(106) Delay of Flower Bud Phenology of Rabbiteye and Southern Highbush Blueberries With Soybean Oil and Abscisic Acid

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  • 1 1University of Tennessee, Department of Plant Sciences, Knoxville, TN, 37996-4561
  • | 2 2North Carolina State University, Department of Horticulture Science

`Legacy' southern highbush blueberry plants at the Middle Tennessee Research and Education Center were sprayed on 22 Feb. 2005 with 0%, 6%, 9%, or 12% soybean oil. The treatments were arranged in a randomized complete-block design with five replications. Flower bud abortion was evaluated by sampling 25 flower buds/plant on 21 Mar., dissecting, and visually examining buds for browning of ovaries. Flower bud phonology was rated periodically until first bloom and then percentage of open bloom was rated every 2 to 3 days. Fruit were harvested for yield and 50-berry samples taken weekly for the first 4 weeks to determine berry size. Sprays of 6%, 9%, and 12% soybean oil delayed the 50% open bloom date of `Legacy' by 2, 4, and 9 days, respectively, but also caused 9%, 35% and 87% mortality of flower buds. `Legacy' bushes sprayed with 0%, 6%, 9% and 12% soybean yielded 11.6, 13.7, and 10.3, and 4.5 lb/bush, respectively. Berry size was increased by 14% to 23% by oil sprays. In a second experiment, `Climax' blueberries in a commercial planting in Spring City, Tenn., were sprayed on 4 Mar. with water, 5% TNsoy14 (96% soybean oil, a.i.), 500 ppm abscisic acid (ABA) (Valent BioSciences Corp., Long Grove, Ill.), or the combination of oil and ABA (seven replications). Flower bud development and bloom were rated as previously described. Spraying 5% TNsoy14 or 500 ppm ABA delayed the 50% open bloom date by 1 day and the combination of the two delayed bloom by an additional day. On 5 Apr., `Climax' bushes sprayed with 5% TNsoy14, 500 ppm ABA, and 5% TNsoy14 plus 500 ppm ABA had 49%, 41%, and 20% open bloom compared to 70% open bloom on control plants. The 5% oil, 500 ppm ABA, and the oil plus ABA treatments did not significantly affect crop load or berry size.

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