at 0, 144, 289, 577, or 1155 μm starting 5 weeks after seeds were sown. Supplemental lighting (60 μmol·m–2·s–1) from 0600 to 2000 hr and night interruption from 2300 to 0300 hr was used throughout the experiment. Data were collected weekly on plant height and leaf count from the start of GA3 treatments through anthesis. Time to flowering was determined as days from seed sowing to anthesis. GA3 treatment of A. majus under a long-day photoperiod increased time to flowering, plant height and leaf count. It would appear that long-days may have overridden the floral induction effects of GA3.

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Kenneth R. Schroeder and Dennis P. Stimart

Three percent hydrogen peroxide (H2O2) was diluted with deionized water (dH2O) to 0.75%, 0.38%, 0.19%, 0.09%, or 0.05% H2O2 plus 1.5% sucrose for use in evaluation of Antirrhinum majus L. (snapdragon) cut flowers. Other vase solutions used as controls included; 300 ppm 8-hydroxyquinoline citrate (8-HQC) plus 1.5% sucrose; dH2O plus 1.5% sucrose; and dH2O. A completely random design with 7 replicationss was used. Flowering stems of three commercial inbreds and one F1 hybrid of snapdragon were cut when the first five basal florets opened. Each stem was placed in an individual glass bottle containing one of the eight different treatments. Flowering stems were discarded when 50% of the open florets wilted, turned brown, or dried. Postharvest life was determined as the number of days from stem cutting to discard. Addition of H2O2 to vase solutions at rates of 0.19 and 0.09% resulted in postharvest life not different from that obtained with 8-HQC plus sucrose. Hydrogen peroxide plus sucrose extended postharvest life of snapdragon cut flowers 6 to 8 days over dH2O and 5 to 7 days over dH2O plus 1.5% sucrose.

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Kenneth R. Schroeder and Dennis P. Stimart

One-centimeter hypocotyl explants from 2-week-old Antirrhinum majus L. (snapdragon) seedlings germinated and grown in vitro under 12-h cool-white fluorescent light and 12 h dark or 24 h dark were placed on Murashige and Skoog (MS) medium containing 0, 0.44, 2.22, 4.44, 8.88, or 44.4 μM N6-benzyladenine (BA). Cultures were maintained under the light/dark regime at 25°C. After 2 weeks, adventitious shoots were counted. A shoot was considered adventitious and counted if a stem and leaf developed. Shoots developed along the entire length of the hypocotyl sections. Mean shoot production per hypocotyl explant ranged from 2.4 to 6.1 shoots when seedlings were germinated and grown in 24 h darkness and 2.2 to 10.9 shoots when started in the light/dark regime. Highest shoot counts were attained /from hypocotyl explants when seedlings were germinated and grown under the light/dark regime for 2 weeks and transferred to 2.22, 4.44, or 8.88 μM BA. Shoot development appeared normal at the 2.22 and 4.44 μM level, while at 8.88 μM BA, development was slightly abnormal along with slightly more callus production.

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Dennis P. Stimart and Kenneth R. Schroeder

Cut flowers of a short(S) lived (3 days) inbred, a long(L) lived (15 days) inbred and their hybrid (F1, 7.3 days) of Antirrhinum majus L. were evaluated for water loss when held in deionized water under continuous fluorescent light at 25°C. Flowering stems for water loss evaluation were harvested when the basal five to six florets expanded. Cut stems were placed in narrowed-necked bottles with the open area between the stem and bottle sealed with Parafilm. Stem weight and water weight in the bottle were taken every 24 h. Water loss evaluation was continued until 50% of the open florets on the flowering stem wilted or turned brown. Overall, water loss from all accessions was highest 24 h postharvest, declined rapidly between 24 to 96 h, and remained unchanged throughout the remainder of postharvest life. Between 24 to 96 h, the slope of the line for water loss was greatest for L, least for S, and intermediate for the F1. It appears that longest postharvest life of A. majus is associated with the most rapid decline of water loss immediately postharvest to a level, which remains constant.

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Kenneth R. Schroeder and Dennis P. Stimart

Flowering stems from three commercial inbreds and their F1 hybrids of Antirrhinum majus L. were cut when the first eight basal florets opened. Tops of the stems were removed above the eighth floret and florets were removed leaving two, four, six, or eight open florets on a stem. A completely random design with 10 replications was used. Flowering stems were placed in plastic storage containers 35 × 23 × 14 cm (L × W × H) with 2.5 L deionized water for postharvest evaluation. Evaluation took place under continuous cool-white fluorescent light (9 μmol·m–2·s–1) at 24°C Postharvest life was determined as the number of days from cutting to discard when 50% of the open florets on a flowering stem wilted, turned brown, or dried. Results showed postharvest life increased as the number of open florets on a stem decreased. Mean postharvest life increased as much as 4.7 days when only two florets remained on a stem. These results indicate a direct relationship between number of florets on a cut flower stem and postharvest life.

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Kenneth R. Schroeder and Dennis P. Stimart

An inbred backcrossing approach was taken to transfer long postharvest keeping time of cut flowers from a white inbred line of Antirrhinum majus L. into a yellow short-lived inbred line. Three backcrosses to the short-lived recurrent parent were done followed by three generations of selfing by single-seed descent. Plants from 56 accessions of BC1S3 through BC3S3 were grown twice (June and August 1995) in a greenhouse and flower stems harvested for postharvest longevity evaluation. Postharvest evaluation was done in deionized water under continuous fluorescent light. Longevity was determined as the number of days from cutting to discard when 50% of the open florets on a flower stem wilted or turned brown. One yellow accession was retrieved that was not significantly different in postharvest longevity from the white long-lived parent. Environment substantially influenced postharvest longevity over harvest dates. Possible causes for variation of postharvest keeping time will be presented.

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Kenneth R. Schroeder and Dennis P. Stimart

Leaf impressions were made from two short-lived (4 and 5 d) inbreds, a long-lived (11 d) inbred, and their hybrids (8 and 9 d) of Antirrhinum majus L. using Super Glue and glass microscope slides. Leaves were taken from mid stem, pressed on glass slides (under side down), spread with a small amount of Super Glue, set for 3 to 4 s. Then, the leaf was peeled off leaving a permanent impression in the glue. Slides were placed under a microscope equipped with a video imaging system and computer images were taken to facilitate counting of stomatal complexes. Number of stomata ranged from 10,400 to 21,300 per cm2 of leaf. A LI-COR LI-3100 area meter (LI-COR, Inc. Lincoln, Neb.) was used to measure total leaf area of 40-cm cut flower stems of each accession. Stomata per flowering stem ranged from 1,074,000 to 2,282,000, with the long-lived inbred having the fewest stomata, the hybrids intermediate with 11% to 21% more, and the short-lived inbreds having 40% to 113% more stomata per stem. It appears long postharvest life of A. majus is associated with flowering stems with fewer stomata per cut stem.

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Kenneth R. Schroeder and Dennis P. Stimart

A phenol-sulfuric acid assay was used to quantify non-specific neutral carbohydrates in Antirrhinum majus L. flowering stems of three inbreds and their hybrids. Flowering stems 40 cm long were harvested with five to six florets open and flower, leaf, and stem tissue separated, freeze-dried, and finely ground. Carbohydrates were extracted from the tissue with 95% ethanol in a 70 °C water bath and combined with a 5% w/v phenol solution and concentrated sulfuric acid. Glucose equivalents were determined with a spectrophotometer at absorbance of 490 nm. Averaged over tissue type, results were genotype dependent, ranging from 213 to 291 μg glucose equivalent per mg dry tissue with a LSD0.05 = 13. Flowers had the highest concentration of 340 μg/mg dry tissue, followed by stems, then leaves with 36% and 38% lower concentrations, respectively. Carbohydrate concentrations in two inbreds were compared when grown under cool (16 °C) and warm (29 °C) conditions. A genotype x environment interaction exists with inbred 3 exhibiting no reduction, 6% increase, and a 45% reduction in carbohydrate concentration when grown in warm conditions, while inbred 2 exhibited 15%, 23%, and 37 % reductions for flowers, leaves, and stems, respectively. Overall, there were 10% and 21% reductions in carbohydrate concentration for inbreds 2 and 3, respectively, when plants were grown under warm conditions.