The Ohio State University Learning Gardens 2006 Osteospermum Cultivar Trial By Stephanie Burns and Dr. Claudio Pasian Department of Horticulture and Crop Science Columbus, Ohio 43210 See results and photos in the Tables below. In 2006, we conducted our ninth Osteospermum/African Daisy Trial in our Departmental greenhouses on the Columbus Campus. Forty three entries from five different companies were trialed from January through early May. Rooted cuttings were received from participating companies early January, 2006. This year, we divided plants from each cultivar into two groups: one was vernalized, the other was grown at warm temperatures (70 F day/night) all the time. Cultural Schedule: January 5 - January 20, 2006 (Week 1 through 3). Rooted cuttings of 20 plants per cultivar were transplanted to 4.5 inch diameter plastic containers. Potting media: Fafard 3-B. Greenhouse temperature: 72F day/night. February 8, 2006 (Week 6). Plants pinched to 5 - 6 nodes. February 23, 2006 (Week 8). Cold vernalization initiated for 6 plants: 46F day/night. Other 4 plants kept at 70F day/night. April 10, 2006 (Week 15). End of vernalization. Temperature changed back to warm: 65F day/55F night. Depending on outside weather conditions, these temperatures could have been occasionally higher especially during late winter sunny days. April 7 - May 27, 2006. Evaluation* of plants without vernalization treatment. April 28 - May 8, 2006. Evaluation* of plants with vernalization treatment. * Each cultivar was evaluated when it reached peak flowering. Fertilization: Plants were fertigated with a 200 ppm N of a 17-5-17 Greencare fertilizer three times a week. If more water was need, tap water was used. Disease Problems: Most cultivars were healthy. Only 3 cultivars (‘Crescendo Orange’, ‘Crescendo Ivory’, and ‘Side Show Bicolor Pink’) had plant mortality due to unknown cause. Height Control: No growth regulators were used in this cultivar evaluation. This provided a good indicator of the natural growth habit of each cultivar. Evaluations Performed: PLANT HEIGHT from surface of the soil to top of flowers was measured on the day each cultivar reached flowering peak. Height is presented in centimeters. CONSUMER EVALUATION was performed by a group of 22 Master Gardener volunteers within 2 to 6 days of peak flowering. Not all non-vernalized cultivars were evaluated by consumers because they were not yet available at the time of peak flowering. The (potential) consumers were asked to indicate if they liked or disliked a given cultivar. The main CULTIVAR EVALUATION was performed by the Trials Director and the Trials Manager for both vernalized and non-vernalized plants. Evaluation Criteria: Ratings were based on a 1 to 5 scale: 1 = poor/not acceptable 2 = fair 3 = good 4 = very good 5 = excellent Plants were evaluated for the following characteristics: Flower number. Flower quality: flower aesthetics; color health and appearance. Vegetative/Foliage quality: plant habit, plant vigor, leaf color, health, and appearance of vegetative portion of plants. Overall: overall rating for all plants in the grouping, taking all the above aspects into consideration. Results: It was very difficult to determine peak flowering for most of the non vernalized cultivars since the time from first and last flower seemed to be much wider than for vernalized plants. Twenty three vernalized cultivars ranked high (with an overall ranking of above 4.0) among consumers (Table 1). Of those, 6 had scores of 4.5 or higher: ‘Side Show Purple’, ‘Tradewinds Deep Purple’, ‘Summertime Lavender’, ‘Summertime Pink Charme 1’, ‘Dwarf Side Show K4-207’, and ‘Summertime Pink Charme 2’. The top entries (with an Overall ranking of above 4.5) in the Cultivar Evaluation of vernalized plants as rated by the Trials Director and Trial Manager at the time of peak flower were: ‘Tradewinds White’, ‘Pinwheel White Eye’, ‘Side Show White’, and ‘Experimental Easter Egg Colors 20457’ (Table 2). Also performing well, and all tied with a ranking of 4.0 were: ‘Tradewinds Deep Purple’, ‘Summertime Spoon Crème’, ‘Summertime Sun White’, ‘Summertime Lavender’, ‘Summertime Yellow Charme’, ‘Summertime Pink Charme 1’, ‘Summertime Pink Charme 2’, and ‘Crescendo Primrose’ (Table 2). Scores of non-vernalized plants sorted by Overall are presented in Table 3. Among the non-vernalized plants, only one cultivar had an Overall score of 4 or higher: ‘Sideshow Purple’. Since no growth regulators are used in this trial, it is always interesting to observe natural plant heights and habits. Final plant heights of vernalized plants doubled from the shortest entry, ‘Side Show White’ (21.8 cm) to ‘Summertime Creme Purple 2' (45.6 cm) (Table 4). There were 11 entries finishing off below 25 cm. On average (of all cultivars) non vernalized plants were slightly shorter (28.65 cm vs. 29.39 cm). Table 5 compares all characteristic evaluated for vernalized and non-vernalized cultivars. In general, consumers preferred vernalized over non-vernalized plants. Of the 25 cultivars of which we have consumer evaluations for both vernalized and non-vernalized plants, only 5 non-vernalized cultivars scored higher than the vernalized ones. Table 6 presents the number of days the plants were subject to forcing temperatures in order to flower. Note how vernalization reduces the forcing time.